Title: Transient reactive exhaust flow from a ring-symmetric HF/DF space laser
Description: Transient diffuser flow in an HF/DF laser is analyzed via a simplified model. A radial laser      configuration is assumed where the diffuser is idealized as a ring-symmetric channel of uniform      width. The outward radial flow following an abrupt start-up of diffuser inflow is computed      numerically using a GRP-type code for integrating the Euler equations, which include an      ongoing reaction of hydrogen recombination. A new kinetic scattering effect is suggested,      resulting from the recoil of an HF or DF molecule assisting as third body in the hydrogen      recombination reaction. The main conclusion is that transient diffuser plume flow effects do not      drastically aggravate the potential for contaminating backflow (HF + DF) caused by either      thermal or kinetic backscattering. Keywords: Laser exhaust; Spacecraft contamination;      Chemical laser; Exhaust plume, Hydrogen recombination; Transient flow.
Subjects: CHEMICAL LASERS, HYDROGEN FLUORIDE LASERS, SPACECRAFT, EXHAUST GASES