Velocity-Space Instabilities in a Simulated Fusion Plasma and Laser Generation of Plasma

摘要

The dispersion of electrostatic waves in a cesium plasma produced by thermal ionization and penetrated by a lithium ion beam is investigated. It is shown that if the ion beam has an anisotropic velocity distribution, instabilities can arise which are analogous to 'velocity-space' instabilities observed in some controlled thermonuclear fusion plasma experiments. Damping of the instabilities due to electron-neutral collisions and thermal velocities of the electrons and lithium beam ions is considered. For the parameters of the experiment, the predominant damping mechanism is the thermal velocity distribution of the lithium beam ions, and the damping is sufficiently strong to explain the absence of observed spontaneous oscillations. The physical mechanisms involved in the production of plasma by intense light pulses from a Q-switched laser are considered. An estimated time schedule is given for the production, expansion, and loss of such a plasma created in a magnetic containment system. The development and testing of a high-peak-power neodymium-glass Q-switched laser is outlined. The design of a nozzle to produce a jet of cesium vapor through the laser focus of sufficiently high density to allow laser induced breakdown is described. (Author)