Speaker
Description
The JT-60SA large research tokamak is being constructed by the National Institutes for Quantum and Radiological Science and Technology (QST) in Japan, as a satellite tokamak project designed to complement the International Thermonuclear Experimental Reactor (ITER) and to produce demonstration data for use in the proposed DEMOnstration Power Plants (DEMO). JT-60SA started cool-down phase in April, 2021 as a part of integrated commissioning. The magnet system is composed of three kinds of coils, central solenoid (CS), equilibrium field (EF) coils and toroidal field (TF) coils. The CS consists of four electrically independent stacked modules covered by structures supporting the TFCs. The maximum voltage between the CS module terminals is designed to be 10 kV. This means that if the voltage is distributed homogeneously, the voltage between layers is 0.38 kV because the number of layers is 52. However, the power supply contains multiple frequency components, which means that the actual voltage between the conductors can become lager than the voltage under ideal condition due to the resonance phenomenon and transient response to supply voltage. It might even produce voltages high enough to damage the insulation between the conductors, and thus affect the operation of the JT-60SA CS. In a previous study, we created a circuit simulation model for the CS (which has four modules), including the structures (ground resistance, CS structure, TFC cases, and EFC covers), and used it to estimate the voltage distribution produced by the resonance phenomenon. In this works, we used the previous circuit simulation model to estimate the influences of the structures capacitance and conductance, the butt joint resistance in the CS and the current leads lengths on the voltage distribution, and the transient response to the power supply voltage in the CS. These results become fundamental data to operate JT-60SA safely.
