GRADES OF VACUUM IN ELECTRONIC AND IONIC TUBES

Abstract

The problems of vacuum are of great importance both for electronic and ionic devices. In this paper it is shown that the most important factor that qualifies the grade of vacuum is not the pressure of the residual gases but the ratio of the mean free path of the molecules to the distance between the cathode and the anode of the device, namely L/r. This ratio, designated as the relative grade o f vacuum, is to be preferred as an index of the vacuum properties of the tube, to the pressure of the residual gases. A higher relative grade of vacuum will ensure better vacuum properties. The ways of achieving high relative grades of vacuum are discussed.