Circuit Cushioning of Gas-Filled Grid-Controlled Rectfiers

In certain common rectifier and inverter circuits, gas-filled rectifier tubes supplying highly inductive loads with firing delayed by grid control, are subjected to the application of high rates of rise of initial inverse voltage. This phenomenon results in short tube life because of the sputtering of anode material by the impact of residual ions attracted at high velocity to the negatively charged anode with consequent gas cleanup. The paper describes a method of slowing down or cushioning this rate of rise of initial inverse voltage. A small resistance and capacitance circuit connected between cathode and anode of each tube delays the voltage rise the few microseconds necessary to eliminate gas cleanup. Life test data and practical applications are cited.