Experimental Study On Surface Flashover Triggered Vacuum Switch

Trigger vacuum switch is a kind of high-power quick closing switch,which is characterized by using vacuum as the insulating medium of switch gap and the medium of extinguishing arc.The excellent insulation strength and arc extinguishing ability make TVS have the advantages that other switches can't compare,such as compact structure,fast medium recovery,noiseless operation and high reliability.Therefore,TVS has been widely concerned in many fields such as pulse switch technology.The conduction process of TVS has always been a hot topic in this field.TVS is widely used in pulse power system and power industry,mainly used for quick closing switch and protection switch,such as pulse discharge system with energy storage,electromagnetic emission system and modulation circuit.In these fields,the performance indicators of TVS are required to be higher,and the research shows that the conduction process of TVS has a great impact on its reliability,accuracy and speediness.The essence of TVS conduction process is the generation and diffusion of initial plasma.The diffusion process of plasma is actually the growth process of plasma sheath near the cathode.However,the instability of initial plasma directly affects the success of TVS conduction,which hinders the further promotion and use of TVS.In this paper,we mainly study the mechanism of the trigger plasma,and the influence of the peak value of the trigger current and the bias voltage on it.Then we simulate the trigger process based on PIC/MCC algorithm.The experimental results show that the initial plasma charge increases linearly with the increase of the peak trigger charge of the trigger current.The initial plasma is affected by the polarity and amplitude of the bias voltage of TVS at the same time.With the increase of the bias voltage,the peak and charge of the trigger plasma current will increase.The PIC/MCC algorithm is studied in detail.The advantages of PIC and MCC algorithm are described.After solving Poisson equation,the equations of speed and position are derived.The establishment of electromagnetic field is also described in detail.Finally,based on the Vsim simulation software,the diffusion process of the initial plasma in the trigger stage of the vacuum trigger switch is simulated,and the intercepted particle development trajectory and the change of the electrode absorption electron are analyzed in detail.