Study On The Integrated Technology Of Switch And Capacitor In LTD

Linear transformer driver is a novel high pulsed power device based on pulsesuperposition principle, it can drive the low impedance load with~100ns rise time currentdirectly without any pulse forming stage. It will remedy the disadvantage of traditionalpulsed power technology that current peak and gradient can’t be improved further.Discharge mechanism of LTD switch and multi-channel discharge theory areresearched, as to gas discharge under nanosecond pulse, the avalanche can’t radiate enoughphotons to ionize the gas molecules near the head of the avalanche, some high energy fastelectrons will run away from the head and ionize the gas extending the boundary of themain avalanche and form low conductivity channel, secondary electrons are mainlygenerated by photoelectric effect of cathode and bremsstrahlung effect of anode, thebreakdown of gap will complete. There are several methods to improve the probability ofmulti-channel discharge, including reducing the jitter of breakdown voltage, improving thegradient of trigger voltage, many-electron initiation discharge and high overvoltagedischarge.A multi-gap gas switch is designed and constructed. Simulation based on AnsoftMaxwell FEA software and experiment based on optical observation system have beendone, and the results show that the reduction effect of inductance of switch andswitch-capacitor integrated structure by multi-channel discharge is very limited, and theposition of discharge channels also has effect on module inductance.The corona discharge characteristics of several gas gaps with different electrode types,according to selection standards of voltage-sharing needle, such as low corona onsetvoltage, high breakdown voltage and so on, voltage-sharing needle should be selected fromnegative tip-positive plane(negative corona) and hemispherical needle-hemisphericalneedle(dipole corona).The low inductance structure of LTD capacitor(buried foil film capacitor) isresearched, and the theoretical method of calculating equivalent series inductance isanalyzed. The effects of distribution types of tabs on capacitor inductance are researchedbased on Ansoft, as well as the effects of leading-out types of terminals on module inductance. The results show that the inductance is lowest when the tabs are in alignmentand placed at the middle of unfolded electrodes, when the tabs are staggered a distance, theinductance value is lowest if the tabs are placed at the first turn. The inductor of modulewith single-end output capacitors is smaller than the inductor of module with double-endoutput capacitors.A100kV/40nF capacitor is designed and constructed, its inductance is14.3nHmeasured by short circuit discharge method. The inductance of another capacitor withdifferent structure is also measured, the results indicate that the inductance will increasewith the increasing of dielectric film thickness, so reducing the thickness of dielectric filmwill reduce the inductance effectively.