Stabilization Of A Hot-electron Plasma By MHD Wall Forces

In past work, we created a hot electron plasma in a single mirror with a density of 2 x 10
¹²
electrons per cm
³
, and a temperature of 2 x 10
⁵
electron volts. One surprising feature of this plasma, as in other hot-electron plasmas, is the remarkable stability of such a plasma in a simple mirror - the loss corresponds to the 90
^°
scattering time for electrons out the mirror ends. To explain the absence of MHD instabilities, we derived a model in which the electrons formed a precessing clump of charge displaced from the mirror axis. This model was supported by RF emission measurements. The model demonstrated mathematically that such stabilization was possible. This occurs by an MHD image in the metal wall of the magnetic dipole moment of the precessing high-beta plasma clump. Moving the clump away from the metal wall by means of a ceramic scraper resulted in an instability and rapid plasma loss.