Eur. Phys. J. B (2013) 86: 382
https://doi.org/10.1140/epjb/e2013-40646-5

Regular Article

Enhanced thermionic currents by non equilibrium electron populations of metals

¹ Departamento de Física EUITA-E Ingeniería Aeronáutica y del Espacio, Univ. Politécnica de Madrid, 28040 Madrid, Spain
² Departamento de Física Aplicada E.T.S.I. Aeronáuticos-E Ingeniería Aeronáutica y del Espacio, Univ. Politécnica de Madrid, 28040 Madrid, Spain

^a e-mail: domenech.garret@upm.es

Received: 3 July 2013
Received in final form: 23 July 2013
Published online: 16 September 2013

Abstract

An analytical expression is derived for the electron thermionic current from heated metals by using a non equilibrium, modified Kappa energy distribution for electrons. This isotropic distribution characterizes the long high energy tails in the electron energy spectrum for low values of the index κ and also accounts for the Fermi energy for the metal electrons. The limit for large κ recovers the classical equilibrium Fermi-Dirac distribution. The predicted electron thermionic current for low κ increases between four and five orders of magnitude with respect to the predictions of the equilibrium Richardson-Dushmann current. The observed departures from this classical expression, also recovered for large κ, would correspond to moderate values of this index. The strong increments predicted by the thermionic emission currents suggest that, under appropriate conditions, materials with non equilibrium electron populations would become more efficient electron emitters at low temperatures.