CURRENT-VOLTAGE CHARACTERISTIC OF A PARTIALLY-IONIZED PLASMA IN CYLINDRICAL GEOMETRY

The properties of a partially ionized plasma in a long cylindrical tub e subject to a uniform axial electric field are investigated. The plas ma is maintained by an external ionizing source balanced by bulk and s urface recombinations. Collisions between neutrals, whose density grea tly exceeds the density of charged particles, and of neutrals with ion s, are sufficiently effective for their velocity distribution to be cl ose to a Maxwellian with the same uniform temperature, independent of the external field. The behavior of the plasma is described by a colli sional two-fluid scheme with charge neutrality in the interior of the tube. Approximate nonlinear equations for the hydrodynamical moments a re obtained from a Boltzmann equation in which electron-neutral, elect ron-ion, and electron-electron collisions are all important. It is fou nd that under certain circumstances the current and the temperature of the electrons undergo a drastic change, with hysteresis, as the elect ric field is varied. (C) 1996 American Institute of Physics.