Simulation And Experimental Study On Pseudospark Switches With A Trigger Unit Based On Flashover

Switch techniques is not only the key of the high power pulse technology,but also one of the bottleneck technology when pulsed-power equipments develop towards high frequency and miniaturization.The pseudospark switch(PSS),known for its compact size,high power transmission and long lifetime,is regarded as ideal substitute for hydrogen thyratron and gas spark switch.Recently,more and more researchers have focused on PSS.In this paper,theoretical analysis,particle simulation and experimental study is used to study on the PSS with a trigger unit based on flashover.The dissertation mainly consists of the following aspects.Detailed theoretical studies on the mechanism of gas discharge related to PSS are carried out.Characteristics of different phases in gas discharge have been studied in detail using Townsend discharge theory.The dissertation pointed out that the glow discharge status,which is the inner condition when the PSS works,has less erosion on the electrodes comparing with the arc discharge status,which contributes itself to a longer lifetime.In the meantime,hollow cathode effect happens when PSS works in a high current circuit due to the special design on its structure,which leads to lower voltage drop,minimal resistance and higher current density.Dynamical model using PIC/MCC in 3D environment for particle simulation is introduced in this chapter,and this method is used to figure out the process of PSS's breakdown mechanism,the relationship between the operating parameters of the switch and its delay time,as well as the different performance between multichannel structure and single-hole structure.The simulation study over the breakdown mechanism gives out detailed pictures of the plasma distribution and potential distribution in the switch,the result consists with theoretical analysis.Further study suggests that as the diameter of the cathode hole or the gas pressure increase,the delay time decreases.If the diameter is too small(<2mm)or too large(>14mm),the virtual anode is difficult to form,which leads to invalid breakdown in switch.The delay time is almost constant while the anode voltage changes from 2kV to 10 kV.During the simulation of the multichannel PSS,the independent virtual anode gradually moves towards the center of the hollow cathode when current magnetic field increases,which makes the PSS gets lower delay time and competitive effect between adjacent channels in the meantime.The competitive effect will make some channels finally shut down.The structure and working parameters of the TDI series PSS are introduced in this chapter,the dissertation designs a kind of coaxial structure,looks like a birdcage,to encapsulate the PSS.New structure ensures much more homogeneous current transmission to avoid partially erosion on electrodes.The PSS with new encapsulation shows lower stray parameters.Its current rise rate is more than 108A/s.In the condition of 10 kV on anode voltage and 4.11 V on heater electrode,the delay time measured is 1.24 us.Further experiment results on the relationship between switch delay time against anode voltage,heater voltage(represents the gas pressure)consist with the particle simulation conclusions.In the last part of the dissertation,two-way compensation for capacitive divider has been designed for high voltage measurement.The calibrating results indicate the divider could be used to measure fast-rise and long-pulse voltage signal.