Single-species Weibel instability of radiationless plasma

Abstract

A Particle-in-Cell (PIC) numerical simulation of the electron Weibel instability is applied in a frame of Darwin (radiationless) approximation of the self-consistent fields of sparse plasma. As a result, we were able to supplement the classical picture of the instability and, in particular, to obtain the dependency of the basic characteristics (the time of development and the maximum field energy) of the thermal anisotropy parameter, to trace the dynamic restructuring of current filaments accompanying the nonlinear stage of the instability and to trace in detail the evolution of the initial anisotropy of the electron component of plasma.

PIC simulations of the temperature anisotropy-driven Weibel instability: analysing the perpendicular mode

“…We choose the large A = 399 here and in the simulation (v th = 20v th⊥ ), so that we get a large growth rate of the instability and a good signal-to-noise ratio for the electromagnetic fields in the simulation. This value of A furthermore allows us to test for a large A the finding [12,14], that the maximum average magnetic energy density is almost independent of the initial anisotropy for A 25. Electromagnetic fluctuations with a wavevector in the perpendicular plane are amplified in this case, according to the well-known dispersion relation for the linear phase of the instability [21] k 2 c 2 ω 2…”

“…A net current and electromagnetic fields develop. The magnetic energy density can reach in extreme cases up to 1/12 of the total energy density [12][13][14] and it exceeds by far the electric one. The focus of previous studies has thus been on the magnetic field.…”

“…Instabilities driven by a thermal anisotropy have been widely examined numerically and analytically [11][12][13][14][15][16][17] and they are considered also in our present work. The thermal velocity of the bi-Maxwellian distribution is larger along the one axis than in its perpendicular plane.…”