Sparking Measurements in a Single Gap Cavity

At first, a review of more general breakdown studies, performed in a specially designed sparking cavity, is presented. Then the long term performance of two prototype cavities is described. Spark rate and x-ray level are reported versus gap gradient, electrode material and conditioning procedure. Mean gap fields up to 25 MV/m have been obtained. It turned out that copper electrodes show the tendency to severe deconditioning developments while the x-ray level for aluminium electrodes remained stable.