Low-pressure gas breakdown in uniform dc electric field

This paper studies in experiment and theory the breakdown of argon, nitrogen, air and oxygen in a uniform dc electric field at different discharge gaps L , discharge tube radii R and cathode materials. At arbitrary geometric dimensions of the cylindrical discharge vessel and cathode materials the ratio of the breakdown electric field value to the gas pressure p at the minimum of the breakdown curves is shown to remain constant, ( E dc / p ) min ≈ constant . A modified breakdown law for the low-pressure dc discharge U dc = f ( pL , L / R ) is obtained. That is, the breakdown voltage U dc is shown to depend not only on the product pL , but also on the ratio L / R . A method is presented enabling one to predict a dc breakdown curve in the cylindrical discharge vessel possessing arbitrary L and R values from the measured data on the dc breakdown.