Design And Development Of The Switch In Electromagnetic Energy Transfer System During Disruption On J-TEXT

Plasma disruption is an inevitable problem in tokamak. It may cause serious damage to the internal parts of the device. J-TEXT is a medium-sized conventional Tokamak in Huazhong University of Science and Technology, which is very suitable for experimental study of plasma disruption. A new disruption mitigation method is developing on J-TEXT, which is based on electromagnetic energy transfer in plasma disruption. During disruption, it transfers the electromagnetic energy out of the device and doing absorption treatment, reducing the energy deep inside the vacuum vessel to realize the effect of disruption mitigation. The energy transfer system consists of three parts, namely energy transfer coils, switch and energy processing device. The switch must be open while J-TEXT is working in normal operation, so that the normal discharge would not be affected, and it should be quickly closed when the plasma is disrupted, so the energy processing device and the energy transfer coil will be connected, and the electromagnetic energy is transferred to the external device to be absorbed and processed. The switch is the key component of energy transfer system, its performance and reliability are critical to the realization of the electromagnetic energy transfer, existing switch cannot fully meet the special functional requirements of the energy transfer system, so the design and development of the switch is required. In this paper, the design and development of the switch is carried out according to the requirement of energy transfer system, the details are as follows:Based on the operating parameters of the electromagnetic energy transfer system on J-TEXT, a hybrid switch scheme with a new topological structure is designed. The electrical parameters of the switch are determined as follows: reliable isolation voltage up to 1k V, non-repetitive surge peak on-state current up to 20 k A(10ms), conduction time less than 1ms. The hybrid switch connects a mechanical switch with a power electronic switch in series. According to the parameters of the hybrid switch, we choose the CNF3-1250A/3600 V vacuum contactor and the 28H2060 5STF fast thyristor. Based on the hybrid switch scheme, the switch control unit with two kinds of operation modes is designed, in one mode, the control unit outputs corresponding control signal by analyzing the acquired signal in real-time; in the other mode, the control signal is given directly by the central control machine. By using the MATLAB/SIMULINK simulation software, the switch with the first control mode is simulated and analyzed, and it turns out that the switch is able to work accurately. Finally, the design and development of the switch in energy transfer system is completed. The experimental test is carried out, and the test results meet the designed requirements.At present, the switch in energy transfer system has been put into application, and the experiment of the electromagnetic energy transfer during disruption on J-TEXT Tokamak is carried out successfully. The result shows that the switch in energy transfer system developed in this paper can work reliably, which provides a guarantee for the reliable operation of the energy transfer system.