High current superconducting gun at 703.75 MHz

A half-cell superconducting RF (SRF) electron gun has been proposed as an injector to the 20 MeV energy recovery linac (ERL) prototype at Brookhaven National Lab (BNL). The design and optimization of the half-cell gun based on RF parameters, higher order mode (HOM) wakefields, and preservation of very low beam emittance in the high current regime are discussed. Comparison of several different shapes based on the above criteria and issues relating to multipacting, cathode insertion, and laser stability will be presented.