The role of secondary electron emission in >snapover= anomalous current collection
Bulletin of the American Physical Society
When a biased conductor is surrounded by a dielectric and immersed in a plasma, the electron current in I-V curves increases dramatically above a positive threshold voltage (~200 V). The current collection jump is termed "snapover," and is particularly relevant to the case of spacecraft high-voltage solar arrays in Earth orbit where it can lead to substantial power losses. We describe the results of a systematic experimental investigation to examine the influence of insulating material, conducting material, size and shape of the conductor, sample history, biasing rate, plasma density, and condition of the dielectric surface (contamination and roughness) on the onset potential and magnitude of the parasitic snapover current. Previous theoretical investigations and computer simulations have proposed that the fundamental physical process underlying snapover is secondary electron emission from the dielectric. Our attempts to confirm the importance of secondary electron emission in the mechanism responsible for snapover were not conclusive, but in general did not support previous simple interpretations based on the secondary emission model.
C.D. Thomson , JR Dennison, B.V. Vayner, J.T. Galofaro, D.C. Ferguson and Win de Groot “The role of secondary electron emission in >snapover= anomalous current collection,”Bull. Am. Phys. Soc. 46(1) Part I, 249, (2001). American Physical Society March Meeting 2001, March 12 - 16, 2001, Seattle, Washington.