Design and development of JT-60 upgrade - Vacuum vessel and first wall

The JT-60 tokamak was modified wherein the original outer-single null vacuum vessel and poloidal field coils, were exchanged with those of large dee-shaped cross sections. The basic dimensions of the new vessel allows plasmas of 6 MA, 70 to 100 m3 volume and vertical elongations of 1.4 to 1.7. The vessel was designed along a new concept of a continuous chamber in a double skin construction. Change of the gas to deuterium from hydrogen is being prepared and will enable neutral beams of 40 MW. The first wall was designed to utilize carbon fiber composite for the divertor and isotropic graphite for the other regions. The divertor tiles are cooled by water, while the other regions are cooled by conduction to the vessel wall. (orig.)