Gas Discharge Tube Research Articles

The influence of radiative heat exchange on the character of gasdynamic flows under conditions of pulsed discharge in high-pressure cesium vapor

The gasdynamics of pulse-periodic radiative discharge in high-pressure cesium vapor has been studied in the framework of a two-temperature multifluid model. It is established that, at a limited volume of the gas-discharge tube, the character of gasdynamic flows depends on the conditions of radiative heat exchange in discharge plasma. In cases in which the main contribution to radiative energy losses is related to a spectral region with optical thickness τR(λ) ∼ 1, there is nonlocal radiative heat exchange in discharge plasma, which is uniformly heated over the entire tube volume and moves from the discharge axis to tube walls during the entire pulse of discharge current. Under the conditions of radiative losses determined by the spectral region where τR(λ) ≪ 1, the reabsorption of radiation is absent and discharge plasma is nonuniformly heated by the current pulse. This leads to the appearance of reverse motions, so that the heated plasma is partly pushed toward the tube walls and partly returned to the discharge axis.

Experimental and theoretical study of a low-frequency inductive discharge of the transformer type

The electrophysical and thermophysical characteristics of a low-frequency inductive discharge of the transformer type were studied in argon within a wide range of discharge parameters: densities of discharge current from 0.1 to 0.8 A/cm2 and argon pressures from 15 to 6000 Pa. A simplified model of the low-frequency inductive discharge of the transformer type, based on simultaneous solution to the balance equations for electrons and metastable atoms at the axis of the gas-discharge tube and balance equations for gas temperature and electron energy, was developed. Dependence of electric field strength of the low-frequency inductive discharge of the transformer type on argon pressure and discharge current was calculated. It is shown that calculation results agree with the measurement data and describe their main features: descending voltage-current characteristic of discharge and local minimum in pressure dependence of electric field strength.

Investigating the characteristics of the commercial gas tube ‘S10 Starter’ using a time-delay measuring method

The results of the commercial gas discharge tube investigation (starter ‘S10 Philips’), using the time-delay measuring method, are presented in this paper. This gas discharge tube is usually used as a starter, that is, for electrode heating regularization in fluorescent tubes. The measurements of time delay are performed for different voltages (from 210 V to 400 V) and different relaxation times (from 1 ms to 3 s). The obtained memory curves show that the used gas discharge tube has a very small memory effect, which indicates a fast response after a long (out-of-use) time. This characteristic of the used commercial gas discharge tube is a consequence of gas tube geometry. It also shows that the time-delay distributions for small relaxation time values have a Gaussian shape; with the increase in relaxation time the right tail of distributions increases and distributions lose symmetry and become exponential.

MnBr vapor active medium with a built-in reactor at 100-kHz pulse repetition frequency

Frequency and energy characteristics of a MnBr vapor laser with a built-in reactor, i.e., with gas vapors being produced within a gas discharge tube, and the dependence of the average output power on different parameters are studied in this work. The values of the GDT wall temperature and buffer gas pressure required for obtaining the maximum output power are determined. It is shown that active media of this kind are as good as media with a conventional method of gas vapor production. A pulse repetition frequency of 100 kHz is attained for the first time for a medium on Mn atom transitions. The use of this active medium as a brightness amplifier in active optical systems is described; the amplifying characteristics are analyzed.

Testing of high voltage surge protection devices for use in liquid argon TPC detectors

In this paper we demonstrate the capability of high voltage varistors and gas discharge tube arrestors for use as surge protection devices in liquid argon time projection chamber detectors. The insulating and clamping behavior of each type of device is characterized in air (room temperature), and liquid argon (90 K), and their robustness under high voltage and high energy surges in cryogenic conditions is verified. The protection of vulnerable components in liquid argon during a 150 kV high voltage discharge is also demonstrated. Each device is tested for argon contamination and light emission effects, and both are constrained to levels where no significant impact upon liquid argon time projection chamber functionality is expected. Both devices investigated are shown to be suitable for HV surge protection applications in cryogenic detectors.

Increasing the amplification in a gas-discharge laser with an active element of nonstandard geometry

An active element of cylindrical geometry in a plane–sphere cavity is traditionally used in a helium–neon laser. Part of the active medium in this case does not participate in generating the radiation. However, it is a laborious task to use a gas-discharge laser tube whose geometry would exactly coincide with the field geometry. It is proposed to use a combined element consisting of two or three sections of different diameters with different lengths. A calculation showed an amplification increase by 30% and 40%, respectively, by comparison with cylindrical geometry. Such active elements present no special difficulties in production in this case.

Basis of the discharge maintenance in a matrix source of negative hydrogen ions

The presented three-dimensional (3D) self-consistent model of a matrix source completed by small-radius planar-coil driven rf discharges in hydrogen is in the scope of the recent research on a new design of the rf sources of negative hydrogen ions for fusion applications. The analysis of the results for the spatial distribution of basic discharge characteristics (electron density and temperature, rf current density and rf field intensity) in the three configurations of the matrix considered aims at conclusions about a manner of rf inductive-mode driving proper for ensuring the same discharge behavior in the gas-discharge tubes of the matrix.

A 58-dBm $S$-Band Limiter in Standard 0.25-$\mu\hbox{m}$ BiCMOS Technology

A series of limiters have been developed for power levels up to 58 dBm in a standard 0.25- μm BiCMOS process. After a thorough analysis of general design tradeoffs, a figure-of-merit (FOM) for limiter technologies is introduced. This FOM indicates the necessity of a high current-to-capacitance ratio, which is obtained by exploiting the base-collector junction. Two designs were implemented for operation up to S- and X-band with optimized power capability for the respective frequency bands. The proposed designs avoid dedicated technologies like PIN-diodes or gas discharge tubes and thus enable integration of the limiter in a receiver front-end chip. The limiters have been designed based on a diode model, which was carefully extracted from measurements on a single diode cell. Reliability aspects, specific to limiters, are discussed. The measurements on the S-band limiter showed that 58 dBm pulses with 10-μs length can be handled, which is similar to power levels obtained by commercial PIN diode limiters.

Formation of a high-frequency discharge in the active metal vapor laser medium

The evolution of an electric discharge in the active self-terminating metal atom laser medium is examined. Electrodes in the gas discharge tube are placed in cold buffer zones at a distance of several centimeters from the thermally insulated gas discharge channel. It is shown that an abnormal glow discharge is initiated in the cold buffer zones, as capacitive components of the discharge circuit charge from a storage capacitor. In this case, the current-voltage characteristic of the abnormal glow discharge in the cold buffer zones exhibiting a steep current growth and sharp voltage drop is illustrated in the right-hand branch of the Pashcen curve. These processes cause the discharge to pinch. As the capacitive components charge from the storage capacitor for the electrodes in the gas discharge tube placed in the cold buffer zones at a distance of ≤1–3 mm from the thermally insulated gas discharge channel, an obstructed discharge is formed in the cold zones. On ignition of the discharge shown in the right-hand branch of the Pashcen curve the current accompanied by gas heating eliminates the contraction of the discharge in the cold buffer zones and initiates a high-frequency discharge in the active medium since the instant the breakdown (pinch) occurs. In this case, the current-voltage characteristic is demonstrated in the left-hand branch of the Pashcen curve.

Formation of an out-of-electrode plasma in a high-voltage gas discharge

The formation of an out-of-electrode plasma in a high-voltage gas discharge is studied. The occurrence and self-maintenance of a gas discharge and its associated plasma fluxes on the straight portions of electrical field lines are predicted theoretically and confirmed experimentally. It is shown that the focusing of the gas discharge and plasma fluxes is provided by increasing the length of the field line straight portions toward the symmetry axis of a hole in the anode. It is found that, when the discharge power (more specifically, an accelerating voltage applied to the electrodes of the gas-discharge tube) rises, the straight portions of the field lines elongate and concentrate near the symmetry axis of the hole in the anode. Recommendations are given on using the out-of-electrode plasma in surface micro- and nanostructuring.

Influence of the electrophysical processes in the discharge circuit on the energy characteristics of a copper vapor laser

The influence of the electrode arrangement in the gas-discharge tube (GDT) on the electrophysical processes in the discharge circuit is considered. The equivalent GDT circuit and the mechanism of its transformation depending on the electrode arrangement in the cold buffer or hot discharge channel zones are designed. The breakdown mechanism at the GDT channel ends is considered. It is demonstrated that the breakdown can be considered as the time moment since which the voltage is redistributed between the GDT ends and the active medium in favor of the last. A high relaxation rate of metastable copper atom states in the near afterglow is caused by ionization electron cooling in the active medium. In this case, the energy stored in the reactive components of the discharge circuit impedance during this time period is dissipated in the cold buffer zones. The energy is dissipated in the cold buffer zones until the time when the plasma resistance at the discharge channel ends reaches the value starting from which the duct capacitive components of the GDT shunt the cold buffer zones. As a result, a high-frequency circuit is formed, and the energy is further dissipated in the active medium. This reduces the relaxation rate of the metastable states during the time period between pulses and determines the characteristic bend in the time dependence of the metastable state population density determining the time moment of forming the high-frequency circuit.

Simulation of Gas Discharge in Tube and Paschen’s Law

According to the related theory about gas discharge, the numerical model of a gas discharge tube is established. With the help of particle simulation method, the curve of relationship between gas ignition voltage, gas pressure and electrode distance product is studied through computer simulation on physical process of producing plasma by DC neon discharge, and a complete consistence between the simulation result and the experimental curve is realized.

Plasma Combustion Nature of Artificial Ball Lightning

Works on the creation of gas discharge origination artificial ball lightning have been carried out with the help of specially designed gas discharge tubes, in which the condensed matter in the form of a thread-type or powder material was deposited. Origination of long-lived luminescent spheres, i.e., artificial ball lightning, has been detected. Some of them exploded during their lifetime. A nature of these objects is discussed.

The Influence of Electrode Surface Mercury Film Deformation on the Breakdown Voltage of a Sub-Nanosecond Pulse Discharge Tube

A sub-nanosecond pulse discharge tube is a gas discharge tube which can generate a rapid high-voltage pulse of kilo-volts in amplitude and sub-nanoseconds in width. In this paper, the sub-nanosecond pulse discharge tube and its working principles are described. Because of the phenomenon that the deformation process of the mercury film on the electrode surface lags behind the charging process, the mercury film deformation process affects the dynamic breakdown voltage of the tube directly. The deformation of the mercury film is observed microscopically, and the dynamic breakdown voltage of the tube is measured using an oscillograph. The results show that all the parameters in the charging process, such as charging resistance, charging capacitance and DC power supply, affect the dynamic breakdown voltage of the tube. Based on these studies, the output pulse amplitude can be controlled continuously and individually by adjusting the power supply voltage. When the DC power supply is adjusted from 7 kV to 10 kV, the dynamic breakdown voltage ranges from 6.5 kV to 10 kV. According to our research, a kind of sub-nanosecond pulse generator is made, with a pulse width ranging from 0.5 ns to 2.5 ns, a rise time from 0.32 ns to 0.58 ns, and a pulse amplitude that is adjustable from 1.5 kV to 5 kV.

가스방전관(GDT)을 적용한 서지보호장치 회로의 DC 동작전압 최적조건 고찰

It is made compulsory to install SPD for the purpose of protecting electric and electronic devices when an abnormal voltage such as lightning occurs to power line using power frequency of 60Hz. Recently, the high speed communication technology utilizing power line is receiving attention again as a communication technology for smart grid. The SPD influences the performances of power line communication when using SPD and power line communication system together. In order to improve the performance of power line communication, a proposed scheme for series connection of gas discharge tube to ZnO varistor was presented. This paper measured the impacts of series connection of GDT to SPD using ZnO varistor on the limit voltage of Class III SPD. This paper also presented the DC operating voltage of GDT which satisfies the limit voltage of power line communication system and SPD simultaneously.

Dependence of characteristics of helium ion diffusion and drift in own gas on its temperature

The gas discharge at a lower atom temperature has a number of features which can appear in experiments with dusty plasma. At cryogenic temperatures of gas-discharge tube walls, strong anisotropy of the velocity distribution function of ions takes place, which, in turn, can cause a significant change in dust structure properties. In this study, the dependences of helium ion drift characteristics in a dc uniform electric field on the temperature of own gas atoms are analyzed.

Modeling technique of capacitive discharge pumping of metal vapor lasers for electrode capacitance optimization

To estimate optimum gas discharge tube (GDT) electrode capacitance of metal vapor lasers (MVLs) pumped by a longitudinal capacitive discharge, we offer to use series connection of capacitors to the electrodes of a conventionally pumped GDT with inner electrodes. It has been demonstrated that the maximum output power in CuBr lasers is obtained when the capacitances of high-voltage and ground electrodes are equal. When using a model circuit an average output power reaches 12 W that suggests the possibility of generating high average output power (>10 W) in MVLs pumped using a capacitive discharge.

Breakdown voltage reliability improvement in gas-discharge tube surge protectors employing graphite field emitters

Gas-discharge tube (GDT) surge protectors are known for many decades as passive units used in low-voltage telecom networks for protection of electrical components from transient over-voltages (discharging) such as lightning. Unreliability of the mean turn-on DC breakdown voltage and the run-to-run variability has been overcome successfully in the past by adding, for example, a radioactive source inside the tube. Radioisotopes provide a constant low level of free electrons, which trigger the breakdown. In the last decades, any concept using environmentally harmful compounds is not acceptable anymore and new solutions were searched. In our application, a cold field electron emitter source is used as the trigger for the gas discharge but with no activating compound on the two main electrodes. The patent literature describes in details the implementation of the so-called trigger wires (auxiliary electrodes) made of graphite, placed in between the two main electrodes, but no physical explanation has been given yet. We present experimental results, which show that stable cold field electron emission current in the high vacuum range originating from the nano-structured edge of the graphite layer is well correlated to the stable breakdown voltage of the GDT surge protector filled with a mixture of clean gases.

Characteristics of electron drift in the low-pressure gas discharge

The features of the energy distribution function of electrons during their drift in neon are analyzed for typical conditions of experiments with dust structures in plasma. The energy balance of electrons and drift characteristics in an electric field at strengths 13 < E/N < 42 Td were calculated taking into account inelastic collisions and the effect of electron loss on gas-discharge tube walls.

A HIGH ATTENUATION ELECTROMAGNETIC PULSE PROTECTOR WITH GDT, MOV AND PARALLEL COUPLED BPF ON HIGH THERMAL CONDUCTIVITY SUBSTRATES

An alternative approach for robust electromagnetic pulse (EMP) protection circuit was proposed by using a parallel coupled band-pass fllter (BPF) with high thermal conductivity alumina nitride (AlN) substrate coupled with a traditional gas discharge tube (GDT) and fast response metal oxide varistor (MOV). This proposed conflguration can suppress slow as well as fast voltage surges. The fabricated BPF with a center frequency of 2.5GHz on the high thermal conductive (180 » 200W/m¢K) AlN substrate could e-ciently suppress high power over voltage surge. Through the purposed cascade protection conflguration, it is observed that 6kV electrostatic discharge (ESD) pulse (5ns/50ns) and 4kV lightning surge pulse (1s/50s) were attenuated to 511V and 396V, respectively, and that is capable to be applied to an EMP protection circuit in the front end of a linear amplifler applications.