Tokamak – Vacuum Vessel

The main JT-60SA vacuum vessel is torus-shaped and double-walled. The space between the walls is filled during operation with borated water to enhance the neutron shielding capability of the vacuum vessel. The coolant will operate typically up to ~50°C.

Every toroidal 40 degrees, a gravity support with spring plates is installed at the bottom of the vessel
These gravity supports withstand the operational electromagnetic forces and absorb the thermal expansion during the baking operation.

Baking the vessel at 200℃ is feasible by means of heated nitrogen gas flow after draining the shielding water. The plasma is not operated during vessel baking due to the reduced neutron shielding capability.

The vacuum vessel system also includes the vacuum pumping and the plasma fuelling subsystems.