LABORATORY SIMULATION OF LOW-EARTH-ORBIT (LEO) ATOMIC OXYGEN EFFECTS

Our pulsed fast oxygen atom source has been used extensively over the last 9 yr to investigate the effects of ambient oxygen atoms that impa ct materials placed in LEG. During this period, we have irradiated ove r 2000 material samples with 8 km/s oxygen atoms generated in our sour ce. Typical irradiance level is 3 x 10(20) O atoms/cm(2) although some materials have been irradiated to fluence levels as high as 6 x 10(21 ) O atoms/cm(2). In this paper, we review the operating principles and characteristics of our source along with the diagnostic and handling procedures appropriate to material testing. We then present representa tive data on the velocity dependence of oxygen atom erosion rates (the PSI source provides oxygen atoms tunable over the velocity range of 5 to 12 km/s) as well as the dependence on material temperature. Specif ic examples of nonlinear oxidative effects related to surface contamin ation and test duration will also be provided.