Simulation of trapped non-neutral plasma dynamics with rotating wall compression

Abstract

A spectral macroparticle simulation scheme is used to model non-neutral plasma dynamics in a Penning-Malmberg trap. This grid-free numerical scheme is well adapted to the specific geometry of trapped plasmas, with varying longitudinal and transverse profiles in a cylindrical conducting pipe. The cutoff spectral harmonics provide control over the trade-off between accuracy and noise smoothing, which is especially important in the three-dimensional case. We demonstrate the ability of this scheme to obtain the dispersion relation of the plasma modes from the inherent simulation noise, providing a valuable tool for understanding the plasma's behavior. In the presence of a rotating wall drive, we show that the numerical scheme can reproduce the time evolution of the driven eigenmodes, identify the onset of mode mixing with increasing drive amplitude and retrieve the compression rate dependency on the drive frequency, known from the weak drive regime of the rotating wall technique. To the authors' knowledge, such simulations have not been reported in the literature so far.