JLC X-BAND TECHNICAL NOTE Feasibility Study of 2D Machining of RDDS1 disks

The present note is to confirm the feasibility of the present machining technology of the RDDS1 disks. Diamond turned fifteen 2D-shaped disks were inspected both by mechanical dimension measurements and by the RF measurements with electrically shorted at both ends. The consistency among the precisely calculated frequencies, the RF measurements and the dimension measurements were studied. Dimensions such as “OD”, "2a" and "2b" were found to agree with the design values within ±1 μm, while frequencies within ±0.5MHz to the calculated values. Based on the studies described in the present note, we conclude that a process such as a moderate feed-forward process is enough to control the average frequency of the accelerating mode over a whole structure. Furthermore, we estimate that the higherorder mode frequencies are to be controlled within ±1 MHz or so. Then we conclude that the fabrication based on the present technology can produce disks, meeting the requirement of the RDDS1. Feasibility Study of 2D Machining of RDDS1 disks T. Higo, T. Suzuki and N. Toge Y. Funahashi, Y. Higashi, N. Hitomi, T. Takatomi and Y. Watanabe KEK, The High Energy Accelerator Organization 1-1, Oho, Tsukuba, Iaraki, 305-0801, Japan Y. Iwashita Accelerator Laboratory, Institute for Chemical Research, Kyoto University Gokanosho, Uji, 611-0011, Kyoto, Japan J. Wang, Z. Li and R. Miller SLAC, Stanford Liner Accelerator Center 2575, Sand Hill Rd., Menlo Park, CA 94025, USA Abstract The present note is to confirm the feasibility of the present machining technology of the RDDS1 disks. Diamond turned fifteen 2D-shaped disks were inspected both by mechanical dimension measurements and by the RF measurements with electrically shorted at both ends. The consistency among the precisely calculated frequencies, the RF measurements and the dimension measurements were studied. Dimensions such as “OD”, "2a" and "2b" were found to agree with the design values within ±1 μm, while frequencies within ±0.5MHz to the calculated values. Based on the studies described in the present note, we conclude that a process such as a moderate feed-forward process is enough to control the average frequency of the accelerating mode over a whole structure. Furthermore, we estimate that the higherorder mode frequencies are to be controlled within ±1 MHz or so. Then we conclude that the fabrication based on the present technology can produce disks, meeting the requirement of the RDDS