Bulletin of the American Physical Society
60th Annual Meeting of the APS Division of Plasma Physics
Volume 63, Number 11
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session NO7: Turbulence and Transport and Strongly Coupled Plasmas
9:30 AM–12:18 PM,
Wednesday, November 7, 2018
OCC
Room: B117-119
Chair: Scott Baalrud, University of Iowa
Abstract ID: BAPS.2018.DPP.NO7.2
Abstract: NO7.00002 : Demonstration of momentum-space diffusive particle acceleration in kinetic simulations of relativistic plasma turbulence*
9:42 AM–9:54 AM
Presenter:
Kai Wong
(Univ of Colorado - Boulder)
Authors:
Kai Wong
(Univ of Colorado - Boulder)
Vladimir V Zhdankin
(Princeton University, JILA)
Dmitri A Uzdensky
(Univ of Colorado - Boulder)
Gregory R Werner
(Univ of Colorado - Boulder)
Mitchell C Begelman
(Univ of Colorado - Boulder, JILA)
We present a statistical study of nonthermal particle acceleration (NTPA) in 3D particle-in-cell (PIC) simulations of driven turbulence in relativistic pair plasmas. NTPA is an important topic for astrophysical systems such as pulsar wind nebulae and black hole accretion flows. However, the diffusive nature of particle energy evolution assumed by Fokker-Planck models of NTPA has not yet been rigorously tested by self-consistent simulations. We develop a novel methodology to measure energy diffusion using the time evolution of tracked particle samples in simulations of relativistic plasma turbulence. We find that the standard deviation of energies for particles with the same initial energy indeed grows in time close to t1/2, i.e., diffusively. The energy diffusion and advection coefficients (Dε and Aε) for the Fokker-Planck equation are measured as functions of particle energy ε. We find Dε to be proportional to ε2 in the nonthermal power-law tail, in line with theoretical expectations. However, we observe a much shallower scaling at lower energies. We also investigate the dependence of Dε and Aε on the magnetization. These results support models of NTPA in which particles stochastically gain energy from scattering by turbulent fluctuations.
*Work is supported by NASA and NSF.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DPP.NO7.2
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