Bulletin of the American Physical Society
58th Annual Meeting of the APS Division of Plasma Physics
Volume 61, Number 18
Monday–Friday, October 31–November 4 2016; San Jose, California
Session BO6: Laser-Plasma Wakefield Acceleration |
Hide Abstracts |
Chair: Felicie Albert, Lawrence Livermore National Laboratory Room: 230 C |
Monday, October 31, 2016 9:30AM - 9:42AM |
BO6.00001: High-performance modeling of plasma-based acceleration and laser-plasma interactions. Jean-Luc Vay, Guillaume Blaclard, Brendan Godfrey, Manuel Kirchen, Patrick Lee, Remi Lehe, Mathieu Lobet, Henri Vincenti Large-scale numerical simulations are essential to the design of plasma-based accelerators and laser-plasma interations for ultra-high intensity (UHI) physics.The electromagnetic Particle-In-Cell (PIC) approach is the method of choice for self-consistent simulations, as it is based on first principles, and captures all kinetic effects, and also scale favorably to many cores on supercomputers. The standard PIC algorithm relies on second-order finite-difference discretization of the Maxwell and Newton-Lorentz equations. We present here novel formulations, based on very high-order pseudo-spectral Maxwell solvers, which enable near-total elimination of the numerical Cherenkov instability and increased accuracy over the standard PIC method for standard laboratory frame and Lorentz boosted frame simulations. We also present the latest implementations in the PIC modules Warp-PICSAR and FBPIC on the Intel Xeon Phi and GPU architectures. Examples of applications will be given on the simulation of laser-plasma accelerators and high-harmonic generation with plasma mirrors. [Preview Abstract] |
Monday, October 31, 2016 9:42AM - 9:54AM |
BO6.00002: On the possibilities of LWFA in the self-guided nonlinear blowout regime for 15-100 Joule lasers Asher Davidson, Adam Tableman, Peicheng Yu, Weiming An, Frank Tsung, Warren Mori The recent implementation of the quasi-3D algorithm into OSIRIS now make it possible to study scaling laws for LWFAs operating in the blowout regime for higher laser energies. We find that self-guiding is possible to at least 26 Rayleigh lengths, reaching energies above 10GeV. We then study how to optimize the energy gain for fixed laser energy, and find that shortening the pulse length and reducing the plasma density produces a higher energy beam. [Preview Abstract] |
Monday, October 31, 2016 9:54AM - 10:06AM |
BO6.00003: Self-guiding of laser pulses and spatio-temporal optical vortices in plasma George Hine, Nihal Jhajj, Howard Milchberg Relativistic self-focusing and self-guiding are processes fundamental to laser-plasma particle acceleration. Recent work in optical filamentation has discovered the existence of spatio-temporal optical vortices (STOVs) [1] and has shown their integral connection to all self-focusing collapse and self-guiding scenarios. Here we show that STOVs are an essential feature of LWFA through their generation by relativistic self-focusing. Three dimensional particle-in-cell (PIC) simulations show the formation of STOVs in the pulse, corresponding to vortical flow of the Poynting vector, which then influences subsequent pulse propagation such as the self-healing of the relativistic self-guiding process. \newline \newline [1] N. Jhajj \textit{et al. arXiv:1604.01751[physics.optics]} [Preview Abstract] |
Monday, October 31, 2016 10:06AM - 10:18AM |
BO6.00004: Filamentation in Laser Wakefields Eva Los, Raoul Trines, Luis Silva, Robert Bingham Laser filamentation instability is observed in plasma wakefields with sub-critical densities, and in high density inertial fusion plasmas. This leads to non-uniform acceleration or compression respectively. Here, we present simulation results on laser filamentation in plasma wakefields. The 2-D simulations are carried out using the particle-in-cell code Osiris. The filament intensity was found to increase exponentially before saturating. The maximum amplitude to which the highest intensity filament grew for a specific set of parameters was also recorded, and plotted against a corresponding parameter value. Clear, positively correlated linear trends were established between plasma density, transverse wavenumber k, laser pulse amplitude and maximum filament amplitude. Plasma density and maximum filament amplitude also showed a positive correlation, which saturated after a certain plasma density. Pulse duration and interaction length did not affect either filament intensity or transverse k value in a predictable manner. There was no discernible trend between pulse amplitude and filament width. [Preview Abstract] |
Monday, October 31, 2016 10:18AM - 10:30AM |
BO6.00005: MeV electron acceleration at 1kHz with $<$10mJ laser pulses Fatholah Salehi, Andy Goers, George Hine, Linus Feder, Donghoon Kuk, Ki-Yong Kim, Howard Milchberg We demonstrate laser driven acceleration of electrons at $1\thinspace kHz$ repetition rate with $\sim pC$ charge above $1MeV$ per shot using$\thinspace <10\thinspace mJ$ pulse energies focused on a near-critical density He or H$_{\mathrm{2}}$ gas jet. Using the H$_{\mathrm{2}}$ gas jet, electron acceleration to$\thinspace \sim 0.5\thinspace MeV$ in$\thinspace \sim 10fC$ bunches was observed with laser pulse energy as low as $1.3mJ$. Using a near-critical density gas jet sets the critical power required for relativistic self-focusing low enough for $mJ$ scale laser pulses to self- focus and drive strong wakefields. Experiments and particle-in-cell simulations show that optimal drive pulse duration and chirp for maximum electron bunch charge and energy depends on the target gas species. High repetition rate, high charge, and short duration electron bunches driven by very modest pulse energies constitutes an ideal portable electron source for applications such as ultrafast electron diffraction experiments and high rep. rate $\gamma $-ray production. [Preview Abstract] |
Monday, October 31, 2016 10:30AM - 10:42AM |
BO6.00006: MOVED TO TO6.003 |
Monday, October 31, 2016 10:42AM - 10:54AM |
BO6.00007: Controlled electron injection using nanoparticles in laser wakefield acceleration Myung Hoon Cho, Vishwa Bandhu Pathak, Hyung Taek Kim, Kazuhisa Nakajima, Chang Hee Nam Laser wakefield acceleration is one of compact electron acceleration schemes due to its high accelerating gradient. Despite of the great progress of several GeV electron beams with high power lasers, the electron injection to the wakefield is still a critical issue for a very low density plasma 10$^{\mathrm{17}}$ electrons/cc. In this talk a novel method to control the injection using nanoparticles is proposed. We investigate the electron injection by analyzing the interaction of electrons with the two potentials - one created by a nanoparticle and the other by the wakefield. The nanoparticle creates a localized electric potential and this nanoparticle potential just slips the present wake potential. To confirm the Hamiltonian description of the interaction, a test particle calculation is performed by controlling the bubble and the nanoparticle potentials. A multi-dimensional particle-in-cell simulations are also presented as a proof-of-principle. Comparing theoretical estimates and PIC simulation, we suggest nanoparticle parameters of size and electron density depending on the background plasma density. Our scheme can be applicable for low plasma density to break though the limitation of self-injection toward extremely high energy electron energy. [Preview Abstract] |
Monday, October 31, 2016 10:54AM - 11:06AM |
BO6.00008: Role of direct laser acceleration of electrons in a laser wakefield accelerator with ionization injection Jessica Shaw, Nuno Lemos, Ligia Diana Amorim, Navid Vafaei-Najafabadi, Ken Marsh, Frank Tsung, Dustin Froula, Warren Mori, Chan Josh We show through experiments and supporting simulations the role of direct laser acceleration (DLA) of electrons in a laser wakefield accelerator when ionization injection of electrons is employed. The laser pulse is intense enough to create a nonlinear wakefield and long enough to overlap the electrons trapped in the first accelerating potential well (bucket) of the wakefield. The betatron oscillations of the trapped electrons in the plane of the laser polarization in the presence of an ion column lead to an energy transfer from the laser pulse to the electrons through DLA. We show that the produced electron beams exhibit characteristic features that are indicative of DLA as an additional acceleration mechanism when the laser pulse overlaps the trapped electrons. [Preview Abstract] |
Monday, October 31, 2016 11:06AM - 11:18AM |
BO6.00009: Stable boosted-frame simulations of laser-wakefield acceleration using Galilean coordinates Remi Lehe, Manuel Kirchen, Brendan Godfrey, Andreas Maier, Jean-Luc Vay While Particle-In-Cell (PIC) simulations of laser-wakefield acceleration are typically very computationally expensive, it is well-known that representing the system in a well-chosen Lorentz frame can reduce the computational cost by orders of magnitude. One of the limitation of this ``boosted-frame'' technique is the Numerical Cherenkov Instability (NCI) -- a numerical instability that rapidly grows in the boosted frame and must be eliminated in order to obtain valid physical results. Several methods have been proposed in order to eliminate the NCI, but they introduce additional numerical corrections (e.g. heavy smoothing, unphysical modification of the dispersion relation, etc.) which could potentially alter the physics. By contrast, here we show that, for boosted-frame simulations of laser-wakefield acceleration, the NCI can be eliminated simply by integrating the PIC equations in Galilean coordinates (a.k.a comoving coordinates), without additional numerical correction. Using this technique, we show excellent agreement between simulations in the laboratory frame and Lorentz-boosted frame, with more than 2 orders of magnitude speedup in the latter case. [Preview Abstract] |
Monday, October 31, 2016 11:18AM - 11:30AM |
BO6.00010: Using Quasi-3D OSIRIS simulations of LWFA to study generating high brightness electron beams using ionization and density downramp injection Thamine Dalichaouch, Asher Davidson, Xinlu Xu, Peicheng Yu, Frank Tsung, Warren Mori, Fei Li, Chaojie Zhang, Wei Lu, Jorge Vieira, Ricardo Fonseca In the past few decades, there has been much progress in theory, simulation, and experiment towards using Laser wakefield acceleration (LWFA) as the basis for designing and building compact x-ray free-electron-lasers (XFEL) as well as a next generation linear collider. Recently, ionization injection and density downramp injection have been proposed and demonstrated as a controllable injection scheme for creating higher quality and ultra-bright relativistic electron beams using LWFA. However, full-3D simulations of plasma-based accelerators are computationally intensive, sometimes taking 100 millions of core-hours on today’s computers. A more efficient quasi-3D algorithm was developed and implemented into OSIRIS using a particle-in-cell description with a charge conserving current deposition scheme in $r-z$ and a gridless Fourier expansion in $\phi$. Due to the azimuthal symmetry in LWFA, quasi-3D simulations are computationally more efficient than 3D cartesian simulations since only the first few harmonics in are needed $\phi$ to capture the 3D physics of LWFA. Using the quasi-3D approach, we present preliminary results of ionization and down ramp triggered injection and compare the results against 3D LWFA simulations. [Preview Abstract] |
Monday, October 31, 2016 11:30AM - 11:42AM |
BO6.00011: Laser-plasma mirrors: from electron acceleration to harmonics generation Maxence Th\'evenet, Ma\"imouna Bocoum, J\'er\^ome Faure, Adrien Leblanc, Henri Vincenti, Fabien Qu\'er\'e Accelerating electrons in the $>10\,$TV/m fields inside an ultrashort ultraintense laser pulse has been a long-standing goal in experimental physics, motivated by promising theoretical predictions. The biggest hurdle was to have electrons injected in the center of the laser pulse. Recent experimental and numerical results\footnote{M. Th\'evenet, \textbf{Nat. Phys. 12}, 355 (2015)} showed that this problem could be solved using a plasma mirror, i.e. an overdense plasma with a sharp ( |
Monday, October 31, 2016 11:42AM - 11:54AM |
BO6.00012: X-ray beam source from a Self-modulated laser wakefield accelerator Nuno Lemos, Felicie Albert, K. A. Marsh, J. L. Shaw, P King, S Patankar, J Ralph, B. B. Pollock, J. L. Martins, L. D. Amorim, F. S. Tsung, C Goyon, A Pak, J. D. Moody, W Schumaker, F Fiuza, S. H. Glenzer, B. M. Hegelichand, A Saunders, R. W. Flacone, C Joshi To diagnose material properties under extreme conditions of temperature and pressure the development of a directional, small-divergence, small source size and short pulse duration x-ray source has become essential. In this work we explore through experiments and PIC simulations the betatron radiation generated in self-modulated laser-wakefield accelerators. The experiment was preformed at the Jupiter Laser Facility, LLNL where electrons with energies up to 200 MeV and Betatron x-rays with critical energies \textgreater 10 keV were observed. OSIRIS 2D PIC simulations indicate that the x-ray critical energy directly scales with the a$_{0}$ of the laser and can easily be increased to critical energies exceeding 50 keV using a laser with a$_{0}$ of 3. [Preview Abstract] |
Monday, October 31, 2016 11:54AM - 12:06PM |
BO6.00013: Probing the K-edge of a laser heated aluminum plasma using X-rays from betatron oscillations in a laser wakefield accelerator with femtosecond resolution Keegan Behm, Amina Hussein, Tony Zhao, Edward Hill, Anatoly Maksimchuk, John Nees, Victor Yanovsky, Stuart Mangles, Karl Krushelnick, Alexander Thomas Presented here are data from a two-beam pump-probe experiment. We used synchrotron-like X-rays created by betatron oscillations to probe a thin metal foil that is pumped by the secondary laser beam. The Hercules Ti:Sapphire laser facility was operated with a pulse duration of 34 fs and a power of 80 TW split. A 75-25 beam splitter was used to drive a laser wakefield accelerator and heat the secondary target. We observed opacity changes around the K-edge of thin aluminum foil as it was heated by an ultrafast pump laser. To understand how the opacity is changing with heating and expansion of the plasma, the delay between the two laser paths was adjusted on a femtosecond time scale from 50 to 400 fs. Experimental data for aluminum shows variation in opacity around the K-edge with changes in the probe delay. The transmitted synchrotron-like spectrum was measured using single photon counting on an X-ray CCD camera and was available on a shot-by-shot basis. The success of this work demonstrates a practical application for X-rays produced from betatron oscillations in a wakefield accelerator. [Preview Abstract] |
Monday, October 31, 2016 12:06PM - 12:18PM |
BO6.00014: Mitigation of ion motion induced emittance growth in plasma wake field accelerator Weiming An, Xinlu Xu, Chan Joshi, Warren Mori Plasma based accelerator is being considered as the main accelerator for building a future linear collider. The nonlinear plasma wake field accelerator have ideal properties for focusing and accelerating electrons. However, for nano Coulomb beams with nanometer scale matched spot sizes, the large space charge forces around the beam can pull the plasma ions inwards and generate nonlinear focusing force inside the wake. As a result, the beam emittance cannot be preserved. We find that although the ion density becomes 100 times larger than the initial density on the axis, the width of the ion density peak is around 1/10 of the beam spot size and the emittance growth of the beam is only 75\% in hydrogen plasma and 20\% in a lithium plasma. To further mitigate the emittance growth, we can use an initial spot size a little smaller than the matched spot size. We also show that, for the same initial beam emittance, the emittance growth will decrease when using a lower plasma density and a correspondingly matched beam spot size. [Preview Abstract] |
Monday, October 31, 2016 12:18PM - 12:30PM |
BO6.00015: High quality electron bunch generation using a longitudinal density-tailored plasma-based accelerator in the blowout regime Xinlu Xu, Fei Li, Weiming An, Peicheng Yu, Wei Lu, Chan Joshi, Warren Mori The generation of very high quality electron bunches (high brightness and low energy spread) from a plasma-based accelerator in the blowout regime using self-injection in tailored plasma density profiles is analyzed theoretically and with three-dimensional particle-in-cell simulations. The underlying physical mechanism that leads to the generation of high quality electrons is uncovered by tracking the particle trajectories of the electrons as they cross the sheath and are trapped by the wake. Details on how the intensity of the driver and the density scale length controls the ultimate beam quality are described.Three-dimensional particle-in-cell simulations indicate that this concept has the potential to produce beams with $\sim$0.5 nC of charge, peak brightnesses of $0.5\times10^{20} A/m^2/rad^2$ and with absolute projected energy spreads of $<0.5 MeV$ using existing lasers or electron beams to drive nonlinear wakefields. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700