LIPAc SRF Linac Couplers Conditioning

Abstract

The LIPAc SRF Linac is a cryomodule with eight superconducting HWR cavities at 175 MHz powered by RF couplers capable of transmitting up to 200 kW in CW. To prepare the couplers for operation,cleaning and high power RF processing are needed. When performed, the couplers will be ready for integration in the cryomodule.

The Couplers Test Bench has been designed to perform the RF conditioning by pairs, providing good matching, low losses and the required UHV level. To preserve the cleanliness of the internal surfaces, after the test bench manufacturing, an ISO5 clean room has been used for the vacuum parts assembly. The size and number of particles was carefully controlled during the assembly process.

The RF conditioning was performed at the IFMIFEVEDA RF Integration Facility using the Prototype RF

Module in travelling wave and standing wave modes. The process started with short pulses at low power and finished when full power CW was reached. Vacuum, multipacting, arcs and matching were continuously monitored to control the process avoiding damages. An overview of the process applied to the prototypes and the RF conditioning results are presented in this paper.