Plasma Acceleration by Area Expansion
Abstract
As the area of a plasma increases, the plasma can accelerate smoothly from subsonic to supersonic velocity. The singularity which ordinarily occurs at the sonic velocity is resolved not by charge separation, as is the case for a sheath; but rather by a zero in the numerator at the same spatial position as the zero in the denominator, the sonic point. That is, at the sonic point, the acceleration due to expansion just cancels out the deceleration due to ion and electron neutral collisions. It turns out that in this configuration, the plasma can accelerate to about three times the ion sound speed. The electron temperature is determined by the geometry, gas species, and mostly, by the gas pressure. Applications to the production of a stream of neutrals for etching, and to space plasma propulsion are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 26, 2000
- Accession Number
- ADA379572
Entities
People
- Richard Fernsler
- Wallace M. Manheimer
Organizations
- United States Naval Research Laboratory