Multiphysics Design of ESS-Bilbao Linac Accelerating Cavities Using COMSOL

J. L. Munoz, and I. Rodriguez
ESS-Bilbao
Bilbao, Spain

A proton linac drives particles using the electric field of a high power RF standing wave in a resonant cavity. The design of these cavities involve several aspects of multiphysics simulation, that have been accomplished using COMSOL. The first step consist on the geometric optimization of the cavities in order to have the correct frequency while maximizing some figures of merit. This task involve extensive use of the RF module eigenvalue solver.

Detailed 3D simulations follows, to get an accurate description of frequency and fields. From these fields the power loss in the cavity walls is computed and linked to the heat transfer module. Different accelerating structures of ESS-Bilbao linac will be discussed: Buncher, DTL and spoke cavities.