Effect of dilution gas composition on the evolution of graphite electrode characteristics in the spark gap switch

Abstract

As the widely implemented electrode material, graphite has the characteristic of sublimation by the thermal shock of the switching arc, and the produced carbon vapor is easy to condense into carbon powders and deposit in the switch. The impact of the type of dilution gas in a mixture of 20% oxygen and 80% dilution gas on the sublimation and oxidation characteristics of the graphite electrode is investigated. It is found that when nitrogen dilution gas was replaced by argon, the heat flux to the electrodes decreased, which led to a 63% reduction of graphite sublimation. At the same time, the cooling rate of the arc was slower in argon, which promotes oxidation of the carbon vapor. The residual solid carbon can be reduced by 70%–85% by using argon as the dilution gas. Consequently, it is demonstrated that the stability and working life of the switch could be increased by appropriate selection of the dilution gas.

Research on dynamic characteristics of arc under electrode relative motion

“…At present, the research on the dynamic characteristics of arc mainly focuses on the fields of switching arc [11][12][13], ultrahigh voltage (UHV) secondary arc [14,15], and pantograph-catenary arc [16][17][18][19]. For the switching arc, scholars studied the influence of electrode contact material, breaking speed, and current level on the dynamic characteristics of the switching arc, and also deeply studied the cutting process of the arc by an insulating grid and the reignition characteristics after arc extinguishment [20][21][22].…”

Special issue on selected papers from HVDP 2020

“…They cover the topics of fundamental processes, diagnostics, and applications of discharge plasmas. Interested readers will find the studies devoted to the microwave transmittance characteristics in plasma photonic crystals [1], the connections between burst pulses and the collective movement of charged species for positive corona discharges in atmospheric air [2], the influence of dilution gas composition on the evolution of graphite electrode characteristics in the spark gap switch [3], the multiple current peaks and spatial characteristics of atmospheric helium dielectric barrier discharges with repetitive unipolar narrow pulse 1009-0630/21/060101+02$33.00 excitation [4], reconstruction of energy spectrum of runaway electrons in nanosecond-pulse discharges in atmospheric air [5], the nonlinearity of initiating and extinguishing boundaries of DBDs with airflows [6], the influence of discharge loop parameters on anode side on generation characteristics of metal plasma jet in a pulsed vacuum discharge [7], charge transfer in plasma assisted dry reforming of methane using a nanosecond pulsed packed-bed reactor discharge [8], diagnostics of OH radicals produced in a DC glow discharge by a laser-induced fluorescence system [9], diagnostics of a microhollow cathode discharge at atmospheric pressure [10], the characteristics of an air arc plasma torch and its application in solidwaste disposal [11], the development and characteristics of a battery-operated floating electrode dielectric barrier discharge plasma device [12], the plasma step gradient modification of epoxy resin [13], the enhanced aerosol deposition by bipolar corona discharge arrays [14]. The objective of this special issue is to bring the up-to-date advances presented on HVDP 2020 to readers of Plasma Science and Technology (PST).…”