Some Consequences of Rotation in Theta-Pinch-Generated Plasma Confined by a Longitudinal Magnetic Field

摘要

A theoretical study was made of the characteristics of structured plasma puffs produced in a two-coil theta-pinch gun. The puffs are fired into a drift tube containing a longitudinal magnetic field, and their subsequent behavior is analyzed. Electron-electron and ion-ion collision times are short enough so that scalar pressures (P = nkT) can be used. Ion-electron collision times, however, are of the duration of the experiment or longer, allowing the use of two-fluid moment equations. An idealized model for the plasma puffs is proposed in which the ion fluid rotates as a rigid body in one direction about the longitudinal axis, and the electron fluid rotates in the opposite direction. This high-Beta model yields self-consistent equilibrium density and magnetic field profiles, stemming from a balance among thermal, magnetic, centrifugal, and electrostatic forces, that are compatible with observation. It is shown that double magnetic pick-up loop signals can be analyzed to ascertain the temperature, peak density, angular momentum, etc., of the plasma as it travels down the tube, and a sample calculation is presented to indicate the probable evolution of a typical puff. Thus, the model provides a self-consistent high-Beta approach to the problem of plasma and magnetic-field interaction. (Author)