title: Communication: Effects of thermionic-gun parameters on operating modes in ultrafast electron microscopy.
abstract: Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes. This has been demonstrated with conventional Wehnelt electrodes and absent any applied bias. Here, by conducting simulations using the General Particle Tracer code, we define the electron-gun parameter space within which various modes may be optimized. The properties of interest include electron collection efficiency, temporal and energy spreads, and effects of laser-pulse duration incident on the LaB6 source. We find that collection efficiencies can reach 100% for all modes, despite there being no bias applied to the electrode.
authors.affiliation: FEI Company , Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: Kieft
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: Karl B
authors.initials: KB
authors.lastname: Schliep
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: Pranav K
authors.initials: PK
authors.lastname: Suri
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Flannigan