Development of a Cryogenically Pumped Mass Spectrometer Probe for Rocket Plume Studies.

摘要

Two cryogenically cooled (20K) mass spectrometer probes were developed for sampling species concentrations in a rocket exhaust plume. A flat-face probe with a cryogenic (20K) skimmer and a conical probe with a warm 20-deg half-angle conical skimmer were evaluated in room temperature free-jet expansions of nitrogen,argon,and gas mixtures containing hydrogen. Cryosorption pumping of hydrogen by 20K CO2 frosts was employed within the probes. Typical probe pressures were maintained on the 10to the 7th power torr scale. Species densities were measured in the room temperature free jets and calibrations determined. The flat-face probe was determined to be unsuitable for rocket testing. The conical probe was tested in the exhaust plume of a 1-lb thrust MMH/N2O4liquid rocket engine and major species concentrations were determined for several O/F ratios. Qualitative minor specie measurements were also made.