Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Plasma Physics
Volume 57, Number 12
Monday–Friday, October 29–November 2 2012; Providence, Rhode Island
Session CP8: Poster Session II: Laboratory Plasma Astrophysics I; Magnetic Reconnection; ICF and HEDP 
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Room: Hall BC 

CP8.00001: LABORATORY PLASMA ASTROPHYSICS I 

CP8.00002: The Caltech experimental investigation of fast 3D nonequilbrium dynamics: an overview Paul Bellan, Taiichi Shikama, Kilbyoung Chai, Bao Ha, Vernon Chaplin, Mark Kendall, Auna Moser, Eve Stenson, Zachary Tobin, Xiang Zhai The formation and dynamics of writhing, plasmafilled, twisted open magnetic flux tubes is being investigated using pulsedpower laboratory experiments. This work is relevant to solar corona loops, astrophysical jets, spheromak formation, and open field lines in tokamaks and RFP's. MHD forces have been observed to drive fast axial plasma flows into the flux tube from the boundary it intercepts. These flows fill the flux tube with plasma while simultaneously injecting linked frozenin azimuthal flux; helicity injection is thus associated with mass injection. Recent results include observation of a secondary instability (RayleighTaylor driven by the effective gravity of an exponentially growing kink mode), colorcoded plasmas manifesting bidirectional axial flows in a geometry similar to a solar corona loop, and spectroscopic measurements of the internal vector magnetic field. Experiments underway include investigating how an external magnetic field straps down a solar loop, investigation of the details of the RayleighTaylor instability, development of a fast EUV movie camera, increasing the jet velocity, excitation of Alfven waves, and investigating 3D magnetic reconnection. [Preview Abstract] 

CP8.00003: 3D MHD simulation of Caltech plasma jet experiment: First results Xiang Zhai, Hui Li, Paul Bellan We present a 3D ideal MHD simulation of the Caltech plasma jet experiment. The simulation uses the 3D adaptive mesh refinement code AMR3d previously developed by H. Li and S. Li (LANL) for simulating magnetically driven astrophysical jets. The simulation involves injection of toroidal magnetic flux continuously into the plasma thereby increasing the magnetic energy and helicity. This flux injection is equivalent to the anodecathode voltage drop in the experiment. In both the simulation and the experiment, the Lorentz force is observed to squeeze the plasma radially and lengthen it axially to form a jet. With suitably chosen parameters, the jet in the simulation agrees quantitatively with the experimental jet in magnetic/kinetic/inertial energy, total poloidal current, voltage, jet radius, and jet propagation velocity. Specifically, the jet velocity in the simulation is proportional to the poloidal current divided by the square root of the jet density, in agreement with both the experiment and analytical theory. This confirms that the jet gains its kinetic energy via the Lorentz force. Imposition of a small nonaxisymmetric perturbation causes the jet in the simulation to a kink, but so far this kinking is only qualitatively similar to the experimentally observed kink. [Preview Abstract] 

CP8.00004: ABSTRACT WITHDRAWN 

CP8.00005: Effects of different strapping field profiles on plasma loop expansion Bao Nguyen Quoc Ha, Paul Bellan The hoop force causes arched, currentcarrying plasma loops to expand unless additional forces are applied. This expansion was slowed and even inhibited by a magnetic field of proper polarity in previous solar coronal loop experiments [1] but there was no attempt to characterize the strapping field's spatial profile. We have reproduced the Hansen results by mounting the coils producing the strapping field on two ports of the vacuum chamber. We plan to enhance the setup by mounting coils on 3 axis adjustable stands that provide precision placement of the coil relative to the plasma. This precise placement allows us to adjust the altitude decay profile of the strapping field which is predicted to determine the slow rise to fast eruption behavior of plasma loops on the sun [2]. Preliminary data on the interaction between the plasma and specified strapping field profiles will be presented. We have also developed 3axis Hall sensors capable of generating vector maps of the strapping field. \\[4pt] [1] J. F. Hansen and P. M. Bellan, Astrophys. J. Lett. \textbf{563}, L183 (2001)\\[0pt] [2] B. Kliem and T. Torok, Phys. Rev. Lett. \textbf{96}, 255002 (2006) [Preview Abstract] 

CP8.00006: Development of a fast EUV movie camera for study of magnetic reconnection in magnetically driven plasma jets KilByoung Chai, Paul Bellan The Caltech MHD driven jet experiment involves a low temperature ($\sim $5 eV) and high density ($\sim $10$^{21}$ m$^{3})$ plasma that travels at 10's of km/s. During and after formation, magnetic reconnections are observed together with kink and RayleighTaylor instabilities [1]. It has also been observed that there are highly transient EUV emissions when there is magnetic reconnection. The first EUV peak occurs when flux tubes merge during formation and the second one occurs when a RayleighTaylor instability causes the jet to break off from its source electrode. It would be helpful for understanding magnetic reconnection to investigate the spatial and temporal behaviors of these EUV bursts associated with magnetic reconnection. In order to achieve this, we are developing a high speed EUV movie camera. It consists of an Al coated YAG:Ce scintillator, an Au parabolic mirror (or a multilayer coated mirror for a specific EUV wavelength) and a fast framing camera (2x10$^{8}$ fps). We tested our system using visible light from the actual plasma jet and obtained image sequence with submicron time resolution.\\[4pt] [1] A. L. Moser and P. M. Bellan, Nature \textbf{482}, 379 (2012). [Preview Abstract] 

CP8.00007: Crossed Flux Tubes Magnetic Reconnection Experiment Zachary Tobin, Paul Bellan The dynamics of arched, plasmafilled flux tubes have been studied in experiments at Caltech. These flux tubes expand, undergo kink instabilities, magnetically reconnect, and are subject to magnetohydrodynamic forces. An upgraded experiment will arrange for two of these flux tubes to cross over each other. It is expected then that the flux tubes will undergo magnetic reconnection at the crossover point, forming one long flux tube and one short flux tube. This reconnection should also result in a halftwist in the flux tubes at the crossover point, which will propagate along each tube as Alfv\'en waves. The control circuitry requires two independent floating high energy capacitor power supplies to power the plasma loops, which will be put in series when the plasma loops reconnect. Coordinating these two power supplies requires the building of new systems for controlling plasma generation. Unlike with previous designs, all timing functions are contained on a single printed circuit board, allowing the design to be easily replicated for use with each independent capacitor involved. The control circuit sequencing has been tested successfully in generating a single flux tube. The plasma gun is currently under construction, with its installation pending completion of prior experiments. [Preview Abstract] 

CP8.00008: Faster, Hotter MHDDriven Jets Using RF PreIonization Vernon Chaplin, Paul Bellan We are studying MHDdriven jets relevant to spheromak formation and to astrophysical jets. Previous experiments at Caltech have focused on plasmas created by breaking down neutral gas using high voltage. The Paschen breakdown criterion governing this process sets an undesirable lower limit for the jet density. To overcome this constraint, we have designed and constructed a preionization system powered by a pulsed 3 kW 13.56 MHz class D RF power amplifier. The RF amplifier is mounted on a compact printed circuit board and powered by AA batteries, allowing it to float at the high voltage of the center electrode of the jet experiment. The lowerdensity plasma jets created with the aid of RF preionization are expected to be faster, hotter, and have higher Lundquist numbers than jets created by Paschen breakdown, opening up a new regime of study with increased relevance to astrophysics. The installation of the preionization system on the MHDdriven jet experiment will be described, and details of the RF source operation and properties of the preionized plasma will be summarized. Results from experiments with preionized jets will be presented if available. [Preview Abstract] 

CP8.00009: Experimental investigation in plasma relaxation by using a compact coaxial magnetized plasma gun in a background plasma Yue Zhang, Alan Lynn, Mark Gilmore, Scott Hsu A compact coaxial plasma gun is employed for experimental studies of plasma relaxation process being conducted in the HELCAT device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes. The gun is powered by a 120pF ignitronswitched capacitor bank which is operated in a range of 5  10kV. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities 1.2Cs and densities 10e20 m3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter lambda determining the operation regime. Additionally, a Bdot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented. [Preview Abstract] 

CP8.00010: Status of the Madison Plasma Dynamo Experiment John Wallace, Mike Clark, Cami Collins, Noam Katz, Dave Weisberg, Cary Forest Construction of the Madison Plasma Dynamo Experiment (MPDX) is complete. This facility creates large, unmagnetized, fast flowing, hot plasma for investigating magnetic field selfgeneration and flow driven MHD instabilities. A 3 meter diameter spherical vacuum chamber lined with a series of high strength samarium cobalt magnets provides plasma confinement. The plasma will be stirred from the magnetized edge using electrodes to produce JxB flows. Plasma sources will include lanthanum hexaboride cathodes and electron cyclotron heating utilizing five 20KW magnetrons. This poster will describe the operational status of the facility including laboratory infrastructure, cast aluminum vacuum chamber, magnets, stirring electrodes, sources, diagnostics and currently produced plasma parameters. Construction was funded by the NSF Major Research Instrumentation program. [Preview Abstract] 

CP8.00011: Initial Results from the Madison Plasma Dynamo Experiment David Weisberg, John Wallace, Christopher Cooper, Ivan Khalzov, Ben Brown, Cary B. Forest The Madison Plasma Dynamo Experiment (MPDX) is a plasma device designed to explore the selfexcitation process across a range of astrophysical dynamos. Numerical simulations have demonstrated that a laminar twovortex flow in a spherical geometry can produce a dynamo at certain values of fluid Reynolds number (Re) and magnetic Reynolds number (Rm); namely when Rm $\ge$ Re for Re=300. This requirement is sought to be achieved in a large, hot, flowing, and unmagnetized plasma in MPDX. This poster presents results from the first plasma created in MPDX using hot, emissive lanthanum hexaboride (LaB$_6$) electrodes. The electrodes are biased up to 400V with respect to anodes, drawing current that both heats and stirs the plasma. The design of these electrodes is discussed, as well as the effectiveness of the discharge currents achieved in the presence of the 3000G multipole cusp magnetic field of MPDX. We also present measurements of plasma flow due to ExB stirring, an important requirement for dynamo excitation. Experimental results are compared to numerical predictions of viscous coupling between flow at the magnetized edge and the unmagnetized core as a function of Re. Work supported by DOE and NSF. [Preview Abstract] 

CP8.00012: Measuring and Optimizing flows in the Madison Dynamo Experiment N.Z. Taylor, M. Clark, C.B. Forest, E.J. Kaplan, M.D. Nornberg, A.M. Rasmus, K. Rahbarnia In the Madison Dynamo Experiment, two counterrotating impellers drive a turbulent flow of liquid sodium in a one meterdiameter sphere. One of the goals of the experiment is to observe a magnetic field grow at the expense of kinetic energy in the flow. The enormous Reynolds number of the experiment and its two vortex geometry leads to a large turbulent EMF. This poster presents results from the MDE after several upgrades were made. First, an equatorial baffle was installed to stabilize the position of the shear layer between the two counterrotating hemispheres. This reduced the scale of the largest eddies in the experiment, lowering the effective resistivity due to turbulence. Next, a probe was used to measure both the fluctuating velocity and magnetic fields, enabling a direct measurement of the turbulent EMF. This EMF is antiparallel to the mean current, consistent with an enhanced resistivity predicted by mean field theory. Finally, vanes with adjustable orientation were installed on the vessel wall, allowing the pitch of the helical flow to be altered. Computational fluid dynamics simulations and inversion of the measured induced magnetic field are used to determine the optimum angle of these vanes to minimize the critical velocity at which the dynamo onset occurs. [Preview Abstract] 

CP8.00013: Fabrication of a vacuum vessel for a cusp confinement plasma using cast Al Mike Clark, Cami Collins, Noam Katz, Dave Weisberg, John Wallace, Cary Forest The Madison Plasma Dynamo Experiment (MPDX) facility will create large, unmagnetized, fast flowing, hot plasma for investigating magnetic field selfgeneration and flow driven MHD instabilities. The scale of the experiment is important to do this science, and so bigger is better. The core infrastructure of MPDX is the matching pair of 3 meter diameter hemispheres. For MPDX the cost and complexity of the vacuum vessel built by traditional means challenged the budget. The path to making this highvacuum vessel led the research team and collaborators to push the limit cast Al. The challenges and solutions of making the MPDX vessel will be discussed and illustrated today. [Preview Abstract] 

CP8.00014: Dynamos in spherical timeperiodic flows Ivan Khalzov, Ben Brown, Cary Forest We study numerically the possibility of dynamo action for a class of timeperiodic, axisymmetric flows of conducting fluid confined inside a sphere. The flows are found as solutions to the NavierStokes equation subject to the boundary conditions specified by timedependent profiles of azimuthal velocity at the sphere. This model is relevant to Madison plasma dynamo experiment (MPDX), whose spherical boundary is capable of differential driving of plasma in the azimuthal direction. We show that a growing magnetic field can be selfexcited for a particular range of flow parameters, such as amplitude and frequency of flow oscillations, fluid Reynolds and magnetic Reynolds numbers. Simulations are performed using the magnetohydrodynamic codes NIMROD and DYNAMO. Both linear and nonlinear regimes of the dynamo instability are studied, effects of the finite wall resistivity are taken into account. Based on the results we propose a scenario for experimental demonstration of the dynamo action in MPDX. [Preview Abstract] 

CP8.00015: Recent Results from the Plasma Couette Experiment Noam Katz, Cami Collins, Chris Cooper, John Wallace, Mike Clark, Ingrid Reese, Carl Wahl, Cary Forest The Plasma Couette Experiment (PCX) has been designed to study the magnetorotational instability (MRI) in a laboratory plasma. As a first step towards this goal, we have achieved solidbody rotation of an unmagnetized plasma for the first time. We apply JxB torque at the magnetized edge region of a ``magnetic bucket,'' and the momentum couples into the unmagnetized bulk plasma through collisional viscosity. In order for momentum to couple inward from the edge, it is crucial that the ion viscosity dominate the drag due to ionneutral charge exchange collisions. The next steps towards laboratory observation of the MRI involve driving sheared flow (since solidbody flow is stable to the MRI) and applying a weak vertical magnetic field to destabilize the plasma. We will describe our recent progress in these areas, as well as development of a laserinduced fluorescence diagnostic to better characterize the velocity profile and measure the ion temperature. [Preview Abstract] 

CP8.00016: Millimeter Wave Interferometer for Measuring Plasma Density in PCX Weifeng Peng, Mike Clark, Weixing Ding, John Wallace, Cary Forest A microwave interferometer is designed to determine the plasma density in the Plasma Couette Experiment (PCX) at UWMadison. PCX is characterized by a cold low density plasma. Two 15 mW, 320 GHz microwave sources and two mixers for detecting the phase shift of the microwaves are employed. The 3 dB radius of the beam is about 1 inch. The size of optical elements in this experiment is determined by the beam shape. The beam splitters are made of a wire mesh in an aluminum frame with the mesh number (MN) = 17. It is found that for MN = 17 half of the power is reflected and half is transmitted. The two source frequencies are offset by 1 MHz, i.e. 320 GHz and 320+0.001 GHz. The 320 GHz beam passes through free space and the other beam passes through the plasma experiment. Both beams terminate on their respective mixer. By measuring the phase difference of the mixers and the path length of the microwave beams, the plasma density can be calculated. Four microwave lenses, 4 flat mirrors, and 4 beam splitters are mounted on a linear motion optics table and used to accurately measure the plasma density in PCX. The design and construction of the system is discussed. [Preview Abstract] 

CP8.00017: Numerical studies of nonaxisymmetric magnetorotational instability in MPCX Darrin Leer, F. Ebrahimi, B. Lefebvre The linear global behavior of nonaxisymmetric magnetorotational instability (MRI) is numerically studied in the MPCX (Madison Plasma Couette Flow Experiment). Here, we extend an earlier study of global axisymmetric MRI in MPCX (Ebrahimi et. al 2011) to also include nonaxisymmetric modes. The global eigenvalue problem for ideal MHD is numerically solved in a compressible flowing plasma. In a Couette geometry with an imposed vertical magnetic field, we study the role of compressibility on both axisymmetric and nonaxisymmetric MRI modes and compare the global solutions with a generalized form of the local WKB approximation. Supported by NSF PHY \#0962244 and DOE. [Preview Abstract] 

CP8.00018: Turbulence experiment with high controllability in a rotating system for dynamo physics Kenichi Nagaoka, Shinji Yoshimura, Hideaki Miura, Youhei Masada, Shoichi Kai, Yoshiki Hidaka, Kenichiro Terasaka, Nobimitsu Yokoi, Saku Tsuneta, Masahito Kubo Magnetic field in space is generated by kinetic energy of plasma in turbulent state (dynamo effect). Pattern formation in rotating fluids can be seen in space plasma, laboratory plasmas and ordinary fluids, and is considered as a key to understand the dynamo effect. Proposed is a new experimental approach of turbulence driven by electrohydrodynamic convection in a rotating system, in which three nondimensional parameters, Reynolds, Prandtl and Rossby numbers can be continuously controllable. The details of the experimental setup and preliminary results of turbulence will be discussed in the conference. The final target of our project is experimental simulation of convective zone in the sun, which is an expansion of experimental study in a rotating spherical cell performed by F.H. Busse [F.H. Busse, Chaos, 4, 123 (1994)] from 2D system to 3D system. [Preview Abstract] 

CP8.00019: Instability of free shear layers in the Princeton MRI experiment A.H. Roach, E.J. Spence, C. Gissinger, E.M. Edlund, P. Sloboda, H. Ji The Princeton MRI experiment is a TaylorCouette device with a liquid metal working fluid. The endcaps of the experiment are split into two differentially rotatable rings. There is a discontinuity in the azimuthal velocity boundary condition at the location of the split between the rings which can be the source of free shear layers that extend into the fluid. When the inner ring rotates faster than the outer ring, these shear layers are unstable to both centrifugal instabilities and shear (KelvinHelmholtz) instabilities. The centrifugal instability can be stabilized by sufficient background rotation or a sufficient applied axial magnetic field, allowing the KelvinHelmholtz instability to grow. While the centrifugal instability remains relatively localized in the shear layer, the KelvinHelmholtz instability has been observed to generate largescale velocity fluctuations throughout the fluid volume. We examine the competition of these instabilities using experimental measurements of the velocity with ultrasound Doppler velocimetry, linear calculations, and results from nonlinear 3D MHD simulations. Supported by DOE contract DEAC0209CH11466. [Preview Abstract] 

CP8.00020: Recent results from the Princeton MRI and HTX experiments Eric Edlund, E.J. Spence, A.H. Roach, C. Gissinger, P. Sloboda, H. Ji The Princeton MRI experiment is a modified TaylorCouette device with a GaInSn working fluid used to study rotating MHD flows. Diagnostics include magnetic pickup coils and ultrasound Doppler velocimetry (UDV). The experiment was designed to study the magnetorotational instability (MRI), which is believed to generate the turbulence that would be required in many accretion disks to explain observed accretion rates. We present results related to the search for the MRI, including a summary of results from 3D nonlinear MHD simulations describing the bifurcation of the MRI mode from residual Ekman flow, with a comparison to experimental measurements at MRIrelevant speeds. We also present experiments from the Hydrodynamic Turbulence Experiment (HTX), a similar TaylorCouette device, which explore the stability of purely hydrodynamic flows. The lifetimes of turbulent states generated by external forcing are measured as a function of the dimensionless rotational shear. Differences in forcing which either preserve or break vertical symmetry will be discussed in relation to the MRI and other possible mechanisms of angular momentum transport. [Preview Abstract] 

CP8.00021: Backward radiation from a horseshoe type cyclotron instability Irena Vorgul, Barry J. Kellett, R.A. Cairns, Robert Bingham, Kevin Ronald, David C. Speirs, Sandra McConville, Karen Gillespie, Alan D.R. Phelps Recent observations of Auroral Kilometric Radiation produced by a beamdriven cyclotron instability suggest that it is generated at a small angle to perpendicular in the backward direction with respect to the beam. New data also suggest backward propagation of cyclotron radiation from some stars with dipole magnetic field. Our experiment at the University of Strathclyde investigating cyclotron maser emission similar to AKR also showed that the fastest growing wave is propagating backward, with this result confirmed by simulations and analytic calculations of the growth rate. We propose here a possible explanation of this phenomenon.~ The instability is driven by a population inversion of the electron distribution in the perpendicular direction and for different directions of propagation slightly away from perpendicular the cyclotron resonance curve passes through the region of maximum gradient for different frequencies.~ Near cyclotron resonance the real part of the dispersion relation is strongly frequency dependent. We show that this leads to the conclusion that the peak growth would be expected for a small backward angle, in line with the results of observation and simulation. [Preview Abstract] 

CP8.00022: Laboratory Magnetospheric Plasma Studies in LDX and CTX M. Mauel, M. Davis, D. Garnier, M. Roberts, M. Worstell, J. Kesner During the past decade, results from the CTX and LDX laboratory dipole plasma experiments have advanced our understanding of magnetized plasma dynamics and shown the influence of magnetic geometry on turbulent transport and highbeta stability. The CTX and LDX devices operate over a wide range of plasma parameters, allow detailed observations spanning global to small spatial scales, and show dynamics relevant to space weather models. Results include slow and fast plasma convection, centrifugal interchange instability and plasma rotation effects, energetic particle and complex waveparticle dynamics, rapid dipolarization in highbeta plasma, intermittent bursty plasma flows, and fascinating plasma turbulence and transport phenomenon. These laboratory magnetosphere experiments confine energetic and relatively collisionless plasma and create unique opportunities for the development and validation of models that help understand turbulent transport in fusion devices and also space weather dynamics. We describe upcoming experiments to investigate (i) turbulence control with electrostatic feedback, (ii) wholeplasma imaging of turbulent dynamics, and (iii) nonlinear gyrokinetic simulations of bounded driven dipole plasma. [Preview Abstract] 

CP8.00023: Using Laboratory Magnetospheres to Develop and Validate Space Weather Models D.T. Garnier, M.S. Davis, M.E. Mauel, J. Kesner Reliable space weather predictions can be used to plan satellite operations, predict radio outages, and protect the electrical transmission grid. While direct observation of the solar corona and satellite measurements of the solar wind give warnings of possible subsequent geomagnetic activity, more accurate and reliable models of how solar fluxes affect the earth's space environment are needed. Recent development in laboratory magnetic dipoles have yielded well confined highbeta plasmas with intense energetic electron belts similar to magnetospheres. With plasma diagnostics spanning from global to small spatial scales and usercontrolled experiments, these devices can be used to study current issues in space weather such as fast particle excitation and rapid depolarization events. In levitated dipole experiments, which remove the collisional loss along field lines that normally dominate laboratory dipole plasmas, slow radial convection processes can be observed. Thus, comparisons between laboratory plasmas and global convection models can be made. [Preview Abstract] 

CP8.00024: Measurement and modeling of the electron pressure profiles in the Levitated Dipole Experiment (LDX) M. Davis, D. Garnier, M. Mauel, J. Kesner Electron pressure profiles in plasmas confined by a dipole are predicted to be centrally peaked whenever crossfield turbulent transport dominates over parallel losses to the poles. This central peaking of the pressure has been observed in planetary magnetospheres by spacecraft during times of magnetic activity. Using magnetic reconstructions and Xray measurements, we also find the electron pressure is centrally peaked in the LDX laboratory magnetosphere. LDX can operate in two distinct modes: mechanically supported and magnetically levitated. When the superconducting dipole magnet is mechanically supported the electron pressure results entirely from energetic trapped electrons and the pressure gradients can exceed the MHD stability criterion because of gyrokinetic effects. Levitation strongly alters the plasma density due to the inward particle pinch [1], and increases the stored plasma energy. By comparing models of the electron pressure profile to equilibrium reconstructions and Xray measurements we find that the thermal pressure profiles appear to be consistent with expectations of turbulent adiabatic equipartition.\\[4pt] [1] A. C. Boxer, et al., Nature Phys. 6, 207 (2010) [Preview Abstract] 

CP8.00025: Active Feedback Control of Interchange Turbulence in a Laboratory Magnetosphere T.M. Roberts, M.E. Mauel, M.W. Worstell The CTX device is a laboratory magnetosphere where low density plasmas are interchange unstable, allowing turbulent plasma dynamics to develop. Previous work has investigated the nature of this turbulence and observed the effects of applied static electric fields. Here we present first work on actively suppressing these turbulent fluctuations through electrostatic feedback control. A new feedback system has been designed and fabricated which allows us to measure potential fluctuations and apply a variably phase shifted response. Phase scan experiments and scans of location the of the sensor/actuator pair in have been performed and the results are presented. Phase dependent changes to the power spectrum are observed via Langmuir probes and gridded energy analyzers. We also present plans for future feedback methods implementing digital signal processing. [Preview Abstract] 

CP8.00026: Controlled Growth of Gigantic Swirls in a Laboratory Magnetosphere M.W. Worstell, M.E. Mauel, T.M. Roberts Space and laboratory plasma confined by a strong magnetic field have remarkable properties. Low frequency mixing of the plasma occurs through the interchange of long plasmafilled tubes aligned with the magnetic field. The plasma dynamics becomes twodimensional because these tubes can only move radially or circulate around the poles of the magnetic dipole. Studies of turbulent interchange dynamics made using the Collisionless Terella Experiment (CTX) show that turbulence appears as chaotic timevarying modes with broad global mode structures that interact nonlinearly and form an inverse cascade.\footnote{B.A. Grierson, M.W. Worstell, M.E. Mauel, {\it Phys. Plasmas} {\bf16} 055902 (2009)} When we drive vortex mixing through the application of electrostatic bias to multiple probes, we break the rotational symmetry of the plasma and small vortex tubes are seen to drive larger ``gigantic'' swirls. Statistical analysis of the timeevolving spectra and measurement of the bicoherence of the turbulence show an increase of three wave coupling during nonaxisymmetric electrostatic drive of the probe array. [Preview Abstract] 

CP8.00027: Turbulence, selective decay, and merging in the SSX plasma wind tunnel Tim Gray, Michael Brown, Ken Flanagan, Alexandra Werth, V. Lukin A helical, relaxed plasma state has been observed in a long cylindrical volume. The cylinder has dimensions $L = 1$~m and $R = 0.08$~m. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at $v \ge 50$~km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. Typical plasma parameters are $T_i = 25$~eV, $n_e \ge 10^{15}$~cm$^{3}$, and $B = 0.25$~T. The relaxed state is rapidly attained in 12 axial Alfv\'{e}n times after initiation of the plasma. Magnetic data is favorably compared with an analytical model. Magnetic data exhibits broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement to the minimum energy eigenstate of $\nabla \times \vec{B} = \lambda \vec{B}$. While the global structure roughly corresponds to the minimum energy eigenstate for the wind tunnel geometry, the plasma is high beta ($\beta = 0.5$) and does not have a flat $\lambda$ profile. Merging of two plasmoids in this configuration results in noticeably more dynamic activity compared to a single plasmoid. These episodes of activity exhibit s [Preview Abstract] 

CP8.00028: Behavior of a laboratory plasma column near the currentdriven instability limit J. Sears, T.P. Intrator, G. Wurden, T.E. Weber, W. Daughton, J. Klarenbeek, K. Gao A plasma column is generated in a longitudinal magnetic field in the Reconnection Scaling Experiment such that current can be drawn along the column axis. At low current density, the column remains straight. At current density slightly above the external kink limit, the column deforms with azimuthal wavevector m = 1. The amplitude of the deformation saturates and the column gyrates at a steady rate for many periods. The instability sometimes gives way to a higherorder mode. At higher current density still, the column disrupts. To investigate the saturated nonideal behavior we measure the vector magnetic field and the plasma temperature and density in a cubic volume measuring 0.1 m on a side with resolution on the order of the electron skin depth. Our 3D probe positioning system uses stereo camera vision to precisely situate the probe tips. Study of the saturated kink mode in laboratory plasma may offer clues to the long lifetime of astrophysical jets. [Preview Abstract] 

CP8.00029: MAGNETIC RECONNECTION 

CP8.00030: Design of a Magnetic Reconnection Experiment in the Collisionless Regime Jan Egedal, A. Le, P. Montag, O. Ohia, A. Vrublevskis, W. Daughton A new model for effective heating of electrons during reconnection is now gaining support from spacecraft observations, theoretical considerations and kinetic simulations [1]. The key ingredient in the model is the physics of trapped electrons whose dynamics causes the electron pressure tensor to be strongly anisotropic [2]. The heating mechanism becomes highly efficient for geometries with low upstream electron pressure, conditions relevant to the magnetotail. We propose a new experiment that will be optimized for the study of kinetic reconnection including the dynamics of trapped electrons and associated pressure anisotropy. This requires an experiment that accesses plasmas with much lower collisionality and lower plasma beta than are available in present reconnection experiments. The new experiment will be designed such that a large variety of magnetic configurations can be established and tailored for continuation of our ongoing study of spontaneous 3D reconnection [3]. The flexible design will also allow for configurations suitable for the study of merging magnetic islands, which may be a source of super thermal electrons in naturally occurring plasmas. \\[1ex] [1] J Egedal et al., Nature Physics, 8, 321 (2012). [Preview Abstract] 

CP8.00031: Magnetic Reconnection Regimes at the Real ProtontoElectron Mass Ratio A. Le, J. Egedal, W. Daughton, H. Karimabadi New fully kinetic simulations of magnetic reconnection demonstrate that the electron dynamics vary qualitatively between simulations at the physical proton mass ratio of 1836 and at mass ratios even as high as 400. Several regimes exist depending on the characteristics of thermal electron orbits in the reconnecting current sheet, which depend on the mass ratio, strength of the guide magnetic field, and upstream electron beta. In all cases, electron pressure anisotropy develops in the inflow following previously derived equations of state [1]. For the lowest guide fields, effective pitch angle scattering causes the outflow electron pressure to become nearly isotropic. Above a certain threshold guide field, the electron orbits remain magnetized in the exhaust and the pressure anisotropy extends into the outflow. At the physical proton mass ratio, these cases include a new regime where electron pressure anisotropy drives magnetized electron current layers [2] longer than 15 ion inertial lengths similar to those inferred from spacecraft observation [3]. \\[4pt] [1] Le et al., PRL 102, 085001(2009).\\[0pt] [2] Ohia et al., PRL (2012).\\[0pt] [3] Phan et al, PRL 99, 255002 (2007). [Preview Abstract] 

CP8.00032: Scaling of GuideField Magnetic Reconnection using Anisotropic Fluid Closure O. Ohia, J. Egedal, V.S. Lukin, W. Daughton, A. Le Collisionless magnetic reconnection, a process linked to solar flares, coronal mass ejections, and magnetic substorms, has been widely studied through fluid models and fully kinetic simulations. While fluid models often reproduce the fast reconnection rate of fully kinetic simulations, significant differences are observed in the structure of the reconnection regions [1]. However, guidefield fluid simulations implementing new equations of state that accurately account for the anisotropic electron pressure [2] reproduce the detailed reconnection region observed in kinetic simulations [3]. Implementing this twofluid simulation using the HiFi framework [4], we study the force balance of the electron layers in guidefield reconnection and derive scaling laws for their characteristics.\\[1ex] [1] Daughton W et al., Phys. Plasmas 13, 072101 (2006).\\[0ex] [2] Le A et al., Phys. Rev. Lett. 102, 085001 (2009). \\[0ex] [3] Ohia O, et al., Phys. Rev. Lett. In Press (2012).\\[0ex] [4] Lukin VS, Linton MG, Nonlinear Proc. Geoph. 18, 871 (2011) [Preview Abstract] 

CP8.00033: Reconnection experiments with 3D magnetic nulls in different topologies A. Vrublevskis, J. Egedal, A. Le Magnetic reconnection has been predominantly investigated in two dimensions. However, depending on the topology and geometry of the magnetic field, a rich collection of magnetic reconnection scenarios is possible in 3D including reconnection at magnetic nulls. At the Versatile Toroidal Facility (VTF) we have implemented a new magnetic geometry with a pair of 3D null points in the background toroidal field. We form a flux rope along the background field and observe it to rapidly restructure and rewire as the nulls develop. We can adjust the topology of the configuration from one where a field line connects the nulls to one where the nulls are no longer linked. A suit of diagnostics will be deployed and results presented for how the topology affects the dynamics of the flux rope. [Preview Abstract] 

CP8.00034: Dipole Experiment with Magnetically Isolated Supports P. Montag, J. Egedal, A. Vrublevskis, A. Le, W. Fox Basics plasma physics experiments in the collisionless regimes require good plasma confinement to permit temperatures and densities in the range of $T_e\sim 30$ eV, $n \sim 1\cdot10^{19}$ m$^{3}$. Our design for a new magnetic reconnection experiment is based on the confinement of the dipole geometry which has also been considered for fusion applications (e.i. the LDX experiment at MIT). Rather than magnetic levitation as applied in the LDX experiment, we use magnetically isolated supports. This magnetic isolation is achieved by applying currents in the support structures configuring the magnetic field such that the plasma cannot stream directly to the support along magnetic field lines. We here report on the first magnetic and electrostatic measurements in this dipole configuration. [Preview Abstract] 

CP8.00035: Laboratory study of arched magnetic flux ropes formed within a solarrelevant potential field configuration C.E. Myers, M. Yamada, H. Ji, J. Yoo, J. JaraAlmonte, E.E. Lawrence Solar eruptive events such as coronal mass ejections (CMEs) are thought to be driven by a sudden release of magnetic energy stored in the solar corona. In many cases, the preeruptive configuration is a nonpotential magnetic structure that can be modeled as a linetied magnetic flux rope. In spite of everimproving observations, directly studying these coronal flux ropes remains a significant challenge. As an alternative, we have designed a laboratory experiment to produce low$\beta$ arched magnetic flux ropes similar to those found in the corona. These linetied flux ropes are formed as a magnetized arc discharge between two electrodes and they evolve quasistatically over hundreds of Alfv\'en times. Recently, we have constructed a new set of magnetic field coils to produce an activeregionlike potential field configuration. Initial results from plasmas formed in this configuration are presented, including fast camera images and internal magnetic measurements. These discharges are expected to access a regime where a slowly evolving flux rope can suddenly undergo a dynamic eruption due to a lossofequilibrium\footnote{Forbes \& Isenberg, {\it ApJ} {\bf373}, 294 (1991)} or the torus instability.\footnote{Kliem \& T\"or\"ok, {\it PRL} {\bf96}, 255002 (2006)} [Preview Abstract] 

CP8.00036: Study of energy transfer in the magnetic reconnection layer in the MRX laboratory plasma Masaaki Yamada, Jongsoo Yoo, Hantao Ji, Clayton Myers, Jon JaraAlmonte, Tim Tharp As the process of magnetic energy dissipation is key to magnetic reconnection, the MRX research focus has recently been shifted to a new phase: the study of the heating and acceleration of plasma particles. We have initiated a study of electron acceleration and heating characteristics while we continue the study of ion flows and heating at the diffusion region. In recent measurements of 2D $T_e$ profiles using triple Langmuir probes, we observe enhanced $T_e$ at the exhaust of the reconnection layer. Likewise, with an improved Ion Dynamics Spectroscopy Probe (IDSP), we observe an acceleration and heating of ions at the exhaust of the reconnection layer. A strong potential well in the reconnection plane has also been measured in MRX. This observation is in general agreement with space observations\footnote{J. Wygant et al., {\it JGR}, 110:A09206 (2005)} and simulations\footnote{P. Pritchett, {\it JGR (Space Phys.)}, 115:10208 (2010)}$^,$\footnote{J. Drake et al, {\it Astrophys. J.}, 700:L16L20 (2009)} regarding the particle dynamics of the reconnection layer. By comparing our experimental data with simulations and analytical theory, we investigate the physics of particle heating. [Preview Abstract] 

CP8.00037: Inplane electric field and its effects on ion dynamics Jongsoo Yoo, Masaaki Yamada, Hantao Ji, Clayton Myers, Jonathan JaraAlmonte The inplane electric field is a signature of twofluid effects in the diffusion layer [1]. The interaction of ions with this electric field leads both to ion acceleration and heating downstream [2]. The measured twodimensional (2D) floating potential profile in Helium discharges indicates that the magnitude of the inplane electric field (250  800 V/m) is larger than the outofplane reconnection electric field (100  200 V/m). For a quantitative study of ion dynamics under the inplane electric field, local ion velocity distributions along all three (radial, axial, and toroidal) directions are measured by Ion Dynamics Spectroscopy Probes (IDSPs), from which ion flow velocities and associated temperatures are determined. The strong inplane electric field accelerates ions up to a significant fraction (0.4  0.6) of the upstream Alfv{\'e}n velocity generating fast ion outflows. 2D profiles of the ion temperature of different directions are considerably different, implying kinetic effects and temperature anisotropy.\\[4pt] [1] Yamada et al, Rev. Mod. Phys., 2010.\\[0pt] [2] Drake et al, J. Geophys. Res., 2008. [Preview Abstract] 

CP8.00038: 3D Measurements of FluxRope Structures in the Magnetic Reconnection Experiment J. JaraAlmonte, H. Ji, M. Yamada, J. Yoo, C.E. Myers, T.D. Tharp In large systems, fast reconnection requires a means of effectively coupling the global MHD scale to the kinetic length scales. The prevailing theory for explaining this coupling is that the plasmoid instability causes a single Xpoint to break up into a hierarchical chain of Xpoints separated by fluxropes. Previous 2D experiments on MRX have observed both impulsive reconnection events and current layer disruptions caused by the ejection of ``fluxrope like'' structures from the current layer.\footnote{Dorfman, S. Experimental study of 3D impulsive reconnection events in a laboratory plasma (Doctoral Dissertation). Princeton University. 2012} These events are inferred to be the result of 3D local physics due to the fast ($\sim 2\mu$s) timescales, and thus full 3D measurements are possible. Using 10 magnetic probes with a combined 350 pickup coils, the magnetic field in a 9cm x 12cm x 16cm volume is simultaneously measured. Here, initial 3D measurements of the structure and dynamics of the ``fluxrope like'' structures in MRX will be presented.\footnote{This work supported by DOE Contract Number DEAC0209CH11466 and the Center for Magnetic SelfOrganization} [Preview Abstract] 

CP8.00039: Particle simulation of highenergydensity laserdriven reconnection experiments A. Bhattacharjee, W. Fox, K. Germaschewski Recently, reconnection between magnetic fields, selfgenerated through the Biermann battery effect, has been observed and studied in highenergydensity, laserdriven experiments on the Vulcan, OMEGA, and Shenguang laser facilities. This is a novel regime for magnetic reconnection study, characterized by extremely high magnetic fields, high plasma beta and strong, supersonic plasma inflow. Reconnection in this regime is investigated with particleincell simulations using the PSC code. Previous 2d particleincell reconnection simulations with parameters and geometry relevant to the experiments identified key ingredients for obtaining the very fast reconnection rates, namely twofluid reconnection mediated by collisionless effects (that is, the Hall current and electron pressure tensor), strong flux pileup of the inflowing magnetic field [1], and secondary instabilities that lead to magnetic island formation. We present further detailed simulations of reconnection in this geometry, exploring the role of binary particle collisions and examining mechanisms for particle energization and acceleration, as has been recently observed in laserdriven reconnection experiments [2].\\[4pt] [1] W. Fox, et al, PRL 106, 215003 (2011).\\[0pt] [2] Q.L.Dong, et al., PRL 108, 215001 (2012). [Preview Abstract] 

CP8.00040: Magnetic reconnection in highenergydensity plasmas in the presence of an external magnetic field W. Fox, A. Bhattacharjee, G. Fiksel, P. Nilson, S. Hu, P.Y. Chang, D. Barnak, R. Betti Magnetic reconnection has recently been observed and studied in highenergydensity, laserproduced plasmas. These experiments are interesting both for obtaining fundamental data on reconnection, and may also be relevant for inertial fusion, as this magnetic reconnection geometry, with multiple, colliding, magnetized plasma bubbles, occurs naturally inside ICF hohlraums. We present initial results of experiments conducted on the OMEGA EP facility on magnetic reconnection between colliding, magnetized blowoff plasmas. While in previous experiments the magnetic fields were selfgenerated in the plasma by the Biermann battery effect, in these experiments the seed magnetic field is generated by pulsing current through a pair of external foils using the MIFEDS current generator (MagnetoInertial Fusion Electrical Discharge System) developed at LLE. Timeresolved images of the magnetic fields and plasma dynamics are obtained from proton radiography and xray selfemission, respectively. We present initial results of the experiments, including comparison to ``null'' experiments with zero MIFEDS magnetic field, and associated modeling using the radiationhydro code DRACO and the particleincell code PSC. [Preview Abstract] 

CP8.00041: Ion and Electron Heating Characteristics of Magnetic Reconnection in TS3, TS4 and MAST Merging Experiments Hiroshi Tanabe, Takuma Yamada, Akihiro Kuwahata, Hirotaka Oka, Masanobu Annoura, Kazutake Kadowaki, Michiaki Inomoto, Yasushi Ono, Setthivoine You, Mikhail Gryaznevich Characteristics of ion and electron heating during magnetic reconnection were investigated by use of 2D tomographic Doppler spectroscopy and 2D electrostatic probe measurement in TS3 and TS4 merging experiments. The magnetic reconnection heats electrons around X point and ions at the downstream, indicating that ion and electron heating are caused by outflow damping and sheet current dissipation, respectively. The different temperature profile of ions and electrons relax with the ionelectron relaxation time $\tau_{E_{ei}}$. The MAST merging experiment has a long confinement time $\sim$100msec and $\tau_{E_{ei}}\sim$20msec is two or three times longer than ion heating time $<$10msec. The current sheet first increases Te quickly up to $\sim$300eV around Xpoint and then slowly does up to 500eV $\sim$20msec after the reconnection. The heating efficiency depends on guide field for electrons and not for ions. The most sensitive parameter for ion heating is reconnecting magnetic field $B_{//}$ due to the outflow heating mechanism. The TS3 and TS4 results agree with the ion temperature increment scaled with $B_{//}^{2}$. We are now installing another 2D Doppler measurement for the MAST merging experiment and will study the reconnection heating in the high field regime $B_{//}>0.1$T. [Preview Abstract] 

CP8.00042: Experimental investigation of plasma pileup and ejection using TS4 plasma merging device Kazutake Kadowaki, Michiaki Inomoto, Yasushi Ono Plasma density pileup and following plasma ejection were observed for the first time by radial electron density profile measurement using an 8channel $\rm{CO_2}$ laser interferometer during the impulsive magnetic reconnection in the TS4 spherical tokamak merging experiment. Two merging spherical tokamaks under the high guide field were merged together in the axial direction and their reconnection was as slow as the steady SweetParker model under the small compressional force of the external coils. Under the strong compressional force, we observed multicycles of impulsive fast reconnection which is composed of the plasma pileup inside the current sheet and its ejection from the Xpoint repetitively. The density pileup in the current sheet and the plasma ejection inward accelerate the reconnection inflow about 2 times faster than the steady case. We modified the SweetParker model to include those two effects [1], and found that its new theoretical inflow velocity agrees well with the measured velocity. \\[4pt] [1] Y.Ono, \textit{et al}., Phys. Plasma, vol.18, 111213(2011). [Preview Abstract] 

CP8.00043: The Stability of Hollow and Zeronet Current Plasmas in a LineTied Geometry Matthew Brookhart, Carlos PazSoldan, Andrew Eckhart, Cary Forest The Linetied Reconnection Experiment, a linear screw pinch with linetied axial boundaries, creates plasma via a hexagonallypacked array of nineteen electrostatic current injectors (washer guns). These guns inject individually controlled current and density filaments which merge to form azimuthally symmetric plasmas. Hollow current profiles are explored and shown to be unstable at high safety factor ($>$10). The eigenmodes of these instabilities display nonline tied behavior. The injection of opposing current at the center of the device stabilizes the hollow current plasmas and may provide more rigorous line tying. Plasmas with no net current are explored and undergo sudden shifts in magnetic topology reminiscent of Magnetic Reconnection. Recent improvements to the device allow simultaneous detailed measurements of equilibrium and stability. [Preview Abstract] 

CP8.00044: Spectroscopic Measurement of Energy Conversion in Magnetic Reconnection during Spherical Tokamak Merging Experiment Shuji Kamio, Koichiro Takemura, Kotaro Yamasaki, Qinghong Cao, Hirotomo Itagaki, Takenori Watanabe, Takuma Yamada, Michiaki Inomoto, Yuichi Takase, Ono Yasushi The University of Tokyo Spherical Tokamak (UTST) is a spherical tokamak device with unique feature of plasma merging (magnetic reconnection), which is utilized as a highpower plasma heating for noninductive startup of highbeta plasma. During the plasma merging in the UTST device, intense emission of He II line (468.58nm) and impurity carbon lines were observed only in the vicinity of the Xpoint. This localized emission indicates the generation of energetic electrons inside the current sheet region, possibly due to the electron acceleration by the strong toroidal electric field induced by magnetic reconnection. This work was supported by JSPS KAKENHI (22246119 and 22686085), MEXT, Japan. [Preview Abstract] 

CP8.00045: Quasilinear Dynamo Effects In TwoFluid RFP Model V.V. Mirnov, C.C. Hegna, J.P. Sauppe, C.R. Sovinec Twofluid effects associated with electronion decoupling on small spatial scales modify tearing eigenmode properties and lead to nonzero flux surface averaged Hall dynamos in both slab and cylindrical models of the reversed field pinch (RFP). This result was originally derived for a forcefree equilibrium configuration [V.V. Mirnov et al., Plasma Phys. Rep. 29, 612 (2003), IAEA FEC TH/P318 (2006)], where contributions from diamagnetic drift effects were neglected. Many authors have investigated the role of equilibrium diamagnetic drift flows on the dynamics of tearing instabilities. For drifttearing instabilities, diamagnetic effects result in nonzero real mode frequency and corresponding changes to the eigenmode phase relations. We use quasilinear theory to evaluate the effect of the modified cross phases on the MHD and Hall dynamo contributions and analyze an additional dynamo mechanism due to the electron pressure term in the generalized Ohm's law. These results will be compared to measurements from the Madison Symmetric Torus RFP experiment. Numerical computations with the NIMROD code are performed and benchmarked with the analytical results to verify the drift behavior in NIMROD's twofluid model. [Preview Abstract] 

CP8.00046: Nonlinear evolution of $m=1$ and higher $m$ tearing modes in tokamaks in cylindrical and slab models Stephen Abbott, Kai Germaschewski The m=1 tearing mode is widely believed to be responsible for sawtooth crashes in tokamaks and, more broadly, as a paradigm of fast reconnection in collisionless plasmas. In past research, we have shown that including the Hall current in a generalized Ohm's Law will in fact exhibit nonlinear explosive growth behavior, though the accelerated evolution competes with pressuregradient introduced diamagnetic flows that can slow down or even suppress the instability. In this work, we quantify the impact of various parameters on the evolution of the $m=1$ mode, particularly in terms of the following length scales: ion sound radius, dissipation layer width, and pressure gradient scale length. We also consider higher poloidal mode numbers and compare the cylindrical extended MHD fluid model to corresponding single and double tearing modes in slab geometry, employing both fluid and kinetic simulations using the Magnetic Reconnection Code (MRC) and Particle Simulation Code (PSC). [Preview Abstract] 

CP8.00047: Magnetic reconnection in space Allen Boozer Models of magnetic reconnection in space plasmas generally consider only a segment of the magnetic field lines. The consideration of only a segment of the lines is shown to lead to paradoxical results in which reconnection can be impossible even in a magnetic field constrained to be curl free or can be at an Alfv\'{e}n rate even when the plasma is a perfect conductor though pressureless. A model of reconnecting magnetic fields is developed that shows the smallness of the interdiffusion distance d$_{d}$ of magnetic field lines does not limit the speed of reconnection but does provide a reconnection trigger. When the reconnection region has a natural length $L_{r}$, the spatial scale of the gradient of magnetic field across the magnetic field lines must reach $L_{g }\sim $ $L_{r}$ / ln($L_{r}$ /d$_{d})^{3}$ for fast reconnection to be triggered, which implies a current density \textit{j $\sim $ B/}$\mu _{0}L_{g}$. The relation between magnetic reconnection in space and in toroidal laboratory plasmas is also discussed. [Preview Abstract] 

CP8.00048: ABSTRACT WITHDRAWN 

CP8.00049: Magnetospheric Reconnection in Modified CurrentSheet Equilibria D.L. Newman, M.V. Goldman, G. Lapenta, S. Markidis Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a currentcarrying Harris equilibrium superposed on a currentfree uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the sheet current be dominated by the \textit{hotter} species  often the \textit{ions} in Earth's magnetosphere. This constraint is not necessarily consistent with observations. A \textit{modified} kinetic equilibrium that relaxes this constraint on the currents was proposed by Yamada et al. [\textit{Phys. Plasmas.}, \textbf{7}, 1781 (2000)] with no background population. These modified equilibria were characterized by an asymptotic converging or diverging \textit{electrostatic} field normal to the current sheet. By reintroducing the background plasma, we have developed new families of equilibria where the asymptotic fields are suppressed by Debye shielding. Because the electrostatic potential profiles of these new equilibria contain wells and/or barriers capable of spatially isolating different populations of electrons and/or ions, these solutions can be further generalized to include classes of \textit{asymmetric} kinetic equilibria. Examples of both symmetric and asymmetric equilibria will be presented. The dynamical evolution of these equilibria, when perturbed, will be further explored by means of implicit 2D PIC reconnection simulations, including comparisons with simulations employing standard Harrisequilibrium initializations. [Preview Abstract] 

CP8.00050: Numerical simulations of separatrix instabilities in collisionless magnetic reconnection Andrey Divin, Giovanni Lapenta, Stefano Markidis, David Newman, Marty Goldman Electron scale dynamics of magnetic reconnection separatrix jets is studied in this paper. Instabilities developing in directions both parallel and perpendicular to the magnetic field are investigated. Implicit particleincell simulations with realistic electrontoion mass ratio are complemented by a set of small scale high resolution runs having the separatrix force balance as the initial condition. A special numerical procedure is developed to introduce the force balance into the small scale runs. Simulations show the development of streaming instabilities and consequent formation of electron holes in the parallel direction. A new electron jet instability develops in the perpendicular direction. The instability is closely related to the electron MHD KelvinHelmholtz mode and is destabilized by a flow, perpendicular to magnetic field at the separatrix. Tearing instability of the separatrix electron jet is modulated strongly by the electron MHD Kelvin Helmholtz mode. Divin et al., PoP, 19, 042110 (2012) [Preview Abstract] 

CP8.00051: Adiabatic Phase Mixing and Fast Electron Heating in Thin current Sheet Haihong Che, James Drake, Marc Swisdak, Melvyn Goldstein Using particleincell simulations and kinetic theory, it's found that strong Buneman instability develop nonlinearly in thin current layer form in plasma with $\Omega_e/\omega_{pe}< 1$. The Buneman instability produces strong electric field and fast phase mixing which leads to the increase of electron temperature by more than a factor of 10 in a few tens of electron gyroperiods. The resonance of waveparticles feeds waves with particle's kinetic energy and causes the growth of waves and strong trapping of electrons in a large velocity range. We discovered it is the adiabatic movement of trapped electrons produce fast phase mixing when the particle's bounce rate is much larger than the growth and decay rate of waves. The adiabatic movement effectively exchange energy between particles and waves and redistribute the energy from high velocity electrons to low energy electrons with the assistance of the nonadiabatic crossing of separatrix of electron holes. The implications of the results for reconnection are being explored. [Preview Abstract] 

CP8.00052: VelocityShear Driven Magnetic Reconnection in ParticleInCell Simulations Carrie Black, Spiro Antiochos, Rick DeVore, Judy Karpen, Kai Germaschewski In the standard model for coronal mass ejections (CME) and/or solar flares, the free energy for the event resides in the strongly sheared magnetic field of a filament channel. The preeruption force balance consists of an upward force due to the magnetic pressure of the sheared field balanced by a downward tension due to overlying unsheared field. Magnetic reconnection is widely believed to be the mechanism that disrupts this force balance, leading to explosive eruption. For understanding CME/flare initiation, therefore, it is critical to model the onset of reconnection that is driven by the buildup of magnetic shear. In MHD simulations, the application of a magnetic field shear is a trivial matter. However, kinetic effects are important in the diffusion region and thus, it is important to examine this process with PIC simulations as well. The implementation of such a driver in PIC methods is nontrivial: it must be done in a selfconsistent manner that avoids the generation of waves that destroy the applied shear. In this work, we discuss methods for applying a velocity shear perpendicular to the plane of reconnection within a 2.5D, aperiodic, PIC system. We also discuss the implementation of boundary conditions that allow a net electric current to flow through the walls. [Preview Abstract] 

CP8.00053: Magnetic Reconnection Scaling from Kinetic Simulations Jeremiah Brackbill A kinetic simulation study of reconnection in two dimensions examines scaling from ion inertial to large scales. The initial conditions model a perturbed, Harris current sheet in a slab geometry with the same plasma conditions as the Geospace Environment Modeling challenge except with an ion to electron mass ratio equal to 180, and with one to many Xpoints in a periodic array. The spacing of the Xpoints is constant, so that a case with 16 Xpoints is 16 times as large as with 1 Xpoint both along and perpendicular to the current sheet. (The largest domain is 200 by 200 ion skin depths.) The reconnection rate and the amount of reconnected flux scales as the length of the current sheet. At saturation, there may be many current filaments, which begin immediately to coalesce and continue to do so until there results a single current filament. The entire process requires a time of the order of an Alfven transit time, and proceeds in basically the same fashion with very small initial perturbations, equal mass ions and electrons, or a zero background density. The simulations were performed with the implicitmoment, particleincell code CELESTE on a workstation. [Preview Abstract] 

CP8.00054: Influence of Spontaneously Generated Turbulence on Magnetic Reconnection William Daughton, Vadim Roytershteyn, Homa Karimabadi The 3D dynamics of reconnection is examined for electronpositron plasmas within Harris sheet geometry with a guide field. This configuration is unstable to tearing modes at resonant surfaces across the layer, corresponding to oblique angles relative to 2D models. Vlasov theory predicts a spectrum of oblique modes which can destroy the flux surfaces and produce interacting flux ropes. These structures coalesce to larger scales leading to the continual formation and breakup of new current sheets and the generation of turbulence. The fluctuation spectrum is highly anisotropic and is characterized by two powerlaws with a break at $k d_i \sim 1$, where $d_i$ is the inertial length. In the large 3D simulations, the dissipation rate is reduced by $\sim40$\% relative to small 2D cases which are steady and laminar. In both limits, the reconnection remains fast (i.e. Alfv\'enic), is insensitive to the system size and ultimately occurs within inertialscale current sheets. These results imply that the physics responsible for setting the time scale is not radically altered by the turbulence. However, the results indicate that a larger fraction of the magnetic energy is accessible in 3D and that many more particles are accelerated into the high energy tails due to the turbulence. [Preview Abstract] 

CP8.00055: Global Fully Kinetic Model of Magnetic Reconnection in a Magnetosphere Vadim Roytershteyn, Homa Karimabadi, William Daughton Magnetic reconnection is thought to play a key role in controlling dynamics of planetary magnetospheres. In the collisionless plasma it is a complex multiscale process, driven by macroscopic dynamics, but crucially dependent upon microscopic physics on the electron kinetic scales. Recent advances in highperformance computing have enabled us to conduct meaningful simulations that incorporate in a selfconsistent manner a large subset of the relevant physics. Here we present and discuss results of 2D simulations that describe reconnection in a selfconsistent global model. The system is driven by interaction of the solar wind with a magnetized body. We discuss reconnection at the magnetopuase with special attention paid to spatial location of the dominant reconnection site, time variability of the reconnection rate, and single vs multiple Xline scenarios. [Preview Abstract] 

CP8.00056: Kinetic Theory and Simulation of Magnetic Reconnection in ForceFree Current Layers YiHsin Liu, William Daughton, Hui Li, Homa Karimabadi While many studies of reconnection have focused on the Harris sheet equilibrium, which is relevant to Earth's magnetosphere, there has been growing interest in forcefree current sheets, which are thought to be more relevant in low$\beta$ regimes such as the solar corona. One important first step is to understand the evolution of tearing modes, which give rise to magnetic flux ropes in large 3D systems. It has been shown that flux rope generation and subsequent interaction can lead to the development of turbulence\footnote{Daughton et al, Nature Physics {\bf 7}, 539, 2011} which may also affect the acceleration of energetic particles. Here, we describe the linear kinetic analysis of the tearing mode for the forcefree configuration. We have verified the linear mode properties using 2D and 3D full particle simulations. In contrast to previous Harris sheet results,\footnote{Ibid.} the tearing instability in a forcefree current layer is unstable over a wide range of oblique angles. This suggests that forcefree current sheets may be even more susceptible to the generation of 3D turbulence in large systems. We will discuss the implications of this effect on the structure of the reconnection layers as well as associated particle acceleration. Heating efficiency in 2D and 3D will be compared. [Preview Abstract] 

CP8.00057: Gyrokinetic simulations of 2D magnetic reconnection turbulence in guide fields P.W. Terry, M.J. Pueschel, F. Jenko, E. Zweibel, V. Zhdankin, D. Told Following the analyses in [M.J.~Pueschel et al., Phys.~Plasmas \textbf{18}, 112102 (2011)], a study of turbulence in driven reconnection is commenced, with a sinusoidal current sheet providing the drive through a Krooktype operator in a biperiodic box. Simulations with the \textsc{Gene} code cover all relevant physical parameters, allowing for encompassing comparisons with expectations from linear simulations. A central observed feature are coherent circular current structures which may be identified as plasmoids. These objects move randomly in the plane perpendicular to the guide field, and may either disappear again after some time or instead merge with one anotherthe setup can thus be described as turbulence driven by reconnection, but simultaneously creating its own reconnection. Such merger events are associated with large bursts in the heating rate $j_\parallel E_\parallel$, and display strong nonMaxwellian components of the distribution function in parallel velocity space. The plasmoid energetics are studied, as are their ability to produce populations of fast particles. Statistics of such populations are used to facilitate direct comparisons with astrophysical scenarios of energetic particle production. [Preview Abstract] 

CP8.00058: Nonlinear gyrokinetic simulations of tearing instability Ryusuke Numata We present numerical results of nonlinear tearing mode simulations in a strong guide magnetic field limit using the \texttt{AstroGK} astrophysical gyrokinetics code. From the comparative study of linear tearing mode between gyrokinetics and twofluid MHD, significant discrepancy of the growth rate scaling have been observed in relatively highbeta plasmas [1] while they show good agreement in lowbeta. Since the Alfv\'en wave dynamics is coupled with the ion sound wave dynamics in highbeta plasmas, it is required to solve parallel ion dynamics kinetically rather than assuming simple adiabatic relations. In this work, we extend our study of the tearing mode to the nonlinear stage where discrepancy between gyrokinetics and fluid models is expected to become more significant. We discuss magnetic island evolution, saturation, and plasma heating due to magnetic reconnection in highbeta plasmas.\\[4pt] [1] R. Numata et al., Phys. Plasmas \textbf{18}, 112106 (2011). [Preview Abstract] 

CP8.00059: Plasmoid and KelvinHelmholtz instabilities in SweetParker current sheets Nuno Loureiro, Alexander Schekochihin, Dmitri Uzdensky A 2D linear theory of the instability of SweetParker current sheets is developed. It is shown that the current sheet is unstable to two modes. Close to the center of the sheet the plasmoid instability is recovered: current sheets are unstable to the formation of a large wave number chain of plasmoids ($k_{max}L_{CS} \sim S^{3/8}$, where $k_{max}$ is the wavenumber of fastest growing mode, $S=L_{CS} V_A/\eta$ is the Lundquist number, $L_{CS}$ is the length of the sheet, $V_A$ is the Alfv\'en speed and $\eta$ is the plasma resistivity), which grows superAlfv\'enically fast ($\gamma_{max}\tau_A\sim S^{1/4}$, where $\gamma_{max}$ is the maximum growth rate, and $\tau_A=Lsheet/V_A$). Away from the center of the sheet, it is found that the KelvinHelmholtz (KH) instability is triggered. The KH instability grows even faster than the plasmoid instability, $\gamma_{max} \tau_A \sim k_{max} L_{CS}\sim S^{1/2}$. The effect of viscosity ($\nu$) on the plasmoid instability is also addressed. In the limit of large Prandtl number, $Pm=\nu/\eta$, it is found that $\gamma_{max}\sim S^{1/4}Pm^{5/8}$ and $k_{max} L_{CS}\sim S^{3/8}Pm^{3/16}$; it is predicted that the critical Lundquist number for plasmoid instability in the $Pm\gg1$ regime is $S_c\sim 10^4 Pm^{1/2}$. [Preview Abstract] 

CP8.00060: MultiHierarchy Simulation of Magnetic Reconnection  HierarchyInterlocking in the Downstream Direction Shunsuke Usami, Hiroaki Ohtani, Ritoku Horiuchi, Mitsue Den In order to understand magnetic reconnection as a multihierarchy phenomenon, we have developed a multihierarchy simulation model which solves macroscopic and microscopic physics simultaneously and selfconsistently. In our multihierarchy model, the domain decomposition method is employed. The physics in the macrohierarchy is calculated by the MHD algorithm (MHD domain), and the dynamics in the microhierarchy is expressed by the PIC algorithm (PIC domain) [1]. Recently, with the hierarchyinterlocking in the upstream direction, we succeeded in the demonstration of multihierarchy simulation of magnetic reconnection. Aiming to apply our multihierarchy model to a larger system of magnetic reconnection in the future, we develop the hierarchyinterlocking model in the downstream direction. Using this model, we perform a multihierarchy simulation in which onefluid plasma flow with a Maxwellian velocity distribution propagates from PIC to MHD domains. We can see that plasma is smoothly and continuously injected from PIC to MHD domains. In our presentation, these multihierarchy simulation results and future plan will be demonstrated.\\[4pt] [1] S. Usami, H. Ohtani, R. Horiuchi, and M. Den, Comm. Comput. Phys. 11 (2012) 1006. [Preview Abstract] 

CP8.00061: Macro and micro physics of magnetic reconnection in a multihierarchy open system Ritoku Horiuchi, Mitsue Den, Takashi Tanaka, Hiroaki Ohtani, Shunsuke Usami Based on particleincell (PIC) simulation results of collisionless driven reconnection in a steady state [1], an effective resistivity model is developed for a global magnetohydrodynamic (MHD) simulation in order to bridge over huge gap between macro and micro physics of magnetic reconnection. A reconnection system evolves into a quasisteady state after an initial transient phase of about one iongyration period if the driving flow satisfies some condition [1]. In the steady state, reconnection electric field controlled by microscopic physics balances flux inflow rate which is determined by global dynamics in a macroscopic system. Thus, this effective resistivity model does not include any adjustable parameters relating to kinetic dissipation processes. This resistivity model is applied to global MHD phenomena controlled by magnetic reconnection in the earth magnetosphere. It is found that some global phenomena such as onset of magnetic substorm, dipolarization, and propagation of flux rope, detailed processes of which are longstanding questions, are well reproduced in a global MHD simulation and consistent with the observations.\\[4pt [1] W. Pei, R. Horiuchi, and T. Sato, Physics of Plasmas, Vol. \textbf{8}(2001), pp. 32513257. [Preview Abstract] 

CP8.00062: Simulation of secondary islands with a Lorentz ion/fluid electron hybrid model Jianhua Cheng, Scott Parker, Dmitri Uzdensky, Yang Chen Secondary islands have been intensively studied due to their role in the energy dissipation process of reconnection. Recently, we have studied magnetic reconnection initiated by the tearing instability. The simulation uses a hybrid model with Lorentz force ions and fluid electrons. For large $\Delta^{\prime}$ tearing mode, we have observed secondary islands forming and coalescing in the nonlinear regime. The competition between the two processes strongly influences the reconnection rate and eventually leads the reconnection to a steady state. To better understand these phenomena, detailed diagnostics are performed. The kinetic treatment of ions allows us to record the abnormally heated ions and the ion flow pattern around the secondary islands. These ion diagnostics help to explain how the hot ions are heated and hence how the magnetic energy is dissipated to the ion kinetic energy. Another interesting problem is the large inplane electric fields inside the secondary islands, which has been observed in magnetosphere. Our simulation will help understand the origin of these inplane electric fields. [Preview Abstract] 

CP8.00063: The plasmoid instability during asymmetric inflow magnetic reconnection Nicholas Murphy, Chengcai Shen, Jun Lin High Lundquist number current sheets have recently been found to be unstable to the formation of plasmoids. Numerical simulations of this instability have usually assumed that the reconnecting magnetic fields are symmetric. We therefore present resistive MHD simulations of the plasmoid instability during asymmetric inflow reconnection. Asymmetry in the upstream magnetic fields modifies the scaling, onset, and dynamics of this instability. Plasmoids develop preferentially into the weak magnetic field region. Outflow jets from individual Xlines impact magnetic islands obliquely rather than directly as in the symmetric case. Consequently, momentum deposition into the magnetic islands from the outflow jets is less efficient and outward advection of the islands is somewhat slower. The islands also develop net vorticity. Finally, we discuss the implications these simulations may have on the dynamics of the plasmoid instability in three dimensions. [Preview Abstract] 

CP8.00064: Distribution of Plasmoids in Large Scale Magnetic Reconnection YiMin Huang, A. Bhattacharjee, Lijia Guo Recent theoretical and numerical studies show strong evidences that current layers in large scale magnetic reconnection events become unstable to a superAlfv\'enic plasmoid instability. The reconnection layer changes to a chain of plasmoids connected by secondary current sheets which, in turn, may become unstable again. Eventually the reconnection layer will tend to a statistical steady state characterized by a hierarchical structure of plasmoids of various sizes. The hierarchical structure naturally suggests selfsimilarity across scales, which often leads to powerlaws. In this work, the distribution function $f(\psi)$ of magnetic flux $\psi$ in plasmoids is studied with resistive MHD simulations in highLundquistnumber regime. The distribution function is found to follow a powerlaw $f\sim\psi^{1}$. We propose an analytic phenomenological model that yields solutions consistent with the numerical findings. We compare the predictions of the model with observations from LASCO and TRACE of plasmoid distributions in postCME current sheets. [Preview Abstract] 

CP8.00065: Spontaneous transition to a fast 3D turbulent reconnection regime Lapo Bettarini, Giovanni Lapenta We show how the conversion of magneticfield energy via magnetic reconnection can progress in a fully threedimensional, fast, volumefilling regime. An initial configuration representative of many laboratory, space and astrophysical plasmas spontaneously evolves from the wellknown regime of slow, resistive reconnection to a new regime that allows to explain the rates of energy transfer observed in jets emitted from accretion disks, in stellar/solar flare processes as well as in laboratory plasmas. This process does not require any preexisting turbulence seed which often is not observed in the host systems prior to the onset of the energy conversion. The dynamics critically depends on the interplay of perturbations developing along the magneticfield lines and across them, a process possible only in three dimensions. The simulations presented here are the first able to show this transition in a fully threedimensional configuration. [Preview Abstract] 

CP8.00066: Simulations of magnetic reconnection in partially ionized plasmas with a reacting multifluid model Vyacheslav S. Lukin, James E. Leake, Mark G. Linton, Eric T. Meier We present the first ab initio reacting multifluid simulations of magnetic reconnection in a partially ionized plasma, where the ionized and neutral fluids are treated as coupled but distinct. Partially ionized plasma environments where magnetic reconnection is known or conjectured to take place range from highly collisional, e.g. interstellar medium and lower solar chromosphere with ionization fraction below $10^{3}$, to weakly collisional, e.g. in the upper solar chromosphere with ionization fraction of 1\%10\%. Different plasma processes, such as ionization and recombination, ionneutral interaction via Coulomb and chargeexchange collisions, Hall currents, and radiative losses can become the dominant factors in determining the reconnection rate and the structure of the reconnection region in different parameter regimes. The HiFi multifluid modeling framework has been used to implement all of the above processes in a single selfconsistent model and to perform 2D simulations of magnetic reconnection under a variety of plasma conditions. We observe the formation of previously predicted nonLTE current layers, as well as explore the associated early onset of the secondary plasmoid instability and the effects of guide field and Hall currents on the dynamics. [Preview Abstract] 

CP8.00067: ICF AND HEDP 

CP8.00068: The Current Beryllium Ablator NIF Ignition Target Design Jay Salmonson, Jose Milovich, Steven Haan, Darwin Ho We report the results of our effort to optimize and control sensitivities for the Beryllium (Be) ablator NIF ignition capsule design. We will show recent work on the latest (Revision 6) Be capsule with a maximum hohlraum radiation temperature of 295 eV and capsule radius 1.2 mm. In particular we will highlight recent efforts to mitigate against an elevated nonthermal, hard Xray ({$>$} 1.8 keV) component to the radiation drive that is predicted by current hohlraum simulations. These efforts include exploration of a variety of different dopants other than the traditional Copper. We particularly seek dopant materials that include Silicon (Si) due to its fortuitously placed absorption Kedge (1.8 keV). Candidates under consideration include SiC and SiO$_2$. We also explore various dopant radial concentration profiles including {\it i}) a uniform dopant throughout the ablator, {\it ii}) a graded, ``Olympic podium'' set of three layers of varying concentration, {\it iii}) as well as a hybrid combination of these two profiles. LLNLABS563631 [Preview Abstract] 

CP8.00069: Simulation of Ge Dopant Emission in IndirectDrive ICF Implosion Experiments Joseph MacFarlane, I. Golovkin, S. Regan, R. Epstein, R. Mancini, K. Peterson, L. Suter We present results from simulations performed to study the radiative properties of dopants used in inertial confinement fusion indirectdrive capsule implosion experiments on NIF. In Rev5 NIF ignition capsules, a Ge dopant is added to an inner region of the CH ablator to absorb hohlraum xray preheat. Spectrally resolved emission from ablator dopants can be used to study the degree of mixing of ablator material into the ignition hot spot. Here, we study the atomic processes that affect the radiative characteristics of these elements using a set of simulation tools to first estimate the evolution of plasma conditions in the compressed target, and then to compute the atomic kinetics of the dopant and the resultant radiative emission. Using estimates of temperature and density profiles predicted by radiationhydrodynamics simulations, we set up simple plasma grids where we allow dopant material to be embedded in the fuel, and perform multidimensional collisionalradiative simulations using SPECT3D to compute nonLTE atomic level populations and spectral signatures from the dopant. Recently improved Starkbroadened line shape modeling for Ge Kshell lines has been included. The goal is to study the radiative and atomic processes that affect the emergent spectra, including the effects of innershell photoabsorption and K$\alpha $ reemission from the dopant, and to study the sensitivity of the emergent spectra to the dopant and the hot spot and ablator conditions. [Preview Abstract] 

CP8.00070: ABSTRACT WITHDRAWN 

CP8.00071: Improved kinetic modeling of Knudsen layer reduction of fusion reactivity B.J. Albright, Chengkun Huang, Kevin J. Bowers, Kim Molvig, Eric M. Nelson, Evan S. Dodd, Nelson M. Hoffman Recent work by Molvig et al. [1] has led to renascent interest in the premise that fuel ions in tails of distribution functions in finite assemblies of thermonuclear fuel can be depleted by proximity to a boundary. This can lead to decreased fusion reactivity and yield in ICF capsules. In this presentation, the theory of Molvig et al. is reviewed, extended, and compared to kinetic particleincell simulations employing a binary collision model between plasma particles and lossy walls that absorb tail ions, reinjecting them as a ``core'' Maxwellian. Inferred reaction rates as a function of temperature and distance from a boundary are obtained from the simulations and compared with those found from various theoretical models. It is found that the Molvig et al. ``Knudsen distribution function'' provides an upper bound to the modification to reactivity, but that a more complete theory is required to accurately obtain these loss effects. \\[4pt] [1] Kim Molvig et al., submitted to Physical Review Letters. [Preview Abstract] 

CP8.00072: ParticleInCell modeling of the Knudsen layer reduction of fusion reactivity at high and low Z plasma interface Chengkun Huang, Brian J. Albright, Kevin J. Bowers, Kim Molvig, Eric M. Nelson, Evan S. Dodd, Nelson M. Hoffman The high Z and low Z ion interfaces produced in ICF capsule during implosion can reduce the amount of tail ions responsible for the majority of the fusion reactivity due to the higher collision rate in the high Z plasma. This effect can be significant at the Knudsen layer of the interface where the layer width corresponds to the mean free path of the tail ions [1]. We employ 1D3V ParticleInCell simulations with binary collision and a lossy wall boundary for the tail ions to model their diffusion across the Knudsen layer. Tail ion population and dynamics are evolved selfconsistently including effects such as slowdown and spreading, pitchangle scattering and ambipolar diffusion. Fusion reactivity of the low Z ion is calculated using BoschHale parameterization of the cross section data. Simulations are compared with result from simplified kinetic models and detailed benchmark will be presented and discussed.\\[4pt] [1] Molvig et al., submitted to Physical Review Letters. [Preview Abstract] 

CP8.00073: Ion distribution in the hot spot of an inertial confinement fusion plasma Xianzhu Tang, Zehua Guo, Herb Berk Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform FokkerPlanck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by FokkerPlanck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated. [Preview Abstract] 

CP8.00074: Compression of matter by hyperspherical shock waves Masakatsu Murakami, Yukiharu Iwamoto, Javier Sanz A novel compression scheme is proposed, in which hollow targets with specifically curved structures initially filled with uniform matter, are driven by a converging shock waves. The selfsimilar dynamics are analyzed for converging and diverging shock waves. Owing to the geometrical accumulation, the shockcompressed densities and pressures are substantially higher than those achieved using spherical shocks. Twodimensional hydrodynamic simulations are developed. A linear stability analysis for the spherical geometry reveals a dispersion relation with cutoff mode numbers that are a function of the specific heat ratio, above which eigenmode perturbations are smeared out in the converging phase. [Preview Abstract] 

CP8.00075: Multiview arealdensity maps of compressed shells in OMEGA directdrive implosions extracted from MMI data Heather Johns, Tirtha Joshi, Daniel Mayes, Tunay Durmaz, Roberto Mancini, Riccardo Tommasini, Jacques Delettrez, Sean Regan, Taisuke Nagayama In a series of implosion experiments performed at the OMEGA laser facility, spherical plastic shells doped with an embedded titanium tracerlayer and filled with deuterium gas were driven with high and lowadiabat laser pulse shapes. The titanium emergent intensity distribution was recorded with a streaked spectrometer and three identical gated, multimonochromatic xray imaging instruments (MMI) that observed the implosion along three quasiorthogonal linesofsight. The data shows spectral signatures due to absorption Kshell line transitions in titanium Lshell ions that are backlit by the continuum radiation from the hot core. To interpret these observations, the MMI spectrallyresolved image data were processed to obtain narrowband images and spatiallyresolved spectra based on the titanium spectral features.\footnote{T. Nagayama, R.C. Mancini, R. Florido, \textit{et al}, J. App. Phys. \textbf{109}, 093303 (2011)} Arealdensity maps were extracted using two independent methods based on narrowband images and spatiallyresolved spectra. The arealdensity maps reveal the 3D structure and state of the compressed shell through the collapse of the implosion and the performance differences between high and lowadiabat implosions. [Preview Abstract] 

CP8.00076: SelfGenerated Magnetic Field Effects in National Ignition Facility Capsule Simulations Joseph Koning The self generated magnetic field effects for the National Ignition Facility tritiumhydrogendeuterium (THD) capsule design are simulated in 2D using the multiphysics code HYDRA. In the simulation the magnetic field is generated through the curl of the electron pressure gradient initiated through the RayleighTaylor instability and evolved due to magnetic diffusion, and advection. The calculation accounts for the magnetic field to determine anisotropic thermal electron and ion conduction as well as effects on the alpha particles in the burn phase. Transport coefficients are calculated using the EpperleinHaines coefficients with LeeMore degeneracy corrections. Maximum field magnitudes in excess of 30 MG are observed in the simulations. Comparisons for capsule designs with and without perturbations on the CH ablator/DT ice layers and radiation source are performed. [Preview Abstract] 

CP8.00077: Raytrace implementation for Polar DirectDrive Targets Andrew J. Schmitt, Jason Bates, David Eimerl An accurate description of laser light propagation in the underdense corona of inertial fusion targets is needed to properly calculate both the distribution and uniformity of the laser deposition, which determines the drive pressure. This is particularly important for asymmetric illumination scenarios such as polar directdrive on the NIF. The customary way of handling light propagation and deposition involves solving the equations of geometrical optics for individual rays in each laser beam, then depositing the absorbed laser energy along the ray trajectory. One problem with raytracing is the noise generated by the deposition of inherently 1dimensional rays. Either very large numbers of rays are used (smoothing as $\sim N_{rays}^{1/2}$) or artificial smoothing is needed. The former requires excessive computation time, while the latter can eliminate the desired nonuniformity structure. In our new implementation of 3D raytracing in the MPIparallel FAST hydro code, we are exploring a new approach that increases the speed of the raytracing while reducing the deposition noise. We will review this approach, describe our progress, and apply the techniques to problems of polar directdrive target design. [Preview Abstract] 

CP8.00078: Analysis and Description of the Sources of Nuclear Signals from ICF Capsules Scott Sepke, Charles Cerjan, Andrea Kritcher, Michael Marinak, Paul Springer, Johan Frenje, Maria Gatu Johnson, Alex Zylstra, Gary Grim, Hans Herrmann Using the ALE multiphysics code HYDRA, a detailed accounting of the various nuclear processes and their relative importance in ICF plasmas is made for each of the main target platforms used at the National Ignition Facility (NIF): symcaps and layered THD and DT capsules. Special attention is given to the individual features observed in calculated and measured neutron spectra and images. These arise primarily from thermonuclear reactions, elastic scattering, and the D(n,2n) reaction. Under NIF conditions, a significant fraction of the neutrons undergo multiple scattering events before escaping the capsule. We examine the signatures of multiple scattering events, their dependence upon $\rho$R and the solid angle sampled by the detector. Generation of protons both by D$^{3}$He fusion during the shock flash in a symcap and from knock on reactions in the plastic ablator in all three platforms is discussed. Models for calculating the proton energy spectrum observed outside of the hohlraum are presented. Finally, the energy spectrum of gamma rays generated within a plastic ICF capsule is presented for both Si and Ge doped capsules. [Preview Abstract] 

CP8.00079: Nonlocal electron transport validation using 2D DRACO simulations Duc Cao, Jeff Chenhall, Eli Moll, Alex Prochaska, Gregory Moses, Jacques Delettrez, Tim Collins Comparison of 2D DRACO simulations, using a modified version\footnote{private communications with M. Marinak and G. Zimmerman, LLNL.} of the Schurtz, Nicolai and Busquet (SNB) algorithm\footnote{Schurtz, Nicolai and Busquet, ``A nonlocal electron conduction model for multidimensional radiation hydrodynamics codes,'' Phys. Plasmas 7, 4238(2000).} for nonlocal electron transport, with direct drive shock timing experiments\footnote{T. Boehly, et. al., ``Multiple spherically converging shock waves in liquid deuterium,'' Phys. Plasmas 18, 092706(2011).} and with the Goncharov nonlocal model\footnote{V. Goncharov, et. al., ``Early stage of implosion in inertial confinement fusion: Shock timing and perturbation evolution,'' Phys. Plasmas 13, 012702(2006).} in 1D LILAC will be presented. Addition of an improved SNB nonlocal electron transport algorithm in DRACO allows direct drive simulations with no need for an electron conduction flux limiter. Validation with shock timing experiments that mimic the laser pulse profile of direct drive ignition targets gives a higher confidence level in the predictive capability of the DRACO code. This research was supported by the University of Rochester Laboratory for Laser Energetics. [Preview Abstract] 

CP8.00080: Collaborative comparison of highenergydensity physics codes (LAUR1222121) Bruce Fryxell, Milad Fatenejad, John Wohlbier, Eric Myra, Don Lamb, Chris Fryer, Carlos Graziani, Zach Medin, Rick Rauenzahn Radiationhydrodynamic simulations are vital to understanding highenergydensity physics (HEDP) experiments. We are in the process of comparing three HEDP codes, including CRASH (U. of Michigan), FLASH (U. of Chicago), and xRAGE (LANL) on a wide variety of problems, ranging from simple tests to full HEDP experiments. The goals are to understand the differences between the codes and how they influence the results, to determine which codes contain the most accurate algorithms and physics models, and where possible, to improve the other codes to produce more faithful representations of HEDP experiments. The calculations discussed here include simple temperature relaxation problems in an infinite, uniform medium, tests of the diffusion solvers (both conduction and radiation), and tests that add hydrodynamic effects, The eventual goal is to compare the results from all of the codes on simulations of radiative shock experiments being performed by The Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan and to understand any discrepancies between the results of the simulations and the experiments. [Preview Abstract] 

CP8.00081: Improvements to the FLASH code for Simulating HEDP Experiments Milad Fatenejad, John Bachan, Sean Couch, Chris Daley, Anshu Dubey, Norbert Flocke, Carlo Graziani, Don Lamb, Dongwook Lee, Anthony Scopatz, Petros Tzeferacos, Klaus Weide FLASH is an open source, compressible spatially adaptive radiation magnetohydrodynamics code that incorporates capabilities for a broad range of physical processes, performs well on a wide range of existing advanced computer architectures, and has a broad user base. Capabilities have been incorporated into the FLASH code to enable simulations of laserdriven HEDP experiments. We summarize recent improvements to the HEDP capabilities of the FLASH code and present results from several collaborations that use FLASH to simulate HEDP experiments. The ray trace that package models laser energy deposition has been substantially improved. Methods have been added for smoothing laser deposition and a ``3Din2D'' ray trace has been added for improved accuracy in 2D cylindrical simulations. Numerous improvements have been made to the FLASH MHD solver, including support for 2D cylindrical geometry and magnetic resistivity. Postprocessing scripts have been generated that enables the SPECT3D simulated diagnostic software to operate on FLASH output. The results of several verification tests will also be presented. [Preview Abstract] 

CP8.00082: Improvements to the FLASH Laser Energy Deposition Package Norbert Flocke, J. Bachan, S. Couch, C. Daley, A. Dubey, M. Fatenejad, C. Graziani, Don Lamb, Dongwook Lee, A. Scopatz, P. Tzeferacos, K. Weide FLASH is an open source, compressible, spatiallyadaptive, radiation magnetohydrodynamics code that is currently used at a number of institutions for simulating laserdriven HEDP experiments. FLASH uses raytracing to model laser energy deposition via the inverseBremsstrahlung process on an Eulerian blockstructured mesh. We describe recent improvements to the laser raytracing package in FLASH which have led to increased accuracy and performance. A ``3Din2D'' raytrace model has been developed which transports rays in threedimensions when FLASH is configured to run in 2D cylindrical geometry. Several options have been added which allow users greater flexibility in choosing the initial ray placement. These options can be used to reduce the number of rays needed to accurately represent the energy deposition. Several models have been added to FLASH for smoothing the deposited laser energy to reduce numerical noise. The laser package has also been modified to use threading and meshreplication for parallelization to improve computational performance. Finally, we will present the results of FLASH simulations that use these improvements and compare results using different laser options. [Preview Abstract] 

CP8.00083: Solutions for the velocitydependent Krook (VDK) model using Helmoltz equations Denis Colombant, Wallace Manheimer, Andrew Schmitt Our previous treatment for the solutions of the VDK model involved the use of a Green's function [1]. We now solve directly the Helmoltz equation describing the model in 1D (and 2D as previously described in ref.2). This involves the numerical solution of a diffusionlike equation for each energy group in steadystate. We present comparisons between the two methods of solution on test problems and on one typical implosion calculation [2]. Sensitivity of the solution to the number of energy (velocity) groups is also presented since this is an important component affecting the total computing time for this model. Further work will also be discussed. \\[4pt] [1] W. Manheimer, D. Colombant and V. Goncharov, Phys. Plasmas \textbf{15}, 083103 (2008).\\[0pt] [2] W. Manheimer, D. Colombant and A.J. Schmitt, Phys. Plasmas \textbf{19}, 056317 (2012). [Preview Abstract] 

CP8.00084: Anomalous Photoionization in Xe Marcel Klapisch, Michel Busquet Photoionization (PI) cross sections are important components of the opacities that are necessary for the simulation of astrophysical and ICF plasmas. Most of PI cross sections (i) start abruptly at threshold and (ii) decrease as an inverse power (e.g.3$^{rd})$ of the photon energy. In the framework of the CRASH project [1] we computed Xe opacities with the STA code [2]. We observed that the PI cross section for the 4d shell has neither of these 2 characteristics. We explain this result as interference between the bound 4d wavefunction (wf), the photon, and the free electron wf. Similar, but less pronounced effects are seen for the 5d and 5p shells. Simplified models of PI not involving the actual wf would not show this effect and would probably be inaccurate.\\[4pt] [1] Doss, F. W., Drake, R. P., and Kuranz, C. C., \textit{High Ener. Dens. Phys.} \textbf{6}, 15761.\\[0pt] [2] Busquet, M., Klapisch, M., BarShalom, A.\textit{, et al.}, \textit{Bull. Am. Phys. Soc.} \textbf{55}, 225 (2010). [Preview Abstract] 

CP8.00085: pF3D modeling of NIF Ignition experiments E.A. Williams, D.E. Hinkel, A.B. Langdon, S.H. Langer, R.L. Berger, C.H. Still We use our laser plasma interaction code pF3d to gain insight into SRS and SBS scattering in NIF ignition hohlraums. pF3d had success in modeling Omega experiments in which a single probe beam was propagated along a hohlraum axis. Satisfactory reflectivities were obtained, saturating via local pump depletion, without invoking reduced models for the nonlinear evolution of the plasma and ion acoustic waves (1). On Omega we had Thomson scattering data to validate the plasma conditions; in NIF we use the SRS and SBS spectra but direct measurements are lacking. Early inconsistency in the observed and anticipated spectra pointed to improved modeling (2). The scale of the Omega experiments allowed for modeling the entire probe beam path. Modeling the entire volume traversed by neighboring NIF beams is not feasible on current machines, necessitating restricting the simulation to the anticipated interaction volume. The larger scale and the beam geometry of NIF make multibeam effects of greater importance. Wavelength tuning gives rise to large, nonuniform energy transfer between the outer and inner beam cones. Multiple beams overlap in the region of SRS inner beam generation. We use a variety of tools, including SLIP, to prepare suitable inputs and postprocess the outputs of pF3d. [Preview Abstract] 

CP8.00086: Toward improved characterization of laser plasma coupling in NIFscale plasmas William Kruer, Pierre Michel, John Moody, Laurent Divol To date laser plasma coupling has been ``good enough'' (i.e., gives sufficient drive as well as sufficiently controllable symmetry) to enable numerous welldiagnosed NIF implosion experiments. On a longer time scale, an improved characterization of laser plasma coupling in NIFscale plasmas is desirable both for ignition and other high energy density physics experiments. Important issues include the timedependence of the cross beam energy transfer, the role of stimulated sideward scattering of laser light in the hohlraum, overlapping beam effects on stimulated scattering, the efficiency with which quartercritical density instabilities generate superhot electrons, and the evolving plasma conditions within the hohlraum. Simple experiments to address some of these issues are discussed. [Preview Abstract] 

CP8.00087: Thermal effects on the electron density fluctuation spectra in NIF plasmas W. Rozmus, T. Chapman, M. Tzoufras, R. Berger, S. Brunner, L. Divol, P. Michel, E. Williams, S. Glenzer The high flux model of ignitionscale hohlraum plasmas includes the strong thermal flux from the region of laser beam overlap at the entrance hole of the hohlraum along the directions of the inner cone beams. We have examined results of this large heat flow at the kinetic level using FokkerPlanck codes, which reproduce the temperature profile and corresponding electron distribution functions on the millimeter scale of NIF plasmas. Using the first harmonic of the electron distribution, we have identified contributions from the energetic, heat carrying electrons and the return current component within the bulk of the distribution function. In hot NIF plasmas, the heatcarrying electrons have energies (2040 keV) that are close to resonance with Langmuir waves produced by SRS. By calculating the plasma dielectric function using distribution functions extracted from FokkerPlanck simulations, we have found a significant reduction in the linear Landau damping for the Langmuir waves propagating in the direction of heat flow, potentially contributing to the onset of backward SRS. This effect was further examined in Vlasov simulations and by calculations of the electrostatic fluctuation levels. [Preview Abstract] 

CP8.00088: Energy Transfer between Laser Beams by Stimulated Brillouin Scattering in Plasmas K.A. Humphrey, D.C. Speirs, K. Ronald, A.D.R. Phelps, S.L. McConville, F. Fiuza, L. Silva, R. Cairns, I. Vorgul, R.M.G.M. Trines, P. Norreys, R. Bingham Energy exchange between crossing laser beams in a plasma is of particular interest for indirect drive inertial confinement fusion. In order to ensure uniform compression of the fuel capsule it is essential that the laser beams incident on the hohlraum deliver symmetrical irradiation and heating to the pellet to mitigate the possibility of the capsule prematurely breaking apart before the fusion process takes place. One mechanism which can be exploited to ensure uniform spherical compression of the target is stimulated Brillouin scattering whereby the laser energy from adjacent beams can be transferred from one to the other to deliver a tuneable mechanism by which laser energy can be redistributed to specific areas of the target. Brillouin scattering is a parametric instability and takes the form of a threewave interaction via the scattering of a high frequency transverse wave by a low frequency ionacoustic wave into a different transverse wave. As the frequency of the ion acoustic wave is typically much lower than the laser frequency a large fraction of the energy can be transferred between the laser beams. Numerical simulations of the laserplasma dynamics associated with this stimulated energy transfer process will be presented and discussed. [Preview Abstract] 

CP8.00089: Increasing beam power and energy with the SBS forward energy transfer instability R.K. Kirkwood, R.A. London, W.H. Dunlop, P.A. Michel, E.A. Williams, K.B. Fournier, O.L. Landen, B.J. MacGowan The understanding of the exchange of forward going power and energy between two crossing beams in a plasma [1] is now sufficiently developed that it can be used to enable access to new experimental configurations. The existing models of the process allow the design of beam combiners that will produce higher energy in individual beams for new applications in ignition and HED physics. For example the Energy Partitioning and Energy Coupling (EPEC) [2] program is simulating nuclear events in various environments by delivering energy to the center of a chamber through a narrow tube that allows minimal perturbation of the surrounding region. We will describe the design of gas filled targets that will allow a 2x to 5x increase in the energy in a single NIF quad to enable higher yield events to be simulated in EPEC. These designs as well as advanced ignition target designs will require models with improved precision to predict their performance accurately. We will also compare the predictions of existing and emerging models of wave saturation [3] with the existing experimental data to determine the uncertainty in the models.\\[4pt] [1] P. Michel Physics of Plasmas 2010.\\[0pt] [2] K. Fournier, these proceedings\\[0pt] [3] P. Michel, E. Williams, these proceedings. [Preview Abstract] 

CP8.00090: ABSTRACT WITHDRAWN 

CP8.00091: VlasovFokkerPlanck Simulation of a Collisional IonElectron Shockwave William Taitano, Dana Knoll, Anil Prinja There has been recent increased interest in a range of kinetic plasma physics phenomena which may be important in simulating ICF pellet performance. [1] have numerically demonstrated the limitations of the classic Spitzer, Braginski fluid closures in collisional plasmas for shockwave problems. [1] has shown the importance of modeling kinetic effects for scale lengths of shockwave much larger than the ion collision mean free path. In [1], the ions were modeled kinetically using the FokkerPlanck approximation while the electrons were modeled as a fluid. An investigation of a full kinetic treatment of electron with collision is computationally intractable with standard explicit schemes due to collision CFL limitation that requires resolving the electronelectron collision timescale. [2] has developed a new, fully implicit and discretely consistent moment based accelerator method to solve the full ionelectron kinetic VlasovAmpere system. A similar moment based accelerator will be extended to a collisionless shock problem in order to accelerate the FokkerPlanck collision source in the kinetic equations. In the presentation, we provide some preliminary results. \\[4pt] [1] M. Casanova and O. Larroche, Phys. Rev. Let. 67(16), 1991. \\[0pt] [2] W.T. Taitano et al. SISC in review. [Preview Abstract] 

CP8.00092: Kinetic simulations of shock ignition targets John Tonge, Michail Tzoufras, Adam Tableman, Frank Tsung, Warren Mori Kinetic effects during the spike of the drive laser pulse are crucial in assessing the feasibility of the shock ignition scheme for inertial confinement fusion. Specifically, the shock efficiency is a function of the hot electron generation in the underdense region, the transport of these hot electrons through the plasma, and the energy deposition and the associated shock formation dynamics. In order to provide a detailed description of the underlying physical mechanisms and their interdependence, and to assist target design and the interpretation of experiments, we have initiated an integrated study employing the ParticleInCell code OSIRIS, the hybridPIC code OSIRISH and the 2D3P VlasovFokkerPlanck code OSHUN. OSIRIS is used to investigate the absorption of the laser energy in the underdense corona due to laserplasma interactions and to provide the detailed structure of the hot electron distribution function. The transport of the hot electrons and the formation of the shock are studied with both OSIRISH and OSHUN. We will present preliminary results from our simulations and discuss their implications for shock ignition and more generally for the generation of shocks in laserirradiated plasmas. [Preview Abstract] 

CP8.00093: Particleincell Simulations on LaserPlasma Interactions in Shock Ignition R. Yan, C. Ren, J. Li, A.V. Maximov, W. Theobald, K.S. Anderson, R. Betti, W.B. Mori, F.S. Tsung We present a series of 1D and 2D particleincell (PIC) simulations using the full PIC code \textit{OSIRIS} for the shock ignition experiments carried out on the OMEGA facility. The laser intensity is $I = 2 \times 10^{15}$/cm$^2$. The density profile used in PIC simulations is provided by the hydro simulation and has the scale length $L = 17\mu$ m at the quartercriticaldensity surface. Physical electronion collisions are included in our simulations with a benchmarked collision package in \textit{OSIRIS}. The 1D simulation covering a larger density range (0.020.4$n_{cr}$) shows that SRS occurs mostly near the quartercriticaldensity surface. The reflected lights due to SRS and SBS are measured in the 1D simulation. The 2D simulations are performed near the quartercriticaldensity surface to include the twoplasmon decay (TPD). The 2D simulations show a bursting pattern of plasma waves near the quartercriticaldensity surface. TPD modes with large $k_{\perp}$'s are found dominant in 2D simulations, which generate much more hot electrons than the 1D simulation. The forward electron flux ($>$50keV) is 10{\%} of the incident laser flux in the 2D simulation by 12ps, which is in good agreement with the experimental measurements. [Preview Abstract] 

CP8.00094: Particleincell Simulations of laser plasma interactions near the quarter critical surface F.S. Tsung, B.B. Afeyan, W.B. Mori We present simulation results on the laserplasma interaction near the quarter critical surface under conditions relevant to inertial fusion. Under these conditions, the high frequency hybrid instability (HFHI) where the backward going daughter wave have mixed polarizations, is likely to be dominant. In high temperature plasmas where HFHI modes is dominant the absorption level can be high (up to 40\%) for systems which are below the two plasmon threshold. This result implies, for laser pulses with a long (compared to the instability growth time, in the order of 1ps) rise time, the mixed polarization modes with small perpendicular wavenumber will play a even more dominant role. The effects of finite spotsize due to laser speckles, and the interaction of overlapping speckles will also be investigated. [Preview Abstract] 

CP8.00095: Kinetic Simulations of Electron Plasma Waves: trapped electron filamentation and sideband instabilities Stephan Brunner, R.L. Berger, J.W. Banks, B.I. Cohen, T. Chapman, J.A.F. Hittinger, W. Rozmus, D.J. Strozzi, B.J. Winjum, E.J. Valeo Kinetic simulations of nonlinear electron plasma waves (EPW) are presented in 2D with the Vlasov code LOKI (2 space and 2 velocity dimensions; Banks et al., Phys. Plasmas 18, 052102 (2011)). Propagating EPWs are created with an external wave potential with uniform transverse amplitude. The evolution of the plasma wave field and its selfconsistent quasisteady distribution of trapped electrons is studied after the external drive is turned off. For finiteamplitude EPWs, the onset of the trappedelectroninduced filamentation instability (H. Rose, Phys. Plasmas 15, 042311 (2008)) and trapped electron sideband instability (S. Brunner and E. Valeo, PRL 93, 145003 (2004)) are studied as a function of wave amplitude and $k_0 \lambda_{De}$, where $k_0$ is the wavenumber of the external potential. We extend the theory of Kruer {\it et al} PRL {\bf 23}, 1969 to 2D to find growth rates of both instabilities and compare these to the ones obtained from the simulations. In the nonlinear state, the distribution of resonant electrons is dramatically modified [Preview Abstract] 

CP8.00096: PIC simulations of the trapped electron filamentation instability in finitewidth electron plasma waves B.J. Winjum, J.W. Banks, R.L. Berger, B.I. Cohen, T. Chapman, J.A.F. Hittinger, W. Rozmus, D.J. Strozzi, S. Brunner We present results on the kinetic filamentation of finitewidth nonlinear electron plasma waves (EPW). Using 2D simulations with the PIC code BEPS, we excite a traveling EPW with a Gaussian transverse profile and a wavenumber $k_0\lambda_{De} = 1/3$. The transverse wavenumber spectrum broadens during transverse EPW localization for small width (but sufficiently large amplitude) waves, while the spectrum narrows to a dominant $k_{\perp}$ as the initial EPW width increases to the planewave limit. For large EPW widths, filaments can grow and destroy the wave coherence before transverse localization destroys the wave; the filaments in turn evolve individually as selffocusing EPWs. Additionally, a transverse electric field develops that affects trapped electrons, and a beamlike distribution of untrapped electrons develops between filaments and on the sides of a localizing EPW. \it{This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC5207NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12ERD061. Supported also under Grants DEFG5209NA29552 and NSFPhy0904039. Simulations were performed on UCLA's Hoffman2 and NERSC's Hopper.} [Preview Abstract] 

CP8.00097: Optical Mixing in the Strong Coupling Regime: A New Method of Beam Conditioning at Hohlraum LEH and Direct Drive ICF Coronal Plasmas Marine Mardirian, Bedros Afeyan, Stefan Huller, David Montgomery, Dustin Froula, Robert Kirkwood We will present theoretical and computational results on Brillouin interactions between two beams in co, counter, and orthogonal propagation geometries. The beams will be structured (with speckle patterns), the plasma will have inhomogeneous flow including the Mach 1 surface. As the growth rate of the instability surpasses the natural frequency of the ion wave, the strong coupling regime (SCR) is reached, where reactive quasimodes with intensity dependent frequency shifts result. This is especially true in laser hot spots. We trace the consequences of operations in this regime with different damping rates on the ion acoustic waves. We consider convective and absolute instabilities as well as the design of experiments which could examine these new regimes of instability behavior with new 10 psec time resolved diagnostics. Whether well enough conditioned beams can result after 10's or 100's of pairwise crossings in direct and indirect drive ICF configurations, and whether SRS can thus be strongly suppressed downstream, remains to be demonstrated. But the prospects exist for such new paths to instability control in a staged manner before STUD pulses are implemented. [Preview Abstract] 

CP8.00098: Measurements of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research Jaechul Oh, J.L. Weaver, S.P. Obenschain, A.J. Schmitt, D.M. Kehne, M. Karasik, LY. Chan, V. Serlin, L. Phillips Experiments\footnote{J. Oh, et al, GO5.4, APS DPP (2010).}$^,$\footnote{J. L. Weaver, et al, GO5.3, APS DPP (2010).} using Nike KrF laser observed LPI signatures from CH plasmas at the laser intensities above $\sim 1\times 10^{15} W/cm^2$. Knowing spatial profiles of temperature ($T_e$) and density ($n_e$) in the underdense coronal region ($0 < n < n_c/4$) of the plasma is essential to understanding the LPI observation. However, numerical simulation was the only way to access the profiles for the previous experiments. In the current Nike LPI experiment, a sideon grid imaging refractometer (GIR)\footnote{R. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993).} is being deployed for measuring the underdense plasma profiles. The GIR will resolve $T_e$ and $n_e$ in space taking a 2D snapshot of probe laser ($\lambda = 263 nm$, $\Delta t = 10 psec$) beamlets ($50\mu m$ spacing) refracted by the plasma at a selected time during the laser illumination. Timeresolved spectrometers with an absoluteintensitycalibrated photodiode array and a streak camera will simultaneously monitor light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay (TDP) instabilities. The experimental study of effects of the plasma profiles on the LPI initiation will be presented. [Preview Abstract] 

CP8.00099: Mitigating LaserPlasma Instabilities in Hohlraum LaserPlasmas Using Magnetic Insulation D.S. Montgomery, A. Simakov, B.J. Albright, L. Yin, J.R. Davies, G. Fiksel, D.H. Froula, R. Betti Controlling laserplasma instabilities in hohlraum plasmas is important for achieving highgain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense lowZ plasma to the dense highZ hohlraum wall [1]. This leads to weaker Landau damping and stronger growth of parametric instabilities. For NIF laserplasma conditions, it is shown that a 10T external magnetic field may substantially reduce crossfield transport and may increase plasma temperatures, thus increasing linear Landau damping and mitigating parametric instabilities. Additional benefits may be realized since the hot electrons will be strongly magnetized and may be prevented from reaching the capsule or hohlraum walls. We will present calculations and simulations supporting this concept, and describe experimental plans to test the concept using gasfilled hohlraums at the Omega Laser Facility.\\[4pt] [1] M.D. Rosen et al., High Eng. Dens. Phys. 7, 180 (2011). [Preview Abstract] 

CP8.00100: Implementation of STUD Pulses at the Trident Laser and Initial Results R.P. Johnson, T. Shimada, D.S. Montgomery, B. Afeyan, S. H\"{u}ller Controlling and mitigating laserplasma instabilities such as stimulated Brillouin scattering, stimulated Raman scattering, and crossedbeam energy transfer is important to achieve highgain inertial fusion using laser drivers. Recent theory and simulations show that these instabilities can be largely controlled using laser pulses consisting of spike trains of uneven duration and delay (STUD) by modulating the laser on a picosecond time scale [1,2]. We have designed and implemented a STUD pulse generator at the LANL Trident Laser Facility using Fourier synthesis to produce a 0.5ns envelope of psecduration STUD pulses using a spatial light modulator. Initial results from laser propagation tests and measurements as well as initial laserplasma characterization experiments will be presented.\\[4pt] [1] B. Afeyan and S. H\"{u}ller, ``Optimal Control of Laser Plasma Instabilities using STUD pulses,'' IFSA 2011, P.Mo.1, to appear in Euro. Phys. J. Web of Conf. (2012).\newline [2] S. H\"{u}ller and B. Afeyan, ``Simulations of drastically reduced SBS with STUD pulses,'' IFSA 2011, O.Tu81, to appear in Euro. Phys. J. Web of Conf. (2012). [Preview Abstract] 

CP8.00101: STUD Pulse performance comparisons between weak and strong damping limits of SBS Stefan Huller, Bedros Afeyan The physical mechanisms that make STUD pulses (spike trains of uneven duration and delay) optimal rely, among other physical effects, on damping of the driven waves in between spikes. By varying the damping of ion acoustic waves in inhomogeneously flowing plasma regions ranging from 8 to 2 of the Mach number, we can establish to what extent STUD pulses can be effective to control SBS growth in various damping levels. By changing the duty cycle of the chain of spikes, by changing their modulation period, by adding random inter spike phase kicks and by changing the spatial hot spot profile scrambling rate, we establish bounds on how much Brillouin backscattering Rosenbluth gain can be tolerated at the average intensity and still have STUD pulses control SBS as compared to RPP or SSD or ISI. The situation is complicated by the implication of the strong coupling regime in hot spots, by pump depletion and by initial noise level dependencies which we also examine. [Preview Abstract] 

CP8.00102: Ponderomotive versus Thermal Filamentation in High Z Targets Robert Bingham, Raoul Trines, Peter Norreys, Luis Silva, Alan Cairns The filamentation instability of lasers in high Z plasmas is investigated. The wavelength dependence of the two principal filamentation mechanisms, namely the ponderomotive force and Joule heating, are examined and deductions made of their relative importance for current holhraum experiments. It is found that the Joule heating mechanism is comparable for short wavelengths and high Z materials while the ponderomotive force becomes more important for longer wavelengths and low Z materials. The effect of plasma density and laser bandwidth is also examined and reported on. [Preview Abstract] 

CP8.00103: The velocity dependent Krook model to calculate energetic electron transport in a laser produced plasma Wallace Manheimer Energetic electrons, with energy from many tens to several hundred kilovolts can be generated in laser produced plasmas by such laser plasma instabilities as the 2$\omega _{p}$ instability, which occurs at the quarter critical density. It is important to know now only how these are produced, but also how they are transported and deposit their energy in the interior and whether they preheat the fuel. This poster reviews approaches used by other laboratories including flux limited multigroup diffusion, Fokker Planck simulations, and PIC simulations in conjunction with Monte Carlo simulations. We introduce the velocity dependent Krook (VDK) approach to this problem. We have used this approach to examine nonlocal electron thermal energy transport in laser produced plasmas. There are important similarities and differences between the two problems which are examined. Also there are important differences between the VDK and say Fokker Planck approach which one should keep in mind. The VDK approach is reasonably accurate and reasonably simple and economical to incorporate into a fluid simulation. [Preview Abstract] 

CP8.00104: Modeling SRS and its Hot Electrons as they occur within Ignition Scale Hohlraums Mordecai Rosen, Judy Harte, Denise Hinkel, Richard Town, Howard Scott, George Zimmerman, Ed Williams, Debra Callahan, Pierre Michel, Cliff Thomas, David Bailey We utilize a package within the Lasnex code that can generate Stimulated Raman Back Scatter (SRS) light within the hohlraum. The user can specify the amount of SRS backward propagating light, its frequency, and the density at which the process occurs. In addition, the user can specify how the remaining energy, which in reality resides initially within the electron plasma wave (EPW), is to be modeled. Choices include a) ignoring the EPW and simply continuing to propagate the rest of the laser energy forward, b) local thermal energy deposition, or c) putting it into a superthermal hot electron distribution. The level and spectrum of these hot electrons can also be chosen. Thus, we can model either the main SRS component of $\sim $ 100 kJ at $\sim $ 20 keV, or the superhots of $\sim $ 1 kJ and 80 keV. The hot electrons are transported in a diffusive, quasi isotropic manner. We present preliminary results using these various deposition models, reporting on capsule implosion symmetry and on the xray spectrum emitted from the Au excited by the hot electrons. The need to model the hot electron transport more as beaming along the direction of the EPW is raised. [Preview Abstract] 

CP8.00105: Selfconsistent treatment of energy redirection due to laser plasma instabilities M.M. Marinak, G.D. Kerbel, P. Michel, L. Divol The flow of laser energy in National Ignition Facility (NIF) hohlraums is substantially affected by energy transfer between crossing laser beams and by backscatter of laser light due to laser plasma instabilities. We present an integrated HYDRA simulation of a NIF ignition hohlraum which includes a selfconsistent inline treatment of energy redirection due to these effects. The simulation utilizes a linear model\footnote{P. Michel et. al, Phys. Plasmas 17, 056305 (2010).} for energy transfer in crossed beams. It also includes empirical models for stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS). Suprathermal electrons generated by the SRS can be transported using a nonlocal electron transport model. We also examine the effect of plasma heating by the ion acoustic wave which mediates the cross beam transfer. For example consider laser energy that is transferred between laser beams, then backscattered by SRS. The redshifted light is partially reabsorbed in the plasma while propagating out of the hohlraum. The simulation includes the resulting effects on energy and momentum deposition. [Preview Abstract] 

CP8.00106: New RADIOM algorithm using inverse EOS Michel Busquet, Igor Sokolov, Marcel Klapisch The RADIOM model, [12], allows one to implement nonLTE atomic physics with a very low extra CPU cost. Although originally heuristic, RADIOM has been physically justified [3] and some accounting for autoionization has been included [2]. RADIOM defines an ionization temperature Tz derived from electronic density and actual electronic temperature \textit{Te}. LTE databases are then queried for properties at \textit{Tz} and NLTE values are derived from them. Some hydrocodes (like FAST at NRL, Ramis' MULTI, or the CRASH code at U.Mich) use inverse EOS starting from the total internal energy \textit{Etot} and returning the temperature. In the NLTE case, inverse EOS requires to solve implicit relations between \textit{Te}, \textit{Tz}, $<$Z$>$ and \textit{Etot}. We shall describe these relations and an efficient solver successively implemented in some of our codes. \\[4pt] [1] M. Busquet, \textit{Radiation dependent ionization model for lasercreated plasmas}, Ph. Fluids B 5, 4191 (1993).\\[0pt] [2] M. Busquet, D. Colombant, M. Klapisch, D. Fyfe, J. Gardner. \textit{Improvements to the RADIOM nonLTE model}, HEDP 5, 270 (2009).\\[0pt] [3] M.Busquet, \textit{Onset of pseudothermal equilibrium within configurations and superconfigurations}, JQSRT 99, 131 (2006) [Preview Abstract] 

CP8.00107: Rarefaction shock waves as a diagnostic of critical points Edward Startsev, Igor Kaganovich, Ronald Davidson Critical points of liquidvapor transition in the warm dense matter regime are difficult to measure due to the high pressure and density of the medium. In this paper, it is proposed to make use of rarefaction shock wave phenomena for identifying the region of the critical point. Rarefaction shock waves only exist near the critical point, and thus they can be used for identification of the critical point. Under normal conditions, only compression shock waves exist due to the requirement that entropy should increase in the shock wave. However, near the critical point the entropy can increase in the rarefaction wave; therefore, the compression shock wave is unstable and the rarefaction shock wave is stable in this region [1]. Moreover, the region of existence of the rarefaction shock wave is rather narrow near the critical point, making it an excellent indicator of the critical point. In this paper the rarefaction shock formation during the expansion of the heated material as it goes through critical point as it expands is studied analytically and numerically. We give examples of calculations of rarefaction shock wave formation during expansion of foils irradiated by an ion beam pulse for the NDCXII facility. \\[4pt] [1] Ya. Zeldovich, Zh. Eksp. Teor. Fiz. 16 , 363 (1946). [Preview Abstract] 

CP8.00108: Spatiallyresolved xray scattering measurements of a planar blast wave E.J. Gamboa, D.S. Montgomery, J.F. Benage, K. Falk, C.C. Kuranz, P.A. Keiter, R.P. Drake In many laboratory astrophysics experiments, intense laser irradiation creates novel material conditions with large, onedimensional gradients in the temperature, density, and ionization state. Xray Thomson scattering is a powerful technique for measuring these plasma parameters. However, the scattered signal is typically measured with little or no spatial resolution, which limits the ability to diagnose inhomogeneous plasmas. We report on the development of a new imaging xray Thomson spectrometer (IXTS) for the Omega laser facility. The diffraction of xrays from a toroidally curved crystal creates highresolution images that are spatially resolved along a onedimensional profile while spectrally dispersing the radiation. An experiment is described in which we used the IXTS to measure the spatial temperature profile of a novel system. A lowdensity carbon foam was irradiated with intensities on the order of 10$^{15}$ W/cm$^{2}$, launching a planar blast wave. After a delay of several nanoseconds, xrays created from irradiation of a nickel foil, scattered at 90\r{ } and were recorded by the IXTS. The resulting spatially resolved scattering spectra were analyzed to extract the temperature profile across the blast wave. [Preview Abstract] 

CP8.00109: ABSTRACT WITHDRAWN 

CP8.00110: Simultaneous, coaxial neutron and xray imaging of inertial confinement fusion experiments at Omega Christopher Danly, Gary Grim, Nevzat Guler, Miranda Intrator, Frank Merrill, Petr Volegov, Carl Wilde The campaign to understand the dynamics of implosions in inertial confinement fusion experiments has generated a desire to compare neutron and xray images of the assembled targets. Several diagnostics currently exist, both at the Omega laser and the National Ignition Facility, which provide either neutron or xray radiography capabilities. However, these diagnostics view the target from different angles, and there is no verifiable coregistration of the images they produce. A system has therefore been developed to produce neutron and xray images simultaneously, through the same aperture and with the same view of the target. Recent experiments at the Omega laser have demonstrated this technique; the results are presented, and compared to images from other xray diagnostics, and to images generated with radiationhydrodynamic simulations. [Preview Abstract] 

CP8.00111: Development of High Resolution XRay Crystal Spectrometry for HED Plasmas K.W. Hill, M. Bitter, L. DelgadoAparicio, N.A. Pablant, P. Beiersdorfer, M. Schneider, K. Widmann, M. Sanchez High resolution ($\lambda$/$\delta\lambda$ $\sim$10,000) 1D spatially resolved xray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of iontemperature and plasma flowvelocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as high energy density plasmas (HEDP) and targets on xray light source beam lines, with spatial resolution of microns, as demonstrated by laboratory experiments using a 250micron 55Fe source, and by raytracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 108  106 times source x rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to HEDP facilities, and predictions of performance on these facilities will be presented. [Preview Abstract] 

CP8.00112: Spectroscopic and Xray Scattering Models in SPECT3D Igor Golovkin, Gianluca Gregori, Joseph MacFarlane, Iain Hall, Pamela Woodruff, James Bailey, Eric Harding, Tom Ao Spectrally resolved Xray scattering has become a very effective method for diagnosing the electron temperatures, densities, and average ionization of warm dense matter. We present a newly implemented capability to compute scattering from realistic experiment configurations, including the influence of plasma nonuniformities and collecting scattered xrays from a range of angles. The method is based on a formalism developed by G. Gregori [1]. The xray scattering modeling has been added to the multidimensional collisionalradiative spectral and imaging package SPECT3D [2]. Ability to compute emissivity and attenuation of scattered photons within a multidimensional plasma with nonuniform temperature and density distributions adds major new functionality to existing models. We will discuss the implementation details and demonstrate results relevant to ongoing experimental investigations at Sandia National Laboratories.\\[4pt] [1] G. Gregori, S. H. Glenzer, W. Rozmus, R. W. Lee, and O. L. Landen, Phys. Rev. E 67, 026412 (2003).\\[0pt] [2] J. J. MacFarlane, I. E. Golovkin, P. Wang, P. R. Woodruff, and N. A. Pereyra, High Energy Density Phys., Vol. 3, p. 181190 (2007). [Preview Abstract] 

CP8.00113: Validation of raw experimental data during shoting at the LIL facility Olivier Henry, Vincent Domin, Philippe Romary, Didier Raffestin The LIL (Laser Integration Line) facility at CESTA (Aquitaine, France) is a facility allowing the delivery of 20 kJ at 3$\omega $. The experiment system includes 13 diagnostics. The facility must be able to deliver, within one hour following shoting, all the results of the plasma diagnostics, alignment images and laser diagnostic measurements. These results have to be guaranteed in terms of conformity to the request and quality of measurement. The LIL has developed a tool for the visualisation, analysis and validation of the data. The software is written in the Delphi language for the main body. The configuration is based on XML files. It is thus possible to reread the external analysis modules in Python (the language used on the future LMJ). The software is built on three pillars: definition of a validation model prior to the campaign, basic physical models to qualify the signal as compliant and exploitable, and intercomparison of the shoting and signals over a given campaign or period. Validation of the raw plasma data must serve to validate and guarantee performances, assure the conformity of the PD configuration to the request from the client, check the consistency of measurements, trigger corrective maintenance if necessary. [Preview Abstract] 

CP8.00114: UV Enhancement of Etch Parameters of Nuclear Tracks in CR39 Graham Jensen, Dante Tufano, Gregory Marks, Joseph Mifsud, Mark Teets, James McLean, Michelle Burke, Craig Sangster The use of CR39 plastic as a nuclear particle track detector is an effective technique for recovering data in high energy particle experiments including inertial confinement nuclear fusion. To analyze particle track data after irradiation, CR39 is chemically etched at elevated temperatures with Sodium Hydroxide, producing measurable pits at the nuclear track sites. When CR39 is exposed to ultraviolet light between nuclear irradiation and chemical etch an increase in pit diameter by a factor of as much as 1.7 occurs, due to an enhancement in the track etch rate relative to the bulk etch rate. We have focused specific attention on pinpointing the critical wavelengths which produce this effect: UV below approximately 320nm is effective, and work is proceeding to determine whether the effect ceases at a shorter wavelength. A detailed analysis of how this effect depends on the intensity and duration of ultraviolet exposure is underway. Initial results suggest that this is not simply proportional to UV energy absorbed. [Preview Abstract] 

CP8.00115: ABSTRACT WITHDRAWN 

CP8.00116: ORION OPTICAL DIAGNOSTIC SYSTEMS Construction and commissioning progress J.B.A. Palmer, D. Drew, J. Fyrth, M.P. Hill, P. Kemshall, K. Oades, E. Harvey, E.T. Gumbrell The Orion facility provides a unique combined long and shortpulse laser capability. We report on the progress in constructing a comprehensive plasma optical diagnostic suite for the facility, developed for a range of warm dense matter and other materials' properties experiments. The first VISAR imaging line for the suite is due to be commissioned in 2012 and its progress will be reported. The system consists of configurable optical elements mounted on a TIM, relay optics to an optical table, optics to direct the light through a VISAR bed onto an optical streak camera and the infrastructure systems to provide remote control and services. Due to the operational model of Orion the diagnostic must have comprehensive remote control for its set up and alignment. This makes the system design more complicated than otherwise. The subsystems required to give the degree of remote control required will be described. A modified version of the suite's ASBO imaging line was used in 2011 to support the commissioning of Orion's long and shortpulse laser beam lines by imaging optical emission from laser targets. The set up of this system and the data it recorded with an optical streak camera during a short pulse experiment will be presented. [Preview Abstract] 

CP8.00117: The National Ignition Facility (NIF) as a User Facility Christopher Keane The 192beam National Ignition Facility (NIF) at LLNL, operational since March 2009, is conducting experiments in ICF ignition and other scientific areas. The NIF ignition program is conducted by the National Ignition Campaign (NIC). In addition to execution of the ignition program, the NIC is providing the necessary infrastructure for operation of NIF as a user facility open to both US and international scientists. NIF has made significant progress towards operation as a user facility. The NIF laser has demonstrated the necessary performance, including energy, power, precision, and reproducibility, to support NIC and other experiments. NIF has demonstrated full energy and power (1.8 MJ, 500 TW) operation at 0.35$\mu $m. Over 50 diagnostics are operational, and a broad range of target fabrication capabilities is in place. Initial experiments by university users and other scientists external to the National Nuclear Security Administration (NNSA) national laboratory system have been conducted, and additional experiments developed by the broader user community are in process and planned. A governance model has been established, and a NIF User Group has been formed. This presentation will discuss implementation of NIF as a user facility, with emphasis on activities at NIF in fundamental science and other areas carried out in addition to the NIC. [Preview Abstract] 

CP8.00118: Plasma Flows Associated with a Flux Ropes Experiment Timothy DeHaas, Walter Gekelman, Patrick Pribyl, Bart Van Compernolle, Sarah Smolenski Magnetic flux ropes are braided magnetic fields associated with helical currents. They are found near the solar surface and are associated with coronal mass ejections. In this experiment, two adjacent flux ropes (I$_{rope}$=50 amps, $\Delta $y=1 cm, L$_{rope}$=10 m) are formed in the LAPD at UCLA (B$_{o}$=330 G, $n_{o}$=2x10$^{12}$ cm$^{3}$, T$_{e}$=4 eV, He). The ropes are fully ionized with electron T$_{e}$ 10 eV and $n_{rope}$=10$^{13}$ cm$^{3}$. Threeaxis magnetic and mach probes are used to measure the volumetric magnetic field and to concentrate on measuring the threedimensional flow fields. Since the ropes are kink unstable,\footnote{Ryutov, D.D.; Furno, I.; Intrator, T.P.; Abbate, S.; MadziqaNussinov, T.; 2006, Phys. Plasmas, 13,032105.} correlation functions using two probe sets are utilized. Previous observations\footnote{Gekelman, W.; Lawrence, E.; Van Compernolle, B. 2012, ApJ, 753, 131.} showed that the field lines move through the quasiseparatrix layer while the ropes reconnect. The flow field is key to the analysis, in light of recent theories of sliprunning reconnection.\footnote{Auliener, G.G.; Pariat, E.; Demoulin, P.; Devore, C; 2006, Sol. Phys. 238, 347.} [Preview Abstract] 
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