Observation of increased space-charge limited thermionic electron emission current by neutral gas ionization in a weakly-ionized deuterium plasma

The thermionic electron emission current emitted from a laser-produced hot spot on a tungsten target in weakly-ionized deuterium plasma is measured. It is found to be one to two orders of magnitude larger than expected for bipolar space charge limited thermionic emission current assuming an unpertur...

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Bibliographic Details
Published in:Journal of applied physics 2015-09, Vol.118 (10)
Main Authors: Hollmann, E. M., Yu, J. H., Doerner, R. P., Nishijima, D., Seraydarian, R. P.
Format: Article
Language:English
Subjects:
Applied physics
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
CURRENTS
DEUTERIUM
Deuterium plasma
ELECTRON EMISSION
Electrons
Emissions control
Gas ionization
HOT SPOTS
LASERS
Neutral gases
PLASMA
Plasmas (physics)
SPACE CHARGE
THERMIONIC EMISSION
TUNGSTEN
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Summary:The thermionic electron emission current emitted from a laser-produced hot spot on a tungsten target in weakly-ionized deuterium plasma is measured. It is found to be one to two orders of magnitude larger than expected for bipolar space charge limited thermionic emission current assuming an unperturbed background plasma. This difference is attributed to the plasma being modified by ionization of background neutrals by the emitted electrons. This result indicates that the allowable level of emitted thermionic electron current can be significantly enhanced in weakly-ionized plasmas due to the presence of large neutral densities.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4930160