Development, fabrication and test of triple gap split-ring bunchers for the TRIUMF ISAC facility

A set of triple gap split-ring 106.08 MHz bunchers (bunch-rotator for MEBT and three DTL bunchers) was designed, fabricated and tested for the ISAC project at TRIUMF. These four devices operate at low /spl beta/ (1.8%, 2.3%, 2.7% and 3.3%) and deliver the peak effective voltages in cw mode of 0.07, 0.19, 0.26 and 0.32 MV respectively. The shape of drift tubes was optimized to have a maximum transit time factor with the fixed value of electric field at the surface (1.5 value of Kilpatrick's criterion). 3D simulations were done to adjust optimized drift tubes with split-rings to have an operating frequency and to unify dimensions of the cavities. The bunchers were fabricated in INR and successfully tested at full power in TRIUMF. Some features of the design and results of the tests are reported in this paper.