Flow of a plasma around a disk in a magnetic field

A study has been made of density perturbations behind an electrically floating disk located in a column of low-density flowing plasma. The problem was studied numerically using the Vlasov equation and uniform plasma distribution as developed by Al'pert (1965). Computer solutions were carried out exactly for the experimental flow velocities with thermal effects in the longitudinal directional included. Plasma density profiles were modeled in the calculation allowing comparison of experimental data taken with nonuniform density. The experiment was conducted in a potassium effects in the longitudinal directional included. Plasma density profiles were 2-4 times the thermal velocity and the ratio of the radius of the body to the ion Larmor radius was approximately 1. Density measurements were made in the near and far wake using Langmuir double probes. The theory satisfactorily describes the far wake of the disk and the density pulsations which immediately follow it. However, it is necessary to consider electric fields due to the density gradients to explain other aspects of the wake structure just behind the disk.