Development of a Frequency Map for the WiFEL SRF Gun

Abstract

SRF cavity design requires the integration of several different software and analytic tools to produce a cavity which, after production and cool down to liquid helium temperatures, has the correct resonant frequency. We describe a ‘map’ which starts with a cold cavity at the correct frequency and moves back through the series of production steps producing an expected resonant frequency at each step. For example, contributions to cavity deformation from vacuum and tuner loading are modeled in ANSYS and a piecewise linear fit is produced which is re-inserted into the SUPERFISH[1] model to determine the new resonance point. We describe the steps and calculations used to develop the frequency map for the Wisconsin SRF electron gun and the specific initial cavity geometry.