Lunar mass spectrometer test program

The procedures used and the results are described, which were obtained in a test program to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The instrument consists of a cold cathode ion source, a small quadrupole mass analyzer, and an off-axis electron multiplier ion-counting detector. Instrument resolution, sensitivity, and S/N ratio were demonstrated over the mass range 0-150 amu and over a partial pressure range from ntorr to ptorr. The subject analyzer was also prepared for extended testing, in conjunction with two other candidate instruments, in a large molecular beam vacuum facility.