A Model of Photoemission Delay with Heterostructure and Coating Barriers

ORAL

Abstract

High performance Free Electron Lasers (FEL) and x-ray FELs (xFEL) seek high quantum efficiency (QE) photocathodes (typically semiconductors), but simultaneously demand low emittance. Photocathodes incorporating heterostructures and/or coatings such as graphene or boron nitride have been under consideration as a means to improve QE (as well as robustness and lifetime) while allowing for methods beyond simple bulk transport, pulse shaping, and surface modifications to tailor emittance behavior. Modifications induced by coatings and heterostructures have lead to an analysis of the transmission probability of the more complex barrier profiles. The potentials over which emission occurs are provided using a ``macro-averaging'' technique applied to the output of density functional theory simulations. This presentation will analyze the behavior of delayed emission effects for short pulses where field conditions at the surface change over the duration of the pulse. The models are in development for the Particle-in-Cell code MICHELLE used to model beam formation and transport in rf injectors and electron sources.

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Presenters

  • Kevin Jensen

    Naval Research Laboratory, U.S. Naval Research Laboratory

Authors

  • Kevin Jensen

    Naval Research Laboratory, U.S. Naval Research Laboratory

  • John Petillo

    Leidos Corp.

  • Nathan Moody

    AOT-AE: Accelerators and Electrodynamics, Los Alamos National Laboratory, Los Alamos National Laboratory

  • Daniel Finkenstadt

    Physics Department, US Naval Academy, U.S. Naval Academy

  • Andrew Shabaev

    Naval Research Laboratory, U.S. Naval Research Laboratory

  • Dimitri Panagos

    Gnosys Systems

  • Samuel Lambrakos

    Naval Research Laboratory, U.S. Naval Research Laboratory

  • Serguei Ovtchinnikov

    Leidos Corp.

  • Aaron Jensen

    Leidos Corp.

  • Hisato Yamaguchi

    MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory, Los Alamos National Laboratory

  • Fangze Liu

    Los Alamos National Laboratory, Materials Physics and Applications Division, Los Alamos National Laboratory