Dissipative trapped electron instability in a linear machine
Abstract
A study of the dissipative trappedelectron instability is greatly simplified, both experimentally and theoretically, when posed in a cylindrical geometry. A derivation of the linear dispersion relation for a finite cylindrical system with two localized magnetic mirrors shows that a linear machine can support the instability with strong localization between the mirrors. The growth rate can be larger than 10% of the wave frequency, which is approximately the drift frequency. A simple physical explanation is provided for the dynamics of the instability. An experiment was performed in a Qmachine converted to an ODEtype device in which the dissipative trappedelectron instability was definitively identified through the dependence of wave amplitude on mirror ratio, axial position, temperature gradient, electroncollision frequency, and radial position. The wave, with the azimuthal mode number 1, is nearly monochromatic at approximately 50 kHz, which is in the neighborhood of the drift frequency. The density fluctuation in the wave can be as high as 30%.
 Publication:

Plasma Physics
 Pub Date:
 October 1975
 DOI:
 10.1088/00321028/17/10/007
 Bibcode:
 1975PlPh...17..785P
 Keywords:

 Linear Systems;
 Magnetic Mirrors;
 Magnetically Trapped Particles;
 Magnetohydrodynamic Stability;
 Plasma Control;
 Plasma Cylinders;
 Q Devices;
 Electron Energy;
 Electron Oscillations;
 Plasma Oscillations;
 Toroidal Plasmas;
 Plasma Physics