A High-Voltage, Cold-Cathode Rectifier

A new cold-cathode, high-voltage rectifier is described. Both theory and extensive experimental data are included. The operation of the tube is based upon an improved type of electron trapping similar to that occurring in a cylindrical magnetron in the cutoff condition, but augmented because of the use of end plates on the cathode. Mercury vapor is used, which at normal operating temperatures, provides a gas at a pressure of from 10-3 to 10-2 mm of Hg. Because of this low pressure and the small dimensions of the tube, ionization is inhibited when the cathode is positive, and highpeak inverse voltages are possible. However, when the anode is positive, the improved electron trapping results in conduction in spite of the low pressure and small dimensions. Experimentally, this rectifier has been operated up to 40-kv peak inverse voltage. Life tests at 30-kv peak inverse voltage and a current of 0.4 ma, at 60 cps, have run to 3,000 hours. Satisfactory operation has been obtained over a temperature range from 20 to 80 degrees C. The upper frequency limit lies between 120 and 240 kcps. This tube appears to offer, for the first time, a practical cold-cathode rectifier for output voltages up to 14 kv and currents up to one ma. Its advantages are particularly valuable in the case of voltage-multiplier rectifier circuits, since high-voltage insulated cathode-heater transformer windings are not necessary.