A new zero impedance vacuum flange has been developed for the accelerators in the ILC. We choose a unisex type with a 90-degree sharp edge forming the vacuum seal and giving a continuous smooth connection providing zero impedance as seen from the bunched beam and rf power. The variation in flatness between the flange and gasket along the inside wall is less than 50-(mu)m. An He super-fluid leak rate of below 10~(-12) [atm/cm~3/sec] was measured using the "build up method", i.e. the test measured the pressure built up over a three hour period while held at below 2-~(deg)K. We tested the several potential gasket materials: OFC (Oxygen Free Copper) alone, Nb (niobium) plated with 10-(mu)m of OFC, and bulk Nb, all at temperatures below 2-~(deg)K. The same unisex type flange has also been used for the input power coupler for coaxial waveguide and for a cold side demountable type rf window. A long test run was carried out at an rf power of 1-MW, and a 1.5-msec pulse width, 5-pps repetition rate. Further, suitability was confirmed by operation at a maximum power of up to 2-MW, and a 1.5-msec pulse width, 3-pps repetition rate for 6 hours.
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