Low-energy sputtering yield measurements of O+ O2+ N+ and N2+ incident on Al and Al2O3 surfaces

摘要

Sputtering yield measurements, which help to quantify the rate at which erosion occurs, were made for low-energy beams (50 - 200 eV) of O$+$PLU$/, O$- 2$/$+$PLU$/, N$+$PLU$/, and N$-2$/$+$PLU$/ incident on Al, and Al$-2$/O$-3$/ surfaces. These materials are likely candidates for exterior portions of Space Station Freedom's power generation system. Potential differences produced by the power generation system (possibly as high as 300 volts) would accelerate the ions in the surrounding plasma to energies well above the sputtering threshold. Atomic oxygen and molecular nitrogen interactions with surfaces play a critical role in surface erosion and space glow that occur for exposed materials in a low-earth orbit. As much as 90% of the atmosphere at these altitudes is comprised of atomic oxygen which is more abundant than the molecular form since the molecular form is quickly dissociated by UV radiation. Mass-loss measurements were conducted using samples that were vacuum deposited on the surface of a quartz crystal and a novel technique was utilized to increase the sensitivity of the quartz crystal microbalance which was used to measure the mass loss.