Effect of solenoidal magnetic field on the multipacting effect in sub-harmonic buncher of Shanghai synchrotron radiation facility (SSRF) linac

During the commissioning of the sub-harmonic buncher of the Shanghai synchrotron radiation facility (SSRF) linac, unexpected multipacting effect is observed, which limits the increase of the input power when the focusing coils are added. A novel method of adding bucking coils is very effective to suppress this effect after investigating different magnetic field configurations. The experimental observations and simulation results of multipacting effect are presented. In addition, details of the multipacting process are analyzed.