ISAC SC‐LINAC PHASE‐II HELIUM REFRIGERATOR COMMISSIONING AND FIRST OPERATIONAL EXPERIENCE AT TRIUMF

ISAC Phase‐II is an upgrade of the radioactive isotope superconducting linear accelerator, SC‐linac, at TRIUMF. The Phase‐I section of the accelerator, medium‐beta, is operational and is cooled with a 600 W helium refrigerator, commissioned in March 2005. An identical refrigerator is being used with the Phase‐II segment of the accelerator; which is now under construction. The second refrigerator has been commissioned and tested with the Phase‐I section of the linac and is used for Phase‐II linac development, including new SC‐cavity performance tests. The commissioning of the Phase‐II refrigeration system and recent operational experience is presented.