Speaker
Description
R. Bazrafshan(1,4), G.H. Kassier(1), M. Fakhari(1), H. Delsim-Hashemi(2), T. Rohwer(1), K. Flöttmann(2), N.H. Matlis(1) and F. X. Kärtner(1,3,4)
(1) Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron, Hamburg, Germany
(2) Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
(3) The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Germany
(4) Physics Department, Universität Hamburg, Germany
We present a compact electron source for a high-temporal-resolution ultrafast electron diffraction (UED) instrument. The source, which employs field-enhancement at a pin-shaped photocathode to produce an extraction field strength of about 100 MV/m driven by a solid-state rack-mountable 10-W-average power, 10-kW-peak power S-band RF amplifier, can generate 180 keV electron bunches of 100 fC charge that compress via velocity bunching down to 30 fs with a radius of 220 μm, and spatial emittance of 0.1 mm-mrad at a distance of 8 cm from the photocathode. The impact of laser spot size and duration, as well as their spatial distribution, on the temporal bunch length of electrons on the specimen was investigated. Following the successful completion of the conditioning phase of the RF gun and multipacting suppression, photo-triggered electrons using a UV laser on the photocathode were observed.
