Analysis Of Ignition Failure Of ICRH RF Amplifier Tube

Ion Cyclotron Resonance Heating(ICRH),as one of the heating methods,plays an important role in achieving nuclear fusion in magnetically confined controlled fusion reactors.The ICRH high-power Radio Frequency(RF)transmitter provides RF wave energy for heating the plasma.The power source of the high-frequency transmitter consists of three stages of RF amplifier chain,which are kilowatt level power amplifier,hundred-kilowatt level valve amplifier and megawatt level valve amplifier respectively.Long-pulse megawatt valve is the core device of transmitter,the valve works in high voltage environment,short circuit ignition failure may occur.When the short circuit energy into the valve is greater than the tube can bear the range,will cause damage to the tube.Therefore,the systematic quantitative analysis of the discharge energy is essential,and the multi-physical field simulation analysis of the arc discharge process in the ignition process will be a good description of the real physical phenomenon of the electrode ignition.Based on the TH535 valve of ICRH high-frequency transmitter system as a platform,the equivalent model is established to analyze the energy storage elements,short-circuit current and inter-electrode arc of the power supply system,so as to obtain the fault energy of the valve ignition short-circuit.Firstly,the components of the power supply system are introduced,including the dry rectifier transformer,PSM power supply,high voltage transmission line,load short circuit equivalent circuit model,analysis of the energy storage component of energy storage and get the simulation of short-circuit current waveform,the power system short circuit of energy,and the fuse short circuit test,the test results show that the power system operation is stable and reliable,Meet the short circuit energy requirements of the tube.Secondly,the valve platform used in the simulation is introduced.On the basis of the structure of the used valve,the ignition between the valve poles is theoretically analyzed in combination with townsend discharge theory.The ignition between the valve poles is the process of arc discharge in essence.The simulation of AC arc is completed by constructing the corresponding model,setting the relevant boundary conditions and dividing the grid of the model.By analyzing the current and voltage waveform of the arc discharge process,each stage of the arc discharge process between the electrodes of the valve is described.