Session JP9: Poster Session IV: Education and Outreach; Undergraduate and High School Research; Heating and Current Drive; Fast Ignition and High Intensity Laser Plasma Interaction

The Creation of a PPPL-NASA Collaboration for Science Education

For the past three years, PPPL's Science Education Program has collaborated with NASA's Microgravity University and The College of New Jersey's Departments of Physics, and Mechanical Engineering. The collaboration provides a unique academic experience for undergraduate students to successfully propose, design, fabricate, fly and evaluate a reduced gravity experiment of their choice over the course of four-six months. Our collaboration has focused on dusty plasmas that measured the sheath electric field using dust particles as probes, dust acoustic waves, and particle dynamics in microgravity . Recently, the collaboration was expanded to include the NASA Explorer School program and K-12 teachers in our DOE-sponsored Academies Creating Teacher-Scientists (DOE-ACTS). Here, experiments focused on measuring convective flow in a varying gravitational field using a plasma ball and ``glitter lamp.'' Data from the experiment was used to create new curricula for 6-12th grade physical science classes. It is expected that both programs will expand in future years.   

Longitudinal Study of the Impact of attending the PPPL NUF/SULI Program on Undergraduates' Careers

The Science Education Program at the Princeton Plasma Physics Labora- tory encourages autonomy and engagement in undergraduate research. Small-scale ex- periments permit students to take control of a project as well as participate in all aspects of the scientific process. Student involvement in larger-scale projects like NSTX and D3D introduce students to the laboratory-wide, collaborative nature of fusion research. Stu- dents involved in the national NUF/SULI programs organized by the SEP are more likely to become plasma scientists than the average physics student. Preliminary data also sug- gests that students return to the SEP on a multi-year basis and that they are likely to pursue a career in plasma physics. Using survey methods, we studied what draws those students to plasma physics and whether practices used at the PPPL can be generalized to other research programs.   

A New Energy-Centered Curriculum for Community College Students

For many years, Princeton Plasma Physics Laboratory's (PPPL) science education program has run ``Energy in the 21$^{st}$ Century'' workshops for K-12 teachers and students. These workshops have focused on non fossil fuel sources of energy including solar, hydrogen fuel cells, and fusion. A new program was recently started at a local community college focusing on these same topics. In the first year, new labs will be woven into the existing physics curriculum. These labs explore advantages and disadvantages of each energy source. The goals of the program include increasing students' interest in science with the expectation that they will pursue higher education at a four year college and beyond. In future years, this program will be expanded to include other topics throughout the existing curriculum. This is just the start of expanding the level of education offered at the local community college.   

An Experimental Undergraduate Laboratory Plasma Station

Plasma physics is an intimidating field to study and can be even a more daunting exercise to teach. At the Princeton Plasma Physics Laboratory we have created an all-inclusive undergraduate lab setup that encompasses three of the major experiments commonly seen in introductory graduate level plasma labs to improve upon the existing teaching tools available in the community and to expose undergraduates to the field. These experiments include Langmuir probe studies (single and double), spectroscopy, and Paschen curve analysis. The apparatus used to conduct the experiments is built upon a mobile station of a minimal footprint and maintenance requirements. The goal of the project was to create an easy to implement design that can be replicated by fledging undergraduate programs, community colleges, small liberal arts school or even established programs looking to streamline or build upon current curriculum.   

Enhancing DC Glow Discharge Tube Museuum Displays using a Theremin Controlled Helmholtz Coil to Demonstrate Magnetic Confinement

Since their discovery in the mid 1800's, DC glow discharge apparatuses have commonly been used for spectral analysis, the demonstration of the Frank-Hertz experiment, and to study plasma breakdown voltages following from the Paschen Curve. A DC glow discharge tube museum display was outfitted with a Helmholtz Coil electromagnet in order to demonstrate magnetic confinement for a science museum display. A device commonly known as a ``theremin'' was designed and built in order to externally control the Helmholtz Coil current and the plasma current. Originally a musical instrument, a theremin has two variable capacitors connected to two radio frequency oscillators which determine pitch and volume. Using a theremin to control current and ``play'' the plasma adds appeal and durability by providing a new innovative means of interacting with a museum exhibit. Educationally, students can use the display to not only learn about plasma properties but also electronic properties of the human body.   

Development of a DC Glow Discharge Exhibit for the Demonstration of Plasma Behavior in a Magnetic Field

The DC Glow Discharge Exhibit is intended to demonstrate the effects a magnetic field produces on a plasma in a vacuum chamber. The display, which will be featured as a part of The Liberty Science Center's ``Energy Quest Exhibition,'' consists of a DC glow discharge tube and information panels to educate the general public on plasma and its relation to fusion energy. Wall posters and an information booklet will offer brief descriptions of fusion-based science and technology, and will portray plasma's role in the development of fusion as a viable source of energy. The display features a horse-shoe magnet on a movable track, allowing viewers to witness the effects of a magnetic field upon a plasma. The plasma is created from air within a vacuum averaging between 100-200 mTorr. Signage within the casing describes the hardware components. The display is pending delivery to The Liberty Science Center, and will replace a similar, older exhibit presently at the museum.   

CPS Seminars on Capitol Hill

The Coalition for Plasma Science (CPS) organizes lunch-time seminars for Washington, DC Congressional staff (and the occasional member), covering a range of plasma science and applications, as part of its effort to inform a wide audience how plasma affects their lives. The talks, held in House facilities such as the Science and Technology Committee rooms, range in topics from plasma science (high density plasmas, the origins of magnetism), to present applications (plasma displays, computer chip fabrication), and to applications under development (fusion, medicine). Presentations have also focused on the spectacular displays of plasma in auroras, solar flares and lightning. A memorable talk, at least for Washington D. C. residents, was titled ``What You Don't Know About Lightning Might Hurt You,'' and featured in its announcement an actual photo of lightning striking the Washington Monument. The broad topic of plasma has been covered through talks about how plasmas can be used to teach hands-on science, and about ``The State of the Universe'' (presented the same week as the State of the Union address). If you know of a dynamic speaker and a ``cool'' plasma topic, let us know.   

Interactive Plasma Physics Education Using Data from Fusion Experiments

The Internet Plasma Physics Education Experience (IPPEX) website was created in 1996 to give users access to data from plasma and fusion experiments. Interactive material on electricity, magnetism, matter, and energy was presented to generate interest and prepare users to understand data from a fusion experiment. Initially, users were allowed to analyze real-time and archival data from the Tokamak Fusion Test Reactor (TFTR) experiment. IPPEX won numerous awards for its novel approach of allowing users to participate in ongoing research. However, the latest revisions of IPPEX were in 2001 and the interactive material is no longer functional on modern browsers. Also, access to real-time data was lost when TFTR was shut down. The interactive material on IPPEX is being rewritten in ActionScript3.0, and real-time and archival data from the National Spherical Tokamak Experiment (NSTX) will be made available to users. New tools like EFIT animations, fast cameras, and plots of important plasma parameters will be included along with an existing Java-based ``virtual tokamak.'' Screenshots from the upgraded website and future directions will be presented.   

Effects of Errors of Velocity Modulation on Maximum Longitudinal Drift Compression of an Intense Neutralized Ion Beam

Neutralized drift compression offers an effective means for particle beam focusing and current amplification with applications to heavy ion fusion. An ion beam pulse is passed through an inductive bunching module that produces a longitudinal velocity modulation. Due to applied velocity tilt the beam pulse compresses during neutralized drift. The ion beam pulse can be compressed by a factor of more than 100; however errors in the velocity modulation affect this compression in complicated ways. We have preformed an analytical and numerical study of how the longitudinal compression of the ion beam is affected by the initial errors in velocity. Higher errors generally proportionally decrease compression. However, some parts of a beam pulse with large errors in the velocity tilt compress to high values while other parts do not compress at all. Without any errors an ideal compression is limited only by the initial thermal velocity of the ion beam. Compression with an experiential velocity tilt is compared to an ideal limit.   

Computational Analysis of Tritium Production from Lithium-6

Future fusion energy devices will require tritium as a fuel component. Due to its short half-life (12.3 years) and limited supply, tritium must be bred to keep up with future demands. At Princeton Plasma Physics Laboratory (PPPL) an effort is underway to produce tritium from lithium-6 using D-T neutrons. Utilizing a DT generator, lithium-6, in solid form, will be subjected to high energy neutrons for the purpose of creating tritium. In this investigation, computational transport codes are employed to simulate and evaluate this reaction. The codes are also used to determine optimal configuration and geometric parameters for this reaction. As data is obtained from the ongoing experiment, the empirical data will be compared to computational code predictions.   

Development of a Mode Beat Frequency Detection Program for Use with NSTX Data

The National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab is a spherical torus used to magnetically confine plasmas for fusion energy research. Confinement ability can be degraded by fluctuations in plasma conditions, including magnetic field. In NSTX-confined plasmas, beat frequencies arise from the interaction of a fluctuating mode in the plasma and the oscillation of the photoelastic modulator that is used to make motional Stark effect (MSE) pitch angle measurements. Over 6,000 plots of magnetic fluctuation data taken during NSTX plasma shots were catalogued according to the presence or absence of these mode beat frequencies. Fewer than five percent of all shot plots generated fit these criteria. Tens of thousands more plasma shot plots will need to be catalogued and this volume of data makes continued human identification of MBFs temporally unfeasible. Development of an IDL-based program that can identify plots containing MBFs has begun. This poster presents a survey of the approaches that can be utilized in the design of such a program and evaluates the expected effectiveness of each.   

Visualization and Analysis Tools for Next-Generation Tokamak Fusion Devices

Recent studies of tokamak fusion nuclear science facilities, which could achieve net electricity generation, have involved searching a rich parameter space for optimal reactor characteristics using a 0-D systems code. Large amounts of data were generated, on the order of one hundred million different sets of reactor parameters. The systems code has been interfaced with PPPL's visualization program called ElVis and tools have been developed to handle large amounts of data. This work has motivated further development of ElVis, allowing it to accommodate the systems code output data. ElVis enables a user to make arbitrary plots of different reactor parameters. The data manipulation and graphing capability has enabled the review of a large number of viable operating points, the observation of trends and the identification of desirable operating points. This will enable a study of the impact of enhanced physics and technology on the operation of a power plant that produces net electricity. This work is supported by U.S. DOE Contract {\#}DE-AC02-09CH11466.   

Measurement of the Emissivity of Liquid Gallium Alloy for Temperature Measurements of Free-Surface Flows

The Liquid Metal Experiment (LMX) has recently been equipped to study the heating of a flowing liquid gallium alloy subjected to an orthogonal magnetic field. The understanding of free-surface heat transfer in strong magnetic fields will be crucial to the design and implementation of a liquid metal first wall or divertor for fusion applications. An infrared camera is used to non-invasively study free-surface flow in LMX. To directly measure absolute temperature with the infrared camera in the presence of an external heat source, the emissivity $\varepsilon$ of the flow must be known. To determine $\varepsilon$ for the liquid gallium alloy, an experimental setup was developed to examine one-dimensional heating in a static pool of gallium with no magnetic field. Heat conduction was both observed with the infrared camera and computationally modeled with a theta-implicit, forward-in-time, centered-in-space code that solved the thermal diffusion equation. Comparison of camera data with computational results produced by the code will yield a value for $\varepsilon$, calibrating the infrared camera for use with LMX by facilitating absolute temperature measurements.   

Temperature Effects on Critical Current and Skin Time of High Temperature Superconducting Flux Conservers for Field Reversed Configuration Experiments

Using odd-parity rotating magnetic fields to heat plasma and drive current, the Princeton-Field-Reversed-Configuration (PFRC) experiment creates plasma with a unity ratio of volume-averaged plasma pressure to magnetic-field energy density. Radial confinement of the plasma will be achieved with an array of co-axial passive flux conservers (FCs) constructed by embedding BSCCO high-temperature-superconductor (HTS) tape in copper rings. The pulse duration of the experiment is limited by the current decay time of the FCs. We examine the performance of the HTS-FC rings between 77 and 105K and test cooling systems to determine a design point for the next-generation PFRC's FC array. The dependence of critical current and skin time on temperature for the FC is tested by measuring the time-dependent current in an aligned-gap HTS-FC ring at different temperatures; skin time is found to range from 800 to 400ms between 77 and 105K. Performance of a proposed cooling system is tested in vacuum at close to real conditions.   

Measurements and Analysis of Collective-Mode Oscillations of the Beam Envelope in the Paul Trap Simulator Experiment (PTSX)

The Paul Trap Simulator Experiment (PTSX) simulates magnetic alternating-gradient (AG) charged particle transport systems. The small size and flexibility of PTSX allows the physicist to experimentally study relevant beam dynamics and transport system properties at a relatively lower cost and in less time. In PTSX, an oscillating quadrupole electric field is used to radially confine a charge bunch for times that correspond to kilometers of equivalent propagation in an accelerator. Random, resonant, or induced variations in the system create transverse collective-mode oscillations about the equilibrium. The presence of these oscillations can lead to beam emittance growth and other forms of beam degradation. A diagnostic was installed to detect azimuthally symmetric and quadrupolar collective-mode excitations. Experimental results are compared with the theoretical model of the collective-mode frequency as a function of experimental parameters. Possible modifications to the diagnostic design and collective-mode analysis processes are addressed. Collective-mode oscillations, and their correlation with beam emittance, are discussed.   

Preparation of the motional Stark effect with laser-induced fluorescence diagnostic for installation on NSTX

The motional Stark effect with laser-induced fluorescence (MSE-LIF) diagnostic allows for the measurement of internal magnetic field pitch angle and magnitude---this data can be used as a constraint for plasma equilibrium reconstructions. The MSE-LIF diagnostic utilizes the Stark effect by injecting into the plasma a neutral beam of hydrogen, which experiences a vxB electric field in its reference frame. This electric field causes splitting and polarization of the Balmer-alpha spectrum, which allows for measurements of magnetic field magnitude and pitch angle respectively. MSE-LIF will improve on the traditional MSE diagnostic by employing a narrow line-width laser and diagnostic neutral beam. Resolution of spectral lines with MSE-LIF will be possible for low magnetic fields ($<$0.1 T). In the future, MSE-LIF could prove to be attractive for low field machines where MSE on a heating beam is not possible. This poster will cover modifications to the diagnostic neutral beam and other components of the MSE-LIF system in preparation for installation on NSTX for the 2011 run year.   

Pre-Lithium Langmuir Probe results from Lithium Tokamak Experiment (LTX)

The LTX research goals encompass the investigation of the effects of low global recycling on plasma equilibrium and transport phenomena. Liquid lithium (Li) coatings on plasma facing surfaces are shown to reduce recycling, increase electron temperature and improve energy confinement time. A Langmuir probe has been constructed to study wall conditions. Edge diagnostics, and identifying and dealing with issues of probe operation in a Li environment, are important to this study. Our probe is specifically designed to deal with the complications of probe operation in a Li environment. Magnesium oxide insulators are employed in the probe; MgO is more resistant to chemical attack by liquid Li than other ceramics, like alumina. Here we report on initial probe measurement results in pre-lithium discharges during the commissioning of LTX. Data will be gathered to characterize both plasma edge conditions and probe behavior prior to Li injection, to provide a baseline for comparison with later, low recycling, results.   

Evaluation of an Electrostatic Dust Removal System with Potential Application in Next-Step Fusion Devices

The ability to manage inventories of dust will become increasingly important as fusion devices become larger and operate with a higher duty cycle. An electrostatic dust conveyor, originally developed to remove dust from solar panels on planetary rovers, has been tested for applicability to fusion devices. It consists of a spiral pattern of three indium tin oxide traces on a glass substrate that is biased to produce a surface electrostatic traveling wave. A digital microscope measured the particle size distribution before and after operation. The transport efficiency for different particle sizes of tungsten, carbon from an NSTX tile, fine glass spheres, and sand versus given different pre-charge voltages, pre-charge durations, driving amplitudes, and driving frequencies, will be presented. The results will be used to determine the optimal settings for a dust conveyor demonstration on NSTX.   

Flow Measurement and Three Dimensional Structure Modeling of Short Taylor-Couette Flow

Rotating fluid flows are of particular interest in many areas of science and engineering. Many devices involving the pumping of fluids, even in the field of medicine (Waluga 2008), involve Taylor-Couette flows or flows of similar schemes. The understanding of these flows is also of interest in modeling rotating fluids on a large scale, such as currents beneath the earth's crust and accretion disks in astrophysical systems. This experiment examines the characteristics of the waves formed by the flow of a short Taylor-Couette apparatus setup with a free surface. These waves include a peculiar wave formed along the inner cylinder producing a drastic radial asymmetry. The conditions of outer and inner cylinder speed necessary for this asymmetry to present itself are studied. This experiment also examines the shape of the free surface, a novel aspect of the flow rarely measured. Additionally, the velocity of the flow within the fluid is measured using laser Doppler velocimetry.   

Vacuum Compatibility of Flux-Core Arc Welding (FCAW)

Typically, vacuum chambers are welded together using gas tungsten arc welding (GTAW) or gas metal arc welding (GMAW). This is demonstrated in the vacuum chamber of Princeton Plasma Physics Lab's (PPPL) National Spherical Torus Experiment (NSTX). These processes are slow and apply excess heat to the base metal, which may cause the vacuum chamber to deform beyond designed tolerance. Flux cored arc welding (FCAW) avoids these problems, but may produce an unacceptable amount of outgasing due to the flux shielding. We believe impurities due to outgasing from FCAW will not greatly exceed those found in GTAW and GMAW welding. To test this theory, samples welded together using all three welding processes will be made and baked in a residual gas analyzer (RGA). The GTAW and GMAW welds will be tested to establish a metric for permissible outgasing. By testing samples from all three processes we hope to demonstrate that FCAW does not significantly outgas, and is therefore a viable alternative to GTAW and GMAW. Results from observations will be presented.   

Study of 3-D Asymmetries in the Magnetic Reconnection Experiment (MRX)

In MRX, two flux cores drive reconnection, forming a layer with the current in the toroidal direction. It is believed that toroidal asymmetry is important in understanding the reconnection process in MRX, due to discrepancies between 2-D simulations and experiments.\footnote{S. Dorfman, et al., PoP. {\bf{15}}, 102107 (2008).} Toroidal asymmetry has also been shown to be important in the onset of reconnection with a strong guide field on VTF\footnote{N. Katz, et al., Phys. Rev. Lett. {\bf{104}}, 255004 (2010).} In this work, a study of asymmetries in the reconnecting magnetic field and the out-of-plane electric field is presented for the case of no guide field on MRX. Using an array of 8 radial probes, toroidal mode structures have been identified in the current layer; the relevance of these modes to reconnection will be discussed. Additionally, previous calculations of the out-of-plane electric field have assumed symmetry, and here this assumption is tested.   

A Reduced Model for Predicting Fast-ion $D_\alpha$ Light in Tokamaks

The fast-ion $D_\alpha$ (FIDA) diagnostic measures visible photons emitted when energetic deuterium ions undergo charge-exchange reactions with an injected neutral beam [1]. The Doppler shift of the light contains useful information about the fast-ion population but the signal also depends upon many other quantities. A sophisticated forward-modeling code [2] treats all of the relevant atomic physics but there is a need for an approximate code that predicts expected FIDA spectra. This rapid code will be used to remove the FIDA contribution to main-ion $D_\alpha$ spectra, for data mining, and to guide the execution of experiments. Comparisons of simplified models with full calculations are described.\par \vskip6pt \noindent [1] W.W.\ Heidbrink et al., Plasma Phys.\ Control. Fusion {\bf 46} (2004) 1855. [2] W.W.\ Heidbrink et al., Comm.\ Comp.\ Phys.\ (2010) submitted.   

Leading-Order Nonlinear Effects on Single-Particle Orbits in Periodic Focusing Solenoidal Fields

Periodic focusing accelerators are used in many contexts including high energy density physics and heavy ion fusion. Therefore, it is important to understand the dynamics of charged particles in applied focusing fields. Theoretical treatments of the beam dynamics in focusing fields describe a thin beam in comparison to the axial lattice period of the focusing field. Such a case allows for a linear approximation of the applied transverse focusing force over the characteristic dimensions of the beam. In this work we analyze single-particle orbits in a periodic focusing solenoidal field including the effects of leading-order nonlinearities in the transverse focusing field. Using a quadratic approximation to the solenoidal fields, the equations of motion for a charged particle are derived. The nonlinearities introduced by the quadratic term are analyzed including questions of stability and the existence of matched-beam solutions. The addition of the quadratic term to the analysis of the beam dynamics may be useful in describing a thicker beam.   

Simulation for the Production of Technetium-99m Using Monte Carlo N-Particle Transport Code

The Monte Carlo N-Particle Transport Code (MCNP) is employed to simulate the radioisotope production process that leads to the creation of Technetium-99m (Tc-99m). Tc-99m is a common metastable nuclear isomer used in nuclear medicine tests and is produced from the gamma decay of Molybdenum-99 (Mo-99). Mo-99 is commonly produced from the fission of Uranium-235, a complicated process which is only performed at a limited number of facilities. Due to the age of these facilities, coupled with the critical importance of a steady flow of Mo-99, new methods of generating Mo-99 are being investigated. Current experiments demonstrate promising alternatives, one of which consists of the neutron activation of Molybdenum-98 (Mo-98), a naturally occurring element found in nature. Mo-98 has a small cross section (.13 barns), so investigations are also aimed at overcoming this natural obstacle for producing Tc-99m. The neutron activated Mo-98 becomes Mo-99 and subsequently decays into radioactive Tc-99m. The MCNP code is being used to examine the interactions between the particles in each of these situations, thus determining a theoretical threshold to maximize the reaction's efficiency. The simulation results will be applied to ongoing experiments at the PPPL, where the empirical data will be compared to predictions from the MCNP code.   

Ultrahigh intensities and contrast using an ellipsoidal plasma mirror with the Z-Backlighter Laser

Plasma-based focusing optics have been proven to increase the peak intensity of ultrahigh intensity lasers without significantly distorting the beam spatial profile or modifying the laser system itself [1]. In this experiment we will make use of an ellipsoidal plasma mirror (EPM) to increase the contrast and decrease the focal size of the ultrashort pulses provided by the Z-Backlighter Laser at Sandia National Laboratories. We predict the EPM setup to reduce the effective numerical aperture from f/3 to f/0.6, which could lead to a 25-fold intensity enhancement compared to flat plasma mirrors. These increased intensities will be demonstrated by observing protons accelerated from laser-plasma interactions via the target normal sheath acceleration mechanism. We expect protons with energies of more than 50 MeV to be generated. \\[4pt] [1] Nakatsutsumi \textit{et al}. Fast focusing of short-pulse lasers by innovative plasma optics toward extreme intensity. Optics Lett. \textbf{35}, 2314 (2010).   

Electron temperature fluctuations correlated with the dominant m = 0 tearing mode in the Madison Symmetric Torus

Electron temperature fluctuations become correlated with the dominant m = 0, n = 1 edge tearing mode during sawtooth events in the Madison Symmetric Torus RFP. Using a Thomson scattering diagnostic, 5 bursts of 6 electron temperature measurements are taken at 25 kHz, allowing use of Bayesian analysis techniques to ensemble and correlate data with magnetic tearing modes. Between sawtooth events the fluctuations are correlated with dominant m = 1 mode remnant island structures and after events they are correlated to the m = 1, n = 5 mode that comes into resonance. However, during sawtooth events the m = 1 magnetic islands grow and overlap and the correlations disappear as the field becomes stochastic. Electron temperature fluctuations instead become correlated with the dominant m = 0, n = 1 mode, forming a coherent structure that is only observed 100 $\mu $s after the sawtooth crash. The fluctuation amplitudes have the same sign across the entire plasma radius with magnitudes of 4 -- 30{\%} of the background electron temperature.   

Control system upgrade for high-repetition-rate Thomson scattering on the Madison Symmetric Torus

The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) is currently being upgraded for high repetition rate operation (maximum 250 kHz). The upgrade includes commissioning of a new custom pulse-burst laser, as well as a new control system based on FPGA (Field-Programmable Gate Array) technology to accommodate high-speed operation of the new laser. Timing accuracy of the FPGA system can be characterized by $\pm $100 ns jitter between the trigger from MST and the laser pulse-burst sequence. The new control system will be described in detail, including control requirements of the new laser, control software on both the FPGA card and the host computer, and hardware layout of the entire Thomson scattering system. The laser control code has been carefully designed such that the Thomson scattering system can be easily and quickly re-programmed for different modes of operation during MST science runs, but can also be tested and optimized in great detail during the development phase.   

Design of an RF System for Electron Bernstein Wave Studies in MST

Motivated by the possibility of current profile control a 5.5GHz RF system for EBW is being developed. The central component is a standard radar Klystron with 1.2MW peak power and 4$\mu $s typical pulse length. Meaningful experiments require RF pulse lengths similar to the characteristic electron confinement times in MST necessitating the creation of a power supply providing 80kV at 40A for 10ms. A low inductance IGBT network switches power at 20kHz from an electrolytic capacitor bank into the primary of a three-phase resonant transformer system that is then rectified and filtered. The system uses three magnetically separate transformers with microcrystalline iron cores to provide suitable volt-seconds and low hysteresis losses. Each phase has a secondary with a large leakage inductance and a parallel capacitor providing a boost ratio greater than 60:1 with a physical turns ratio of 13.5:1. A microprocessor feedback control system varies the drive frequency around resonance to regulate the boost ratio and provide a stable output as the storage bank discharges. The completed system will deliver RF to the plasma boundary where coupling to the Bernstein mode and subsequent heating and current drive can occur.   

High Resolution X-Ray Measurement on MST

A custom-built x-ray detector, with a 20 nanosecond shaping time, will provide a spectral measurement of photons in the 2 to 10 keV energy range. Output pulses from a shaping amplifier are directly digitized at 500 MHz to maximize spectral resolution. Each pulse can be fit to a Gaussian, and noise pulses are easily discriminated. This method is highly advantageous for plasmas with strong x-ray emission to avoid pulse pile-up. The new detector's 20 nanosecond pulse resolution is a ten-fold improvement in time resolution over x-ray detectors currently installed. It can be installed at several locations on the machine, to establish a toroidal survey of x-ray emission. With the help of a large set of pinhole collimators the diagnostic can be run under a wide variety of plasma conditions with the highest possible count rate. The photon energy and time of the pulse are recorded to generate the energy spectra for many time windows. X-ray spectra under various plasma conditions will be analyzed and compared with data from slower x-ray systems. Resulting data can then be used to estimate temperature and plasma effective charge.   

Magnetic Diagnostics and Field Structure in the Madison Dynamo Experiment

The Madison Dynamo Experiment(MDE) is expected to spontaneously self-generate a magnetic field in a two vortex flow geometry driven by counter rotating impellers in a $1 m$ diameter sphere filled with liquid sodium. This poster will focus on the spatial structure of the magnetic field associated with the dynamo eigenmodes and the turbulent fluctuations. A new internal array of Hall probes will increase the number of probe locations from 60 to 100 (in addition to 74 existing surface probes), including 40 spanning the center of the experiment. Three orthogonal measurements of the magnetic field are taken at each internal location, whereas previous internal probes took one directional data (2 directional after probe rotation on a different run). This will allow resolution of harmonic modes up to a poloidal order of $\ell=7$ and a toroidal order of $m=5$. Cross correlation analysis between the surface probes and internal probes will be used to determine the internal structure associated with each $\ell$ and $m$. This work is supported by the NSF/DOE partnership in plasma physics.   

Experimental Measurement and comparison to theory of Whistler Waves at the LAPTAG high school plasma laboratory

The vector magnetic field of whistler waves above and below half the electron cyclotron frequency is measured in 2 dimensions in a 51$\times $31 plane with $dx=dz=1cm,\delta t=0.4ns,30G\le B_{0z} \le 100G$. The experiments are performed in a high school plasma physics lab featuring a 1.5 meter long, 30 cm diameter pulsed, inductively coupled RF Argon plasma $\left( {\tau _{on} =10ms,\tau _{off} =50ms,10^8\le n\le 10^{11}cm^{-3}} \right)$. A three magnetic probe, single loop launch antenna and signal detection amplifiers were constructed by the high school students. A phase-locked tone burst is generated at a fixed frequency and launches a whistler wave. Data is acquired with a computer controlled 2D drive and a networked 2.5 Gs digital oscilloscope. We present maps of the phase fronts of the wave, and group velocity as a function of frequency. Index of refraction curves are generated from the measured plasma parameters. Appleton's equation with a point source antenna is used to simulate the wave propagation in a plane and the results compared to the acquired data.   

Experiments on the ducting of Whistler waves at the LAPTAG high school plasma laboratory

A low density duct$\left( {5\% \le \frac{\delta n}{n}\le 50\% } \right)$ in the quiescent afterglow of an RF plasma (L= 1.5 m, dia = 0.3 m $\left( {30G\le B_{0z} \le 100G} \right)$, $n\simeq 10^{11}$cm$^{\mbox{-3}})$ is formed by biasing a 3 cm diameter grid. Whistler waves are launched with a single loop antenna (1 cm diameter), placed within the duct using a phase-locked tone burst ( $40\le f_{wave} \le 110$ MHz). The vector magnetic field of the whistler waves is measured in a plane with dx=dz =1cm, dt = 0.4 ns along with the local plasma density. The whistlers are observed to propagate within the duct, however waves with a different wavelength and angle of propagation radiate from the duct edge. The ducting is studied as a function of the depth of density minima, width of the density channel, and wave frequency, $\frac{f}{f_{ce} }$ . The results will be compared to computer simulations of a two-dimensional electron MHD model.   

Development of a processing and visualization software suite, and optical hardware for the fast infrared diagnostic on NSTX

Infrared (IR) video is regularly captured at a rate of up to 1.6 kHz during plasma discharges in the National Spherical Torus Experiment (NSTX). Analysis of data collected by this diagnostic is complicated by the recent enhancement to dual-band infrared operation, in which both bands are projected side-by-side on the IR detector. In this work, a suite of IDL and JAVA-based processing and visualization tools have been developed to implement automatic image recognition, incorporate temperature and heat flux calibration, and present key video features essential for study of plasma interaction with the NSTX divertor. In addition, design and development work has been carried out for a broadband, low-aberration optical relay for the fast IR camera to make it possible to move the camera outside of the high magnetic field of the machine where electromagnetic interference sometimes leads to unreliable operation.   

Analyzing Heat Flux in the NSTX Diverter with Fast and Slow Infrared Cameras

Studying heat fluxes in NSTX's plasma facing components (PFCs) with the use of fast and slow IR cameras reveals what conditions PFC materials are subject to and how different materials withstand those conditions. Analytical, 1-D heat flux calculations are used to demonstrating fluctuations in heat flux as a function of diverter radius and time. Existing 1-D analysis software has been modified to include new liquid lithium divertor (LLD) trays and ATJ graphite tiles in the NSTX diverter and to utilize temperature dependant material parameters. Preliminary studies have shown that the LLD trays undergo a higher heat flux than the graphite tiles. A numerical, 2-D code, THEODOR, is also investigated as an improved solution for calculating heat fluxes. THEODOR includes the effect of a thin lithium film which is not necessarily in good contact with the underlying materials. Finally, both 1-D and 2-D codes are applied to the ORNL fast IR camera which, in 2010, was upgraded to capture simultaneous images in two IR wavelength bands. The first results of the heat flux study with the fast IR camera will be discussed.   

Monitoring of spectral emissions using the Compact Spectrometer Array diagnostic on NSTX

An array of four high-speed (integration time 1 ms or more), medium resolution (2048 pixel CCD, 0.10 nm/pixel dispersion, 0.43 nm optical resolution), broadband (370-590 nm optical coverage), miniature (0.1 m focal length, f/4 symmetrical crossed Czerny-Turner design) spectrometers have been installed on NSTX in a new diagnostic called the Compact Spectrometer Array (CSA). A C++-based program was also developed to operate multiple spectrometers simultaneously in concert with the NSTX discharge clock, and automatically upload data into the MDSplus database. This diagnostic complements existing high resolution spectrometers on NSTX in spectral coverage and speed, and are an essential tool in understanding how plasma interacts with the walls of the NSTX fusion device. Analysis of spectra from the CSA viewing the divertor targets of a variety of plasma configurations are presented along with interpretation of particle flux and erosion characteristics using measured discharge parameters and available atomic databases.   

Impact of Lithium-coated PFCs on the Edge Neutral Density on NSTX

Wall recycling of deuterium is reduced on NSTX by applying solid lithium coatings to the carbon composite plasma-facing components. The impact of the reduced recycling on the neutral density profile in the scrape-off layer (SOL) is inferred using a high-speed camera (268 Hz) with an H-beta filter and a chordal view of the SOL (0.2 cm resolution). The recorded intensity profile is converted to a radial profile of plasma emissivity using an absolute calibration of the camera and an Abel Inversion. The neutral density is computed by dividing the plasma emissivity by a function of the electron density and temperature, which are estimated using data from the Thomson scattering diagnostic. Initial calculations indicate that the neutral deuterium density decreases as the total amount of pre-shot lithium deposited in NSTX increases. The error in the profile measurement is quantified via Monte Carlo techniques. This work is supported by US DOE contracts DE-AC02-09CH11466 and DE-AC05-00OR22725.   

MTF-FRC Optimization via Single Mode Interferometry

Containment of thermonuclear fusion is a key challenge in the ongoing pursuit of sustainable fusion energy. Over the last decades, various approaches to achieve this goal have been developed. One such method for producing laboratory fusion conditions at lower costs than conventional approaches is magnetized target fusion (MTF). MTF lies between the domains of low-pressure magnetic fusion energy (MFE) and high-pressure inertial confinement fusion (ICF) by first forming an intermediate magnetized plasma which is subsequently quasi-adiabatically compressed by an imploding flux conserving shell (liner), thus achieving the necessary pressures and temperatures required for DT fuel ignition. In our experiment (FRX-L), a field reversed configuration plasma (FRC) with closed magnetic flux surfaces and high plasma pressure equilibrium is first created in a quartz tube and later translated via a plasma injector array of theta coils into a metal liner where it is later compressed via a high current implosion mechanism. For our experiment we describe the development of a fiber-coupled interferometer in order to measure the FRC as it is translated into the liner. This will be important as we optimize the formation and translation of an FRC suitable to subsequent liner implosion compression.   

Investigating D-T Reaction Spectra with the Gas Cherenkov Detector

In this study, a new analysis of the gamma ray spectra of the D-T fusion reaction using a Gas Cherenkov Detector (GCD) is presented. The D-T reaction is an essential process to understand for the future of fusion science. The reaction produces a He$^{5}$* nucleus that usually decays into a He$^{4 }$+ n. ~It has been seen that this reaction produces a 16.75 MeV gamma ray .0025{\%} of the time. The Gamma Ray History (GRH) group at Los Alamos proposes that there is an even less often occurrence where a gamma ray of around 12 MeV is produced. As the truth of this statement would affect the future potential yield of fusion reactors using D-T fuel, it is worth investigating. D-T spectra were obtained by detecting the produced gamma ray with the GCD at the University of Rochester OMEGA laser facility. A GCD response curve, calculated by the Monte Carlo modeling software ACCEPT, was used to forward convolve theoretical spectra into what the theoretical curves would have looked like in the GCD data. Results are presented.   

Numerical Modeling of Imploding Plasma liners Using the 1D Radiation-Hydrodynamics Code HELIOS

The Plasma Liner Experiment (PLX) is attempting to form imploding plasma liners to reach 0.1~Mbar upon stagnation, via 30--60 spherically convergent plasma jets. PLX is partly motivated by the desire to develop a standoff driver for magneto-inertial fusion. The liner density, atomic makeup, and implosion velocity will help determine the maximum pressure that can be achieved. This work focuses on exploring the effects of atomic physics and radiation on the 1D liner implosion and stagnation dynamics. For this reason, we are using Prism Computational Science's 1D Lagrangian rad-hydro code HELIOS, which has both equation of state (EOS) table-lookup and detailed configuration accounting (DCA) atomic physics modeling. By comparing a series of PLX-relevant cases proceeding from ideal gas, to EOS tables, to DCA treatments, we aim to identify how and when atomic physics effects are important for determining the peak achievable stagnation pressures. In addition, we present verification test results as well as brief comparisons to results obtained with RAVEN (1D radiation-MHD) and SPHC (smoothed particle hydrodynamics).   

Multi-Detector Array for Measuring Tertiary Neutron Anisotropies in DT ICF Targets

A nuclear diagnostic is being developed to ascertain if tertiary neutrons are distributed anisotropically during a DT ICF shot at the NIF. The system will use 8 ultra pure carbon disks as detectors. These disks will be strategically placed around the equatorial plane and polar regions of the NIF target chamber. Due to the high neutron activation threshold for carbon only tertiary neutrons will contribute to the 12C(n,2n)11C reaction. After the shot each disk will be placed between a matched pair of NaI detectors such that the 511 keV gamma rays produced by radioactive 11C can be measured in coincidence. The entire system will consist of eight pairs of detectors. A partial detector array with three NaI detector pairs encased in lead has been constructed at SUNY Geneseo. The optimal detector configuration, which reduced accidental coincidences, minimized background gamma counts and maximized geometric counting efficiency, was determined with this test bench in preparation for the construction of the full array. Funded in part by the DOE.   

RaPToRS Sample Delivery System

At various labs (NIF, LLE, NRL), activated material samples are used to measure reaction properties. The Rapid Pneumatic Transport of Radioactive Samples (RaPToRS) system quickly and safely moves these radioactive samples through a closed PVC tube via airflow. The carrier travels from the reaction chamber to the control and analysis station, pneumatically braking at the outlet. A reversible multiplexer routes samples from various locations near the shot chamber to the analysis station. Also, the multiplexer allows users to remotely load unactivated samples without manually approaching the reaction chamber. All elements of the system (pneumatic drivers, flow control valves, optical position sensors, multiplexers, Geiger counters, and release gates at the analysis station) can be controlled manually or automatically using a custom LabVIEW interface. A prototype is currently operating at NRL in Washington DC. Prospective facilities for Raptors systems include LLE and NIF.   

Calibration of a Thomson parabola ion spectrometer using proton beams from a pelletron accelerator

The position-to-energy calibration of a Thomson parabola ion spectrometer (TPIS) was measured using proton beams from the 1.7 MV tandem pelletron accelerator at SUNY Geneseo. The TPIS was designed for use on the multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE). The TPIS implements parallel electric and magnetic fields to separate ions of a given mass-to-charge ratio onto parabolic curves on the detector plane. The position of the ions along the parabola is used to determine the ions' energy. Monoenergetic proton beams with energies between approximately 1 and 3 MeV were directed into the TPIS. Both radiochromic film (RCF) and Fujifilm imaging plates (IP) were placed at the rear of the TPIS and were used to detect the protons. The horizontal deflection due to the electrostatic plates and the vertical deflection due to the permanent magnetic field were studied as a function of the proton energy. This research was funded in part by DOE.   

Electron diffusion region phase space distribution for collisionless antiparallel reconnection

Observations in the Earth's magnetotail and kinetic simulations of magnetic reconnection have shown high electron pressure and temperature anisotropy in the inflow of the electron diffusion region. This anisotropy is accurately accounted for in a new fluid closure for collisionless reconnection [1]. By tracing electron orbits in the fields taken from particle-in-cell simulations [2], we study the details of the electron phase space distribution in the region where the fluid model breaks down. At enhanced velocity-space resolution, a highly structured distribution is observed, which causes the violation of the frozen in condition due to the off-diagonal terms of the pressure tensor. We find that while the shape of the distribution and thickness of the region depend on the reconnection electric field, the total current through this layer is determined solely by the inflow pressure anisotropy. \\[4pt] [1] A Le, et. al. Phys. Plasmas 17, 055703 (2010). \\[0ex] [2] W Daughton, et al., Phys. Plasmas 13, 072101 (2006).   

NIMROD Simulations for a Spheromak Compression Experiment at General Fusion

NIMROD simulations are being conducted in support of a spheromak compression experiment being conducted at General Fusion. These simulations model the formation of a spheromak plasma within the compression chamber. Multiple vessel designs, magnetic field geometries and strengths are being analyzed in the simulations. The compression stage of the machine utilizes high-speed explosives placed symmetrically around the cylindrical chamber. These explosives collapse the flux conserver structure radially inward and compress the spheromak to produce sub-gain thermonuclear conditions. Preliminary experimental operations of the spheromak formation have begun within a mobile platform that will be taken out to a remote location for conducting compression experiments. Results from compression tests will be presented if these proceed according to plan. Estimates of expected DD neutron yields have been calculated from expected values of temperature, density, and confinement time determined by both simulation and collected data. Actual DD neutron yields may be collected from an indium-activation detector system, using a high-purity germanium detector for gamma spectroscopy.   

Measurement of the growth/damping rate of the $m$=1 diocotron mode in a toroidal electron plasma

The $m$=1 diocotron mode is induced in a toroidal electron plasma (the Lawrence Non-neutral Torus II) by connecting an RC circuit to a sector of the conducting boundary. The relationship between the circuit impedance and growth or damping rate of the mode has been measured and compared to results from cylindrical Penning-Malmberg traps [W.D. White, J.H. Malmberg, and C.F. Driscoll, Phys. Rev. Lett. \textbf{49}, 1822 (1982)] and to the results of numerical modeling of the mode in toroidal geometry. Attempts to compare the growth or damping rate of the mode in the partial torus to that in the full torus will be presented. The relationship between the shape of the end potentials of the partial torus and the growth or damping rate of the mode is explored and compared to expectations from rotational pumping theory [S.M. Crooks and T.M. O'Neil, Phys. Plasmas \textbf{2}, 355 (1995)]. This work is supported by the National Science Foundation, Grant PHY-0812893.   

Runaway Electrons in the Presence of MHD Instabilities in DIII-D

Runaway electrons (REs) accelerated from a seed nonthermal electron population during tokamak disruptions can damage plasma-facing components. Recent experiments at DIII-D correlate post-disruption RE current and pre-disruption magnetic topology. Diverted plasmas rarely produce REs, while limited plasmas almost invariably do. Applying an external nonaxisymmetric magnetic field before the thermal quench significantly reduces RE likelihood. These distinctions may result from variations in the MHD instabilities assumed to deconfine the seed electrons during the thermal quench, averting REs. We report results of linear MHD stability analysis correlating the spectrum of eigenmodes with varying RE current. Although the resistive modes that follow ideal instability growth cause reconnection and RE loss, correlation of widely varying ideal MHD eigenspectra with RE current indicates differences in the resistive phase as well.   

Coherently Averaged Signals from Rotating Magnetic Islands in the DIII-D Tokamak

Electron Cyclotron Emission (ECE) routinely provides radially and temporally resolved maps of electron temperature fluctuations associated with rotating magnetic islands. These measurements are equivalent to instantaneous horizontally cut images of the island, relevant to the study of its seeding, growth, saturation and stabilization. These images, however, suffer from radiometer noise, thermal fluctuations (wave noise) and non-thermal fluctuations (e.g., turbulence). To improve the signal-to-noise ratio, we coherently average over several ECE images using magnetic probe signals as a reference for the transit of the island. The technique is the software equivalent of analog lock-in amplification, and automatically accounts for rapid changes of rotation frequency, on the time-scale of a period. Results are compared with singular value decomposition and with a de-convolution technique in which ECE and magnetic probe Fourier-spectra are multiplied by each other and the results are anti-transformed.   

Quantifying Statistical Uncertainty in Tokamak Transport Modeling

An essential component of model validation is quantifying the uncertainty of model predictions, and including these uncertainties in assessments of model fidelity. Within the context of tokamak transport modeling, this requirement translates into propagating uncertainties in the input parameters into uncertainties in the model output. Towards this end, we present initial results from a newly implemented workflow based upon a Monte-Carlo approach to uncertainty quantification. This approach uses an ensemble of plasma profile fits to first calculate a corresponding ensemble of ONETWO power balance analyses. These ensembles are then used to calculate a corresponding ensemble of profile predictions, using the quasilinear TGLF transport model with the TGYRO transport solver. By using the ensemble statistics of the experimental profiles, the ONETWO results, and the TGYRO-TGLF results, more discriminating validation metrics can be devised.   

Improved RF Phase and Amplitude Detection for ICRF Heating Experiments

For diagnosis and control of high-power rf heating systems, it is necessary to measure the rf amplitude and phase of signals at multiple points in the rf transmission lines. We are upgrading the signal processing modules used in the fast-wave system on the DIII-D tokamak to improve reliability and temporal resolution. The goal is to enable resolution of phenomena on microsecond timescales for studies of antenna arcing and ELMs. This work compares several possible approaches to this upgrade, including ICs that contain most of the functionality of the original designs on a single chip, schemes involving digitizing the rf in bursts, and updates of the existing systems. The techniques are compared in the achievable time resolution, accuracy, precision, dynamic range and unit cost.   

Emissive Probe in the HelCat Linear Plasma Device

Langmuir probes are often used to measure plasma potential, but are prone to problems, including fluctuations of ion and electron density, finite mean-free path and spatial variation of plasma parameters. Emissive probes are able to overcome some of these problems and can be used to verify measurements made with Langmuir probes, but they also have many other uses, including lighting in a dark vessel and creating a localized plasma beam which may be used to map lines of force and align probes. This poster discusses the construction of the probe and associated electronics, uses of emissive probes and comparisons of emissive probe and Langmuir probe measurements in the HelCat Linear Plasma Device, limitations of emissive probes, and details of future uses and expectations of the probe.   

Wear Testing of Moving Components in Ultra-High Vacuum

Wear and friction in moving parts in an Ultra-High Vacuum (UHV) environment is a fundamental challenge in the design of mechanical assemblies in fusion experiments. In a reactor-scale experiment, constraints have been placed on the material choices and mechanical motions within the system due to their vacuum environment. Wear and friction only serve to complicate these constraints. Textured surfaces, bonded lubricants, and vacuum compatible greases have shown promise as possible means of reducing friction and wear. We have designed a machine for testing wear in a UHV environment, at room temperature, and elevated temperatures. This poster describes the design of the wear test machine and its operating parameters. We have presented an outline of the material test program along with a discussion of the pros and cons of anti-friction and anti-wear treatments.   

Wear Testing of Motion in an Ultra-High Vacuum

Mechanical motion in an Ultra High Vacuum (UHV) has been a challenge in fusion experiments due to the evaporation of lubricants and the excessive wear on the metals used because of out-gassing. We are designing a machine to test the wear and friction of smooth and textured surfaces of metals while also measuring the capabilities of various bonded and vacuum compatible lubricants in an UHV environment. Results from the current experiment are still to come but previous experiments have shown that metals with textured surfaces and metal- based lubricants show promise of handling the harsh environmental conditions. This poster describes the design of the wear testing machine and its operating parameters. Anti-friction and anti- wear treatments are discussed.   

Potential Application of a Graphical Processing Unit to Parallel Computations in the NUBEAM Code

NUBEAM is a comprehensive computational Monte Carlo based model for neutral beam injection (NBI) in tokamaks. NUBEAM computes NBI-relevant profiles in tokamak plasmas by tracking the deposition and the slowing of fast ions. At the core of NUBEAM are vector calculations used to track fast ions. These calculations have recently been parallelized to run on MPI clusters. However, cost and interlink bandwidth limit the ability to fully parallelize NUBEAM on an MPI cluster. Recent implementation of double precision capabilities for Graphical Processing Units (GPUs) presents a cost effective and high performance alternative or complement to MPI computation. Commercially available graphics cards can achieve up to 672 GFLOPS double precision and can handle hundreds of thousands of threads. The ability to execute at least one thread per particle simultaneously could significantly reduce the execution time and the statistical noise of NUBEAM. Progress on implementation on a GPU will be presented.   

Analysis of Fiber-Optic Spectroscopic Measurements on the Compact Toroid Injection Experiment (CTIX)

Spectroscopic analysis of accelerated plasmas, such as those created in CTIX, can be used to determine plasma impurity content, density and temperature via line ratios, and velocity via asymmetric Doppler shifting. Optical fibers have been installed at various locations around the CTIX plasma and connected to a visible spectrometer. The fibers can be distributed by axially, radially or by orientation. An intensified charge-coupled camera is used to view the spectrometer output with $\sim $1.0 {\AA} resolution. By vertically stacking the fibers, multiple viewing locations can be monitored simultaneously. To interpret the raw camera data, new software has been developed to process the camera image as a lattice where rows correspond to fiber positions, and columns to wavelengths. By simultaneously acquiring multiple fiber positions, errors arising from shot-to-shot plasma variations are eliminated and the overall amount of spectral data per plasma shot is increased. Specifics on data processing and analysis techniques as well as preliminary results obtained on CTIX will be presented.   

Spectroscopy of High Velocity Compact Toroids on CTIX

High density toroidal plasmas can reach speeds exceeding 200 km/s using coaxial accelerators such as CTIX at UC Davis. Applications of these compact toroids (CTs) include the fueling of next generation tokamaks and stellarators. An important CT diagnostic is to monitor atomic line radiation from CT ions. In this investigation we develop a reliable method of measuring a broad range (40 nm) of the CT spectrum from multiple positions. Our system employs fiber-optic cables to transmit the signal to a spectrometer operating in the 300-1300 nm range. A gated, intensified, CCD camera surveys the CT emission spectrum at a fixed time over a range of wavelengths. Additionally, a photomultiplier is used to investigate the time dependence of particular wavelengths of interest (monochrometer mode). Such measurements enable the study of CT temperature, density, impurity content, and CT velocity. The fiber-optic system will first be used to survey the emission spectrum of CTIX in typical operation, and to identify candidate lines for monochrometer operation.   

Particle Simulations in Relaxed Taylor States

Results from particle orbit simulations in force-free (Taylor state) magnetic fields in a cylindrical boundary are presented. An expansion in eigenfunctions of the curl ($\nabla \times {\bf B} = \lambda {\bf B}$) is used to represent a relaxed Taylor state in a conducting cylinder of dimensions $L=1~m$ and $R=0.08~m$. A particle-pushing code (PPC) is used to simulate collision-free ion and electron orbits in this geometry. Particle confinement results from the simulation are compared with data from experiments done at the SSX facility in a cylinder with the same dimensions. In addition, a simulation-based calibration of the SSX Mach probe is described. The effects of random electric field fluctuations and/or particle collisions on particle confinement will be presented if available.   

Mach probe studies in SSX wind tunnel

Mach probe calibration and performance is examined for weakly-magnetized SSX plasmas. Peak initial flows exceeding 50 km/s are observed in a high-velocity wind tunnel. Velocity measurements using a linear array of magnetic probes offers independent calibration of Mach probe parameters. Calibration for a cylindrical probe geometry in a weakly-magnetized plasma extends existing Mach probe models to more realistic geometries. Rotation of plasma at 10--15 km/s, verified by ion Doppler spectroscopy (IDS), is also observed. Vacuum ultraviolet (VUV) spectroscopy and IDS measures typical electron temperatures, $T_e$ = 7--12 eV, and ion temperatures, $T_i$ = 10--25 eV, resolved throughout the duration of plasma flow. Additional experiments are underway to examine dynamic alignment of plasma flow with magnetic field fluctuations. Numerical simulations with realistic SSX plasma conditions also underway. Results for dynamic alignment and simulations will be presented if available.   

Physical Vapor Deposition Chamber for Coating Microchannel Plates in X-Ray Radiography

Experiments to characterize microchannel plates (MCPs) at the University of Michigan aim to maximize the quantum efficiency of our detector by coating the layers of a photocathode directly on a bare MCP. These experiments can be improved with more control over the processing of coating MCPs, parts often used in diagnosing high-energy-density laser experiments. Process control will allow us to alter factors that influence photocathode quantum efficiency, such as film thickness, coating angle, and substrate baking. This should ultimately reduce costs of characterizing MCPs and improve our x-ray radiography data. A thin film deposition chamber was designed and built, achieving high vacuum pressures of 1E-7 torr and temperatures of 1800 C to vaporize coating materials. A rotating substrate platform and a quartz crystal microbalance help achieve precise, even coatings. A design overview of this system is presented, with a discussion of most recent coating results.   

Comparison of the Results of 2D Rayleigh-Taylor Models in FLASH and CRASH

The FLASH hydrodynamics code has been used extensively for simulating astrophysical phenomena and laboratory astrophysics experiments, including experiments investigating the Rayleigh-Taylor (RT) instability exhibited by the He-H interface of core-collapse supernovae. The Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan is developing a simulation code to accurately predict radiation-hydrodynamics (RH) problems. Since the FLASH RT model has been studied extensively, it is compelling to recreate this model using the CRASH code in order to study its results alongside those given by the mature FLASH code. The addition of radiation physics in the CRASH code also allows for further investigation into the RT experiments. The results of both models are presented here along with a comparison between morphological features and the rate of instability growth exhibited. Funded by the NNSA-DS and SC-OFES Joint Prog. in High-Energy-Density Lab. Plasmas, by the Nat. Laser User Facility Prog. in NNSA-DS and by the Predictive Sci. Acad. Alliances Prog. in NNSA-ASC, under grant numbers DE-FG52-09NA29548, DE-FG52-09NA29034, and DE-FC52-08NA28616.   

Validation of Multi-Mode transport model with a new drift resistive ballooning mode component

The drift resistive inertial ballooning mode (DRIBM) transport model is implemented as a component of the Multi-Mode transport model. Validation of the new transport model is carried out by comparing experimental data from three L-mode discharges with PTRANSP simulations. The DRIBM two-fluid model consists of six coupled reduced Braginskii equations. These equations take into account diamagnetic effects, parallel electron and ion dynamics, electron inertia, magnetic perturbations, gyro-viscous stress terms, electron and ion equilibrium density and temperature gradients, and temperature perturbations. It is found that the model contributes essential transport in the edge region of tokamak plasmas. Comparisons are made, with and without DRIBM, between experimental data and predicted plasma profiles for temperature and current density. The comparison includes the entire profiles from the magnetic axis to the plasma edge. Overall, good agreement is found with experimental data with inclusion of DRIBM as a component of the Multi-Mode transport model.   

Identifying global system parameters from microscopic data

A dissipative Yukawa model is often employed to describe strongly coupled systems such as dusty plasmas. It is fully described by three parameters: i) The coupling parameter $\Gamma$, ii) the screening parameter $\kappa$ and iii) the friction coefficient $ \nu$. These three parameters fully govern the structural and dynamical properties of the system which can be obtained, for example, through molecular dynamics simulations. In this contribution, we follow the reverse path and pose the question: Is it possible to obtain, from the microscopic phase- space trajectories of the system alone, the governing parameters? It has been shown previously that the short-range order depends on a non-unique combination of $\kappa$ and $\Gamma $~[1]. We therefore extend our analysis to dynamical quantities such as the mean-squared displacement to establish a mapping between the system's parameters and its microscopic behaviour. Our results should be directly applicable as a non-invasive diagnostic method for dusty plasma experiments. \\[4pt] [1] Hartmann \textit{et al.}, Phys. Rev. E, {\bf 72}, 026409 (2005)   

Evolution of the bump-on-tail instability in compressing plasma

Using particle-in-cell simulations, the evolution of bump-on-tail instabilities in plasmas subject to one-dimensional compression is investigated. Changes in the compression history for identical initial distributions reveal that energy is not a state variable for plasmas containing resonant waves; specifically, the amount of mechanical work required to compress a plasma to a particular final state changes depending on the time-history of the compression. Such compressing plasmas enable the production of high $k\lambda_D$ waves. The final wave energy and the peak wavelength compression can be optimized by varying the compression as a function of time and the shape of the initial distribution.   

Measurements of Edge Toroidal Magnetic Fields at the Maryland Centrifugal Experiment

A magnetic probe is being constructed to measure the total magnetic field, including in the toroidal direction, at the plasma edge of the Maryland Centrifugal Experiment (MCX). The probe design consists of 3 clusters of commercial chip inductors, with each cluster containing 3 inductors oriented in orthogonal directions [C.A.Romero-Talam\'as, et al., Rev. Sci. Instr. 75, 2664 (2004)]. The probe output will be digitized and integrated numerically. Measurements of the toroidal magnetic field along the z (axial) direction of MCX will allow for estimation of the current decrease on the center electrode as a function of z, as well as provide insight of where input power gets deposited in the plasma volume.   

Plasma Expansion and Imaging in WIRX

We examine the expansion and evolution in space and time of a plasma arcade in the Wheaton Impulsive Reconnection Experiment (WIRX). In our investigations of the expansion we find a long lived `tail' feature emanating from the arcade. We attempt to explain this phenomenon with a computer model of magnetic field lines near the arcade, and find that the tail does not align with the field lines in the model. We also find other fast time scale events, which seem to influence the intensity of the tail. These other events may be related to magnetic reconnection. Photodiode cameras are nearly complete which will allow continuous light intensity measurements to further study the expansion and evolution of the arcade. Work supported by U.S.D.O.E. grant DE-FG02-08ER55002.   

ECRH Modulation Results in Varied Density Profiles Due to Inward Turbulent Pinch In Dipole Confined Plasma

The Levitated Dipole Experiment (LDX) studies plasmas confined in a dipole magnetic field generated by a levitated superconducting magnet. In the past, it has been observed that this method of confinement results in centrally peaked density, as measured by a four-chord microwave interferometer. Here, the interferometer, along with two 16 channel photodiode arrays has been used to study density profiles as well as fluctuations and particle source during 10Hz and 450Hz power modulations of ECRH sources ranging from 10.5 to 2.45GHz. These modulations result in varied density profiles, with stronger peaking being observed when high frequency ECRH sources are turned off. This peaking appears to be due to the inward turbulent pinch, which becomes more significant when heating at inner radii is reduced. This is consistent with a particle source near the edge of the plasma, rather then at the ECRH resonance zones.   

Density Profile Measurements in LDX using Microwave Reflectometry

The levitated dipole experiment (LDX) has a sharply peaked, stationary plasma density profile as shown recently by measurements with a four-channel microwave interferometer. More precision in profile measurement is needed to fully explore the stability of high beta LDX plasmas. A 4-8 GHz O-mode scanning reflectometer is being implemented that will probe the entire LDX density profile (the density in LDX varies in the range of 2-8x10$^{17}$ m$^{-3})$. This will add to information obtained from the four channels of the interferometer array and will be the first time a continuous density profile measurement is achieved in a levitating dipole plasma. This is important because it is needed to confirm predictions of a 1/r$^{4}$ density profile obtained by Abel inversion of the interferometer data and to obtain the exact location of the peak density in LDX for the first time.   

Effect of Wall Reflections on Hot Electron Temperature from ECE Diagnostics in LDX

The Levitated Dipole Experiment (LDX) uses a floating donut-shaped superconducting magnet to study magnetic dipole plasma confinement. Plasma is generated and sustained by microwave electron cyclotron resonance heating. Two radiometers at 110 and 137 GHz are used to diagnose harmonic electron cyclotron emission (ECE). The ratio of these two signals is primarily a function of hot electron temperature. Previous analysis to interpret this ratio in terms of hot electron temperature assumed a direct view of the plasma with no reflection from the chamber walls, effectively neglecting emission from the inside of the ring. In this analysis we integrated local emission over all angles to model a reflection signal component, examining cases of complete reflection, zero reflection, and combinations of the two extremes. As reflection is added, the calculated temperature for a given ratio decreases, suggesting that previous models ignoring reflections may overestimate hot electron temperature.   

Calculation of fractal dimension of magnetic footprint in double-null divertor tokamaks

The simplest symplectic map that represents the magnetic topology of double-null divertor tokamaks is the double-null map, given by the map equations: x$_{1}$=x$_{0}$-ky$_{0}$(1-$y_0^2 )$, y$_{1}$=y$_{0}$+kx$_{1}$. k is the map parameter. The map parameter k represents the generic topological effects of toroidal asymmetries. The O-point is at (0,0). The X-points are at (0,$\pm $1). We set k=0.51763, and N$_{p}$=12. N$_{p}$ is the number of iterations of map that are equivalent to a single toroidal circuit of the tokamak. The width of stochastic layer near the upper and the lower X-points is exactly the same and equals 1.69 mm. We start 100,000 filed lines in the stochastic layer near the X-points and advance them for at most 10,000 toroidal circuits. We use the continuous analog of the map to calculate the magnetic footprints in the double-null divertor tokamaks. We calculate the area of the footprints and their fractal dimension. The area is A=0.0024 m$^{2}$, and fractal dimension is d$_{frac}$=1.0266. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.   

Calculation of the inboard magnetic footprint in the DIII-D from the low mn magnetic perturbation

The equilibrium EFIT data for the DIII-D shot 115467 at 3000 ms is used to construct the equilibrium generating function for magnetic field line trajectories in the DIII-D tokamak in natural canonical coordinates [1,2]. The generating function represents the axisymmetric magnetic geometry and the topology of the DIII-D shot very accurately [1,2]. A symplectic map for field line trajectories in the natural canonical coordinates in the DIII-D is constructed. We call this map the DIII-D map. The natural canonical coordinates can be readily inverted to physical coordinates (R,$\phi $,Z) [1,2]. Low mn magnetic perturbation with mode numbers (m,n)=(1,1)+(1,-1) is added to the generating function of the map. The amplitude for the low mn perturbation is chosen to be 6X10$^{-4}$, which is the expected value of the amplitude in tokamaks. The forward DIII-D map and its continuous analog are used to calculate the inboard magnetic footprint from the low mn perturbation in the DIII-D. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.   

Calculation of the outboard magnetic footprint in the DIII-D from the low mn magnetic perturbation

The equilibrium EFIT data for the DIII-D shot 115467 at 3000 ms is used to construct the equilibrium generating function for magnetic field line trajectories in the DIII-D tokamak in natural canonical coordinates [1,2]. The generating function represents the axisymmetric magnetic geometry and the topology of the DIII-D shot very accurately [1,2]. A symplectic map for field line trajectories in the natural canonical coordinates in the DIII-D is constructed. We call this map the DIII-D map. The natural canonical coordinates can be readily inverted to physical coordinates (R,$\phi $,Z) [1,2]. Low mn magnetic perturbation with mode numbers (m,n)=(1,1)+(1,-1) is added to the generating function of the map. The amplitude for the low mn perturbation is chosen to be 6X10$^{-4}$, which is the expected value of the amplitude in tokamaks. The backward DIII-D map and its continuous analog are used to calculate the outboard magnetic footprint from the low mn perturbation in the DIII-D. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.   

Tangles of the ideal separatrix from low mn perturbation in the DIII-D

The equilibrium EFIT data for the DIII-D shot 115467 at 3000 ms is used to construct the equilibrium generating function for magnetic field line trajectories in the DIII-D tokamak in natural canonical coordinates [A. Punjabi, and H. Ali, \textit{Phys. Plasmas} \textbf{15}, 122502 (2008); A. Punjabi, \textit{Nucl. Fusion} \textbf{49}, 115020 (2009)]. The generating function represents the axisymmetric magnetic geometry and the topology of the DIII-D shot very accurately. A symplectic map for field line trajectories in the natural canonical coordinates in the DIII-D is constructed. We call this map the DIII-D map. The natural canonical coordinates can be readily inverted to physical coordinates (R,$\phi $,Z). Low mn magnetic perturbation with mode numbers (m,n)=(1,1)+(1,-1) is added to the generating function of the map. The amplitude for the low mn perturbation is chosen to be 6X10$^{-4}$, which is the expected value of the amplitude in tokamaks. The forward and backward DIII-D maps with low mn perturbation are used to calculate the tangles of the ideal separatrix from low mn perturbation in the DIII-D. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.   

A linear theory of waves in partially ionized space plasmas

Partially ionized plasmas consist mainly of electrons, ions and significant neutral atoms. The nonlinear interactions amongst these species take place predominantly through direct collision or charge exchange processes. These interactions modify linear and non linear properties of the partially ionized plasma. In this work, we develop a one dimensional linear theory to investigate evolution of waves. In our model, the electrons and ions are described by a single fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral fluid via compressible hydrodynamic equations. Based on our self-consistent model, we investigate the propagation speed of Alfvenic modes in space and astrophysical plasma, interactions with the neutral fluid, growth rate, damping rate.   

Numerical optimization of magnetic surfaces of CNT

The Columbia University Non-neutral Torus (CNT) is a stellarator built to study the equilibrium, stability, and transport of non-neutral plasmas confined on magnetic surfaces. CNT uses four circular, planar coils: two interlocking coils and two poloidal field (PF) coils. A computational re-optimization of CNT has been performed, adding a second set of PF coils. Two relevant physics parameters were varied, the current running through the coils and their locations - the two additional coils were placed symmetrically at three different distances from the machine center: 0.203 m, 0.305 m, and 0.406 m. The magnetic surface quality was assessed by a C++ program producing graphs of the cross-section of magnetic surface. A configuration was identified with a larger confined volume and a potentially increased confinement time. Possible applications include positron trapping and confinement of positron-electron plasmas. Creation and study of the first earthbound electron-positron plasmas is a future goal and relevant to fundamental plasma physics. CNT studies plasmas with extreme electric fields relevant for fusion research, which has the goal of clean energy.   

HHFW Heating Efficiency and Spatial Deposition Profiles on NSTX

High Harmonic Fast Waves (HHFW) are used to heat plasmas in NSTX (National Spherical Torus Experiment). Thomson scattering measurements and EFIT equilibrium reconstructions are used to obtain the change in electron and total plasma stored energy, respectively. Previous research has shown that the HHFW heating efficiency decreases as the launched wavelength increases [1]. This trend has been confirmed for a larger set of discharges, and sensitivity to experimental uncertainties has been explored using several methods for fitting the data in order to extract the stored energies and energy confinement times. Rolling volume integrals of the electron stored energy over EFIT surfaces have been used to infer, for the first time from the data, a spatial profile of HHFW power absorbed by electrons. These inferred local power deposition profiles can be used to validate the accuracy of existing full wave models of RF heating that are used for scenario planning in future devices such as ITER. \\[4pt] [1] J. Hosea et al, Phys. Plasmas 15, 056104 (2008)   

A novel tomographic hard-X-ray spectrometer for suprathermal electron studies in the TCV tokamak

ECRH and ECCD, disruptive events, and sawtooth activity have been demonstrated to produce suprathermal electrons in fusion devices, motivating increasingly detailed studies of the generation and dynamics of this suprathermal population. Past hard-X-ray (HXR) and ECE measurement in the TCV tokamak, which is equipped by a 4.5-MW ECRH system, have led to the identification of the crucial role of spatial transport in the physics of ECCD. The observation of a poloidal asymmetry in the emitted suprathermal bremsstrahlung radiation has motivated the design of a novel, 4-camera tomographic HXR spectrometer, now in the final construction phase. The design, based on CdTe detector technology and on a modified Soller collimator concept, was aided by simulations of tomographic reconstruction and optimized for the greatly variable shapes and positions of TCV plasmas. Two of the cameras are rotatable to allow tangential viewing in selected scenarios. Energy analysis is performed by digital signal post-processing.   

Synergetic second and third harmonic electron cyclotron power absorption in TCV: experiment and Fokker-Planck modeling

The TCV tokamak is equipped with nine electron cyclotron (EC) wave gyrotron/launcher systems: six 0.5 MW in the 2nd harmonic X-mode (X2) and three 0.5 MW in the 3rd harmonic X-mode (X3). TCV experiments have been expressly devised to study the X2/X3 interplay, especially through the dynamics and transport properties of the suprathermal electron population generated primarily by X2 and its influence on the X3 wave absorption. Fokker Planck modeling of X2/X3 TCV experiments with the quasilinear fully relativistic LUKE code, coupled with the C3PO ray-tracing module and the R5X2 bremsstrahlung module, is presented here. Two series of experiments are discussed: 1) X2/X3 synergy when both X2 (82.7 GHz) and X3 (118 GHz) waves are injected into the plasma and 2) X2/X3 synergetic absorption at the same frequency (82.7 GHz). The role of suprathermal electron transport has been investigated by comparing the bremsstrahlung emission measured by a hard X-ray camera with the simulated signal.   

Phase Space Dynamics of Runaway Electrons in Current Overdrive Regime

Phase space structure of runaway electrons in current overdrive regime is studied. During current overdrive, RF waves drive current in the opposite direction of the Ohmic field, which recharges the central solenoid in steady state tokamak. High power RF waves can push electrons to the high energy region in the momentum space, which is able to generate a large population of backward runaway electrons. Phase space evolution of runaway electrons mainly depends on the balance of Ohmic field, radiation, and collisions. It is shown that it's easier to generate backward runaway electrons in some momentum space regions than others. In the current overdrive regime, we need to carefully choose RF wave parameters to avoid generating too many backward runaway electrons.   

Particle-in-cell simulations of an alpha channeling scenario: electron current drive arising from lower hybrid drift instability of fusion-born ions

Particle-in-cell (PIC) simulations of fusion-born protons in deuterium plasmas demonstrate a key alpha channeling phenomenon for tokamak fusion plasmas. We focus on obliquely propagating modes at the plasma edge, excited by centrally born fusion products on banana orbits, known to be responsible for observations of ion cyclotron emission in JET and TFTR. A fully self-consistent electromagnetic 1D3V PIC code evolves a ring-beam distribution of 3MeV protons in a 10keV thermal deuterium-electron plasma with realistic mass ratio. A collective instability occurs, giving rise to electromagnetic field activity in the lower hybrid range of frequencies. Waves spontaneously excited by this lower hybrid drift instability undergo Landau damping on resonant electrons, drawing out an asymmetric tail in the distribution of electron parallel velocities, which constitutes a net current. These simulations demonstrate a key building block of some alpha channeling scenarios: the direct collisionless coupling of fusion product energy into a form which can help sustain the equilibrium of the tokamak.   

Self-consistent full wave analysis of lower hybrid current drive in weak and strong absorption regimes on Alcator C-Mod

We have developed [1] a coupled solver for the lower hybrid problem that solves for the full wave fields with a self-consistent electron distribution function. We will discuss the results of simulations of experiments on Alcator C-Mod in the weak and strong absorption regimes through comparisons between a synthetic hard X-ray (HXR) diagnostic and the experimentally measured HXR. Ray tracing simulations will be used to quantify the importance of full wave effects in the two scenarios. Additionally, we will describe recent improvements in the solver efficiency and the development of a python driver for automating the iteration between the Fokker-Planck and full wave code and ensuring input consistency. \\[4pt] [1] J. C. Wright et al, Phys. Plasmas 16, 072502 (2009).   

Comparison of Quasi-linear and Exact Ion Cyclotron Resonant Diffusion

These studies investigate the validity of ICRF quasilinear(QL) diffusion theory by comparison with coefficients calculated from Lorentz orbits in full-wave fields. We also compare power deposition and distribution functions obtained with the coupled CQL3D Fokker-Planck code[1], using the two RF diffusion sets. Results are obtained within the context of the Alcator C-Mod ICRF experiment. QL theory is examined using the new, parallelized, diffusion coefficient code, DC, which calculates RF diffusion by suitable average of results of direct numerical integration of the Lorentz force equation for ion motion in the combined equilibrium fields and the RF full wave EM fields from the AORSA full-wave code. Resulting tail ion distributions with DC are substantailly smoothed in pitch angle compared to QL results. \newline [1] R.W. Harvey and M. McCoy, The CQL3D Fokker Planck Code, www.compxco.com \newline [2] E.F. Jaeger et al, Nucl. Fusion \textbf{46}, (2006) S397-S408   

Upgrade of the CQL3D Fokker-Planck code

Recent modifications of the bounce-averaged Collision-Quasilinear Fokker-Planck equation solver, CQL3D [1], are discussed. A fully-implicit 3D (2D-in-momentum, 1D-in-generalized radius) iterative solve using sparse matrix techniques provides for time-steps up to near the transport time, and can be used as the main option. The fully-relativistic nonlinear collisional operator is updated and tested. The radial transport module has been improved. Multi-species QL diffusion capability is added. Neutral particle analyzer synthetic diagnostic is modified. A non-symmetric up-down equilibrium capabilty is added. Example applications are given. Work on including finite-orbit-width effects is in progress and will also be discussed. \\[4pt] [1] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' www.compxco.com/cql3d.html   

ICRF sheath BC for fast wave propagation

The formation of rf-sheaths on the boundary surfaces in ICRF-heated fusion devices can cause deleterious interactions which limit the ability to heat and drive currents. Although the ICRF antenna is designed to launch a fast wave (FW), a slow wave (SW) is also obtained due to interaction of the FW with material surfaces in the boundary. Quantitative calculation of the sheath properties can be included in rf codes by means of a sheath BC [D. A. D'Ippolito et al., Phys. Plasmas \textbf{13}, 102508 (2006); J.R. Myra et al., Phys. Plasmas \textbf{1}, 2890 (1994)]. However, this requires resolving both the long FW (ion) and short SW (electron) space scales in the simulation, and thus high resolution (e.g. see [H. Kohno et al., this meeting.]). Here, we discuss the approach of incorporating an evanescent SW near the wall into the sheath BC analytically, so that the simulation only has to solve the FW equations numerically. An analytic solution then determines the SW field at the sheath-plasma boundary, the sheath width, and the sheath potential.   

Geometry and Modeling of Single ITER Antenna Module

We present FDTD simulations of a single ITER antenna module in cold-test, and in the vicinity of representative edge plasma. We cover the construction of the module geometry from both CAD data and from parametric representation. Simulations with plasma will also look at RF sheath potentials using the time- domain sheath sub-grid model, as this work provides the first practical full-scale application of this model. At this stage, we push the simulation volume as large as possible for both office-cluster scale and super-computing scale platforms, and explore the feasibility of extending the computations to a partial or full ensemble of modules. This work also includes the creation of post-analysis and visualization scripts targeted for the large datasets implied by these computations, which will also form the core analysis tools to provide predicted figures-of-merit, such as impedance loading, peak field strengths, and areas of significant sheath voltage. We present a summary of progress in this area as well.   

Simulations of ICRF Heating of Tokamak Core Plasma using $\delta$f Particles

Heating and current drive using the ion cyclotron range of frequencies (ICRF) has been regarded as an important facet of ITER. ICRF power from the edge can be transferred to the core without destroying the favorable properties of the plasma. Most simulations of the core plasma use full wave codes like AORSA or TORIC which assume that the local plasma approximation is valid. When this approximation is not valid, a new approach is necessary. We employ a $\delta$f particle-in-cell method for ions and a fluid model for electrons that does not make this assumption. Here, we present recent progress on employing these tools in large scale tokamak simulations using the VORPAL computational framework. We illustrate our ability to model ion cyclotron waves and ion Bernstein waves which are key components for heating and current drive. Furthermore, we present recent work on computing quasi-linear diffusion coefficients which is a necessary prerequisite for coupling to a Fokker-Planck code that permits self-consistent simulations.   

Core-edge coupling in Tokamak RF simulation via the multidomain pseudospectral method

The primary uncertainty in heating Tokamak plasmas with RF power in the ICRF regime are the various linear and non-linear interactions of RF waves with the plasma edge. This will be of particular importance in ITER. The linear problem can be addressed by extending spectral full-wave core plasma calculations to the vessel wall. However, a uniform mesh of sufficient resolution to resolve the fine scale antenna features is not tractable for the core hot plasma calculation, even on todays peta-scale supercomputers. To retain all relevant physics the core plasma calculation requires a pseudospectral (or collocation) method (PSM). As such, here we investigate the implementation of the multi-domain (MD) PSM to achieve a variable mesh, device geometry matching and tractable runtime. While the MD-PSM has been successfully employed for simple dielectrics and interfaces[1], its application to a hot plasma is complicated by the non-local plasma current. This prevents implementation of the standard MD patching boundary conditions. Here we discuss these complications and present progress towards a MD all-orders core/antenna coupled simulation. [1] Q.H. Liu, IEEE Antenn. Wireless Popag. Lett., 1, 131-134, 2002   

First Order Corrections to the Plasma Conductivity Tensor for Wave Heating Simulations with AORSA

Spectral wave solvers such as AORSA [1] have been used extensively to model electromagnetic wave heating in two dimensional (2D) tokamak plasmas. Spectral methods allow wave solutions to all orders in the ratio of ion Larmor radius to wavelength ($\rho $/$\lambda )$. However 2D simulations with AORSA have so far assumed a plasma conductivity that is zero order in the ratio of ion Larmor radius to equilibrium scale length ($\rho $/$L)$. Here we extend these calculations to include first-order corrections proportional to gradients in equilibrium quantities such as density, temperature and magnetic field [2]. These are equivalent to odd-order derivative terms used in finite difference schemes and are necessary for conservation of energy when mode-converted electrostatic waves propagate in regions of strong gradients.\\[4pt] [1] E.F. Jaeger, L.A. Berry, E.F. D'Azevedo, \textit{et al}., Phys. Plasmas \textbf{8}, 1573 (2001). \\[0pt] [2] D. N. Smithe, Plasma Phys. Controlled Fusion \textbf{31}, 1105 (1989).   

Finite Element methods for simulating RF wave propagation in plasmas

A two-dimensional finite-element propagation code is being developed in order to efficiently capture multi-scale structures in rf wave fields that can arise from such effects as mode conversion between long and short wavelength modes, complicated rf launcher geometry, and open field lines and localized density perturbations in the equilibrium plasma. In laboratory plasmas, in particular, these effects enter importantly in determining propagation through the plasma periphery and thus the efficiency of coupling to the core. In space plasmas, localized mode conversion can play an important role in energy transport. To demonstrate the code capability, we present the results of computations of fast wave propagation in a tokamak from a model antenna up to the region of closed flux surfaces, and of fast wave propagation in the earth's magnetosphere.   

PIC simulations of interaction between ICRF waves and edge plasma

The interaction between ion-cyclotron-range of frequencies (ICRF) waves and edge plasma has been intensively studied in recent years to understand the effect on ICRF heating. It has been observed experimentally that the incident wave deposits its energy at plasma edge. It is generally believed that the sheaths formed by the interactions between ICRF waves and the conducting surfaces of the antenna affect ICRF heating in an unfavorable way and cause the boundary absorption of the wave[1]. Theoretical models have been proposed to account for the detrimental effects; however, experimental observations suggest that in some cases, nonlinear plasma-wave interactions such as parametric decay instabilities near the boundary are also important to the wave absorption. In this work, full-PIC simulations using the VORPAL computational framework [2] of ICRF heating experiment with parameters of the EAST tokamak are presented. The effects of the sheaths as well as the nonlinear plasma-wave interaction near plasma edge on ICRF heating are explored and discussed. [1] Myra J R., D'Ippolito D A., Berry L.A, Jagger E F and Carter M D, Nucl. Fusion 46, S455 (2006). [2] C. Nieter and J. R. Cary, J. Comp. Phys. \textbf{196}, 448-472 (2004).   

A numerical analysis of the RF wave propagation under the sheath boundary condition in the ion cyclotron range of frequencies

Applying radio-frequency (RF) waves to heat plasmas and drive current is an important technique for magnetic fusion, and much research effort has been spent on improving the methods, particularly in the ion cyclotron range of frequencies. In this study, a numerical analysis is carried out to observe the RF wave propagation and its interaction with the sheath in the scrape-off layer. A two-dimensional finite element code is developed to test the effect of sheaths on waves in cold plasma with the equilibrium magnetic field having a small component into the wall. Through the analysis, the short scale modes, which are localized in the vicinity of the sheath, are observed as a consequence of imposing the sheath boundary condition, and it is found that the amplitude and the wavelength of the modes depend on the sheath width. The significance of the nonlinear interaction of waves with the sheath is also investigated under various conditions.   

Mitigation of RF potentials by an appropriate antenna design using TOPICA

The final goal of this work is to set a list of rules to design a new Ion Cyclotron (IC) launcher with the aim to mitigate the RF potential generated by the antenna and its surroundings; to achieve this challenging task, we will adopt as our main tool the TOPICA code [1]. One peculiarity of the code is the capability to compute the accurate electric field map everywhere inside the antenna and the plasma regions; in fact, in this specific task, we are interested in finding a geometrical solution that mitigates the RF potentials and the precise knowledge of the electric field distribution close to conductors is essential to properly optimize the antenna geometry. The tasks of this work consist of the analysis of alternative innovative solutions taking advantage of all the crucial features of the TOPICA analysis tool namely the possibility to simulate the full 3D antenna geometry and the possibility to account for an accurate plasma model in front of the antenna. These solutions will exploit all the possible features in order to minimize the generated RF potentials.\\[4pt] [1] Nucl. Fusion, 46 (2006) S476.   

Analysis and design of ICRF antennas for cylindrical plasmas with TOPCYL

On recent years TOPICA[1] has shown its capabilities as a designing and predicting tool for ICRF antennas on tokamaks, handling at the same time realistic geometrical detail of the structure as well as a complete description of the plasma region. Now, expanding these capabilities, the TOrino POlitecnico CYLindrical (TOPCYL) code has been released in order to give a full wave simulation of ICRF antennas in front of cylindrical plasma columns, thus inheriting from TOPICA the geometrical accuracy and keeping the completeness of the specific plasma model. This feature allows the analysis and design of RF heating systems for specific applications as plasma thrusters and plasma-surface-interaction experiments; nevertheless in general the only requirement is for the plasma to be cylindrical. In the present work, the theoretical basis, the implementation and validation of TOPCYL is presented.\\[4pt] [1] Nucl. Fusion, 46 (2006) S476.   

UWB radar technique for arc detection in coaxial cables

UWB signals constituted by a sequence of chips (properly chosen to reduce side lobes and to improve detection accuracy) are transmitted along the transmission lines at a specified Pulse Repetition Frequency (PRF) and their echoes are received by means of directional couplers. The core of the receiver is an ultra high-speed correlator implemented in a Digital Signal Processor (DSP). When a target (arc) is detected, its position and its ``radar cross section'' are calculated to be able to provide the arc position along the transmission line and to be able to classify the type of detected arc. The ``background scattering'' is routinely extracted from the received signal at any pulse. This permits to be resilient to the background structure of transmission lines (bends, junctions, windows, etc.). Thanks to the localization feature, segmentation is also possible for creating sensed and non- sensed zones (for example, to be insensitive to antenna load variations). A complete test bed has been installed using standard coaxial cables (RG58) to demonstrate the system capabilities.   

An Optical Diagnostic for Electric-Field Measurements of ICRF Antenna

The interaction of the near-field of Ion Cyclotron Range of Frequency (ICRF) antenna and the edge plasma can lead to undesirable effects such as unipolar arcing and localized regions of high parallel heat flux. In order to mitigate these effects, while launching the required megawatts of ICRF power across the scrape off layer, control of this nonlinear interaction must be achieved. Currently, a diagnostic utilizing optical emission spectroscopy is under development that will be capable of experimentally determining the magnitude of the rectified and RF electric field associated with ICRF antenna near-field. The physical principle behind the diagnostic is the dynamic Stark effect where the RF electric field associated with the ICRF wave allows for multi-photon processes to occur. The electric field parameters can then be extracted from the resulting spectral line profile.   

Direct, Non-Invasive Measurement of the Electric Field near an ICRH Antenna

Characterization the Stark effect on the D I Balmer-series spectral profiles is a promising approach for the measurement of the rectified, dc electric field in the tokamak scrape-off layer plasma near an ICRH antenna. However, the strong magnetic field-induced Zeeman effect on these same profiles greatly complicates this approach. Furthermore, unperturbed, background D I emission can obscure the Stark effect features. A high-resolution, optical spectrometer has been set-up on Tore Supra to view one of the 3 ICRH antennas and to explore the feasibility of this measurement. Spectral profile modeling has been carried out, including combined Stark and Zeeman perturbations, the geometry of the viewing chord with respect to antenna surfaces and the directions of the fields. First spectra will be presented and techniques to overcome background emission will be discussed. This work is being pursued in connection with mapping studies of the plasma potential, and its gradient, near an antenna using Langmuir probes, which provide indirect measurements of the electric field [L. Colas et al., J.Nucl.Mater. 363-365 (2007) 555].   

Quasilinear theory revisited: general kinetic formulation of wave-particle interactions in plasmas

In fusion plasmas, radio frequency (RF) waves are being commonly used for heating the plasma and for generating plasma currents. RF waves impart energy and momentum to particles through wave-particle interactions. These interactions bring about changes in the distribution function of the particles. We have recently formulated a theory for the evolution of the distribution function due to wave-particle interactions in which the waves are coherent RF waves [1,2]. The formalism takes into account the complexity of the dynamical phase space of the particles in the presence of waves. The diffusion coefficient is time dependent which is distinctly different from the one used in traditional quasilinear theories. We will present our formalism and compare the results with those obtained from the usual quasilinear theories. \\[4pt] [1] Y. Kominis, A.K. Ram and K. Hizanidis, {\it Phys. Plasmas} {\bf 15}, 122501 (2008). \\[0pt] [2] Y. Kominis, A.K. Ram and K. Hizanidis, {\it Phys. Rev. Lett.} {\bf 104}, 235001 (2010).   

Nonlinear heating of ions by electron cyclotron frequency waves

We study the nonlinear interaction of ions with electron cyclotron (EC) wave packets in a magnetized plasma. Previous studies have shown that such interactions with high frequency electrostatic lower hybrid waves can lead to coherent energization of ions. It requires the frequency bandwidth of the wave packet to be broader than the ion cyclotron frequency [1,2]. For the electromagnetic high frequency EC waves we have developed a more general theory, based on the Lie transform canonical perturbation method [3,4]. We apply the theory to the case of two overlapping EC beams. The wave frequency of each beam is assumed to be frequency modulated with a modulation bandwidth comparable to the ion cyclotron frequency. We present results for both X-mode and O-mode and illustrate the conditions for ion energization. \\[4pt] [1] D. Benisti, A. K. Ram, and A. Bers, {\it Phys. Plasmas} {\bf 5}, 3224 (1998). \\[0pt] [2] A. K. Ram, A. Bers, and D. Benisti , {\it J. Geophys. Res.} {\bf 103}, 9431 (1998). \\[0pt] [3] J.R. Cary and A.N. Kaufman, {\it Phys. Fluids} {\bf 24}, 1238 (1981). \\[0pt] [4] R.L. Dewar, {\it J. Phys A-Math. Gen} {\bf 9}, 2043 (1976).   

Scattering of particles by spatially localized wavepackets

The dynamics of particles in the presence of electromagnetic waves has been an important paradigm for the theory of nonlinear Hamiltonian dynamics and chaos. It is also of interest in fusion plasmas where wave-particle interactions are important in heating and current drive by radio frequency waves. Previous studies of wave-particle interactions have generally assumed that the waves are periodic, thereby having a discrete spectra. We consider wave fields that range from ordinary wave packets with continuous spectra to ultra short, few-cycle and subcycle, transient pulses. The electrostatic wave fields are assumed to propagate in a magnetized plasma at arbitrary angles with respect to the magnetic field. The effect of finite particle Larmor radius is included in our model. The theoretical work is a generalization of a previous study on the interaction with localized wave packets propagating in an unmagnetized plasma [1]. The results from our theoretical analysis are compared with detailed numerical simulations for a variety of cases. The study provides an insight into heating, current drive, and transport of particles by wave-particle interactions. \\[4pt] [1] Y. Kominis, K. Hizanidis and A.K. Ram, \textit{Phys. Rev. Lett.} \textbf{96}, 025002 (2006).   

Scattering of radio frequency waves by edge density blobs in tokamak plasmas

The density blobs present in the plasma edge in magnetic fusion devices can scatter radio frequency (RF) waves through refraction and diffraction. Using the geometric optics approximation for the waves, a Fokker-Planck equation for the scattering of rays by a random distribution of blobs has been derived [1]. It is found that the scattering can diffuse the rays in space and in wave-vector space. The diffusion in space can make the rays miss their intended target region, and the diffusion in wave-vector space can broaden the wave spectrum and modify the wave damping profile. For ITER-type plasmas the wave scattering can lead to the electron cyclotron beams missing their intended target region of growing neoclassical tearing modes. The model is extended to include diffraction and determine changes in spatial propagation and in wave spectra of the RF waves. \\[4pt] [1] K. Hizanidis, A. K. Ram, Y. Kominis, and C. Tsironis, \textit{Physics of Plasmas} {\bf 17}, 022505 (2010).   

Theoretical and numerical study on non-inductive current drive at the ECH pre-ionization

During the 2008's and 2009's campaign, we observed ECH driven current in ECH assisted startup experiments and ECH pre-ionization assessing experiments. A few hundreds of Ampere was repeatedly measured before the onset of loop voltage attributing it not to the Ohmic current but to pure ECH driven current. The current was induced even in the case of vertical launch of ECH beam to the toroidal magnetic field. In this case, there is no preferable toroidal direction of electron because of symmetry. The only thing breaking the symmetry is a tiny vertical magnetic field near ECH resonance layer. The grad-B and curvature drift directions tilted slightly by the vertical field from its straight downward direction to a certain toroidal direction. It gives finite connecting length to the electrons but it differs from an electron to an electron and surely depends on toroidal direction. In this point of view, the average life time of electrons flying to a certain direction is longer than the opposite direction and this could possibly cause the electron current. If we accept this as one of the current deriving mechanism we can deduce the current for a given density and temperature. From this, we could explain the current, at least in same order, be agreed with experiments. In this work, we also discuss about the Pfirsh-Schluter current and compare it with the current here we proposing.   

High Gain Fast Ignition Point Design

The fast ignition (FI) approach to inertial confinement fusion offers the potential for achieving the high target gains required for Inertial Fusion Energy (IFE). In FI a D-T fuel capsule is first compressed via a quasi-isochoric implosion to form a high density core, and then ignited with a short-pulse laser-generated relativistic electron beam. This paper reports progress on the development of a point design for an indirect-drive re-entrant cone FI target. The design incorporates 2-D radiation-hydrodynamics modeling of the capsule implosion around a cone, particle-in-cell (PIC) modeling of the short-pulse laser absorption and electron generation at the cone tip, and hybrid-PIC modeling of the electron transport and heating in the compressed fuel. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.   

Assembling Fuel for Fast Ignition in Cone-shell targets for Good Transport Coupling

Coupling highly divergent electron beams to the fuel in Fast Ignition designs will require putting the critical surface where the electrons are born close to the high fuel density region and creating magnetic structures that can guide the flows of relativistic electrons. We use asymmetric implosions to protect the cone tip from a high pressure jet launched from the compressed,high pressure fuel region. In order to protect the cone from hard xray photons photons generated in the hohlraum we have studied using hard photon absorbing layers in the ablator as well as high-density carbon cones that don't couple to these hard photons. We have studied how to produce material structures that will produce large magnetic fields for electron guiding when the fuel is driven with relativistic electrons. In particular, we have studied how to insert materials of differing resistivities in the electron paths, so that azimuthal fields can be generated via Faraday's law. In addition, we have studied the structure of axial and radial magnetic fields produced by compression of seed fields.   

Integrated simulations of indirect drive fast ignition targets*

To understand the dynamics of thermonuclear ignition and burn in fast ignition targets we require simulations that resolve both bulk plasma evolution and transport of fast electrons. The 2D/3D hybrid plasma simulation code Zuma has been integrated with the 2D/3D HYDRA multiphysics ICF code to simulate thermonuclear burn of indirect drive fast ignition targets. The implosion of the capsule mounted on a cone is simulated in HYDRA, which also contains all of the physics necessary to simulate thermonuclear ignition and burn. Zuma simulates the transport of hot electrons from where they are produced by a petawatt laser to their deposition in the dense fuel. Zuma treats the fast electrons kinetically, while the background high density plasma is modeled as a resistive fluid. Electrons from the petawatt laser deposit hundreds of KJ over 10 psec in a region of the fuel 50 microns in radius. Results for indirect drive fast ignition implosion designs considered for the National Ignition Facility will be presented. We consider the yields obtained for capsules having self-consistent implosion symmetry. These use a hot electron source having a realistic angular spread and energy distribution derived from particle in cell simulations. *This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.   

Three-dimensional Core Plasma Dynamics in Cone-guided Implosion for Fast Ignition

We have been studied the formation of high-density and high-areal-density core plasma in cone-guided non-spherical implosion for Fast Ignition. These simulations were based on two-dimensional radiation hydrodynamic code, where the center of the implosion was always on the axis of the guiding cone. This assumption was ideal, and in reality, there must be a displacement due to the target fabrication error, and laser non-uniformity. Three-dimensional implosion simulation where all physics are included is very expensive and difficult. Therefore the dynamics of imploded core plasma using 3-D Eulerian hydrodynamic code where a 2-D rad-hydro simulation result is extrapolated with 3-D perturbation is investigated for preliminary study. In the result, dynamics of imploded core, formation of the high-density jet, and breakdown of the tip of the cone are simulated. The affection of the 3-D dynamics to the Fast Ignition will be discussed also.   

LSP simulations of proton-driven fast ignition

Shortly after the first measurements of energetic proton beams produced in high-intensity laser-solid interactions, the possibility of using a laser-accelerated proton beam as a driver for fast ignition was recognized [1]. This work aims at presenting some preliminary LSP results on proton-driven fast ignition in a more realistic scenario than previously considered [2]. We assume an imploded configuration for the DT plasma, with a cone inserted in the fuel assembly. A hemispherical target positioned inside the conical structure is the source for the igniting proton beam. The energy delivered by the proton beam to the DT fuel will be compared to Atzeni's ignition conditions [3] and to current results on electron-driven fast ignition. \\[4pt] [1] M.~Roth \textit{et al.}, Phys.~Rev.~Lett.~\textbf{86}, 436 (2000) \newline [2] M.~Temporal, J.~J.~Honrubia, and S.~Atzeni, Phys.~Plasmas \textbf{9}, 3098 (2002) \newline [3] S.~Atzeni, Phys.~Plasmas \textbf{6}, 3316 (1999)   

Simulation of ion generation and dynamics for Fast Ignition*

The ePLAS$^{1}$ implicit/hybrid code is being used to model fast ion generation in a variety of studies involving picosecond time scales on the Titan, and Omega EP lasers. Applied to Cu foils 200 $\mu $m in radius and 20 $\mu $m thick, under 1 ps of 5 x 10$^{19}$ W/cm$^{2}$ laser illumination in a 10 $\mu $m radius spot, ePLAS shows (in particle electron mode) the generation of 10$^{17}$ cm$^{3}$ ion beams travelling 80 $\mu $m by 2.9 ps. The corresponding calculation for a hydrogen foil (with fluid hot electrons) shows a forward 10$^{18}$ cm$^{3}$ beam crossing $\sim $250 $\mu $m. Such calculations complete in 24 min on a 2 GHz PC. The talk will detail the expansion of Titan-driven deuterium beams from a 25 $\mu $m foil. For EP we explore ion beams from hemispheres with 400 $\mu $m curvature radius, again with a $\sim $25 $\mu $m thickness under 1 kJ, 40 $\mu $m diameter, 10 ps illumination. We compare the ion flows calculated for fluid vs. particle ions, and discuss the energy spectrum calculated with PIC. 1. R. J. Mason, JCP \textbf{71,} 429 (1987), and R. J. Mason, PRL \textbf{96,} 035001 (2006). \newline \newline *Research supported in part by the USDOE under SBIR Grant DE-FG02-07ER84723.   

Observation of Fast Protons in Recent Electron Fast Ignition Experiments at OMEGA

Wedge-range-filter proton spectrometers and magnet-based charged-particle spectrometers have been used during integrated fast-ignition (FI) experiments at the OMEGA laser facility. These diagnostics measured a significant population (3$\times $10$^{13})$ of energetic protons (E$_{p,max }$= 7.5MeV) produced from the Au/Cu cone, indicating the presence of strong accelerating mechanisms. Measurements of the proton spectra were conducted at various locations around the FI implosion, for different cone geometries and relative timing between the short- and long-pulse lasers. From these measurements, it was found that the strength of the accelerating fields depends little on cone-tip material and thickness, or even whether the cone-tip is intact when the short-pulse laser is fired. These results have been modeled using a plasma expansion model. This model was used in conjunction with these measurements to infer a hot electron distribution function at each measurement location. This work was supported in part by DOE, LLE and LLNL.   

Proton energy loss measurements in high density, low temperature plasma

There is a great need for experimental verification of energy loss physics in plasma modeling codes. This is particularly true in the moderately-strongly coupled regime. Under this condition, the charged projectile experiences collisions with multiple particles simultaneously (many-body collisions). In inertial confinement fusion and stellar interiors, fusion reactions predominately occur in the moderately-strongly coupled. Understanding the charged particle stopping in this regime is critical to successfully designing and modeling burning plasma in these systems. We have embarked on an ambitious campaign to experimentally test stopping power models. The technique utilizes two short-pulse laser generated proton beams. One beam is used for isochoric heating of solid density matter while the second is used to probe the heated matter. The experiment will be compared to current stopping power models and the molecular dynamics code ddcMD. The measurement and comparison will serve as a bench mark and help further the understanding of energy exchange in ICF and astrophysics models.   

The impact of contaminants on laser-driven ion acceleration in the TNSA regime

Acceleration of light ions (deuterium and carbon) in the Target Normal Sheath Acceleration regime is studied theoretically and experimentally in the presence of contaminants residing on the rear target surface. Experimental data from 6 $\mu $m thick aluminum foil coated with a 1 $\mu $m deuterated plastic (CD) layer on the back surface show that the protons of the contamination layer are preferentially accelerated, while the acceleration of deuterons is strongly suppressed. Two-dimensional particle-in-cell simulations are used to assess the role of contaminants and suggest a remedy to the problem. Laser fluence in excess of 1 J/$\mu $m$^{2}$ is required to overcome the contaminants problem and ensure efficient ion acceleration, while for laser fluence below 1 J/$\mu $m$^{2}$ the contamination layer over the CD surface inhibits the deuteron acceleration.   

Beam Quality Requirements of Dosage Control in Laser Ion Acceleration for Radiotherapy

Ion beam accelerated by laser solid target interaction has vested interested in medical applications. Particle therapy for cancer treatment is one of the most promising prospects. Typical proton beam energy spread for cancer treatment is Delta E / E $\sim $ 0.2{\%} for synchrotron accelerator and Delta E / E $\sim $1{\%} for cyclotron after energy selection system. Passive scattering irradiation mechanism is a common practice to induce SOBP (spread out Bragg peak) for cancer treatment. We examine depth and lateral dose distribution of hardons energized by radiation pressure via various energy selection criteria. Monte Carol codes use PIC simulation results as the input of particle beams. Dose uniformity, distal falloff and lateral penumbra are discussed in related to beam energy spread, emittance and entrance spot size will be presented.   

Recent results of full-spatial scale modeling of fast ignition and shock ignition

We show recent results of full-spatial scale modeling of fast ignition and shock ignition, from both full-PIC and the recently developed hybrid-PIC capability of OSIRIS 2.0. Our results show full-scale modeling of fast ignition over full density and time scales, where laser absorption, electron beam divergence, and energy deposition in the compressed core will be addressed in a self-consistent manner. Full-PIC and hybrid-PIC simulations of isolated targets will be presented, illustrating the importance of this type of modeling in order to accurately infer the beam divergence and transport properties. We will also demonstrate the possibility of performing full-scale simulations of shock ignition with the new hybrid-PIC capability, using compressed target profiles from hydrodynamic simulations, and studying the self-consistent laser absorption, electron transport, and energy deposition that can lead to the generation of the shock required for ignition. Work supported by DOE under DE-FC02-04-ER54789 and DE-FG52-09NA29552, and NSF under NSF-Phy-0904039, FCT (Portugal), and the HiPER project. Simulations performed on Hoffman at UCLA, Thresher at SDSC, and Intrepid at ANL supported by Incite grant FastIgnitionPIC.   

Analytical and computational study of nonlinear collisionless filamentation of a relativistic electron beam in plasma

The nonlinear stage of Weibel instability of a relativistic beam propagating through ambient plasma is studied analytically and through computationally efficient hybrid simulations. In our hybrid approach [1], beam electrons are modeled using numerical macroparticles while plasma electrons are modeled as a passive fluid instantaneously responding to the beam evolution. But in contrast to [1], present numerical analysis captures the effects of violation of the charge quasi-neutrality near the boundaries of high-current filaments. Assuming for analytical tractability that the beam density is small, we find the self-similarity law for nonlinear dynamics of the Weibel instability. It is found that the electron energy distribution of the beam particles trapped in the filaments is close to Maxwellian. Using the Boltzmann distribution of the electron density in transverse plane, we derive a closed equation describing filament structure. This analytical model of fully thermalized filament allows us to evaluate the fraction of initial beam energy transferred to transverse particle beam motion, to plasma electron motion, and to the magnetic field. The analytical results are compared with those from hybrid simulations. [1] Oleg Polomarov et al., Phys. Plasmas 14,043103 (2007). Supported by the US DOE grant DE-FG02-05ER54840.   

Electron beam instabilities in fast ignition

In fast ignition inertial fusion intense relativistic electron beams, generated by the ignition laser, propagate into the dense plasma where the energy is deposited. The beam undergoes a number of instabilities. In particular the two stream and Weibel instabilities have been identified as important in the evolution and absorption of the beam. The two stream results in Langmuir waves that undergo parametric decay into ion acoustic waves and lower frequency Langmuir waves that heat the ions. The Weibel instability on the other hand generates small scale magnetic field structures. These magnetic structure can be responsible for a reduction in thermal conductivity. Studies of these instabilities and there effectiveness with in the fast ignition scheme will be presented.   

Molecular Dynamic Studies of Particle Wake Potentials in Plasmas

Fast Ignition studies require a detailed understanding of electron scattering, stopping, and energy deposition in plasmas with variable values for the number of particles within a Debye sphere. Presently there is disagreement in the literature concerning the proper description of these processes. Developing and validating proper descriptions requires studying the processes using first-principle electrostatic simulations and possibly including magnetic fields. We are using the particle-particle particle-mesh (P$^3$M) code ddcMD to perform these simulations. As a starting point in our study, we examined the wake of a particle passing through a plasma. In this poster, we compare the wake observed in 3D ddcMD simulations with that predicted by Vlasov theory and those observed in the electrostatic PIC code BEPS where the cell size was reduced to .03$\lambda_D$.   

Hybrid simulations for magnetized fast ignition targets and analyzing cone-wire experiments

The 2D/3D hybrid plasma simulation code Zuma is used to analyze the advantages of imposing a magnetic field in order to enhance the transport of energetic electrons from the source region to the dense fuel assembly. Results from a variety of target and cone configurations will be presented. Zuma also calculates the K$\alpha $ production detected in experiments using cone-wire targets. Image analysis combined with simulation yields information about the conversion efficiency and transport characteristics of the hot electrons. Results from a spectrum of hot electron energy distributions will be presented and compared to experimental data.   

Effects of pre-plasma scale-length on fast electron generation in laser-matter interactions

The effect of pre-plasma scale-length on fast electron generation in laser-matter interaction is studied with 1-D PIC simulations using hybrid/PIC code LSP. The simulations are performed for various pre-plasma scale-lengths (1 m, 5 m, 15 m) at the laser intensities ranging from 1 10$^{19}$W/cm$^{2}$ to 1 10$^{21}$W/cm$^{2}$. Increase in both, the mean and maximum energy of the fast electrons with increasing pre-plasma scale-length and laser intensity is observed. The charge separation longitudinal electric field in the underdense plasma is found to be responsible for increase in maximum energy of fast electrons with pre-plasma scale-length whereas the stochastic heating by counter propagating Electromagnetic waves seems to be the dominant fast electron heating mechanism. The dynamics of fast electron generation will be discussed in detail at the meeting.   

Effect of pre-pulse generated plasma on short-pulse laser-cone-wire interactions*

Experiments on $\sim $10 picosecond long pulses were conducted at the Omega EP laser. The presence of a pre-pulse containing over 300 mJ resulted in the formation of extensive plasma within the cone, extending out to over 100 microns from the cone apex.$^1$ We have conducted computational investigations of the effect of the plasma with the 2D implicit hybrid simulation code ePLAS, implemented to study short-pulse laser interactions with cone-wire targets. The code deposits laser light near critical density, and tracks resultant megavolt ``hot'' particle-in-cell (PIC) electrons through an ionized copper or gold target material or in the surrounding vacuum. Dynamic ionization of the initially cold metallic target components can dramatically alter the transport of hot electrons through and around the targets. This ionization evolution has been modeled both parametrically and through a variable mean atomic number Z from analytic models. The use of Sesame Tables is also being explored. Direct comparisons are drawn between time-dependent transport in targets with and without the presence of a pre-pulse ``blow-off'' plasma. 1. R. J. Mason, et al. Bull. Am. Phys. Soc. \textbf{53}, 152 (2008). \\[4pt] *Work partially supported by the USDOE under DE-FG02-07ER84723.   

The Effect of Preplasma on Intense Laser Produced Positrons

Using ultra-intense lasers to generate positrons was theorized some time ago and demonstrated experimentally [1]. Here we focus on the effect of preplasma on the positron generation using lasers. Pre-formed plasmas are made by either of the ASE of the short pulse laser, or a separate laser, and are known to affect the hot electron generation on the solid target. Few studies have been done on the effect of preplasma to the positron creation. We have performed extensive simulations using PIC and LSP on this subject as well as initial experiments on the LLNL Titan laser to study this effect. The results of experiments and the simulations will be presented. \\[4pt] [1] T. Cowan et al, LPB 17, 773 (1999); Gahn et al, APL 73, 3662 (1998); Chen et al, PRL 102, 105001 (2009); Chen at al., PRL 105, 015003 (2010)   

$K_{\alpha}$ Production in Solid Targets as a function of Laser Pre-Pulse and Pulse Length

$K_{\alpha}$ production from solid targets interacting with the Titan laser has been measured as a function of laser prepulse and pulse length. An artificial pre-pulse was added using the Titan long pulse beam co-linearly with the short pulse beam allowing the pre-pulse to be varied from its inherent value of roughly 20mJ up to 5J with 3 ns pulse duration. The main laser parameters for the pre-pulse scan were $\sim$300J laser energy, 40ps pulse length. For the pulse length scan, the Titan short pulse laser was varied from 0.7ps to 190ps keeping the laser energy fixed at 150 J. Relative Ka production was measured using a Transmission Crystal Spectrometer as well as the HOPG Crystal Spectrometer and absolute values were calculated by cross calibrating a Single Hit CCD camera with both spectrometers. Detailed experimental results will be presented at the meeting.   

Spectral measurements of a short-pulse driven quasi-continuum backlighter for absorption spectroscopy

In order to verify that the modeling of radiation flow is correct, experimental measurements are required. Typically lasers irradiate a hohlraum producing an x-ray source. These x-rays heat a medium, often a low-density foam, driving a temperature front. Characterization of this front is crucial for understanding radiation flow. Absorption spectroscopy measures a material's charge state and requires a quasi-continuum source of x-rays. Often a tracer material is used to localize the measurement. There are two options for making the absorption spectroscopy measurement; long duration ($>$ 1ns) or short duration ($<$ 30 ps) backlighter (BL). A long duration BL allows for data to be collected at different times, however, care must be taken in analyzing the spectral measurements because the experimental conditions may change on this timescale. A short pulse measurement might only allow for a single measurement, but the system will have less time to evolve. Experiments have been performed at the OMEGA EP laser studying a quasi-continuum spectrum of a foil target generated by both long pulse (1ns) and short pulse (20 {\&} 40 ps) laser beams. We present the requirements for a planned NIF radiation flow experiment, the experimental measurements from OMEGA EP and future plans.   

K-Shell Spectroscopy of Au Plasma Generated with a Short Pulse Laser

The production of x-rays from electron transitions into K-shell vacancies (K-Alpha/Beta emission) is a well known process in atomic physics and has been extensively studied as a plasma diagnostic in low and mid Z materials. Such spectra from near neutral high-Z ions are very complex and therefore difficult to describe with analytical models. In this experiment a Au plasma emission spectrum was measured with a transparent cylindrically bent quartz crystal. The Titan laser system at Lawrence Livermore National Laboratory was used to deliver a 350 joule, 10 ps, laser pulse to the Au target. K-Alpha(1,2) and K-Beta(1,2,3) transitions were observed over a range of target sizes. Additionally, a series of shots was conducted with a backside pre-ionizing long pulse. FLYCHK, an atomic NLTE code designed to provide ionization and population distributions, will be used to diagnose the plasma temperature, density and ionization states. This information will ultimately be used to gain insight into how the plasma conditions affect the production of positrons.   

Generation of energetic electrons in laser-irradiated foil targets

The ability to generate copious energetic ions is critical for a number of applications. One way to generate energetic ions is via irradiation of solid targets with intense laser beams. We consider a foil target with dimensions greater than the laser wavelength irradiated by a laser with an ultra-relativistic intensity. We investigate the regimes where the laser creates a two-component electron distribution with a cold majority and an energetic collisionless minority. The work examines mechanisms generating the energetic electron population and discusses the effect of this population on ion acceleration. We consider a target with a relatively thick underdense preplasma at its front surface produced by the laser prepulse. The hot electrons are generated near the critical surface and in the preplasma. They spread out inside the target and eventually emerge at the surface. The electrons set up a sheath, whose electric field confines some of them inside the target. The confined electrons may undergo additional stochastic heating when they re-emerge at the surface of the target irradiated by the laser.   

Dynamics of a laser-induced relativistic electron beam inside a solid dielectric

Two-frame interferometry and shadowgraphy were used to investigate the dynamics of interaction of a powerful laser (UNR Leopard 2x10$^{18}$ W/cm$^{2}$, 0.5ps, 1057nm) with a glass target. The two-frame laser diagnostic reveals an ionization wave propagating inside the glass with half the speed of light. The interferometry delineates regions of ionization and excitation inside the glass target. A ``fountain effect'' of fast electrons inside the solid dielectric has been observed for the first time: a radially compact electron beam with sub-light speed fans out from the axis of the original beam, heading back to the target surface. Comparison with French ($\sim $10$^{19}$W/cm$^{2})$ and UK ($\sim $10$^{17}$W/cm$^{2})$ experiments implies a logarithmic dependence of the ionization depth with the laser intensity. Relativistic electron beam dynamics stemming from intense laser-glass interaction is a critical concern for the NIF ``fast ignition'' concept.   

Dynamics of ionization wave produced by relativistic electron beam inside a glass target

Recent laser-matter experiments have revealed interesting features of the motion of electrons at the front of an ionization wave propagating inside a solid density silica glass target. Using an ultra-intense ultra-short pulse laser, highly relativistic electrons were created in the interaction region at the interface of the glass and were subsequently accelerated longitudinally inside the target. Results showed the ionization bubble inside the target expanding anisotropically with a heavy bias towards the lateral direction after a few picoseconds. Furthermore, electrons at the front of the ionization wave appeared to curve back on themselves creating a ``fountain effect.'' Using a 2D particle-in-cell code capable of resolving collisions and ionization of solid density materials, we simulated a scaled version of this experiment and show the anisotropic expansion bias as well as the electron fountain effect. Analysis of the results reveal a very strong buildup of the electrostatic field at the front of the ionization wave due to strong gradients in the longitudinal current. Fast free electrons respond to the field buildup by curving outwards and back upstream with respect to the path of the laser beam.   

Numerical modeling for energy transport and isochoric heating in ultra-fast heated high Z target

Collisional Particle-in-Cell (PIC) code is an effective tool to study extreme energy density conditions achieved in intense laser-solid interactions. In the continuous process of developing PIC code, we have recently implemented models to incorporate dynamic ionizations, namely Saha and Thomas Fermi, and radiation cooling (due to Bremsstrahlung and line emissions). We have also revised the existing collision model to take into account bounded electrons in dynamically ionizing target (partially ionized target). One-dimensional PIC simulation of a gold target with new collision model shows strong local heating in a micron distance due to shorter stopping range of fast electrons, which reflects the increased collision frequency due to bound electrons. The peak temperature in the heated region drops significantly due to the radiation cooling to a level of a few hundred eV from keV. We also discuss the target Z dependence on radiation loss and two-dimensional effects such as the resistive magnetic fields in the hot electron transport in metal targets.   

An Absorption Mechanism for High Intensity Lasers at a Steep Overdense Plasma

In both fast ignition (FI) and the radiation pressure acceleration (RPA) of ions it is essential to understand how electrons are accelerated and reabsorbed at a sharp overdense plasma interface by very intense lasers. To investigate this question, we use the PIC code OSIRIS to model the interaction of high intensity lasers ($I \ge 5 \times 10^{19} W/cm^2$) with a sharp boundary of an overdense plasma ($n \gg n_c$). These results indicate that the commonly proposed absorption mechanisms (Brunel, JxB) cannot explain the acceleration of the electrons. Through the use of particle tracking and a test particle model, we propose a new mechanism in which only electrons which can resonantly interact with the standing wave in vacuum can gain energy. Heating can only occur if the plasma temperature is sufficiently high such that electrons leaving the plasma at large angles are able to interact with the peak electric field. For circularly polarized lasers, the surface B field of the standing wave prevents electrons from leaving the plasma leading to significantly less heating. The process is conformed in test particle simulations. Applications to FI and RPA will be discussed.   

Laser Channeling and Hosing in Fast Ignition

We present recent two-dimensional (2D) and three-dimensional (3D) particle-in-cell (PIC) simulation results for laser channeling in mm-scale underdense plasmas. The mm-scale 2D simulations show many new phenomena including plasma buildup to above critical density in front of the laser, laser hosing/refraction, channel bifurcation and self-correction, and electron heating to relativistic temperatures. The channeling speed is much less than the linear group velocity of the laser. A scaling from the simulations shows, that low-intensity channeling pulses are preferred to minimize the required energy. Significant improvement of the transmission of the ignition pulse in a preformed channel has been demonstrated. The 3D PIC simulations show that the channeling speed is larger in 3D than in 2D due to stronger laser self-focusing. Laser hosing in both transverse planes simultaneously was also observed in these 3D PIC simulations for the first time. This work was supported by DOE under Grants No. DE-FC02-04ER54789 and DE-FG02-06ER54879.   

Advanced backward Raman amplification seeding

Next generations of ultrapowerful laser pulses, reaching exawatt and zetawatt powers within reasonably compact facilities, might be based on the backward Raman amplification (BRA) in plasmas. Amplified pulse intensities hundreds times higher than the pump intensity are already observed experimentally. More advanced BRA stages should produce even higher intensities. The largest nonfocused intensity, limited primarily by instabilities associated with the relativistic electron nonlinearity of the amplified laser pulse, is, roughly speaking, 0.1 of the fully relativistic value. It corresponds to the amplified pulse final (and shortest) duration be about the electron plasma wave period. The needed seed pulse should be at least that short then to stay ahead of the amplified pulse, rather than be shadowed by it (which would much reduce the seeding efficiency). However, at earlier BRA stages, when the amplified pulse is longer, the optimal duration of the seed pulse is also longer. This work proposes the use of self-contracting seed pulses for further optimizing the advanced BRA.   

Initial tests of a high magnetic field generator to increase the neutron yield of fusion plasmas produced by laser irradiation of clusters

The interaction of ultrafast intense terawatt laser pulses with clusters can create high density plasmas with temperatures much greater than 1 keV. The neutron yield from cigar-shape deuterium fusion plasmas is believed to be limited by the fast expansion time ($<$ 100 ps) mainly in the radial direction. A large magnetic field ($>$ 100 T) could limit the radial transport, increasing the fusion time and neutron yield considerably. We present initial tests of the prototype magnetic field generator intended to produce 50 T (upgradeable to 200 T). The device consists of two 100 kV capacitors that can deliver 500 kA through 12 coaxial cables into a conical transmission line. A destructible double coil of 1 cm diameter is connected at the center of the line to create a high magnetic field in a mirror configuration for 1 $\mu$s. We will use a cryogenically cooled gas jet to produce 10 nm deuterium clusters as the laser target. The jet will be irradiated initially by a 20 TW laser beam propagating on the axis of the 200 T magnetic field. The experiment will be conducted later using petawatt-class lasers.   

Harmonic generation induced by an interaction between carbon nanotubes and intense laser field

When an intense laser is irradiated on atomic clusters, strong electromagnetic radiation is generated in a wide frequency range. We reported about a nonlinear resonance absorption takes place when a laser intensity exceeds a threshold value determined by the size of a cluster [1--2]. Such a resonance drives a large electron motion and then strong coherent electromagnetic waves are generated. When a broad-band laser is used for such an interaction, the nonlinear electron motion couples different frequency modes. As a result, it is expected that a wide range of coherent radiation is emitted including waves whose frequency is lower than the incident laser light. Since carbon nanotubes can be used as cylindrical clusters, we have analysed the radiation spectrum from a laser-carbon nanotube interaction using our collisional-ionization PIC code. Enhancement of the low frequency radiation from periodically aligned carbon nanotubes will also be shown.\\[4pt] [1] T. Taguchi, et al., Phys. Rev. Lett., 92, 20, 2004, 205003.\\[0pt] [2] T. M. Antonsen, Jr., et al., Phys. Plasmas 12, 5, (2005), 056703.   

New micro-cone target design can efficiently produce higher energy and lower divergence particle beams

Conical targets have been used in high intensity laser target interactions for less than 10 years, mostly in the context of fast ignition. Throughout the community excellent work has brought to light key parameters such as alignment, absorption, preplasma effect, maximum energy of electron and protons...all this points to cones being an efficient High Energy Density target under certain requirements. They can create well-defined areas of high energy density and particles beams that are \textit{no longer as much driven by the characteristics of the laser beam}. This has not been fully investigated, especially on bigger scale facilities and holds an important potential for fast ignition where, for example, reducing the divergence of the beam lowers the energy requirement and enhances the energy deposition into the compressed fuel, but also for other HED applications such as shocks, opacities, EOS...   

Laser Burnt-through Cone for the Control of Plasma Instabilities in Fast Ignition Thermonuclear Fusion Pellets

I propose a laser burnt-through cone for the suppression, (elimination), of plasma instabilities in fast ignition pellets.\footnote{M. Tabak, J. Hammer, M.E. Glinsky, W.L. Kruer, S. C. Wilks, J. Woodworth, E. M. Campbell, and M.D. Perry, Phys. Plasmas 1 (5), 1626 (1994).}$^,$\footnote{V. Alexander Stefan, Bulletin APS-DPP, 2006;2007.} Laser-REB, relativistic electron beam, hybrid\footnote{V. Alexander Stefan, \textit{Nonlinear Electromagnetic Radiation Plasma Interactions}, (S-U-Press, 2008).} may prove to be, (if the burnt-through laser intensity is 20{\%} of the total intensity), an effective tool for the control of variety of plasma instabilities, in particular for instabilities leading to the generation of colossal B-fields: Weibel instabilities and filamentation of the REB. In the latter case, (B-fields due to $\nabla $n x $\nabla $T mechanism), laser radiation, ($\omega _{o}$, k$_{o})$, ``breaks'' the unstable waves, k $\sim $ k$_{0}$ ($\omega _{pe}$/$\omega _{o})$, through the Kolmogorov\footnote{ A. N. Kolmogorov, Doklady Academii. Nauk SSSR, 30, 301, (1941).\par } cascades into shorter wavelengths, transferring the energy into a nonlinear Landau damping domain. The stabilization take place on the time scale $\sim $REB propagation length/ion acoustic velocity.   

Predictive capability for Z-Petawatt-driven high-energy K$\alpha$ x-ray yields used to image HEDP experiments on the Z Machine

The Z-Petawatt laser (ZPW) will provide a high-energy, ultra-short- duration K$_{\alpha}$ x-ray source for imaging HEDP experiments on the Z Machine. Crucial to the best imaging performance is the attainment of the highest possible conversion efficiency ${\epsilon}$ of laser energy into K$_{\alpha}$ x-rays. We test novel target and imaging concepts aimed at dramatically increasing ${\epsilon}$, which, if realized, would be an outstanding benefit to the quality of our experiments on Z. The measured ${\epsilon}$ in recent ZPW experiments was correctly predicted within the experimental uncertainty, and so provides confidence for our established capability to predict high-energy x-ray yield in other, novel target arrangements for increasing ${\epsilon}$. Quality and contrast improvements in high- energy x-ray imaging, whether from traditional or novel sources, are directly beneficial to HEDP experimental platforms such as Z and NIF. \\[4pt] Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000. Support provided by the Laboratory Directed Research and Development Program at Sandia.   

Focusing of picosecond laser pulses in cone geometries

Short-pulse laser applications like K-alpha based X-ray backlighters, or the fast-ignition approach to inertial confinement fusion require relativistic laser intensities $>$1019W/cm$^2$ over relatively small spots, i.e., radius $\sim$10$\mu$m, while high power laser systems will deliver most of their energy in $\sim$200$\mu$m spots. We study the focusing of picosecond-scale laser pulses in converging target geometries over an intensity range 1017-1020W/cm$^2$ using particle-in-cell simulations, paying special attention at the interaction of intense light with the cone walls.   

Modeling Double Hole Dynamics in Intense Laser Produced Xenon Cluster Plasmas

When femtosecond laser pulses with intensities greater than $\sim $10$^{19}$W/cm$^{2}$ interact with a cluster of xenon atoms, the atoms are stripped of their N-shell electrons in less than a femtosecond and a Coulomb explosion ensues with ions initially in the ground state of Ni-like xenon. X-ray lasing at $\sim $2.86 {\AA} has been observed in such cluster explosions [1] and gain coefficients were measured. Gains comparable to those measured have been obtained in the single hole states of Co-like xenon in an initial non-equilibrium theoretical analysis of these experiments [2]. Alternatively, x-ray amplification has also been attributed to the generation of population inversions between double and single hole states in the M-shell ions of xenon [3]. In order to investigate the viability of this possibility, we have added double hole states to the Fe-like ionization stage of our detailed ionization dynamic model of Ni-, Co-, and Fe-like xenon [2]. Results from our model calculations will be presented in this talk. \\[0pt] [1] A. B. Borisov, \textit{et. al}., J. Phys. B: At. Mol. Opt. Phys. \textbf{40} (2007) F307. [2] Tz. B. Petrova, \textit{et. al}., J. Phys. B: At. Mol. Opt. Phys. \textbf{43} (2010) 025601. [3] W. Andreas Schroeder, \textit{et. al}., J. Phys. B: At. Mol. Opt. Phys. \textbf{34} (2001) 297.   

Modeling the Effects of Cluster Size on X-ray Amplification at $\sim $3 {\AA} in Strong Laser Field -- Xe Cluster Interactions

An extensive xenon time-dependent ionization dynamic (TD-ID) model that includes a complex set of lumped excited states in the Ni-, Co- [1], and Fe-like ionization stages, as well as 3 single hole states in Co-like xenon and 16 single and 9 double hole states in Fe-like xenon that are self-consistently coupled to the ionization dynamics. The TD-ID model receives input on the cluster's electron and ion temperatures and densities from a 3D Relativistic Molecular Dynamics Model in which electrons and ions are treated classically according to a coupled set of relativistic equations of motion. One of the important effects found in MD calculations, not seen in hydrodynamic descriptions of laser-matter interactions, is the fast ion heating that occurs during the cluster's explosion. The combined model enables us to study the influence of cluster size and laser intensity (10$^{18}$-10$^{20}$ W/cm$^{2})$ on the cluster's amplified x-ray emissions when they are subject to a 248 nm laser field.\\[4pt] [1] Tz. B. Petrova, \textit{et.al.}, J. Phys. B \textbf{43} (2010) 025601.