Investigation of pulsed discharges in a dielectric channel with ablating walls

The current-voltage characteristics of a pulsed discharge in a hollow cylindrical channel formed by dielectric walls are investigated. The erosion of the channel walls is measured, together with the mean velocity of the plasma flowing into a vacuum through an opening in one of the electrodes, and related to the channel geometry. Conclusions are drawn regarding the temperature of the plasma in the channel and the mechanism of heat transfer to the walls.Notation d channel diameter - l channel length - C capacitance of capacitor bank - U capacitor voltage; - M consumption of dielectric per discharge - m specific consumption - W discharge energy - r₀ resistance of discharge gap at instant of maximum current - R variable resistance of discharge channel - I_m maximum discharge current - W₁ chemical bond rupture energy of dielectric of mass M - W₂ ionization energy of dielectric of mass M - W₃ kinetic energy of dielectric of mass M - W₄ electrode heating energy per discharge - W₅ thermal energy of dielectric of mass M - T mean temperature of channel plasma - S energy of light flux on dielectric layer - h depth of dielectric layer heated to temperature T - density of dielectric - c specific heat of dielectric - m₀ mass of dielectric layer heated to temperature T - T temperature of heated layer - k₁, k₂ constants - u residual stress