Theory of space charge limited regime of thermionic energy converter with negative electron affinity emitter

Joshua Ryan Smith, Griff L. Bilbro, Robert Nemanich

Research output: Contribution to journalArticle

25 Scopus citations


A theory of the space charge limited output current regime of a vacuum thermionic energy conversion device (TEC) employing a negative electron affinity (NEA) diamond emitter electrode is derived. The theory is developed by assuming that the electrons behave as a collisionless gas and self-consistently solving Vlaslov's equation and Poisson's equation. Special cases of the theory are addressed. Calculations are performed to model a TEC with a nitrogen doped diamond emitter material under various conditions. It is shown that the NEA material outperforms a similar positive electron affinity material in terms of output power and efficiency because the NEA lowers the electrostatic boundary condition at the emitter and therefore mitigates the negative space charge effect.

Original languageEnglish (US)
Pages (from-to)1132-1141
Number of pages10
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Issue number3
StatePublished - 2009


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this