Accession Number:

ADA159998

Title:

Molecular Back Flow from the Exhaust Plume of a Space-Based Laser

Descriptive Note:

Master's thesis

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s):

Report Date:

1985-06-01

Pagination or Media Count:

56.0

Abstract:

Back flow from the exhaust of a chemical laser in low earth orbit may be detrimental to the integrity and operation of the selfsame system. Difficulties arise in the calculation of exhaust plume properties and molecular flux as the gas expands from continuum to free-molecular flow. The solution of the governing Boltzmann equation is exceedingly complex similarly, numerical solutions such as the Direct Simulation Monte Carlo technique required prohibitive amounts of computer processing time. This thesis presents and alternate method of the assessment of molecular flux in which the continous transition from viscous to collisionless flow is approximated by a suitably defined breakdown surface. The molecular flux incident on a given area of the spacecraft surface is determined by integration of flux from all significant portions of the breakdown surface. Results are presented for exhaust plumes of various stagnation and exit plane conditions emanating from an axisymmetric ring nozzle. Keywords Spacecraft contamination Rarefied gas dynamics Exhaust gases FORTRAN FLUX computer program Rarefaction.

Subject Categories:

  • Lasers and Masers

Distribution Statement:

APPROVED FOR PUBLIC RELEASE