Slow-wave electrode structures for the ESS 2.5 MeV fast chopper

摘要

Slow-wave electrode designs for the European Spallation Source (ESS) 2.5 MeV fast beam chopper are described. Broad-band transmission line properties for the initial planar and helical designs have been refined by modelling electromagnetic fields in the Finite Difference Time Domain (FDTD) 'Microwave Studio' code. A compact, radiation hard, vacuum compatible helical structure made from linked strip-line and micro-strip sections has been developed. Simulated characteristics in the frequency and time domain, and the effects of E-field non-uniformity are presented.