CONDITIONS FOR THE EXISTENCE OF A POSITIVELY CHARGED STRUCTURE IN A PENNING DISCHARGE

An analytical model is developed for the high-current form of a low-pr essure glow discharge in a magnetic field. Expressions are derived for the critical magnetic induction and critical pressure, below which it becomes impossible for this form of discharge to exist. It is shown t hat the transition from the high-voltage form to the high-current form of discharge with increasing pressure is not attributable to an incre ase in the ionization rate, but to an increase in the drift velocity o f plasma electrons across the magnetic field. Estimates based on the e xpressions derived in the article agree in order of magnitude with the experimental data. It is shown that the region in which discharge exi sts can change considerably in the presence of electron emission. (C) 1998 American Institute of Physics. [S1063-7842(98)01007-1].