Highly Ionized Dense Plasma in a Cesium Penning Arc

Abstract

A stable cesium plasma with a density of 1015 ions/cm3 and 50% ionization was produced by a Penning arc. A hot, high work function, anode is shown to be a significant factor in the achievement of this very dense highly ionized plasma. Plasma instabilities, which are normally present in the Penning arc, were found to be rotating in the j × B direction. These instabilities are damped when the arc pressure is 0.5 torr and the arc boundary is irregular. Radial and axial plasma density variations were measured. The radial density gradient decreased when the plasma became stable. The axial plasma density variation indicates that the prime source of plasma electrons is the hot cathode.

Rotating Plasmas

“…Instabilities similar to the Kelvin-Helmholtz mode have earlier been observed in a strongly sheared magnetohydrodynamic flow in mercury [41,42]. Similar phenomena should also arise in rotating plasmas and it is likely that they are present in experiments with the so-called Q-machines [149,195]. 3.…”

“…4., and a strong ion-neutral drag and an associated instability [146,147] may then develop in crossed electric and magnetic fields. The instabilities observed in some experiments are likely to be explained by this mode [194,195], whereas the unstable behaviour in some other cases is likely to be produced by different mechanisms such as those from microinstabilities [176].…”

Effect of Resonant Microwave Power on a PIG Ion Source

“…We operated the source in a non-sputtering mode using argon gas under fairly moderate operating conditions. We ran in a pulsed mode, with pulses several milliseconds long at a repetition rate of about 30 Hz.…”