N. V. Landl

Auxiliary glow discharge in the trigger unit of a hollow-cathode thyratron

Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500–600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current−voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

Mechanism of the current quenching phenomenon in pseudospark discharge

Experimental data on the current quenching phenomenon in the pseudospark discharge in typical conditions of EUV source operation (extremely short pulse duration and high current) are presented. The mechanism of the phenomenon is proposed.

Experimental setup for investigation of the pseudospark discharge as applied to generation of EUV radiation

The paper describes the main features of the experimental installation for investigation of a high current pulsed gas discharge, which burns in typical conditions of EUV source operation.

Specifics of operation of a cold-cathode thyratron with a backward voltage half-wave

The specifics of operating a metal-ceramic TPI1-10k/50 thyratron in electric circuits with capacitance, inductance, and active resistance have been examined under circuit parameters that establish oscillatory current. Experiments have been performed at an anode voltage as high as 30 kV, a forward current of up to 7.6 kA, and a length of the first current half-period that varies from 0.38 to 1.9 μs. The data on operating modes in which this thyratron may handle a backward current wave and when current interruption is observed in the second half-period have been obtained. It has been demonstrated that a certain current flows through the thyratron in the backward direction during the interruption process. The amplitude of this current and the maximum backward voltage at the thyratron define whether the current is interrupted or repeat back-voltage device breakdown occurs. If the maximum backward current is on the level of several hundred amperes, complete current interruption occurs at backward voltages of up to 12 kV. The physical mechanisms of current interruption have been discussed.

Methods of triggering for the cold cathode thyratrons with auxiliary glow discharge in trigger system

The paper describes the schematic design and principle of operation for the ceramic-metal sealed-off pseudospark switches with the auxiliary glow discharge in the trigger unit. The switches are produced commercially by the Pulsed Technology Ltd., Ryazan, Russia [http://www.pulsetech.ru/index.htm] and are known as the switches of TPI-series whose anode voltage ranges from several to 50 k V. Proceeding from the switch design and the methods of triggering, the TPI switches can be referred to as the cold cathode thyratrons. Triggering methods for the electric circuits corresponding to grounded grid thyratron and to classical thyratron with cold cathode are considered.

Non-steady processes in a plasmatron for hydrocarbon combustion and partial oxidation

This paper deals with investigation of a new regime in a plasma ignition and flame control system. The system is based on a classical high-current arc plasmatron. The glow-to-spark transitions, the current spark pulses are accidentally superimposed on the non-equilibrium plasma of the plasma torch. The spark discharges initiate the combustion process, which is efficiently sustained due to the presence of the glow background plasma in the anode cavity. Although average power dissipation in the discharge does not exceed 200 W and averaged gas temperature at the plasmatron exit for discharge in air is less than 500 K, the device demonstrates reliable ignition and flame stabilization in a wide range of equivalence ratios. The principal physical properties of the discharge are discussed in the paper.

Current quenching in the pseudospark discharge and generation of a fast electron beam

The quenching of a high pulsed current in the pseudospark discharge is accompanied by an inductive voltage kick at the gap and by formation of an electron beam at the discharge axis. The paper deals with the investigation of this phenomenon. The main idea of the proposed physical mechanism is that the electrons are accelerated in a double electric layer, The main electrode gap of the pseudospark discharge forms by which forms during the quenching process between the hollow cathode plasma and the near-anode plasma. Interpretation of the experimental data on this basis is presented.

Method for externally triggering a pseudospark switch for the case where the trigger unit is located on the potential side of an electrode system

A great variety of trigger systems for pseudospark switches have been described in current publications. In most cases the trigger units are mounted at the grounded cathode. However, in some cases, a specific requirement for triggering is required, namely, that the trigger unit be located at the cathode. Direct application of previous experience, as applied to these cases, leads to a rather intricate design for both the mechanical parts of the trigger unit and the electric circuit. This paper proposes a simple triggering method for such conditions.

Hollow-cathode auxiliary discharge in a trigger unit of pseudospark switch

A special design of pseudospark switch in which a high-emissivity insert is placed in the cathode cavity is described. The insert allows the forward voltage drop of the switch to be decreased Just the same, the insert influences the burning modes of the auxiliary glow discharge in the trigger unit. The characteristic features of the auxiliary discharge are discussed in the paper.

External triggering of cold cathode thyratron in the system with blocking electrodes

One of the widely used systems for external triggering of the cold cathode thyratron (pseudospark switch) is based on a trigger unit with an auxiliary glow discharge. In most cases, the trigger unit is mounted at the grounded cathode. However, in some cases a specific requirement for triggering is demanded, namely, a trigger unit has to be located at potential cathode electrode. Direct application of the previous experience as applied to these cases leads to a rather intricate design for both mechanical parts of the trigger unit and electric circuit. This paper describes a simple trigger system for such conditions. Simultaneously with the function of external triggering, the system provides the so-called blocking effect, i.e. increasing a pulsed breakdown voltage and preventing the accident breakdowns in the regime of high pulse repetition rate.