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- N. Shigeoka, S. Miura, D. Suzuki
MHI, Hiroshima, Japan
- T. Asaka, T. Inagaki, Y. Otake, T. Sakurai
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
- H. Ego
JASRI/SPring-8, Hyogo-ken, Japan
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In April 2013, MITSUBISHI HEAVY INDUSTRIES, LTD. contracted with RIKEN to produce six C-band disk-loaded type and constant gradient (CG) accelerating structures for removal of SCSS. These structures were newly designed by RIKEN for operation with an acceleration gradient of over 45 MeV/m and a repletion rate of 120 pps. The first structure was delivered in August 2013 to RIKEN and the other five was also delivered in March 2014. The accelerating structures were stacked from one hundred accelerating cells and formed by the vacuum brazing method. These cells using oxygen free copper were ultra-precisely machined. Unlike the C-band choke-mode type structures, which MHI manufactured in past for SACLA, the accelerating cells of the CG structure can be tuned after the brazing by pushing dimpling at the tuning hole of each cell. Demands of a VSWR < 1.1 and a phase error < 3 degree are fulfilled after the tuning by using the nodal shift method, which corrects cell frequency shifts due to the machining errors of cells and a cell’s deformation by the heat cycle of the brazing. The detailed results of the production and low-power RF tests will be presented in this presentation.
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