Equilibrium of non-neutral plasmas with weak axisymmetric magnetic perturbations

The effect of weak external axisymmetric magnetic and electrostatic perturbations on the equilibrium of a non-neutral plasma confined in a Malmberg-Penning trap is analyzed. A semi-analytic solution for the potential variations inside the trap is found in a paraxial limit of the perturbations for the case of global thermal equilibrium. The populations of magnetically and electrostatically trapped particles created by the external perturbations are characterized, and their fractions are calculated explicitly for a bi-Maxwellian distribution function. 2D numerical simulations of the thermal equilibrium of a pure electron plasma in the presence of axial magnetic field perturbations are performed to check the limits of validity of the analytical 1D approximation.