Accession Number:

ADA595592

Title:

Background Pressure Effects on Krypton Hall Effect Thruster Internal Acceleration

Descriptive Note:

Conference paper

Corporate Author:

AIR FORCE RESEARCH LAB EDWARDS AFB CA

Report Date:

2013-08-01

Pagination or Media Count:

32.0

Abstract:

This study uses krypton propellant in a medium power Hall effect to amplify the effect of background pressure due to the greater mobility of neutral krypton compared to neutral xenon. The use of krypton amplifies the effect of elevated background pressures by enhancing the population of neutrals capable of reaching into the critical ionization and acceleration regions within a Hall effect thruster discharge. As ground test facilities cannot reach pressures comparable to those in LEO or GEO, these measurements provide a useful benchmark for determining the effects and methods to mitigate the inherent limitations of available ground test facilities as well as providing data for comparison to future simulations and experiments. Using the 728.98 nm 5d4 D72-5p4 P 9702 Kr II transition, we successfully measured ion velocities via laser-induced fluorescence in the near-plume and within the acceleration channel of a laboratory model, medium power Hall effect thruster. With these measurements and historical data, we are able to estimate the neutral number density from neutral velocity and propellant utilization estimates for both xenon and krypton operation. From these measurements and calculations, we show that the relative number density of the neutrals in the acceleration channel compared to the background neutral number density at the thruster exit appears to be an important parameter to determining the degree to which the thruster is sensitive to background pressure.

Subject Categories:

  • Inorganic Chemistry
  • Electric and Ion Propulsion

Distribution Statement:

APPROVED FOR PUBLIC RELEASE