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Zener diodes are widely used in electrical barriers to protect equipment operating in a potentially explosive atmosphere. Although normally not conducting, the zeners must have a high power rating so that their junction temperature meets safety factors when shunting the maximum fuse current. This often requires two or three lower voltage commercial zeners connected in series. Silicon carbide diodes have much higher thermal conductivity and maximum allowed junction temperature, so it should be possible to use one SiC zener in the place of two or three commercial diodes and/or allow use of higher fuse ratings. Low voltage SiC Zener diodes were fabricated and tested to evaluate potential benefits of their application as a component of intrinsically safe barriers. The diodes demonstrated mixed avalanche-tunnel breakdown at reverse bias voltages of 23 V with positive temperature coefficients of breakdown voltages of about 0.4 mV/°C. The diodes with mesa area of 4×10-4cm2 had maximum DC Zener current of 1.2 A and were capable of operating at ambient temperatures up to 500°C.

As electronic technology to the continued progress of the requirements of electronic devices is also rising. Power circuit as a source of motive is playing an increasingly important role, Regulators sources in various laboratories or other places are indispensable. SCM technology with the continuous development and D / A and A / D technology continues to mature NC Power makes it possible, Digital control technology becomes more and more popular in the field of power supplies. NC current source is in control regardless of the accuracy or operability have the traditional power unmatched advantages. Foreword Regulators sources in various laboratories or other places are indispensable, Traditional AC stabilized voltage supply is basically belong to dissipation ofenergy. It's theory is using nonlinear device such as voltage regulator tube or ferroresonance steady voltage transformer assisted with necessary circuit to realize the autoregulation of output voltage. It's ciruit is mature and theory is consummate. But thiskind of supply has some idiopathic shortage.For example, supply using magnetismsaturation has the following shortage: size is big, weight is heavy; cost is high, efficiency is low, self-consuming is high; high ripple coefficient of output voltage and low stabilization and efficiency. SCM technology with the continuous development and D / A and A / D technology continues to mature NC Power makes it possible. Compared with analog controllers, digital controllers have many advantages. The digital controller can realize some complicated control strategies and has higher reliability and stability, and the design of the digital controller is flexible. The digital controller can realize the intelligent power and reduce the design cycle of new products.

International audience; Avalanche diodes have been fabricated on 4H-SiC substrate. These diodes show an abrupt avalanche voltage of about 59 V which corresponds to the calculated theoretical one using our previously determined impact ionization coefficients. This avalanche voltage increases by as small as 3.7 mV/K over the investigated temperature range (150K-420K).

Wireless sensor networks may be used in the explosion environment, such as underground tunnel in coal mine. In order to assure sensor node work normally, the power of a sensor node must be intrinsic safe. The intrinsic safe power of a sensor node, which consists of power supply module and intrinsic safe protection module, is developed. The power supply mainly consists of current-mode controller chip LTC1871 which assures a stable output voltage of a sensor node. The intrinsic safe protection consists of a dual-stage electric current monitor chip and a voltage regulator tube, which are combined with an over-voltage protection that was integrated in LTC1871 to make up intrinsic safe protection circuit of double over-voltage and over-current protection. Theory analysis and simulation test on discharge process of intrinsic safe power are described. The results display that the discharge energy is nonlinear proportion to the current, increases with the current increasing, and the maximum discharge energy is less than 0.02mJ; the discharge power is linear proportion to the current, increases with the current increasing, and the maximum discharge power is less than 60W, which meets the intrinsic safe standard, therefore the power of the sensor node is intrinsic safe.

A novel DC spark-over voltage measuring instrument for gas discharge tube is presented in this paper. With a new voltage acquisition theory, which is detailed introduced in the paper, and a zooming input voltage as the testing voltage, the voltage value of gas discharge tube can be detected, when the electricity current passes the gas discharge tube and it is broken. The voltage value is DC spark-over voltage of the gas discharge tube. Hardware and software design are introduced in the paper. Experiment data show the design of the instrument is successful.

A new Zener diode structure for bipolar transistor is proposed and analyzed. By placing the Zener diode at junction termination, we could obtain stable clamped breakdown voltage without deterioration of device performance. P+ layer of the Zener diode is embedded with base of transistor simultaneously so that whole functional behaviors of the composite transistor could be realized with relatively simple process. The breakdown voltage of the Zener diode is controlled only by adjusting of the phosphorus implantation dose. The breakdown voltage distribution of the fabricated Zener diode is less than ±4%. The BVCBO and BVCEO of bipolar transistors are about 50 V, same as the breakdown voltage of Zener diodes. And the DC current gain is 300 at VCE=2 V and IC=0.5 A

The zener diode is primarily used for providing voltage reference, for biasing, stabilization, switching, and clamping. This chapter presents a complete zener diode family tree. The characteristics of the zener diode are described. The zener diode is a two-terminal, single-junction semiconductor device that passes meaningful electrical current in only one direction and simultaneously provides a stable reference voltage between its terminals. It is usually operated so that it is in parallel (shunt) with the load, as with a two-terminal bandgap reference. It is unique among other discrete semiconductors, because its electrical properties are based on operating a diode's P-N junction in the reverse breakdown region. Compared to a rectifier diode, the zener operates in reverse. The zener diode can be useful at higher voltages, where the maximum operating voltage limits of integrated circuit (IC) references cannot operate. Therefore, the Zener diode finds much popularity in industrial applications, where higher voltages and currents often apply.

The breakdown voltages of 6H- and 4H-SiC rectifiers as function of temperature were modeled analytically in both non-reachthrough diode and reachthrough diode. The breakdown voltage was derived by the ionization integral employing accurate hole impact ionization coefficient. The breakdown voltage of SiC rectifiers was increased with increasing temperature and the positive temperature coefficient of breakdown voltage indicates that SiC rectifiers are suitable for high temperature applications. The breakdown voltages of both 6H- and 4H-SiC diodes were increased by M(T)-1/4 in NRDs and M(T)-1/8 in RDs.

The breakdown characteristic through a narrow discharge tube, such as a plasma tube of gas lasers, is different from that between parallel electrodes given by Paschen's law. The physical modelling of the gas breakdown process in a narrow tube is established based on Townsend discharge theory. This kind of breakdown process can be divided into two stages. The first one is the changing process of the guiding electrical field of wall charges formed by the deposition of charged particles from the avalanche, and the second one is the electron avalanche process through the whole discharge tube. From the physical modelling mentioned above, the parameters just before breakdown and the breakdown characteristic through a narrow discharge tube will be analysed theoretically. It can be seen that the breakdown potential is dependent not only on the pressure, the tube length, and the species of gas but also on the diameter of the discharge tube. Finally, the calculated results are compared with the experimental results and the errors are discussed.

The existing theory of the discharge mechanism in the cold-cathode pulsed X-ray tube based on ionization of residual gas and plasma formation is reviewed and is shown to fail for a high-vacuum tube. A new theory is presented which is based on the production at the cathode of a vapour jet having a velocity of approximately 106 cm sec-1. This results in an expanding region of low voltage discharge, and leaves most of the applied voltage across a rapidly contracting vacuum region adjacent to the anode. It is shown that the tube current and voltage as functions of time and the X-ray pulse duration can be predicted from a knowledge of the voltage supply and tube parameters, and the results are verified experimentally.

If a glow discharge is established between a cylindrical anode and two identical coaxial cylindrical cathodes separated by a small gap in the presence of an axial magnetic field, the conductance between the two cathodes may be negative. The mechanism of this negative conductance is explained and discussed in terms of a simple model. A discharge tube of this type may be used as the basis of an oscillator in the audio or supersonic frequency range which may operate at an efficiency of the order of 70%. A theoretical treatment of the efficiency is given and agreement between theoretical and measured efficiencies is satisfactory. The construction of a tube operating on mercury vapour and suitable for commercial production is described. The possible use of this type of tube as a counter is briefly discussed.

High voltage diodes made of PνN (or PπN) structures sometimes fail by second breakdown when high voltage pulses are applied. The avalanche characteristics of PνN junction diodes are analysed and it is theoretically shown that they have negative resistance regions caused by the space charge effect of the carriers. Experiments on the second breakdown are also reported and it is concluded that the current concentration induced by the negative resistance may cause diode failure.

Some little-known characteristics of glow-discharge voltage regulator tubes are discussed. In particular, the negative resistance discontinuities sometimes observed in static characteristics and the hysteresis voltage effects which occur under dynamic conditions are demonstrated.

Discharge tubes are described in which a low pressure glow discharge is initiated by means of a magnetic field pulse. A tube has been developed in which a glow discharge so triggered leads to the formation of a cathode spot on a mercury pool; this tube will hold off 20 kv until fired and will then pass a current pulse of several hundred amperes. Its use in radar modulator circuits is envisaged.

This paper describes a method for determining the dynamic current voltage characteristic curves of glow discharge tubes. The technique differs from that previously used for the oscillographic study of glow tubes in that the manner in which the current varies with time is under control. This is accomplished by the use of a vacuum tube to limit the current passed by the glow tube. The rate at which the current rises and falls, the current amplitude, the frequency of repetition of the current cycle, and the interval between cycles can be varied at will by changing the wave form of the voltage applied to the grid of the control tube, and the grid bias of the control tube. A number of oscillograms obtained by this method are shown, and the form of the characteristics is explained on the basis of time taken for ionization and deionization of the gas.

The use of a vacuum tube as the isolating element in the charging of a high voltage capacitor bank was investigated analytically and experimentally. The series tube effectively open circuited a 60 kV power supply from a 20 μF capacitor bank upon command during bank discharge and when there was a ``crowbar'' or fault in the rf system. The tube cutoff capability allowed its operation as a switching regulator, providing precision voltage regulation for the capacitor bank. Programming the series tube grid circuitry for constant charging current allowed reduction of the peak current requirements of the charging power supply and smoothing of the load on the utility lines. Analysis of the modes of operation, description of the circuitry employed, and operational results are presented.

The nature of electron irradiation‐induced changes in the avalanche breakdown voltage has been investigated for Zener diodes with breakdown voltages from 5.6 to 25.5 V. Their breakdown‐voltage change is proportional to the irradiation electron fluence and inversely proportional to the impurity gradient in the linearly graded silicon p‐n junction.

A circuit is described whereby a corona tube may be used to regulate the output of a full-wave rectifier and therefore to control the excitation of a generator to give constant voltage. Performance curves are given for a five-kva. generator whose voltage is controlled by such a regulator.

Stud-mounting voltage regulator diodes can form very convenient sources of heat for the control of the temperature in cryogenic equipment. The characteristics of a range of such diodes at temperatures between 4°K and 300°K are reported.

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A new type of 25 KV glow regulator suitable for color television receiver applications has been developed. The output voltage varies less than 2% over a current range of 50 µa to 2 ma. The device also provides a novel fail-safe feature and a regulated focus voltage output. Glow discharge devices have been used extensively in the past as voltage regulators. They are characterized by simplicity, low cost, long life, stable characteristics and low dynamic impedance. Single tubes typically operate at 100 or 150 volts. Regulation of potentials in the kilovolt range has been performed by employing series chains of glow regulators, by corona discharge devices or by vacuum tube or transistor regulator circuits. In many applications, these approaches have not satisfactorily met cost, size, regulation, noise or x-radiation requirements.

Measurements have been made of the drifts in running voltage which occur in glow-discharge voltage-regulator tubes in the first few minutes of operation after striking. Several common types of tube have been examined. Values are also given for the temperature coefficients of running voltage to be expected for the various types of tube.

The temperature coefficient of the breakdown voltage of a Zener (voltage-reference) diode has become accepted as an implicit function of the breakdown voltage. The letter describes a simple technique whereby the temperature coefficient may be independently controlled by altering the doping profile. To illustrate the technique, design criteria for a silicon diode with a breakdown voltage of 20 V and a nominally zero temperature coefficient are derived.

This letter describes the results of testing the effect of hydro-static pressure up to 8000 atm ( 785 MN/m2) on the current/voltage characteristics obtained when using a Zener diode as a hydrostatic pressure gauge with the temperature coefficient of pressure close to zero.

For optical indication of numerals or symbols glow discharge tubes or fluorescence devices are often utilized. These have a multitude of luminous elements and the symbol is obtained by paralleling some of these elements. A new tube having several equal anodes has been developed to switch such indicators in a simple way. The number of the anodes is the same as the number of the lighting elements in the optical device. Utilizing the GT-mechanism, it is possible to operate the tube with a signal voltage of about 5 V only. Circuits for controlling both a glow discharge indicator tube and a fluorescence plate, are shown.

A new voltage regulator is described, suitable for large power units of standard construction. This regulator uses vacuum tubes as the controlling element, in place of vibrating contacts that have hitherto been employed. The voltage variation is less than 0.1 per cent when the load is gradually changed from no load to a little above full load. When this regulator is applied to d-c unit, some a-c source is necessary to supply the B-eliminator which is an essential part of it. The voltage of this a-c source, however, need be only fairly constant; it may safely vary by ± 3 volts (in the case of a 110-v source) without causing more than ± 0.1 per cent variation in the d-c line under regutlationt. When an a-c unit is to be regulated, on the other hand, the same unit may supply the B-eliminator.

The design and operation of a CO2 laser based on a glow discharge in a metal tube is described. Up to 15 W power was obtained. The operating voltage is low compared with a similar discharge in an insulating tube.

A new low work function surface, Au-Cs-O, is described which can be used as the cathode of a glow discharge tube. Using neon as the gas filling, a maintaining potential of 30?35 V is obtained; with helium the potential is 22?26 V. The variation of breakdown and maintaining potentials with gas pressure and electrode separation are shown for parallel-plate discharge gaps in neon, using this cathode surface. The gas similarity laws are not obeyed. Ways in which the current-maintaining voltage characteristics differ from those for conventional discharges are also discussed. Possible applications are considered, especially the use of the Au-Cs-O surface in a trigger tube or surge diverter.