These guns are part of the UCSB FEL electron beam systems. One is installed in the
6 MV accelerator and the other is part of the 2 MV CW, MM-FEL project.
This is a low-compression Pierce type gun optimized for minimum spherical aberation. It uses a thermionic dispenser cathode
operated between 800 and 1000 deg C. A control electrode, conforming to an equipotential surface and operated between -2 KV and
+10 KV, switches the beam in <100 ns.
These guns were developed for a defunct 2 stage FEL project. One was once used to provide a 3 Amp beam, but its quality was disappointing.
The two existing guns are in storage and may be used for future development.