Numerical and experimental investigation of dielectric recovery in supercritical N2 Article Swipe
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· 2015
· Open Access
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· DOI: https://doi.org/10.1088/0963-0252/24/2/025008
· OA: W2168891972
A supercritical (SC) nitrogen (N2) switch is designed and tested. The dielectric strength and \nrecovery rate of the SC switch are investigated by experiments. In order to theoretically study \nthe discharge and recovery process of the SC N2 switch under high repetition rate operation, a \nnumerical model is developed. For SC N2 with initial parameters of p = 80.9 bar and \nT = 300 K, the simulation results show that within several nanoseconds after the streamer \nbridges the switch gap, the spark is fully developed and this time depends on the applied \nelectric field between electrodes. During the whole discharge process, the maximum \ntemperature in the channel is about 20 000 K. About 10μs after the spark excitation of 200 ns \nduration, the temperature on the axis decays to Taxis 1500 K, mainly contributed by the gas \nexpansion and heat transfer mechanisms. After 100μs, the dielectric strength of the gap \nrecovers to above half of the cold breakdown voltage due to the temperature decay in the \nchannel. Both experimental and numerical investigations indicate that supercritical fluid is a \ngood insulating medium that has a proved high breakdown voltage and fast recovery speed.