Bulletin of the American Physical Society
62nd Annual Meeting of the APS Division of Plasma Physics
Volume 65, Number 11
Monday–Friday, November 9–13, 2020; Remote; Time Zone: Central Standard Time, USA
Session VP15: Poster Session: Particle acceleration, Beams and Relativistic Plasmas II (2:00pm - 5:00pm)On Demand
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VP15.00001: BELLA Petawatt Laser for Ultrahigh-Intensity High Energy Density Physics within LaserNetUS Kei Nakamura, Sven Steinke, Lieselotte Obst-Huebl, Jianhui Bin, Qing Ji, Anthony J. Gonsalves, Stepan S. Bulanov, Cameron G. R. Geddes, Carl B. Schroeder, Eric Esarey, Thomas Schenkel In this presentation, we will report on the status of HEDP at the BELLA petawatt facility with a large laser spot beamline (f$\backslash $65, \textasciitilde 1019 W/cm2). Based on accelerated ion beams with a strongly reduced divergence and increased charge, we built an all-plasma-based beamline for controlled material processing and radiobiological studies. We will give an outlook on science enabled by a short-focal length (f$\backslash $2.5) laser beamline that is currently under construction. The new short-focal length beamline will be equipped with a re-collimating double-plasma mirror to study laser-plasma interactions at the highest temporal contrast and intensities \textgreater 1021 W/cm2 with a repetition rate up to 1 Hz, enabling, e.g., ion acceleration experiments with energies at the 100 MeV level. The BELLA center is part of LaserNetUS providing access to domestic and international users. [Preview Abstract] |
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VP15.00002: ZEUS: A National Science Foundation Mid-Scale User Facility for Laser-Driven Science in the QED Regime. Anatoly Maksimchuk, John Nees, Galina Kalinchenko, Bixue Hou, Yong Ma, Andrew McKelvey, Tan Shi, Igor Jovanovic, Carolyn Kuranz, Alexander Thomas, Louise Willingale, Karl Krushelnick The Zettawatt-Equivalent Ultrashort pulse laser System (ZEUS) is being developed at the University of Michigan as the National Science Foundation mid-scale user facility. The ZEUS facility will include a repetitive dual-beamline 3 PW laser system, a 100 J programmable shape multi-ns pulse driver, three radiation shielded experimental areas and will provide unique new capabilities to explore nonlinear quantum electrodynamics, relativistic plasmas, particles acceleration, extreme laboratory astrophysics, basic plasma physics and nuclear photonics. Once completed, the ZEUS laser system will be the highest-power laser system in the US and will become a user facility for the US scientists and wider international research community. [Preview Abstract] |
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VP15.00003: Experimental study of deformable mirror on ZEUS (Zettawatt-Equivalent Ultrashort pulse laser System) Qian Qian, Bixue Hou, Yong Ma, Anatoly Maksimchuk, John Nees, Karl Krushelnick, Alexander Thomas The G\'{e}rard Mourou Center of Ultrafast Optical Science in the University of Michigan will upgrade its 300 TW Hercules laser to a new 3 PW laser system called ZEUS in the near future. A deformable mirror is an important part in this system. It not only enables focusing of laser beams to diffraction limited spots, but also allows for active feedback to control and fine-tune laser-plasma interactions. In the current Hercules laser, the output beam after the deformable mirror is focused to 1 micron spot size, producing intensity over 10\textasciicircum 22 W/cm\textasciicircum 2. For the upcoming ZEUS laser, the highest laser intensity after the deformable mirror is expected to be on the order of 10\textasciicircum 23 W/cm\textasciicircum 2. This extremely intense laser pulse could greatly exceed the quantum electrodynamic critical field when colliding with a 5 GeV electron beam. ZEUS also allows for a high repetition-rate operation mode, which means we could use the deformable mirror to adaptively control and optimize laser-plasma accelerators. The large amount of data generated from the system allows the application of machine learning. This may offer a new way to understand complex physical processes in nonlinear laser-plasma interactions. [Preview Abstract] |
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VP15.00004: Proposed Strong Field Ionization Experiments on the Texas Petawatt Laser Andrew Yandow, Herbie Smith, Constantin Aniculaesei, Hernan Quevedo, Michael Spinks, Sandra Bruce, MacKenzie Darilek, Erhard Gaul, Michael Donovan, Bjorn Manuel Hegelich, Todd Ditmire We present experimental plans for studying strong-field ionization of noble gas atoms on the Texas Petawatt Laser at intensity exceeding $10^{20}$ W/cm$^{2}$. We propose indirect measurement of the K-shell ionization yields by using plastic scintillators to detect the high-energy ATI electrons produced by these ionization events. A new f/1.4 focal geometry we are commissioning on the Texas Petawatt will allow peak intensity exceeding $10^{20}$ W/cm$^{2}$ on rod amplifier shots and $3 \times 10^{21}$ W/cm$^{2}$ for full-energy system shots, enabling the exploration of neon and argon K-shell ionization. The methods we propose should be scalable to intensity beyond $10^{21}$ W/cm$^{2}$, an intensity regime where ponderomotive scattering of ions from the focus will complicate direct measurements of the ion charge state yields by ion time-of-flight. [Preview Abstract] |
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VP15.00005: Investigating Self-Induced Relativistic Transparency in Plasmas with Ultrafast High Intensity Laser Pulses Brendan Stassel, Brandon Russell, Paul T. Campbell, Hongmei Tang, Anatoly Maksimchuk, Louise Willingale We model high intensity laser plasma interactions on thin film and solid targets to study the self-induced relativistic transparency regime. The 2D OSIRIS 4.0 particle-in-cell simulations were designed to model the HERCULES laser pulse. The wavelength $\lambda$ was 800 nm, pulse duration was 30 fs, and the normalized vector potential $a_0$ was varied between 0.5 and 30. Also, the target thickness was varied between 50 nm and 200 nm. In preparation for experiments with HERCULES, an analysis of the data is presented along with a study of the transmitted and reflected laser characteristics, and electron spectra. [Preview Abstract] |
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VP15.00006: First demonstration of the Global Spectrometer for Positron and Electron Characterization (GSPEC) G. D. Glenn, C. B. Curry, G. Dyer, E. Galtier, S. Kuschel, C. Schoenwaelder, F. Treffert, S. H. Glenzer, M. Gauthier, B. M. Hegelich, E. McCary, R. Roycroft, G. Tiwari, T. Ditmire In high-intensity laser interactions with solid targets, electrons are accelerated to relativistic energies by the laser electric field, with the temperature of their approximately Maxwellian energy distribution serving as an indirect measurement of the laser-plasma interaction. Nonthermal components of the electron spectrum may be indicative of astrophysically relevant plasma processes such as magnetic reconnection or instabilities driving particle acceleration. To study such interactions, we have developed an imaging plate-based magnetic energy spectrometer to measure the energy spectrum of laser-accelerated electrons with energies from 3--150 MeV.\textsuperscript{a} The spectrometer has been designed to optimally resolve the characteristic energies (3--50 MeV) of electrons generated during overcritical laser-plasma interactions. We present preliminary data from a recent experiment using the Titan short-pulse laser in a split-beam configuration (700 fs, 1053 nm, 2x65 J) to identify signatures of magnetic reconnection from nonthermal electron populations.\\ \textbf{References}: a. G. D. Glenn et al., \textit{JINST} \textbf{14} P03012 (2019) [Preview Abstract] |
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VP15.00007: Characterization of Planar Cryogenic Hydrogen and Deuterium Jets with Interferometry Measurements C. Schoenwaelder, C. B. Curry, G. D. Glenn, F. Treffert, S. H. Glenzer, M. Gauthier Cryogenic micro-jets are created by liquefying an ultra-high purity gas in a copper assembly cooled down to cryogenic temperatures. The liquid is continuously injected into a vacuum chamber through a micron-sized circular or rectangular aperture, where it quickly solidifies by evaporative cooling [1]. As such, this target system enables the transition to high-repetition rate high energy density science. The tunable dimensions of the cryogenic jets allow numerous plasma regimes to be systematically explored. Using 2D/3D particle-in-cell (PIC) simulations, we have identified initial target conditions to access advanced laser-driven ion acceleration mechanisms, such as Collisionless Shockwave Acceleration (CSWA). In both simulations and experiments, the dominant acceleration mechanism strongly depends on the initial dimensions and density of the target. In this work, we present high resolution interferometry measurements of cold, non-ionized planar jet targets to support the interpretation of results obtained at recent petawatt laser-driven ion acceleration experiments. References: 1. C. B. Curry, C. Schoenwaelder et al., J. Vis. Exp. 159, e61130 (2020). [Preview Abstract] |
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VP15.00008: Improving the current understanding of TNSA experiments at the Laser Light Ion beam-Line via high-fidelity Particle-In-Cell simulations Pablo Bilbao Santiago, Elisabetta Boella, Leonida Gizzi, Dario Giove Despite Target Normal Sheath acceleration being the most robust ion acceleration scheme proposed so far, promising practical applications are limited by the stability of the acceleration parameters and the lack of control of the spectral and angular properties of TNSA accelerated beams. We report on detailed numerical modelling of Target Normal Sheath Acceleration under the same experimental conditions of the Laser Light Ion beam-Line (CNR, INFN, Italy) [1]. Realistic one-to-one multidimensional Particle-In-Cell simulations performed with the code OSIRIS [2] are used to gain deeper insight into the physics of laser energy deposition into the plasma and subsequent ion acceleration. The role played by different parameters with low experimental control, such as target ionization and contaminant layer, is also explored with the aim of better understanding their impact on the maximum ion energy. [1] Gizzi L.A., et al., Nucl. Instrum. Methods A909, 160 (2018). [2] Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002). [Preview Abstract] |
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VP15.00009: TNSA using twisted laser pulses and shaped targets Camilla Willim, Jorge Vieira, Victor Malka Multi-MeV proton beams find various applications such as proton beam therapy or "fast ignition" of inertial confinement fusion targets. Target normal~sheath acceleration (TNSA) driven by short intense laser pulses is, in this context, a well-established proton acceleration model. The generation of multi-MeV proton beams with ultrashort duration (ps) and a high number of protons in a bunch (10$^{\mathrm{11}}$~-- 10$^{\mathrm{13}})$~has been successfully demonstrated in~experiments, but beam properties still need improvement for applications. Improving the properties of TNSA schemes is thus very important for future~progress. Here, we explore the phase-space properties of protons accelerated from shaped targets by intense lasers with orbital angular momentum~(OAM) and discuss how these lasers could be used to address key issues in proton acceleration in plasma, such as their divergence and energy. The self-consistent laser---plasma dynamics is investigated analytically and by relying on three-dimensional particle-in-cell simulations in OSIRIS. [Preview Abstract] |
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VP15.00010: Absolute Flux Calibration of Neutron Time-of-Flight Detectors for Laser-Generated Neutron Beam Experiments F. Treffert, C. B. Curry, G. D. Glenn, C. Schoenwaelder, S. H. Glenzer, M. Gauthier, N. Fotiadis, C. Prokop, H. Quevedo, M. Zimmer, M. Roth Neutron beams are a powerful tool to probe the structure, composition and evolution of nuclear material or biological systems. With the recent development of high repetition rate, high power lasers, laser-generated neutron sources are promising to reach favorable beam characteristics including short pulse duration, high single-shot fluxes and controllable energy profiles. Collocation of such a neutron source with an X-ray free electron laser will enable pump-probe studies of radiation damage in fusion materials, requiring precise characterization of the absolute neutron number and energy distribution. Here we present an approach to absolutely calibrate the neutron yield obtained with nTOF detectors using neutron beams of known flux and energy at flight path 60R at Los Alamos Neutron Science Center with 0.1\textrm{-}400\,MeV energy range and peak fluxes of $10^{-4}$\,n/MeV/bunch. We will show that this new technique is more robust to determine neutron yields and can be used to cross calibrate bubble detector data. An application of this calibration technique will be shown on nTOF traces acquired during an experimental campaign at the Texas Petawatt laser facility. [Preview Abstract] |
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VP15.00011: High Energy, Relativistic Intensity Laser Channeling and Direct Laser Acceleration of Electrons from an Underdense Plasma H. Tang, A. McKelvey, P. T. Campbell, B. K. Russell, Y. Ma, A. V. Arefiev, G. J. Williams, H. Chen, F. Albert, J. Shaw, P. M. Nilson, L Willingale Direct Laser Acceleration (DLA) of electrons by a relativistically intense laser pulse is a dynamic and complex process. We perform experiments using the OMEGA EP laser and 2D particle-in-cell simulations to study the acceleration of electron beams from underdense plasma using high-energy, picosecond-duration laser pulses. Gas-jet targets were used to control and change the target density and the focusing conditions are altered by apodizing the beam near-field from having a square profile to a round profile. Proton radiography observes the evolution of the electromagnetic fields within the channel formed and magnetic spectrometers measure the electron spectra. 2-D Particle-in-cell simulations investigate how the plasma density and laser parameters, like energy and focusing conditions, affect the interaction and DLA mechanism to help optimize the experiment configuration. This work is support by the Department of Energy / NNSA under Award Number DE-NA0003944. [Preview Abstract] |
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VP15.00012: Stochastic electron acceleration in laser-plasma interactions Yanzeng Zhang, Sergei Krasheninnikov, Alexey Knyazev Direct laser acceleration (DLA) is identified as one of the most important ways to accelerating electron, in the laser-plasma interactions, to high energies beyond the ponderomotive scaling. Many experimental, numerical, and theoretical works reveal that the presence of self-generated or externally applied quasi-static electric and magnetic (QEM) fields or a counter-propagating laser wave could facilitate electron acceleration. However, the analytic investigations of the mechanism of electron acceleration in the earlier studies of DLA are quite limited and complicated. In this work, we examine the electron acceleration in the laser waves and QEM fields by employing a new Hamiltonian approach by using proper canonical variables and system symmetry. The new Hamiltonian approach significantly simplifies the analysis of the electron dynamics and enables us to exhaustively explore the physics of electron acceleration, where we pay attention to the electron acceleration via the onset of stochastic motion. By deriving the Chirikov-like mappings, we obtain the stochastic conditions and thus the upper limits of the electron energy depending on system parameters. [Preview Abstract] |
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VP15.00013: Numerical Modeling of Relativistic Harmonic Structure from Plasma Mirrors: Insights into Relativistic Plasma Dynamics Nicholas Fasano, Julia Mikhailova Specular reflection of intense lasers from relativistic plasma mirrors produces a source of high-power, broad bandwidth radiation which, in addition to being a useful secondary light source for probing electron dynamics, encodes the information of the complex plasma dynamics that takes place during extreme light-matter interactions. The appearance of harmonic peaks in the reflected spectrum can be explained as a result of periodically spaced attosecond pulses emitted once every laser cycle. For multi-cycle laser pulses, cycle-to-cycle emission times of attosecond pulses varies due to evolving laser and plasma parameters. In this work, we use particle-in-cell simulations to relate the temporal spacing of attosecond pulses to different observed harmonic structure, including harmonic broadening, harmonic splitting, and the appearance of integer and half-integer harmonics. We demonstrate how a small amount of temporal chirp applied to the driving laser can compensate for the non-periodic emission time of attosecond pulses which results in narrower, more intense individual harmonics. The results of this work provides insight into the rapidly evolving plasma dynamics of intense laser-solid interactions and how these dynamics are encoded in the reflected radiation. [Preview Abstract] |
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VP15.00014: High-Power THz Sources for High-Energy-Density Physics Applications Gerrit Bruhaug, Hans G. Rinderknecht, Mingsheng S. Wei, Gilbert W. Collins, J.R. Rygg, Yiwen E, Kareem Garriga, X.C. Zhang THz radiation provides a unique probe into matter that is currently not available at high-energy-density facilities like the Laboratory for Laser Energetics (LLE). Currently THz radiation is used to measure dc conductivity, provide insight into chemical and phonon structure, and even measure temperatures$^{\mathrm{,}}$ of static targets at standard conditions. THz radiation would provide an entirely new diagnostic window into HED matter and allow for new insights to be gained in conductivity and chemical structure. Extremely powerful THz sources can also be used as phase change drivers or heaters for targets. Recent work has shown that high-intensity lasers can be used to generate never before seen THz powers that are of interest as drivers.$^{\mathrm{3}}$ This poster will outline current work being done at the LLE to develop THz diagnostics and powerful THz sources. W. Ghann and J. Uddin, in \textit{Terahertz Spectroscopy}, edited by J. Uddin (IntechOpen, Rijeka, Croatia, 2017), Chap. 1. C. L. Davies \textit{et al.}, J. Infrared Milli. Terahz. Waves \textbf{39}, 1236 (2018). G. Liao \textit{et al.}, Proc. Natl. Acad. Sci. \textbf{116}, 3994 (2019). [Preview Abstract] |
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VP15.00015: Experimental Measurements and First Principles Modeling of Secondary Electron Yield of Materials of Interest to High Power Vacuum Electron Devices Talal Ahmed Malik, Mark Gilmore, Salvador Portillo, Raul Enrique Gutierrez, Maciej Polak, Ryan Johnson, Ivana Matanovic, Dane Morgan, Edl Schamiloglu Multipactor breakdown (MPB) is a RF breakdown phenomenon that decreases the overall efficiency of high power RF systems operating in vacuum. In worst case scenario, MPB might also lead to complete failure of the device. Among other factors, secondary electron emission (SEE) from device electrodes in synchronism with E-field oscillations forms the important basis for triggering MPB. Therefore, minimizing SEE is important in improving RF vacuum device performance. This presentation will show the results of secondary electron yield (SEY) measurements in the low energy regime (10 eV to 1000 eV) for the materials of interest to space electronic system, including copper, aluminum 6061 and silver. In addition, different surface treatment methods adopted in this study to suppress SEY will be shown. Furthermore, simulations of copper SEY will be presented. Electronic structure properties of copper were first calculated using Exciting code after which the SEY curve was obtained from Monte Carlo simulations using MAST-SEY code. This approach is unique as it uses momentum dependent energy loss functions from density functional theory, and the prediction of SEY is made entirely from the first principles. [Preview Abstract] |
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VP15.00016: Helicon wave modelling for the Madison Awake Prototype MAP Marcel Granetzny, Jacob Dwinell, Barret Elward, Kole Rakers, Michael Zepp, Oliver Schmitz Next generation electron colliders need acceleration fields greater than 1 GV/m which is beyond the capabilities of superconducting RF cavities. A promising new acceleration concept is plasma wakefield acceleration for which plasma densities of order $10^{21}$ $m^{-3}$ are needed. As part of CERN's AWAKE collaboration, UW-Madison is building the Madison Awake Prototype MAP. In MAP the plasma will be generated inside a 26 mm radius quartz tube, immersed in a 1000 G field. 30 kW RF power are used to excite a very high density helicon plasma. Starting with the HELIC code we model the EM fields inside a given plasma profile for different antenna geometries. This is the basis for modelling the Helicon wave in COMSOL which allows for arbitrary field geometries. Starting with measured plasma profiles we use a simplified transport and heating model to find equilibrium states for a given antenna configuration. Using this coupled model we optimize the antenna geometry for maximum core plasma density. Predicted RF fields and plasma profiles can then be compared to measurements. This research directly contributes to the qualification of a comparably sized cell at higher power density that is being qualified at CERN. [Preview Abstract] |
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VP15.00017: Negative AC Contact Resistance Yue Ying Lau, Foivos Antoulinakis Forty percent of all failures in electronic devices, from consumer electronics to large scale defense systems, are due to poor electrical contacts. Electrical contact resistance, and the enhanced ohmic heating that results, have been treated mostly under steady state (DC) condition. We consider the AC contact resistance for a simple geometry [1], namely, that of two long conductor slabs of different materials joint at z $=$ 0. The contact resistance, also known as the constriction or spreading resistance, is defined as the difference between the total resistance and the sum of the bulk resistances from the contacting members. In the DC case, this contact resistance equals to zero when the two slabs have the same dimensions, in which case the current flow is uniform across the junction at z $=$ 0, and the bulk resistance constitute the total resistance. At some frequencies, we found that the contact resistance can become negative, meaning that the total resistance is less than that due to bulk resistance [1]. The physical interpretation in terms of current spreading near the junction is given. New features that accompany the AC condition, such as the resistive skin effects, are illustrated. Scaling laws for the contact resistance as a function of frequency are constructed for several cases. [Preview Abstract] |
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