Secondary electron yield of N[lc]b RF cavity surfaces

Abstract

Multipacting continues to be a significant issue in the performance of superconducting RF cavities. In order to better understand multipacting behavior observed in these cavities, measurements of secondary electron yield (SEY) have carried out on Nb samples that have been given different elements of standard KEK cavity treatments. These include electropolishing to 100 micrometer depth, 700 C annealing, further electropolishing of 15 micrometer, rinsing with ordinary or ozonized water, and 150 C baking with final exposure to air, nitrogen, or argon. Measurements were made with a specially adapted SEM that allows detailed measurements of SEY as a function of position. Varying degrees of SEY uniformity on sample surfaces, and clear differences in SEY for differing surface treatments are found.