Measurement of energy losses in a hydrogen-filled thyratron in modulator duty

The energy loss in a hydrogen thyratron during a current pulse may be considered as made up of three components, occurring respectively at the leading edge of the pulse, during the steady state and at the trailing edge after the end of forward conduction. In the experiments described the three components were separated by pulse chopping and the dissipation was measured by means of a calorimeter. The conclusions were confirmed by tests with a saturable reactor in series with the thyratron. The leading-edge dissipation is predominantly that due to the discharge of the anode-to-cathode capacitance, except that at low gas pressures there is a pulse-front component which increases rapidly with decreasing pressure. The steady-state loss is proportional to the mean value of current. The trailing-edge loss increases directly with the rate of fall of pulse current, with the square of the inverse voltage and with its duration (up to the completion of deionization). The pulse-front and trailing-edge components can be eliminated to a considerable extent by the use of a saturable reactor. The leading-edge losses in deuterium and in hydrogen are similar; but the steady-state and trailing-edge losses are 20¿30% lower in deuterium. The results are discussed in relation to the method of rating of hydrogen thyratrons for modulator duty.