Type tests of welded bellows for ports of JT-60 vacuum vessel

Type tests of three kinds of welded bellows were carried out to examine their applicability to the ports of the JT-60 vacuum vessel, because strict specifications on the mechanical, vacuum and thermal properties were required for them. The following results were obtained. Spring constant and stress measurement tests showed good agreement between the measured values and the calculated ones, and the validity of calculation formulae was confirmed. The results of the helium leak and outgassing rate measurement tests were better than the specifications and showed the good vacuum properties of the welded bellows. The welded bellows maintained their structural integrity after the thermal cycle, life and pressure tests, and adequate thermal and mechanical properties of the welded bellows were confirmed. (author)