Potential Drops Supported by Ion Density Cavities in the Dynamic Response ofPlasma Diode to an Applied Field

摘要

Experiments showed that an applied voltage drop may either be supported by acathode sheath or by a quasi-linear variation over the plasma lasting for several electron transit times. In the latter case an ion density cavity existed initially. An analytical model and numerical simulations are used to show that a cavity gives rise to a quasi-linear potential variation for applied voltage drops below a certain critical value. For larger values the drop concentrates to a cathode sheath. The quasi-linear profile steepens to a double layer for large cavity depths.