DESIGN AND CONSTRUCTION OF COIL SUPPORTING STRUCTURE AND CRYOSTAT VESSEL FOR LHD

The Large Helical Device is a fusion experimental machine with all superconducting coils. Electromagnetic force generated by the coils is supported by the torus shaped “supporting structure” of 100 mm thick 316 stainless steel. This structure consists of 20 fan shaped parts that were welded together on site. The coils needed to be positioned within 2 mm accuracy in the absolute coordinates so that the supporting structure had to be assembled within 5 mm accuracy prior to the coil setting. After completion of the welding, the overall accuracy of < 5 mm was achieved.