Comparison between test-particle simulations and test-particle theories for cosmic ray transport: II. Plasma wave turbulence

Abstract

The standard theory for the description of cosmic rays is the quasilinear theory. Whereas it was assumed for a long time that quasilinear theory is a reliable and useful tool to describe transport of charged particles, recent test particle simulations have demonstrated that for certain parameter regimes a linear description of transport is not suitable. In the first part of this series, we compared quasilinear theory with different test-particle simulations within the magnetostatic approach. The key result of the first paper was that a linear description of transport seems to be inappropriate. In the current paper we explore the validity of the quasilinear theory for the more realistic plasma wave model. We demonstrate that nonlinear effects are also essential for particle transport in this turbulence model.