Prediction of In-Space Durability of Protected Polymers Based on Ground Laboratory Thermal Energy Atomic Oxygen

Development of a Ground Based Atomic Oxygen and Vacuum Ultraviolet Radiation Simulation Apparatus

“…The low energy thermal plasma can be manipulated through interactions with geometric surfaces or magnetics to form a directional discharge; this will cause the pits and cones to grow larger, but still will not compare to the erosion of materials on the ram facing side of a spacecraft. 18 Low energy RF plasmas and microwave discharges can still provide pertinent results, recalling the Maxwellian distribution from Chapter II, a certain amount of these low energy particles will have enough energy to replicate AO erosion. 18 Every incident AO atom that interacts with a surface material has a finite probability of reacting with said material, this probability decreases as the overall energy of the plasma decreases.…”

“…18 Low energy RF plasmas and microwave discharges can still provide pertinent results, recalling the Maxwellian distribution from Chapter II, a certain amount of these low energy particles will have enough energy to replicate AO erosion. 18 Every incident AO atom that interacts with a surface material has a finite probability of reacting with said material, this probability decreases as the overall energy of the plasma decreases. In order to compensate for this loss, low energy plasma systems must produce a higher number density of AO to manifest the desired results.…”

“…Energetic AO ions have a spectral line that emits UV radiation at a wavelength of 130 nm, [18][19][20] which can accelerate the erosion process as discussed in Chapter II. Methods have been developed that can eliminate a direct line of sight between the AO source and the samples in order to reduce this side affect.…”

“…22 These systems tend to be the most practical systems in terms of cost and simplicity, as well as their ability to be scaled to provide large area and high flux exposures. 18 One version at NASA's Glenn Research Center in Cleveland, Ohio, has an exposure area of 1.5 by 2.1 m. 23 These systems will run either on air or oxygen at pressures below 200 mTorr while provided fluxes on the order of 10 15 atoms/cm 2 /s or greater. 18,22 When operating on air it has been found the ambient nitrogen, which also becomes ionized, does not affect the results of AO erosion.…”

“…18 One version at NASA's Glenn Research Center in Cleveland, Ohio, has an exposure area of 1.5 by 2.1 m. 23 These systems will run either on air or oxygen at pressures below 200 mTorr while provided fluxes on the order of 10 15 atoms/cm 2 /s or greater. 18,22 When operating on air it has been found the ambient nitrogen, which also becomes ionized, does not affect the results of AO erosion. 18 As mentioned before, although plasma ashers create an AO plasma that is characteristically different from orbital AO they still generate material erosion that is qualitatively similar to orbital AO.…”