Electromagnetic Design of SRF Cavities Using Continuum Sensitivity Analysis

This study proposes a multi-objective electromagnetic (EM) design method for optimizing superconducting radio-frequency (SRF) accelerating cavities using continuum sensitivity analysis. The design objective is to maximize the electric field within the cavity and minimize the magnetic field on the superconducting surface. An expression for design sensitivity to the EM wave system shape was derived using the material derivative concept of continuum mechanics. Design optimization of the SRF cavity was performed based on the design velocity obtained from the sensitivity expression. In the design example, a 1.3 GHz SRF cavity was designed with different combinations of the weight coefficients of the objective function and the initial equator radius of the cavity. In addition, RF characteristic parameters were analyzed according to the optimal cavity shape.