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.

*KLJ, JJP, DNP, SO, AJ acknowledge the support of DOE through SBIR/STTR grant DE-SC0013246. NM acknowledges the support of U.S. Department of Energy through the LANL/LDRD Program.

–

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