UTILIZATION OF MASS SPECTROMETRY FOR CHARACTERIZATION OF THE INTERACTION OF HYPERTHERMAL O-ATOM BEAMS WITH MATERIALS

摘要

A first objective of this study was to analyze the species present in the beam of a facility used for atomic oxygen testing of spacecraft materials and employing a laser detonation neutral beam source. A second objective was to characterize the oxidation products evolved during interaction of this beam with materials. An analysis technique employing a quadrupole mass spectrometer has been specially developped in order to authorize time-of-flight measurements of fast ions and neutrals arriving in pulsed mode. It has permitted to characterize the source beam, evidencing VUV photons, ionic species O~+ and O_2~+, and neutral species O and O_2. The velocity distributions and the relative ratios between the various components of the beam have been calculated. A selective analysis of the oxidation products which are present very close to surfaces bombarded with the pulsed beam has been carried out using non-resonant multiphoton ionization and ion transfer. It has allowed a characterization of the products emanating from surfaces bombarded either by the raw source beam, or by a purified beam after elimination of the ions. The study, has given insight in the damage mechanisms when using laser detonation neutral beam sources for space simulation.