Two-dimensional PIC simulations of ion beam instabilities in Supernova-driven plasma flows
- 19 May 2008
- journal article
- Published by IOP Publishing in Plasma Physics and Controlled Fusion
Abstract
Supernova remnant (SNR) blast shells can reach the flow speed $v_s = 0.1 c$ and shocks form at its front. Instabilities driven by shock-reflected ion beams heat the plasma in the foreshock, which may inject particles into diffusive acceleration. The ion beams can have the speed $v_b approx v_s$. For $v_b ll v_s$ the Buneman or upper-hybrid instabilities dominate, while for $v_b gg v_s$ the filamentation and mixed modes grow faster. Here the relevant waves for $v_b approx v_s$ are examined and how they interact nonlinearly with the particles. The collision of two plasma clouds at the speed $v_s$ is modelled with particle-in-cell (PIC) simulations, which convect with them magnetic fields oriented perpendicular to their flow velocity vector. One simulation models equally dense clouds and the other one uses a density ratio of 2. Both simulations show upper-hybrid waves that are planar over large spatial intervals and that accelerate electrons to $sim$ 10 keV. The symmetric collision yields only short oscillatory wave pulses, while the asymmetric collision also produces large-scale electric fields, probably through a magnetic pressure gradient. The large-scale fields destroy the electron phase space holes and they accelerate the ions, which facilitates the formation of a precursor shock.
Keywords
This publication has 33 references indexed in Scilit:
- Cosmic rays X. The cosmic ray knee and beyond: diffusive acceleration at oblique shocksAstronomy & Astrophysics, 2006
- On reformation of quasi-perpendicular collisionless shocksAdvances in Space Research, 2006
- Perpendicular Shock Reformation and Ion AccelerationSpace Science Reviews, 2005
- Selected Problems in Collisionless-Shock PhysicsSpace Science Reviews, 2004
- Electron Acceleration in the HeliosphereSpace Science Reviews, 2001
- Strong Electron Acceleration at High Mach Number Shock Waves: Simulation Study of Electron DynamicsThe Astrophysical Journal, 2000
- Acceleration of cosmic ray electrons by ion-excited waves at quasiperpendicular shocksMonthly Notices of the Royal Astronomical Society, 1997
- Particle acceleration by astrophysical shocksThe Astrophysical Journal, 1978
- The acceleration of cosmic rays in shock fronts - IIMonthly Notices of the Royal Astronomical Society, 1978
- The acceleration of cosmic rays in shock fronts - IMonthly Notices of the Royal Astronomical Society, 1978