Measurements of the Electrodynamic Parameters of a Cylindrical RF-Cavity with Stainless-Steel Samples

Stainless steel with a galvanic copper coating is often used as a material for the radio-frequency (RF) cavities of linear ion accelerators. However, for cavities with complex inner surfaces obtaining a uniform copper coating is technologically challenging. The solution might be found in manufacturing a cavity without a copper coating, though in this case the amount of power losses in the cavity should be carefully estimated. To get such an estimation, an experiment is carried out where the electrodynamic properties of a test cavity with two coupling loops are measured with stainless-steel samples placed inside it. The results of this experiment show a sufficient difference between the simulated and measured Q factor values for the same 12Cr18N10Т sample steel grade. Thus, an assumption is made that the magnetic properties of austenitic steel samples could have changed during the manufacturing process. The magnetic-permeability values for the steel samples are also estimated.