Abstract
The MO (Matsumoto-Ohtsuka)-type vacuum flange was applied to a beam duct of the KEK B-Factory (KEKB) positron ring, following a previous basic experiment1). The aperture was complicated, i.e., a circular beam channel with two rectangular antechambers, but a stable vacuum sealing was achieved with a reasonable fastening torque of 14-15 Nm. The final gap between flanges was larger than that in the case of a test with a blank flange. Welding of the flange to a beam duct seemed to increase its mechanical strength. Up to the stored beam current of 1700 mA, no problem, such as excess heating or arcing, was found. A copper-ally MO-type flange was also examined, considering a case of connecting to a copper beam duct. The vacuum sealing was successfully achieved at a fastening torque of 12-144Nm, even with a baking at 150°C for 24 hours.
