Inductance Of Discharge Circuit Research Articles

Influence of the discharge circuit inductance on the process of galvanic wastes electrospark purification

Influence of the discharge circuit inductance on the process of galvanic wastes electrospark purification

ОСОБЛИВОСТІ ПЕРЕХІДНИХ ПРОЦЕСІВ У КОЛАХ ДРУГОГО ПОРЯДКУ З НЕЛІНІЙНОЮ МОДЕЛЛЮ ІСКРОЕРОЗІЙНОГО НАВАНТАЖЕННЯ В УМОВАХ ПРИМУСОВОГО ОБМЕЖЕННЯ ЇХНЬОЇ ТРИВАЛОСТІ

In the Mathlab Simulink software environment a model of a second-order discharge-pulse system with a nonlinear de-scription of the equivalent electrical resistance of a spark-erosion load was created. Under conditions of forced limita-tion of the duration of discharge pulses for a series of values of the inductance and capacitance of the discharge circuit, as well as the initial conditions in them, transients in the system are calculated. In groups of modes with fixed values of the initial voltage on the working capacitor and in groups of modes with fixed values of voltage amplitude of the free discharges on load, the dependences on duration of the discharge pulses of their energy, pulse power in the load, and the rate of its change are plotted and analyzed. It is shown that in both groups of modes for each set of parameter val-ues of: the duration of the discharge pulses, the capacitance of the working capacitor and the initial voltage on it, there is a value of the inductance of the discharge circuit, which provides the highest values of the rate of change of the pulse power in the load. In the groups of modes with fixed values of the voltage amplitude of free discharges on the load, for the set of parameters described above, there are also values of the discharge circuit inductance that provide the highest values of energy and pulse power in the load. For three values of the inductance of the discharge circuit, the problems of increasing the above pulse parameters are graphically solved. References 27, figures 11.

Influence of the discharge circuit inductance on the ablative pulsed plasma thruster performance

The most promising option for motion control of small spacecrafts with weight less than 50 kg is a pulsed plasma thruster with an energy of less than 20 J (micro-PPT), which has such advantages as low weight, structure simplicity, precise pulse control, sufficiently long life time, constant operational readiness and low inertia. It was believed that PPT with low discharge energy (less than 20 J) needed reduction of the initial inductance, despite the fact that the low capacity of the capacitor bank would not allow to achieve the optimal C/Lo ratio. However, the results of calculations and experiments show that a slight increase in the initial inductance of the discharge circuit, contrary to the assumptions, has a positive effect on the micro-PPT characteristics, reducing the propellant consumption and mainly increasing the specific impulse without significant reduction of the thrust impulse (unit impulse). This feature of the discharge circuit of the PPT with a low discharge energy allows us to discover new solutions in micro-PPT designing and improve the thruster specific characteristics.

Influence of discharge parameters on pulsed discharge of coaxial gun in deflagration mode

Coaxial gun can produce high-speed and high-density plasma jet and has some potential applications in many research areas such as space thruster, space debris impact simulation, nuclear fusion, and material processing. The coaxial gun is usually composed of a pair of coaxial cylindrical and hollow electrodes. The pulsed discharge of coaxial gun has two discharge modes, i.e., deflagration mode and pre-fill mode. Compared with the pre-fill mode, deflagration discharge mode can induce a plasma jet with few impurities, high collimation, and fast speed. In this paper, the effect of gas injection mass and discharge voltage on the discharge characteristic of deflagration mode are studied with electrical and optical diagnosis including the emission spectrum, plasma velocity and discharge current measurements. The experimental results show that when the gas injection mass is relatively low, such as 1.4 mg, many plasma clusters eject from the muzzle. As the gas flowing into the coaxial gun bottom increases, the plasma density increases and the jet velocity decreases. Eventually, when the gas injection mass increases to 2.6 mg, one cluster of plasma is found and ejects from the muzzle of the gun. In the discharge process, as a small quantity of gas flows into the bottom of the coaxial gun through the electromagnetic valve continuously, new current paths will be generated at the bottom of the coaxial gun and move forward. This results in the observation of multiple plasma jet at the exit of the coaxial gun. It is noted that the plasma densities are different for different gas mass flowing into coaxial gun bottom, but the currents have little effect in the first discharge half cycle due to the small plasma inductance in discharge circuit. Meanwhile, the plasma characteristics under different voltages with the fixed gas mass of 2.6 mg flowing into the coaxial gun bottom are experimentally measured. The results show that the plasma density and speed increase with voltage increasing, which is attributed to the stronger discharge current and larger self-induced Lorentz force. More neutral particles can be ionized into plasma with discharge voltage increasing, and the transport speed becomes faster under the enhanced force. In addition, the multiple ionization phenomena are observed again when the discharge voltage increases from 5 kV to 8 kV. This study provides an insight into how to better apply the coaxial gun discharge plasma to practical engineering field. The article further verifies the phenomenon of multiple discharges at the bottom of the coaxial gun by changing the charging capacitance and analyzing the magnetic probe signals.

Oscillatory–Discharge Processes in Capacitive Ignition Systems with a Unipolar Pulse

The discharge processes in a capacitive ignition system with a unipolar pulse, which offers advantages as compared with ignition systems of oscillatory discharge, are investigated. It is noted that the received wisdom concerning the dynamics of development of a unipolar discharge pulse is rather conditional. It is shown that, for small values of inductance of discharge circuit, the discharge in the plug becomes oscillatory, with a pronounced oscillating component being superimposed onto the aperiodic component of the current. An experimental setup and a technique for investigating the oscillatory discharges when changing the parameters of the discharge circuit including the storage-capacitor capacitance and the inductances in the circuit of a shooting semiconductor plug and in the circuit of a high-voltage diode are described. The results of oscilloscope experimental studies and an analysis of results of measuring of the energy of spark discharges in the shooting semiconductor plug are presented depending on the parameters of the discharge circuit. The regularities of development of oscillatory discharges are laid out. It is shown that oscillatory discharges are generated not only under small inductances of the discharge circuit, but also when increasing the inductance in the case of connecting an additional inductance, the value of which is lower than the value of the main inductance, to the high-voltage diode circuit. It is proved that the energy efficiency of the capacitive ignition system of oscillatory discharge can exceed the efficiency of modern ignition systems with a unipolar pulse.

The influence of circuit inductance on the energy characteristics of electric discharge and deformation of plates in water

We have experimentally studied the influence of discharge-circuit inductance on the efficiency of conversion of energy stored in a capacitor bank, evolved in the electric-discharge channel in water, and spent for the resulting plastic deformation of plates. It is established for the first time that a growth in inductance of the discharge circuit produces a positive effect on the deformation of plates by increasing the amount of energy spent in this process.

The effect of working gas pressure on the switching rate of a kivotron

The switching rate in gas-discharge devices (kivotrons) based on an “open” discharge with counterpropagating electron beams is studied experimentally. Structures with a total cathode area of 2 cm2 were used. A monotonic reduction in the switching time with an increase in the working gas pressure and in the voltage amplitude at the time of breakdown is demonstrated. The minimum switching time is ~240 ps at a voltage of 17 kV. The maximum current rise rate, which is limited by the discharge circuit inductance, is 3 × 1012 A/s.

Study of the switching rate of gas-discharge devices based on the open discharge with counter-propagating electron beams

The switching rate of gas-discharge devices “kivotrons” based on the open discharge with counter-propagating electron beams has been experimentally studied. Structures with 2-cm2 overall cathode area were examined. The switching time was found to show a monotonic decrease with increasing the working-gas helium pressure and with increasing the voltage across the discharge gap at breakdown. The minimum switching time was found to be ∼240 ps at 17 kV voltage, and the maximum rate of electric-current rise limited by the discharge-circuit inductance was 3 × 1012 A/s.

Magnetic dipole discharges. II. Cathode and anode spot discharges and probe diagnostics

The high current regime of a magnetron-type discharge has been investigated. The discharge uses a permanent magnet as a cold cathode which emits secondary electrons while the chamber wall or a grounded electrode serves as the anode. As the discharge voltage is increased, the magnet develops cathode spots, which are short duration arcs that provide copious electrons to increase the discharge current dramatically. Short (1 μs), high current (200 A) and high voltage (750 V) discharge pulses are produced in a relaxation instability between the plasma and a charging capacitor. Spots are also observed on a negatively biased plane Langmuir probe. The probe current pulses are as large as those on the magnet, implying that the high discharge current does not depend on the cathode surface area but on the properties of the spots. The fast current pulses produce large inductive voltages, which can reverse the electrical polarity of the magnet and temporarily operate it as an anode. The discharge current may also oscillate at the frequency determined by the charging capacitor and the discharge circuit inductance. Each half cycle of high-current current pulses exhibits a fast (≃10 ns) current rise when a spot is formed. It induces high frequency (10–100 MHz) transients and ringing oscillations in probes and current circuits. Most probes behave like unmatched antennas for the electromagnetic pulses of spot discharges. Examples are shown to distinguish the source of oscillations and some rf characteristics of Langmuir probes.

Highly efficient pulse-periodic XeCl lasers

The parameters of electric-discharge pulse-periodic XeCl lasers with a pulse duration of 25 - 40 ns, an energy of 0.2 - 0.7 J, and a pulse repetition rate up to 100 Hz have been investigated. It is shown that the total laser efficiency of 2.6 % and the maximum efficiency with respect to the stored energy of 3.8 % are obtained at a specific pump power of 2.8 - 3.3 MW cm-3 and a discharge circuit inductance of 3.5 - 4 nH.

Electric Explosion of Aluminum Metallized Film

Two types of capacitor-grade aluminum metallized polypropylene film were studied to investigate the factors that affect specific action integral and energy dissipation in the electrical explosion of a film, a phenomenon that occurs when a film is exposed to a high-density current pulse on the order of 107 - 108 A/cm2. The factors studied include film cross-sectional area, film length, film sheet resistance, and discharge circuit inductance. All film samples were subjected to a 2.5-kV capacitive discharge. The basic principles of the exploding-film phenomenon and the detailed effects of the stated factors are discussed.

Influence of discharge circuit parameters on the repetition rate-energy output characteristics of a laser on self-terminating transitions of atomic copper

The excitation circuits of a copper vapour laser (CVL) with a partial or total discharge of the storage capacitor were analysed. Based on this analysis, the effect of prepulse electron density on the repetition rate-energy characteristics of a CVL was shown to be minimal when the following conditions are fulfilled: R>2(L/C)1/2 and L/R<τc (for partial-discharge pump schemes; C is the storage capacitor capacity, L is the discharge circuit inductance, R is the prepulse resistance of the active medium, and τc is the switch turn-on time) and for a high frequency of free oscillations in the discharge circuit of a CVL. The conclusion was drawn that traditional pump schemes limit the energy capabilities of a CVL. The repetition rate-energy characteristics of a CVL can be improved by resorting to schemes with a shock or complex excitation circuit or their combination.

Nitrogen laser pumped by a longitudinal discharge from inductive and capacitative energy storage units

An experimental investigation was made of the influence of various pump-pulse generators on the output radiation power of a nitrogen laser (λ=337.1 nm) pumped by a longitudinal discharge. In addition to a magnetic switch and a semiconductor circuit-breaker, use was made of generators with inductive energy storage, with intermediate inductive energy storage, and with capacitative energy storage. Pumping by an inductive energy storage unit reduced the influence of the discharge circuit inductance and broadened the range of the operating pressures at which lasing was possible. Peaking capacitors, connected in parallel with a discharge tube, reduced the energy losses in the circuit-breaker and could increase laser output radiation energy.

Matching between generator and reactor for producing pulsed corona discharge

The matching between generator and reactor is a crucial aspect in optimizing the pulsed corona discharge. Several methods can be adopted to reach the matching, reducing inductance in discharge circuit, regulating relative humidity of flue gas, and paralleling a suitable condenser with the reactor. The detail of the matching discussed in this paper is based on experimental results and the theories of streamer formation as well. The matching not only makes the injection of pulsed energy effective, but also promotes the formation of pulsed streamer in the reactor.

MEASUREMENT OF DISCHARGE CIRCUIT DISTRIBUTIVE INDUCTANCE FOR BLUMLEIN EXCIMER LASER

Technique on measuring discharge current of Blumlein circuit using magnet-light method is described briefly in this paper. The more exact method estimating distributive inductance of discharge circuit is presented. The circuit equations are solved and the analytic expression of distributive inductance is derived. Finally, the calculated result is discussed.

Laser utilizing an Ar–Xe–NF3mixture with a discharge stabilized by a short-pulse electron beam

A study was made of an XeF laser excited with a discharge controlled by a 50-nsec pulsed electron beam. It was found that, for an appropriate choice of the discharge circuit inductance and of the shape of the electron beam current pulse, the maximum discharge power was reached while the beam current was decreasing and values of ~106 W/cm3 or more were obtained. A high-power pump pulse was thus combined with a high plasma voltage (of the order of the charging voltage), suitable for obtaining shortduration radiation pulses. The output energy and the energy fed into the gas were determined as a function of the composition of the gas mixture, charging voltage, storage capacitance, and pressure. A specific output energy of 2.5 J/liter was obtained.

Physical and Technical Parameters of Flashtubes

Studies were made of flashtubes with a limited discharge column (capillary tubes); and with an unlimited discharge (lamps with spherical bulbs), in a minimum inductance circuit. The investigations included extreme cases of the construction and supply parameters. Discharge characteristics in capillaries are similar to those in wide-diameter tubes, though corresponding values of specific resistance occur at electric fields some 5 to 10 times higher. — The specific resistance of plasma becomes almost constant (equalling ∼ 0.02 ohm cm) at E ≳ 120 v/cm. The discharge extinction voltage is approximately inversely proportional to the inner diameter of the tube. The increase of the light efficiency stops at E ≅ 400 v/cm (reaching very high values of about 40 lm/w). The dependence of the flash duration r on construction data and on supply parameters was determined, over a wide range of conditions. Within narrow limits of parameter modifications the following expression may be used: τ = AU0-0.6 (C1)pd-q — Here A is the proportionality coefficient; U0, the initial voltage on the supply condenser; C, the condenser capacity; I and d, the length and the inner diameter of the tube; p and q, approximately constant exponents, which change respectively from 0.5 to 1 and from 0.5 to 2, for wide variation of the parameters. The influence of the inherent discharge circuit inductance on the luminous characteristics of tubular lamps is almost insignificant. The working temperatures of quartz and glass tubular lamps, which are on long-duration stroboscopic duty (750C and 250C respectively) are attained at mean powers of about 10 and 1.8 w/cm of tube length, respectively. The tubes perform for a few seconds (without forced cooling) at powers of 40 and 4 w/cm, respectively. — The load factor, (CU4)max, which determines load limits in single-flash operation conditions, does not depend on the diameter, d, for glass tubes in the range from 0.5 to 11 mm, and for quartz tubes in the range from 0.5 to 2 mm. The time necessary for the deionization of the gas gap in capillary quartz tubes, dissipating ∼ 2 w/cm increases from 80 to 270 μsec for an increase of the initial electric field from 140 to 280 v/cm. At higher power the deionization period drops from 500 to 300 μsec. Accordingly, the critical flash frequencies of such tubes (without any additional commutation element in the discharge circuit) are equal to 12 kc/sec at low wattages, and of about 3 kc/sec at higher wattages. — To investigate extreme discharge performances in lubes with spherical bulbs, various low-inductance condensers and tube designs were tried. These included disc-shaped, pot, and cylindrical ceramic condensers; cylindrical and spherical quartz condensers; cylindrical film condensers; disc-shaped and coaxial lead-ins, connections and electrodes. As a result data were obtained for discharge circuits of the minimum possible inductance. Investigations were made of discharge column expansion velocities, and of discharge characteristics for various supply parameters. Construction data and supply parameters for tubes with a flash duration of 0.1 μsec, a flash frequency of 3 kc/sec, and a power of 1 kw were established.