Construction of JT-60 and development of nuclear fusion technology

Four countries in the world carry out the test on the break-even condition, and JT-60 is one of them. JT-60 comprises toroidal magnetic field coils, poloidal magnetic field coils, vacuum equipment, a vacuum container, a magnetic limiter, a neutral beam heater, a high frequency heater and so on. JT-60 was completed in April, 1985, and the first current was passed. The mean electron density was 1 x 1013/cm3, and the plasma current was 150 kA. In order to develop the highest performance of JT-60, the plasma current must be increased to 2.7 MA. Only by flowing plasma current, the plasma temperature is limited to 20 million or 30 million deg, and other means are required for further heating. The criticality is expected around 1987. After the scientific feasibility of nuclear fusion is verified with this large scale tokamak, as the next stage, an experimental reactor is considered. Its experiment is considered to be carried out in the latter half of 1990s. INTOR is a tokamak reactor designed by the international team under IAEA, and its linear size is 1.8 times, but the power output is 30 times as compared with JT-60. The thermal data required for an experimental reactor can be obtained with JT-60. The experience of the construction of JT-60 is very useful. (Kako, I.)