Spark Switch Research Articles

微型平面式气体火花开关的设计和制作

微型平面式气体火花开关的设计和制作

CO2激光器高压脉冲触发系统的设计

To trigger the rotated spark switch in a CO2 laser stably and reliably,a high-voltage pulse trigger system is designed and a new method for driving and protecting Insulated Gate Bipolar Transistor(IGBT) is proposed.According to the trigger structure of rotated spark switch in the CO2 laser,a pulsed source which can output 100-500 Hz repetition-rate pulses and a single pulse is developed with the EPM3512 CPLD chip and the IGBT drive circuit with over-current,over-voltage protection and Electromagnetic Compatibility(EMC) design is proposed by a optocoupler HCPL-3120.Besides,the model of a high-voltage pulse transformer is simulated by PSPICE software.Finally,an experimental platform is buit to test the system performance online.Experimental results indicate that the high-voltage pulse trigger system can output high-repetition-rate pulses higher than 38 kV continuously and stably,which satisfies the requirements of the rotated spark switch in the CO2 laser for stability and reliability.

±100 kV三电极场畸变气体火花开关

±100 kV三电极场畸变气体火花开关

A high repetitive rate intense electron beam accelerator based on high coupling Tesla transformer

AbstractTesla transformers are widely used in short pulse, repetition pulsed power generators. In this paper, a high repetitive rate intense electron beam accelerator (IEBA) based on high coupling (~1) Tesla transformer, which consists of a primary charging system, coaxial pulse forming line (PFL) charged by Tesla transformer and gas spark switch is described, especially stressed on the high coupling Tesla transformer. By introducing magnetic core to enhance the coupling factor between the primary and secondary windings, the transformer is capable of producing high voltage pulse up to 1.4 MV in approximately 45 µs. A coaxial pulse forming line is closely attached to the transformer that the outer and inner magnetic cores are parts of the PFL's outer and inner conductors respectively. In addition, the parameters of the Tesla transformer and PFL are calculated, including the dimension of the PFL and Tesla transformer. Some experiment results showed that the IEBA is capable of producing electron beams of 300–700 kV/7–13 kA at repetitive rate 100 Hz, with the pulse width 35 ns. The maximal energy efficiency of the Tesla transformer is 83%.

A compact submicrosecond, high current generator

Pulsed current generator was developed for experiments with current carrying pulsed plasma. Main parts of the generator are capacitor bank, low inductive current driving lines, and central load part. Generator consists of four identical sections, connected in parallel to one load. Capacitor bank is assembled from 24 capacitor blocks (100 kV, 80 nF), connected in parallel. It stores 9.6 kJ at 100 kV charging voltage. Each capacitor block incorporates a multigap spark switch, which is able to commute by six parallel channels. Switches operate in dry air at atmospheric pressure. The generator was tested with an inductive load and a liner load. At 17.5 nH inductive load and 100 kV of charging voltage it provides 650 kA of current amplitude with 390 ns rise time with 0.6 ohms damping resistors in discharge circuit of each capacitor block. The net generator inductance without a load was optimized to be as low as 15 nH, which results in extremely low impedance of the generator (approximately 0.08 ohms). It ensures effective energy coupling with a low impedance load such as Z pinch. The generator operates reliably without any adjustments in 70-100 kV range of charging voltage. Jitter in delay between output pulse and triggering pulse is less than 5 ns at 70-100 kV charging voltage. Operation and handling are very simple, because no oil or purified gases are required for the generator. The generator has dimensions 5.24x1.2x0.18 m(3) and total weight about 1400 kg, thus manifesting itself as simple, robust, and cost effective apparatus.

Mega-ampere submicrosecond generator GIT-32

The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17 microF, 40 nH, 100 kV) capacitors, connected in parallel. It stores approximately 18 kJ at 80 kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20 nH inductive loads. At 10 nH load and 80 kV of charging voltage it provides 1 MA of current amplitude and 490 ns rise time with 0.8 Omega damping resistors in discharge circuit of each capacitor and 1.34 MA530 ns without resistors. The net generator inductance without a load was optimized to be as low as 12 nH, which results in extremely low self-impedance of the generator ( approximately 0.05 Omega). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80 kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40 kV charging voltage is about 7 ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200 x 3200 x 400 mm(3) and total weight of about 2500 kg, thus manifesting itself as a simple, robust, and cost effective apparatus.

Compact high current generator for x-ray radiography

We report here a design of the portable high current generator, which can be used for a row of experiments and applications, including, but not limited to, X pinch, plasma focus, vacuum spark, etc. The X generator consists of the capacitor bank, multigap spark switch, load chamber, and built-in high voltage triggering generator. The capacitor bank consists of 12 General Atomics 35404 type capacitors (20nF, 25nH, 0.2Ω, 100kV). It stores ∼0.8kJ at 80kV charging voltage. Each three capacitors are commuted to a load by the multigap spark switch, which is able to commute by eight parallel channels. Switches operate in ambient air at atmospheric pressure. At 76kV charging voltage the generator provides ∼260kA with 120ns rise time and 5nH inductive load and ∼220kA with 145ns rise time and 10nH. Delay of output pulse relative to high voltage triggering pulse is ∼65ns with 5ns jitter. The dimensions of the generator are 1240×1240×225mm3 and the weight is ∼250kg, and only one high voltage power supply is required as additional equipment for the generator. The generator with a pumping system is placed on area about 0.5m2. Operation and handling are very simple, because no oil nor purified gases are required for the generator. The X generator has been successfully employed for experiments on the Ni X pinch load. X-ray pulse duration (full width at half maximum above 1keV) was about 5ns. Radiation yield Wr⩾500mJ was observed in the 1.2–1.5KeV range and Wr⩾20mJ in the 3–5keV energy range, which is comparable to results, obtained on the nanosecond accelerators. Clearly resolved images of 6μm wire indicate micron level size of hot spot. These results demonstrate possibility of this generator for application for x-ray backlighting.

Pulse generator for pumping electric-discharge excimer lasers

A pulse generator is developed for pumping electric-discharge excimer lasers in which the capacitive energy storage is connected with the gas-discharge chamber of the laser with the help of a multichannel spark switch via a low-inductive strip line. This scheme of the generator reduces energy losses in the switch and the inductance of the discharge circuit of the capacitive storage. For the pump power equal to 800 MW, the efficiency of the stored energy transfer to a load achieves 85%. To ignite a homogeneous volume discharge, the generator produces a prepulse, which initiates a low-current volume discharge in the gas-discharge chamber. Upon excitation of an electric-discharge XeCl laser with the 3 × 5.4 × 80-cm active region and the Ne : Xe : HCl= 2000 : 2.5 : 1 mixture at a pressure of 4 atm, radiation pulses with energies up to 3.4 J and the FWHM duration up to 260 ns were obtained with a homogeneous energy distribution over the laser aperture.

Experimental Study of the Multi-Gap Multi-Channel Gas Spark Closing Switch

A coaxial multi-gap multi-channel spark switch with stainless-steel-spring ring gap electrodes is designed and investigated. The switch is triggered by a pulse applied to the cylindrical electrode outside the discharging channel through a parasitic capacitance coupling. The jitter of the switch is reduced by several short-distance gas gaps in series, and its inductance is reduced by a multi-channel discharge on account of the inductance isolation between the coils of the spring ring electrode. The experimental results indicate that the switch is of low inductance (15-30 nH), low jitter (∼3 ns), and stable breakdown performance.

Investigation of an electric-discharge XeCl laser with a radiation energy of 5 J per pulse

An investigation was made of an electric-discharge XeCl laser with the active region of 4 cm × 5.5 cm × 100 cm dimensions. The laser was pumped by one of two pulse generators: a generator with a two-circuit configuration, a peaking capacitor, and a spark switch or a thyratron magnetic generator. An Ne(He, Ar)—Xe—HCl working mixture was preionised by x rays of 25–30 keV energy. A study was made of the conditions needed for the initiation of a homogeneous volume discharge. When the buffer gas in the mixture was neon, the radiation energy per pulse was 5 J, in a mixture with helium it was 2.5 J, and in a mixture with argon it was 1.2 J.

1-ns pulse-generating, compact, low-pressure N2 lasers

Effects of a pressurized spark switch on N2 laser output have been observed optically with quartz fibers. The output power increased with decreasing the gap of the spark switch while keeping pgd=0.51 kg/cm (pg is the N2 gas pressure in the spark switch and d is the gap distance) and pN2=40 Torr (pN2 is the pressure of the laser medium gas). One nanosecond pulses with peak powers of 120 kW have been generated for the first time for low-pressure operating N2 lasers.

Surface Aging in High Repetition Rate Spark Switches with Aluminum and Brass Electrodes

The surface aging of the electrodes of miniature spark switches (A/d ~ 50) is explored using commercial dry nitrogen as the working gas. Both brass and aluminum electrodes were investigated for aging characteristics using a constant gas flow rate of 8 cm3/s. The gas pressure was varied from 760 torr-5200 torr. The switches were constructured as an integral part of a miniature LC oscillator which has a ringing frequency of approximately 150 MHz. The aging process was halted at intervals ranging from one to several thousand discharges and the electrode surface examined with a scanning electron microscope.

High Repetition Rate Miniature Triggered Spark Switch

A miniature triggered spark switch designed to operate at high repetition rates has been constructed. The device, along with associated triggered circuitry, has been incorporated into a simple LC generator which produces an oscillatory discharge at a frequency of 150 MHz. The switch is operated in the pressure range 760 torr-2.6 × 103 torr using commercial dry nitrogen as the working gas. Both brass (70/30) and aluminum (99.95 percent) electrodes were investigated for repetition frequencies as high as 20 kHz and for gas flow rates as high as 8 cm3/s. The effect of repetition rate on switch jitter and switch breakdown voltage is presented and discussed in terms of gas pressure and flow rate.

Effects of a spark switch and stray capacities on the operation of a N2-laser

The laser-tube stray capacity and the time dependent spark resistances of the pulsing system influence the operation of a N2-laser. Their analysis with experimental and analog-computer methods yields an optimum value of the stray capacity. In the case of a 40 kV pulse from a 2-gap Marx generator with a 0.4 J energy input we obtain 120 kW laser output with 2.5 ns halfwidth at an optimum stray capacity of 120 pF. A substantially reduced threshold value and increased laser output were observed with a fast single-gap transmission line pulser of the “Nanolite” type.

Switching Characteristics of a Spark Switch in Air

Switching Characteristics of a Spark Switch in Air