AREA EFFECT ON ELECTRIC BREAKDOWN OF COPPER AND STAINLESS-STEEL ELECTRODES IN VACUUM

The breakdown field strength E//b( equals alpha Vb/d) of gaps made with pure copper and stainless steel depends on the effective area S//e//f//f. It can be expressed by the single experimental equation E//b equals K//1S//e//f//f** minus **n, where K//1 is a constant, n is about 0. 24, S//e//f//f is the electrode area subjected to more than 90% of maximum field strength, alpha is the shape factor, d is the gap length, and V//b is the breakdown voltage. The field intensification factor beta //l obtained through the measurement of prebreakdown current can be expressed by a single experimental equation beta //l equals K//2S//e//f//fn, where K//2 is a constant. This means that the area of effect of E//b is represented by the area effect of beta //l and that the vacuum breakdown may be initiated by field emission.