Molecular dynamics simulations of temperature relaxation in strongly magnetized, non-neutral, equal-density two-component plasmas.

Abstract

An important process for antimatter experiments is the cooling of particles in a Penning-Malmberg trap to experimentally useful temperatures. A non-neutral plasma of one species (e.g., antiprotons) can be collisionally cooled on another colder species (e.g., electrons). Modeling temperature relaxation in these devices is challenging from a plasma physics perspective because the particles are strongly magnetized (the gyrofrequency exceeds the plasma frequency). Recently, a theoretical model based on the generalized collision operator was proposed to describe the temperature evolution in these conditions, predicting a multistep relaxation process where temperatures parallel to the magnetic field relax much faster than perpendicular to it [L. Jose et al., Phys. Rev. E 111, 035201 (2025)2470-004510.1103/PhysRevE.111.035201]. Here, this model is tested using molecular dynamics simulations. Two analysis methods are applied: one based on an imposed temperature difference, and the other based on a Green-Kubo relation. The results of the simulations support the predictions of this new model. This work extends previous molecular dynamics simulation studies of temperature anisotropy relaxation in one-component non-neutral plasmas to two-component systems.