The Application of High Potentials to Vacuum-Tubes

Abstract

A brief progress-report is made on the results so far obtained in the development of vacuum-tubes to which the very high voltages produced by Tesla coils (greater than ${10}^6$ volts) can be applied. One cascade tube has been constructed which withstood repeatedly a voltage of 1,400,000 volts, and others have been used at lower voltages. This method, originally developed by Coolidge, gives promise of being suitable for voltages of several million, and eventually perhaps even higher. No effort has been made so far to use these tubes with a definite and controlled emission, since experience has shown that single-section tubes operated at several hundred kilovolts have approximately the same voltage-limitation with or without hot cathodes. The chief difficulty with very high-voltage tubes is that of preventing the uncontrollable (cold-cathode) emission which limits the voltage which can be applied. An electrodeless tube which withstood 1,000,000 volts is briefly described.