A fast atomic oxygen beam facility with in situ testing/analysis capabilities

Abstract

A fast atomic oxygen beam facility consisting of a beam source, a mass spectrometer, an Auger electron spectroscope, a scanning tunneling microscope, and a friction tester has been developed to investigate interaction of energetic atomic oxygen with solid surfaces. The fast atomic oxygen beam has been characterized by time of flight distribution, quadrupole mass spectrometry, and quartz crystal microbalance. The time of flight distribution of the beam has shown that the average translational energy of the atomic oxygen beam reaches 4.7 eV and that the full width at half-maximum is 5.5 eV. A flux of the atomic oxygen is calculated from the frequency shift of the quartz crystal microbalance with silver electrodes, and typical flux of the atomic oxygen beam being 4.0×1012 atoms/cm2 s. The flux of atomic oxygen of this source is fairly low, but is corresponding to that in the altitude of 500 km in low Earth orbit. The surface sensitive analysis methods equipped with the facility, such as Auger electron spectroscopy and scanning tunneling microscopy, have provided changes in the surface composition and morphology caused by the atomic oxygen exposure, without receiving any effect of ambient air. The ultrahigh vacuum friction tester especially designed for this facility is used to measure tribological properties of solid lubricants under the atomic oxygen exposures. Such in situ testing capability of this facility enables fundamental research for understanding the reaction scheme of atomic oxygen as well as engineering-oriented research for obtaining high reliability of the space systems.