Nuclear fusion device

Purpose: To provide a nuclear fusion device provided with a coil in which a vacuum vessel is embedded, and maintaining functions sufficient for thermal stresses and the like discharged from plasma and having a high safety. Constitution: In a heat insulating material filled in a space between a coil conductor and an outer cylinder of the coil is embedded a porous pipe which constitutes a degassing pipe along the coil conductor, and a plurality of holes are formed in the outer wall of this porous pipe. The end part of this pipe is taken off to the outside of a vacuum vessel. Air expanded within the heat insulating material accompanied by the temperature fluctuation of the outer cylinder of the coil due to the plasma heat is discharged to the outside of the vacuum vessel through the porous pipe. (Aizawa, K.)