Development of high field pulse tokamak using force free coil concept for fusion reactor safety research

The study of the fusion reactor safety using the real reactor relevant plasma to examine the safety is essential for meeting new energy having the potential of public acceptance. If we have a high magnetic field technology that is three times higher than the present day tokamak, it is easy predict using the resent experimental result that the very small tokamak can reach the reactor grade plasma. These supporting experimental machines are important for the fusion reactor development to add the review method for safety and environmental view points. To obtain ultra-high field, the force free coil concept is developed. This force balanced coil (FBC) idea has a possibility to get higher field by canceling magnetic forces themselves. The magnetic configuration near plasma is tokamak-like one by using the multi-helical windings. The difference from ordinary tokamak is that the coils generate the toroidal and poloidal field all together and they ramp up with plasma current. Thus, this device needs the special operation to break down and ramp up phase of plasma. In this paper the high field ramp-up tokamak for fusion reactor safety research is proposed, and the feasibility applying the single layered multi-helical force balanced coil to tokamak is investigated with consideration to plasma confinement. The scenario to the nuclear burning phase in a pulse operation is simulated including the effect of the increase of the toroidal field with plasma current.