Reliability tests of 40 CM ID all metal gate valve and 54 CM ID ceramic break for JT-60

The present paper describes the results of reliability tests for 40 cm inner diameter (ID) all metal gate valve (AMGV) and 54 cm ID ceramic break (CB) used in JT-60 vacuum pumping system. Thirty six AMGVs are used above turbomolecular pumps (TMP) and sputter ion pumps (SIP), and the vacuum pumping system is electrically isolated by 4 CBs from a vacuum vessel. Reliability tests of both components have been carried out before the construction of the system. Test results for AMGV show that (1) its life is over 103 cycles with the leak rate through the seat less than 1.3 x 10-6 Pa.m3/s, that (2) its bakeable temperature is up to 3000C, and that (3) it has enough toughness under 1 G acceleration. On the other hand, the test results for CB show that it has enough strength against the external force such as magnetic force under a room temperature and the electrical isolation of 1.1 kV A.C. has been confirmed sometimes during the tests. These fruitful results show assurance of reliability for 40 cm ID AMGV and 54 cm ID CB for use in JT-60 vacuum pumping system