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 de 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) approximate to constant. A modified breakdown law for the low-pressure de 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 de breakdown curve in the cylindrical discharge vessel possessing arbitrary L and R values from the measured data on the de breakdown.