A Compact DC Gun for Ultrafast Electron Diffraction Studies on Solid-State Systems

RODRIGUEZ DÍAZ, FERNANDO. A.; CORTHEY, G.; GITARIC, D. ; MILLER, R. J. D.

Banff

Conferencia; 6th Banff Meeting on Structural Dynamics; 2019

We have been working on the design and development of a compact table-top single-chamber DC ultrafast electron diffraction (UED) setup with the major aim of optimizing the electron pulse stability with an accelerating field of 10 MV/m and a short drift path chatode-anode-sample-lens of 20 mm to minimize the pulse broadening due to space-charge effects and optimize the quality of the diffraction pattern. The evaluation of the electrostatic accelerating field was performed through finite elements method (FEM) simulations using Agros2D software1. Three cathode shapes were tested resulting that the Bruce-type profile2 might offer a better balance between arcing origin points and positive field gradient3, as described previously4. From particle tracing simulation using ASTrA5, beam coherence length, pulse duration and beam profile were assessed, which allowed us to design the electromagnetic lens configuration, satisfying our chamber spatial constraints. We present the details of the simulations and the setup design and construction and the first tests performed.