Accession Number:

AD0829211

Title:

A STUDY OF THE USE OF CHEMICAL ADDITIVES FOR THE ALLEVIATION OF THE PLASMA SHEATH PROBLEM,

Descriptive Note:

Corporate Author:

SPACE SCIENCES INC WALTHAM MA

Personal Author(s):

Report Date:

1967-12-18

Pagination or Media Count:

74.0

Abstract:

The relative importance of various electron removal process such as attachment, diffusion, and recombination are discussed and it is shown that electron attachment is an important process. The relationship between physical cooling and frozen flow is outlined. Factors that determine the relative effectiveness of a gaseous additive includes the molecular weight, the electron attachment cross section as well as the energy dependence and the ability of the additive molecule to resist thermal dissociation. Molecular additives containing highly electronegative atoms have larger attachment cross sections than the additives in the atom form. Not only are the initial effects of the additive important, but the survival lifetime in a high temperature thermal plasma must be considered. Potentially harmful effects of solid refractory additives can include thermionic emission and Saha-Langmuir ionization, both of which can increase the free electron concentration. The role of additives in increasing the threshold microwave power for breakdown of the plasma sheath is also discussed. Author

Subject Categories:

  • Plasma Physics and Magnetohydrodynamics
  • Unmanned Spacecraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE