The DIMEX experiment: results and analysis

Summary form only given, as follows. The DIMEX (dipole plasma microwave exposure) experiment tests the feasibility of using a magnetic dipole confined plasma as a plasma cloak. A plasma is magnetically confined about a small permanent magnet that is sheathed in stainless steel to produce stabilization of magnetohydrodynamic (MHD) instabilities. The plasma is formed by firing a low-voltage electron beam down the magnetic field lines to the magnet pole, using argon gas as the chamber fill gas. A plasma shell is observed to form around the magnetic, having a plasma-free region near the magnet, an abrupt rise to peak density just outside of the plasma-free region, and a slow, monotonically decreasing density profile outward to the chamber wall from the region of peak density. Peak electron densities of 10¹¹ /cm³ at electron temperatures of 1 eV have been measured. Following beam shutoff, a quiescent period of plasma confinement, characterized by very little diffusion, is observed, lasting 1.5 ms. This period of low diffusion is followed by a period of Bohm-like diffusion with density decay times of 2 ms. Microwaves at 1 GHz are strongly absorbed at intensities up to ~10 W/cm². At intensities above this value strong reflection begins