TRIUMF ISAC RF system improvements after 2 years of operational experience

The TRIUMF ISAC accelerator has been successfully operating since spring 2001 with very little downtime. The machine comprises 16 independent RF systems including a 35 MHz RFQ, a 106 MHz DTL and several sub-harmonic choppers and bunchers. The post stripper DTL enables fully variable output energy up to 1.5 MeV/u for rare isotopes with A/q<6 in cw mode. This sets rather stringent requirements for the RF system as a whole and the RF controls in particular. A new RF phase measuring system has been commissioned, which together with other modifications has improved machine tunability. During initial operation the DTL frequency tuners and power couplers showed some problems, which could affect the machine reliability. Modifications to these components together with additional diagnostics have solved these problems. In this paper we will describe the overall operation of the RF system and present details of the modifications.