The filamentation instability driven by warm electron beams: Statistics and electric field generation

Abstract

The filamentation instability of counterpropagating symmetric beams of electrons is examined with 1D and 2D particle-in-cell (PIC) simulations, which are oriented orthogonally to the beam velocity vector. The beams are uniform, warm and their relative speed is mildly relativistic. The dynamics of the filaments is examined in 2D and it is confirmed that their characteristic size increases linearly in time. Currents orthogonal to the beam velocity vector are driven through the magnetic and electric fields in the simulation plane. The fields are tied to the filament boundaries and the scale size of the flow-aligned and the perpendicular currents are thus equal. It is confirmed that the electrostatic and the magnetic forces are equally important, when the filamentation instability saturates in 1D. Their balance is apparently the saturation mechanism of the filamentation instability for our initial conditions. The electric force is relatively weaker but not negligible in the 2D simulation, where the electron temperature is set higher to reduce the computational cost. The magnetic pressure gradient is the principal source of the electrostatic field, when and after the instability saturates in the 1D simulation and in the 2D simulation.

10 pages, 6 figures, accepted by the Plasma Physics and Controlled Fusion (Special Issue EPS 2009)

References in corpus (4)

• Exact relativistic kinetic theory of an electron beam-plasma system: hierarchy of the competing modes in the system parameter space
• Simulation study of the filamentation of counter-streaming beams of the electrons and positrons in plasmas
• One-dimensional particle simulation of the filamentation instability: electrostatic field driven by the magnetic pressure gradient force
• Numerical solution of the linear dispersion relation in a relativistic pair plasma

Cited by in corpus (7)

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• PIC Simulations of the Temperature Anisotropy-Driven Weibel Instability: Analyzing the perpendicular mode
• Electron Weibel instability and~quasi-magnetostatic structures in~an~expanding collisionless plasma
• Multi-scale magnetic field structures in an expanding elongated plasma cloud with hot electrons subject to an external magnetic field
• Electric field generation by the electron beam filamentation instability: Filament size effects
• Density filamentation nonlinearly driven by the Weibel instability in relativistic beam plasmas