Design And Development Of Coaxial Auto-UV Pre-ionization Gas Spark Switch

As an important device for energy compression on the time scale in pulsed power systems,gas spark switch is widely used because of its advantages such as large on-current,short breakdown delay,and wide application range.Gas spark switches are often used in high-voltage,high-current systems.These systems usually requires multiple branch circuit modules to operate in parallel,its transient current and single transfer energy is large.Therefore,the low jitter,long-life gas spark switch has always been the focus of pulse power technology at domestic and foreign.According to the engineering needs of low-jitter,long-life gas spark switch,a coaxial auto-UV pre-ionization switch is designed and performance tested.In this paper,the conduction mechanism of three-electrode field-distorted gas spark switch is introduced first,and then the common three-electrode field-distorting gas spark switch is analyzed.According to the different structure and performance of the switches,they are divided into "type of emphasis on jitter" and "type of emphasis on life".Two types of switches were selected for experiments.By comparing the trigger characteristics of the switch and the ablation conditions after the experiment,the design points of the “low jitter,long life” gas spark switch were obtained.Based on the above points,a novel three-electrode field-distorting gas spark switch,a coaxial auto-UV pre-ionization switch,is proposed.First of all,the pre-ionization mechanism of UV light was introduced.Then,the UV pre-ionization effect of the trigger gap spark discharge on the overvoltage gap was studied under different pressures,different distances and different working factors.The appropriate working condition of the switch was determined,and the stable distance of UV pre-ionization was obtained,which provided guidance parameters for the construction of the subsequent switch model.Combined with the above experimental results,a switch model was built,and the electrode chamfer size,insulation gap distance,overall electrode size,material ofthe bottom end cover flange,and design method thereof were determined through simulation calculations.Then developed a prototype of the coaxial auto-UV pre-ionization gas spark switch.The switch performance was tested including self-breakdown voltage,operating range,triggering characteristics,and switch ablation.Experimental findings: Under0.1Mpa air pressure,when the switch's work coefficient is 67.0% and above,the triggering characteristic is relatively stable,the jitter is less than 2ns.Comparing the triggering characteristics of the overvoltage gap with and without UV pre-ionization,the breakdown time delay and jitter under UV pre-ionization are far better than those without UV pre-ionization.After the experiment,the ablation distribution of the switch electrode was uniform and there was no obvious ablation concentration point.