Nonlinear saturation of relativistic Weibel instability driven by thermal anisotropy

Abstract

The present paper investigates nonlinear saturation of the relativistic Weibel instability by employing theory and a particle-in-cell simulation technique. It is found that the early phase of the instability is in excellent agreement with linear theory. Qualitative agreement with quasilinear prediction is also found. An analysis based on an alternative magnetic trapping saturation theory reveals that a relativistic formula leads to a substantial discrepancy between theory and simulation. However, excellent agreement is recovered in the nonrelativistic regime. The analysis of the Weibel instability beyond the quasilinear saturation stage reveals an inverse cascade process via a nonlinear decay instability involving electrostatic fluctuation. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3172941]