Characterization of the electrical breakdown for DC discharge in Ar-He gas mixture

The characteristics of gas breakdown were studied for argon-helium gas mixture using DC discharge between two planer electrodes. The breakdown voltage of the pure helium gas is about 363 V which is higher than that for pure argon gas of about 309 V. The modified Paschen curve is obtained by involving the atomic mass of used gas. It showed an overlap for all curves of different Ar-He gas ratios. The first Townsend coefficient decreases with increasing the helium gas ratio, due to the higher ionization energy of helium gas which, in turn reduces the required breakdown voltage. Also, for low gas pressure, the ionization efficiency has the lowest value when using pure helium gas and it increases by increasing the ratio of argon gas in the mixture. Townsend secondary coefficient has a reverse trend as compared to the first Townsend coefficient; it is decreased by increasing the ratio of argon gas in the mixture.