Design improvement of 75 MHz heavy ion RFQ

A prototype Heavy Ion RFQ operating at 75 MHz with 1.34 m modulated vanes was RF conditioned to 1 KW for the ECR based Heavy Ion Accelerator being developed at NPD, BARC. The measured Quality Factor was 2300 compared to design value of 6500. The measured shunt impedance in the four quadrants showed large variations and the frequency spectrum of prototype RFQ showed other modes with equivalent Quality Factor, necessitating the redesign of resonant structure of RFQ. Unit RF cell optimization methodology utilized for designing RFQ led to improvement in unloaded Quality Factor to 9000. This paper presents the study of improved design of room temperature RFQ. (author)