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TT: Fachverband Tiefe Temperaturen

TT 57: Focused Session: Frontiers of Electronic Structure Theory 6 (jointly with HL and O)

TT 57.9: Talk

Thursday, March 14, 2013, 12:45–13:00, H36

Thermionic emission from metal surfaces: A first principles study — •Johannes Voss¹, Sharon Chou¹, Aleksandra Vojvodic^1,2, Igor Bargatin³, Roger Thomas Howe¹, and Frank Abild-Pedersen² — ¹Stanford University, USA — ²SLAC National Accelerator Laboratory, USA — ³University of Pennsylvania, USA

The ability to lower the temperatures required for sufficient electronic emission from hot cathodes would lead to more efficient thermionic energy converters and electron guns. Thermionic emission of electrons from metal surfaces is governed by the work function and tunneling probabilities. While the former can be extracted easily from ab initio band structure calculations, for the latter, scattering properties of the surface need to be taken into account.

Here, we present density functional theory calculations of thermionic emission currents based on a non-equilibrium Green’s function approach. We compare these results to experiments both for clean and coated metal surfaces. Based on an analysis of interactions in the coating layers, we suggest design pathways for new materials with higher emission current densities.