High gradient silicon carbide immersion lens ultrafast electron sources

We present two compact ultrafast electron injector designs with integrated focusing that provide high peak brightness of up to 1.9 × 1012 A/m2 Sr2 with 10’s of electrons per laser pulse using silicon carbide electrodes and silicon nanotip emitters. We demonstrate a few centimeter scale 96 keV immersion lens electron source and a 57 keV immersion lens electron source with a 19 kV/mm average acceleration gradient, nearly double the typical 10 kV/mm used in DC electron sources. The brightness of the electron sources is measured alongside start-to-end simulations including space charge effects. These sources are suitable for dielectric laser accelerator experiments, ultrafast electron diffraction, and other applications, where a compact high brightness electron source is required.