Flow Velocity Measurements in Nirogen Plumes Stimulated by REMPI

Kurzfassung

In the DLR- high vacuum plume test facility STG,experiments have been performed to study the expansion of supersonic plumes into vacuum with N2 as a test gas. The measured values were the Pitot pressuere, the molecular nuber flux, the rotational temperature and the velocity. The last two quantities were measured by the 2+2 REMPI- technique with a stimulation wavelength of 283 nm - 284 nm. ( REMPI = resonance enhanced multi photon ionozation ). This study is focussed on the experimental procedure to measure the flow velocity of N2 in rarefied plumes expanding from supersonic nozzles into vacuum.