Vacuum Thermionic Energy Conversion Based on Nanocrystalline Diamond Films

Abstract:

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Vacuum thermionic energy conversion achieves direct conversion of heat into electrical energy. The process involves thermionic electron emission from a hot surface and collection of the electrons on a cold surface where the two surfaces are separated by a small vacuum gap. Results are presented which indicate that nanocrystalline diamond films could lead to highly efficient thermionic energy conversion at temperatures less that 700°C. A critical element of the process is obtaining a stable, low work function surface for thermionic emission. Results are presented which establish that N-doped diamond films with a negative electron affinity can exhibit a barrier to emission of less than 1.6 eV. Films can be deposited onto field enhancing structures to achieve an even lower effective work function. Alternatively, nanocrystalline diamond films prepared with S doping exhibit field enhanced thermionic emission and an effective work function of ~1.9 eV. The field enhanced structures can reduce the effect of space charge and allow a larger vacuum gap. The possibility of a low temperature nanocrystalline diamond based thermionic energy conversion system is presented.

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Periodical:

Edited by:

P. VINCENZINI and E. CAPPELLI

Pages:

83-92

DOI:

10.4028/www.scientific.net/AST.48.83

Citation:

F.A.M. Koeck et al., "Vacuum Thermionic Energy Conversion Based on Nanocrystalline Diamond Films", Advances in Science and Technology, Vol. 48, pp. 83-92, 2006

Online since:

October 2006

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$35.00

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