Simulation study of a capacitively coupled plasma torch array

Using capacitively coupled electrical discharges, an array of three plasma torches powered by a single 60-Hz source are lit up simultaneously to produce a dense plasma in the open air. The discharge voltage and current of each torch is measured for three cases of one to three torches being lit up in the array. The results determine the v-i characteristic of the discharge which indicates that the torch is operating in a diffuse arc mode. The torch array is modeled by an equivalent circuit for simulating its operation. The simulation results of the discharge voltage and current of a torch are shown to agree well with those from the experimental measurements for the three cases. The lump circuit model is then used to carry out numerical simulations of the discharge for a broad parameter space of plasma species. By fitting the simulation results, a function giving the parametric dependence of the consumed average power density

on the normalized average electron density <n_e> maintained in the plasma is determined to be

= 48<n_e>^1.9 α^0.4 (W/cm³), where <n_e> is normalized to 10¹³ cm^-3 and α, the electron-ion recombination coefficient normalized to 10^-7 cm³·s^-1, is used as a variable parameter in the simulation.