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| MOPLS085 |
Experience with a Zero Impedance Vacuum Flange at He Super-Leak Temperature for the ILC
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753 |
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- H. Matsumoto, F. Furuta, I.H. Inoue, K. Saito, S.N. Sakamoto, K. Ueno
KEK, Ibaraki
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Several tens of thousands of vacuum flanges will be used in the construction of the ILC. So the reliability and large scale reproducibility of these elements are important issue. To arrive at a standardized vacuum flange, a new design of a unisex flange has been developed. This important component has to serve in two roles at He-super-leak temperature; both as an rf seal and as a vacuum seal. We chose the unisex type with a 90-degree sharp edge forming the seal. The design is a modification of the DESY S-band rectangular waveguide flange. The variation in flatness between the flange and gasket along the inside wall is within 50 micrometer. This should present zero impedance for a bunched beam and for rf power. The He-super-leak performance was measured using the "build up method", i.e.the test was carried out for three hours at 2 degrees Kelvin. The measured He leak rate was below 1·10-13 Atm*cc/sec for a test flange after three successive tests. We describe the design concept and the operational experience at various rf frequencies. These span the frequency range corresponding to warm and cold accelerators.
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