KINETIC THEORY SOLUTION FOR THE SPHERICAL ELECTROSTATIC PROBE IN A STATIONARY PLASMA.
Abstract
The spherical electrostatic probe immersed in an infinite weakly ionized gas is studied from the kinetic theory point of view. The Boltzmann equations are transformed into an energy-angular momentum phase space. The charged particle motion is fully analyzed in this phase space. By using a Krook-type model for charged-neutral particle collision, a formal integral solution of the distribution function is discussed. Lees' moment equations are derived, and sample solutions for those moment equations are computed. From the sample solutions it is found that (1) The sheath effect is much more pronounced for a positive potential probe than a negative one. (2) On decreasing the ratio of Debye length to probe radius the ion current is decreased, the sheath effect is more pronounced, and the saturation ion current is reached at smaller negative probe potential. (3) The effect of collisions is to help the plasma to sustain more potential, to decrease both the ion current and electron current, as well as to reduce the excess ion number density in the sheath region. (4) In the collisionless case, when the ion temperature is increased the ion current is also increased. This increase becomes negligibly small at large negative probe potentials.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1966
- Accession Number
- AD0484528
Entities
People
- Yon-sun Chou
Organizations
- University of California, Berkeley