25+2 poles, 4.3 T wiggler at BMIT – 7 years operational experience

The research program at the Biomedical Imaging and Therapy (BMIT) Facility at the Canadian Light Source (CLS) required a unique radiation source that would provide a wide beam fan with high critical energy and high dose rates. A superconductive wiggler was the only practical solution that could be installed inside the CLS ring. Design requirements were defined in 2005 [1-2]. The wiggler, optimized for a 3 GeV ring, was to match operating parameters of an equivalent hard X-ray source on a 6 GeV ring. Manufacturing started in 2006 and the wiggler was installed in November of 2007 [3-5]. Several modifications to external hardware and to the power supplies' controls were implemented to address the air leaks into the He space and to provide the ability to change the field of the wiggler during normal operation without affecting other research groups. The original burst disk and pressure relief valves were replaced with commercial units. Most of the buna O-rings were replaced with metal O-rings, helping to provide air-tightness of external connections. Over the years, the nominal, no-load temperatures went up by 0.3 K at the LHe space and up by 4 K at the 50 K shield space due to deterioration of thermal links and insulation, resulting from thermal cycling and vibrations generated by cryo-coolers. In October of 2014 the wiggler went through major maintenance to improve the thermal links operation, to improve the LHe transfer line connection, to install additional heaters to mitigate potential ice growth, and to provide a separate exhaust path for the rupture disk port.