Test of a miniature double-focusing mass spectrometer for real-time plasma monitoring

Abstract

A miniature double-focusing mass spectrometer with an 8 mm radius was tested at the Advanced Space Propulsion Laboratory (ASPL) at NASA Johnson Space Center (JSC). The purpose of these experiments was to provide residual gas-analysis and single-ion-monitoring capabilities for the vacuum chamber where NASA's new plasma propulsion system, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), is being developed. The instrument used here was an alpha (α) version of the Integrated Leak Detector System (ILD 50) and represents a smaller version of the original 20 mm-radius Compact Double Focusing Mass Spectrometer prototype (CDFMS) developed at the University of Minnesota. The instrument successfully provided gas-composition information on the vacuum test chamber and several different plasma formulations, provided resolving powers close to the theoretical value of 40 at full width half maximum (FWHM) and demonstrated an operational mass range of 1–50 Da.