Particle Simulation of Drift-Cyclotron Instability

Abstract

The drift-cyclotron instability may occur in a collisionless Maxwellian magnetized plasma, driven by the free energy associated with a spatial density gradient normal to the magnetic field. Electrostatic particle simulations are used to study this instability with both species magnetized and treated fully nonlinearly. During the linear stage simulations show exponential growth in time over a few ion cyclotron periods, with the growth rates in fair agreement with a linear nonlocal theory, while the real parts of frequencies are not well resolved in the short growth period. The total electrostatic field energy reaches a peak of a few percent of the initial ion kinetic energy for most runs, with ωpi2/ωci2 and mass ratios ranging from 25 to 200. These simulation saturation levels are somewhat above those predicted by existing nonlinear theories. At the time of saturation, the phase space pictures of electrons and ions show bunching and density profile modification occurs.