Design, fabrication and performance test of heating and cooling system of JT-60 vacuum vessel

This report describes design, fabrication and performance test of heating and cooling system of JT-60 vacuum vessel. The vacuum vessel was designed to be bakable up to 500℃ by electric heaters as a means of ultra-high vacuum treatments, and was required to be cooled down by water or nitrogen gas. Results of the on-site baking test after assembly of the machine showed that the design requirements for the maximum temperature, temperature difference, heating time, ultimate vacuum and outgassing rate were satisfied, and no leaks were detected with helium leak testing. It was also found that the slide mechanism for thermal expansion during the heating-up and cooling-down phase functioned satisfactorily. (author)