Study and observation of multipacting in new RF cavity of INDUS-1 SRS

Indus-1 is 450 MeV / 150 mA synchrotron radiation source indigenously built at RRCAT, Indore, India. The RF system of Indus-1 consists of 31.613 MHz RF amplifier its associated LLRF (Low Level RF) control & RF cavity for compensation of synchrotron loss of the stored electron beam in storage ring. For proper operation ultra high vacuum is required in RF cavity. To achieve required gap voltage in RF cavity initially RF conditioning is done. During the RF conditioning and initial operation of new RF cavity of Indus-1, multipacting phenomenon was observed at certain RF power levels which was limiting the gap voltage in cavity and degrading the vacuum inside RF cavity. To increase the gap voltage without damaging the cavity surface due to multipacting a systematic approach for RF conditioning of cavity was adopted.