Breakdown Characteristics of Plasma Closing Switch Filled With Air, N₂, CO₂, and Ar/O₂

Abstract

One of the critical components of high energy density pulsed power systems used to generate short high-voltage and high-power impulses is gas-filled plasma closing switch. In recent years significant research efforts have been aimed at finding environmentally friendly gases which can be used in the plasma closing switches, and several gases including dry air, nitrogen, carbon dioxide, argon and their mixtures have been considered as potentially suitable working fluids in such switches. However, the lack of knowledge of the breakdown characteristics of complex switching topologies filled with these gases limits their practical applications. Therefore, further investigation of the breakdown performance of plasma closing switches is required, in order to establish their applicability for practical use in high voltage pulsed power systems. The present paper reports on the investigation of the breakdown characteristics of a triggered plasma closing switch topology with corona discharge electrodes. The self-breakdown voltage of the switch, variation in the self-breakdown voltage, time to breakdown, and jitter have been obtained for the switch filled with "Zero Grade" air, N2, CO2 and an Ar/O2 mixture up to a pressure of 10 bar (abs). It was shown that the switch can provide a stable breakdown performance with jitter as low as 1 ns.

Postbreakdown Transient Characteristics of a Gas-Filled Plasma Closing Switch

“…The present study continues the work reported in [21], in which a multi-electrode plasma closing switch was designed and developed, and its self-breakdown characteristics were obtained for the gases and pressure range detailed in Section I.…”

“…The central electrode of the switch with the corona discharge needles was at a floating potential. This plasma closing switch was described in detail in [21].…”

“…In [32], it was found that  is proportional to El/p, where E is the electrical field strength at breakdown. In [21],  was derived for the inhomogeneous field in the PCS topology by field simulations and was found to be 1/11. Thus, the product of K and  is ~2.25 for the present switch topology.…”

“…All three methods were used to obtain the transient resistance of the plasma channel(s) in the PCS reported in [21], when filled with different gases: dry air, CO2, N2 and a 90%/10% Ar/O2 mixture, in the pressure range from 0 bar (gauge) up to 10 bar (gauge). Using the experimental datasets obtained and presented in [21], direct calculation of the time-dependent plasma resistance was conducted using Kirchhoff's approach.…”

“…All three methods were used to obtain the transient resistance of the plasma channel(s) in the PCS reported in [21], when filled with different gases: dry air, CO2, N2 and a 90%/10% Ar/O2 mixture, in the pressure range from 0 bar (gauge) up to 10 bar (gauge). Using the experimental datasets obtained and presented in [21], direct calculation of the time-dependent plasma resistance was conducted using Kirchhoff's approach. The plasma resistance values were also obtained using two analytical approaches: the Braginskii model, based on the transient radius of the plasma channel; and the modified Kushner approach, in which the analytical radius of the channel and the experimental breakdown current waveforms were used.…”