Characteristic Time of Oxygen: Calculations and Theoretical Study

We present an equation for the characteristic time ¿, through which we can calculate the formative time lag of breakdown tf more accurately than previously obtained. This equation takes into consideration both the effect of the first Townsend ionization coefficient ¿ and the second Townsend ionization coefficient due to positiveion bombardment ¿i. Calculations of the characteristic time ¿were carried out for oxygen, using the presented equation, at uniform field and over wide ranges of the breakdown parameters. The results obtained are presented together with a brief study. It was found that the characteristic time is independent of the electrode separation d, with an error much less than 1 percent, at constant gas pressure p and electricfield strength E, over certain ranges of d. Also it was found that the characteristic time is inversely proportional to the gas pressure raised to a constant power over a wide range of pressure, at constant percentage overvoltage and constant product of gas pressure and electrode separation. In addition, the coefficients A and B of the well-known equation of the first Townsend ionization coefficient ¿,¿,=Ap exp = (-Bp/E), are obtained.