Feasibility of a photoemission source with superconducting RF cavity

Abstract

Photoemission RF guns have been developed as sources of high brightness electron beams in the recent past. But equipped with normalconducting RF cavities, they are limited to pulsed operation with duty cycles typically below 103 due to the high RF field required at the photocathode. This limitation could be overcome by using a superconducting acceleration cavity, in principle enabling continuous operation with the same gradient, that means the same beam quality. But the sensitivity of the superconducting cavity imposes severe constraints on the photocathode operation. On the way towards a superconducting prototype gune we have set up experiments to investigate the mutual interferences of these two components and to demonstrate the feasibility of this injector scheme. I’d like to present the results which we have obtained and to discuss their consequences on the design of a prototype source.