Fabrication of the vacuum vessel for JT-60 machine upgrade

The JT-60U (JAERI Tokamak-60 upgrade) vacuum vessel was successfully constructed in a very short period under severe technical requirements and constraints. The fabrication processes of the high-performance vessel feature application of hot sizing, computer-aided abrasive jet machining, electron beam welding and antidistortion measures of welding, and final assembly of poloidally divided blocks at site. The new vacuum vessel features a three-dimensionally curved, thin double-skin torus with multi-arc D-shaped cross section. The double-skin structure is strengthened with square pipes placed in between the outer and inner skins.<
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