Proceedings of the 38th American Institute of Aeronautics and Astronautics Meeting on Aerospace Sciences
American Institute of Aeronautics and Astronautics
We describe a systematic experimental investigation of the phenomenon termed "snapover." In snapover, the current collected by a positively biased conductor, surrounded by a dielectric and immersed in a plasma, increases dramatically when the conductor potential is raised above some threshold value. The phenomenon is particularly relevant to the case of high-voltage solar arrays in Earth orbit. Our experiments examined the importance of conducting material, insulating material, size and shape of the conductor, sample history, biasing rate, and condition of the dielectric surface (contamination and smoothness) to the onset potential and current jump. In addition to a primary snapover occurring at approximately 200-350 volts positive bias, we observed numerous smaller current jumps from `100 V to 20 V and much larger current increases at biases from +350 V to +600 V attributed to gas discharges. Both surface roughening and surface coatings were found to substantially inhibit snpover and gas discharge. Theoretical investigations and computer simulations have proposed that the fundamental physical process underlying snapover is secondary electron emission form the dielectric. Our attempts to confirm the importance of secondary electron emission in the mechanisms responsible for snapover were not conclusive, but in general did not support previous simple interpretations of the SE model.
C.D. Thomson, JR Dennison, R.E. Davies, D.C. Ferguson, J.T. Galafaro and B.V. Vayner, “Investigation of the First Snapover of Positively Biased Conductors in a Plasma,” 38th American Institute of Aeronautics and Astronomics Meeting on Aerospace Sciences, Reno, NV, January, 12, 2000.