Role of outgassing in surface flashover under vacuum

Andreas A. Neuber, M. Butcher, H. Krompholz, Lynn L. Hatfield, Magne Kristiansen

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

Results of high-speed electrical and optical diagnostics are used as a basis to discuss a new surface flashover model. Outgassing, caused by electron stimulated desorption, is found to play a crucial role in the temporal flashover development. Dielectric unipolar surface flashover under vacuum is experimentally characterized by a three-phase development, which covers a current range from 10-4 A to 100 A. Phase one comprises a fast (several nanoseconds) buildup of a saturated secondary electron avalanche reaching current levels of 10 to 100 mA. Phase two is associated with a slow current amplification reaching currents in the Ampere level within typically 100 ns. The final phase is characterized by a fast current rise up to the impedance-limited current on the order of 100 A. The development during phase two and three is described by a zero-dimensional model, where electron-induced outgassing leads to a Townsend-like gas discharge above the surface. This is supported by time-resolved spectroscopy that reveals the existence of excited atomic hydrogen and ionic carbon before the final phase. The feedback mechanism toward a self-sustained discharge is due to space charge leading to an enhanced field emission from the cathode. A priori unknown model parameters, such as outgassing rate and gas density buildup above the surface, are determined by fitting calculated results to experimental data. The significance of outgassing is also discussed with a view to microwave surface flashover.

Original languageEnglish
Pages (from-to)1593-1598
Number of pages6
JournalIEEE Transactions on Plasma Science
Volume28
Issue number5
DOIs
StatePublished - Oct 2000

Fingerprint Dive into the research topics of 'Role of outgassing in surface flashover under vacuum'. Together they form a unique fingerprint.

  • Cite this

    Neuber, A. A., Butcher, M., Krompholz, H., Hatfield, L. L., & Kristiansen, M. (2000). Role of outgassing in surface flashover under vacuum. IEEE Transactions on Plasma Science, 28(5), 1593-1598. https://doi.org/10.1109/27.901239