Development of Spectroscopic Tools to Study Rarefied Gas Flows in Non-Equilibrium
Technical Report,11 Mar 2018,11 Mar 2019
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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Satellites, such as CubeSats, are used for a variety of educational and scientific purposes including surveillance, communication, and research. Their utility while in orbit can be greatly enhanced and prolonged by propulsion mechanisms such as micro-resistojets, which operate by expansion of gas through the nozzle. Although computer simulations have progressed in describing the high-speed viscous flow, experimental efforts are needed to validate and verify these models. Because of the low pressures 1 Torr in which micro-resistojets operate and because of the high spatial resolution 100 um required to resolve the nozzle exhaust at its exit diameter 1-2 mm, diagnostics of the micro-resistojet exhaust are difficult to achieve. To address this obstacle, a fiber-coupled, multiple-pass cell for spontaneous Raman scattering spectroscopy of the nozzle exhaust in a vacuum chamber was developed. Proof of principle measurements are successfully performed and illustrated at 1 Torrand 500 mTorr for H2 thermometry. Each spectral acquisition takes 15 and 30 minutes, respectively.
- Atomic and Molecular Physics and Spectroscopy
- Fluid Mechanics