Gas Switch Research Articles

六间隙串联气体开关触发放电过程

六间隙串联气体开关触发放电过程

气体开关自击穿概率的分析方法比较

气体开关自击穿概率的分析方法比较

KrF Laser Development for Fusion Energy

The United States Naval Research Laboratory is developing an electron beam pumped krypton fluoride laser technology for a direct drive inertial fusion energy power plant. The repetitively pulsed krypton fluoride laser technology being developed meets the fusion energy requirements for laser beam quality, wavelength, and repetition rate. The kryptonfluoride laser technology is projected, based on experiments, to meet the requirements for wall plug efficiency and durability. The projected wall plug efficiency based on experiments is greater than 7 percent. The Electra laser using laser triggered gas switches has conducted continuous operation for 90,000 shots at 2.5 Hertz operation (ten hours). The Electra laser has achieved greater than 700 Joules per pulse at 1 and 2.5 Hertz repetition rate. The comparison of krypton fluoride laser performance with krypton fluoride kinetics code shows good agreement for pulse shape and laser yield. Development and operation of a durable pulse power system with solid state switches has achieved a continuous run of 11 million pulses into a resistive load at 10Hz.

轨道式多间隙气体开关设计与性能测试

轨道式多间隙气体开关设计与性能测试

Repetitive operation of multigap gas switch for fast linear transformer driver

Fast linear transformer driver (FLTD) has some advantages in repetitive operation compared with traditional pulsed power generators. However, different types of gas switches applied in the field of pulsed power technology in recent years cannot reach the requirements of repetitive operation of FLTD. Therefore, the capability of repetitive operation of a multigap gas switch has been investigated in a circuit similar to the basic discharge loop named as brick in this paper. The switch has been triggered more than 2000 times and the distribution of delay time and switch jitter are analyzed and reported. Also, the self-breakdown voltages of the switch during different segments of the triggered breakdown experiment have been tested. The experimental results indicate that the delay time obeys the Gauss distribution and the jitter of 2000 times of discharge is about 2.3 ns.

Investigation of a Magnetic Pulse Compression System Containing Gas Switch

A high repetition-rate circuit that combines a magnetic pulse compression (MPC) system and a spark gap is described. The novel feature of incorporating an MPC system and a spark gap together eliminates the bulky magnetizing subsystem of the magnetic switch and reduces the spark gap loss, thus improving the repetition-rate frequency. The preliminary test result of this circuit is presented.

A triggered multigap gas switch

The design, operating principles, and actual structure of a high-voltage triggered multigap gas switch (GS) that provides nanosecond switching of gigawatt-level power fluxes are considered. Its operation is based on a new model of a switching structure, in which the switching process is ensured by the overvoltage propagation along a chain of switching gaps through the mechanism of its interaction with two capacitive dividing circuits, which are formed by the GS electrodes. The GS is intended for operation in generators of high-voltage nanosecond pulses on the basis of a discharge of double coaxial-type forming lines. It is shown that the GS can be used to switch a 25-Ω forming line that is charged to a voltage of 600 kV.

Measurement of trigger and cascade section runtimes in 6 MV switches using fiber coupled photodetectors

Since October 2007 Sandia National Laboratories has operated the refurbished $Z$ machine at an improved load current of 26 MA yielding 400 TW of x-ray power. The current pulse shape to the load is controlled by 36 independently timed laser triggered gas switches. As part of the refurbishment effort, a fiber coupled laser spark detector system has been installed which is able to detect the laser generated plasma in situ inside the trigger section of the high voltage switch. In this paper we describe how this detection system can be used to characterize the discharge dynamics of these 5.9 MV, 820 kA switches.

Research on Erosion Property of Field-Distortion Gas Switch Electrode in Nanosecond Pulse

Pulsed power technology is one of the technological foundations in high and new technology research, which has extremely broad development and application prospect. Gas switch is one of the key elements in pulsed power devices, and electrode erosion is a key restrictive factor in high-power gas switch development and application. According to the 1-D equation of heat conduction and thermal equilibrium equation near the electrode surface, this paper researches the electrode heat conduction mechanism, establishes the electrode erosion calculation model, calculates electrode erosion heat fluxes and their peak powers caused under different discharge conditions, and proceeds to calculate the depth of electrode etch pit. Calculation results indicate that arc joule heat is the main reason for electrode erosion when discharge current is not too high. In the light of different discharge parameters, that is, peak current, electric quantity, and current waveform, as well as single discharge electrode erosion experiments, the calculation formula of etch pit depth is fitted. The results indicate that model and fitted calculation results are relatively approximate to the experiment results.

Study on pre-fire phenomenon for multiplex high-energy spark gap switches with graphite electrodes

In a high-power laser facility with multiplex power modules, the dispersion of self-breakdown voltages of spark gap switches might result in a so-called pre-fire problem. Pre-fire probability of spark gap switches with graphite electrodes must be constrained at extremely low level. In this paper, Pedersen model was used to explain the causes of pre-fire. The microscopic surface roughness of worn graphite electrodes had a major impact on pre-fire. And this paper had deduced the cumulative probability distribution of pre-fire, and given a relevant Weibull distribution equation. Several typical graphite materials were tested too. The experimental results revealed that electrodes should use graphite with higher hardness, smaller particle size and greater flexural strength. This was consistent with the analysis of Pedersen model. More significantly, based on the experiments of typical graphite materials, two Weibull constants of the cumulative probability distribution of pre-fire were obtained by a graphing method. Therefore, it is possible to calculate, reduce or control the occurrence of pre-fire in a facility with many gas switches. Via optimizing the operating under-voltage ratio of multiplex switches, the expectable pre-fire probability can be achieved.

A Plasma Focus Electronic Neutron Generator

An electronic neutron generator based on the dense plasma focus emits fast neutron pulses (~20 ns at the source) that allow for the time-of-flight detection of target materials at a standoff of ~3 m. Pulse-power-driven neutron generators have been considered unreliable due to the short lifetime of components such as gas switches and electrodes. The reliable operation of a plasma focus has been demonstrated for up to 25 000 shots at 1 Hz over several experiments with <; 25% variation in the mean neutron yield. The repetition rate is limited to 1 Hz for thermal management reasons. The peak current was 61 kA, with the neutron yield varying from 2.6 × 105 neutrons/pulse to 4.4 × 105 neutrons/pulse (a standard deviation of ~50%) within a given run. The neutron yield distribution variation more strongly correlates with the minimum in the time derivative of the current rather than the peak current in the narrow operating current window of 61 ± 2 kA. Each experiment used a fixed deuterium fuel gas charge. Insulator coating was shown not to be a problem after a total of 250 000 shots. The primary lifetime-limiting factor was a deep hole that was bored into the SS304 anode, eroding it at a rate of ≈6 μg/shot. With a refractory cooled anode, the source could realize an increase in electrode lifetime and a reduction in insulator coating, leading to a long lifetime (~106 pulse) and a fast pulse electronic neutron generator that operates at up to 100 Hz at 108-n/s D-D output.

多间隙气体开关的电场分布特性

In order to optimize the structure of multi-gap gas switch used in fast linear transformer driver(FLTD) module, the electric field distribution of gas switches with different structured electrodes before and after trigger were simulated. The effect of pressure balance measures on the electric field distribution of the gaps in the gas switch before trigger was studied by applying the new circuit model of the gas switch. Moreover, the relationship between the stray capacitances of the middle electrodes and the electric field distribution in the gas switch after trigger was studied. The results show that the ring electrode of circular section is conducive to the formation of a stable multi-channel discharge, and it can reduce the switch inductance and jitter; the DC voltage characteristics of the switch can be effectively improved by using the resistor of the same resistance in parallel between the gaps. At the trigger moment, the voltage distribution of each gap is mainly related to the trigger voltage rise time, the resistance and stray capacitance, and the shorter the trigger voltage rise time is, the more obvious the effect of the stray capacitance on the gap voltage distribution is.

多间隙气体开关光纤诊断

A set of fiber detector which consists of an optical fiber array detector and a solar-blind plug-in optical sensor was developed for multi-gap gas switch optical diagnosis. The detailed discharging process was monitored using the detector and the influence of trigger voltage, gas pressure and UV pre-ionizing on the performance of the switch was also analyzed. The timing precision of the fiber array detector is better than 0.6 ns, and its time response is 3.2 ns. The solar-blind sensor responds to light whose wavelength lies between 260 nm and 320 nm. The following results were obtained by the diagnostic system: the order of the gaps breakdown is 3rd-2nd-1st-4th-5th-6th, and statistic delay and over-voltage breakdown delay take the majority of the whole time delay. The jitter of the switch can be reduced by raising the trigger voltage, lowering the gas voltage and stabilizing the intensity of the ultraviolet light.

多间隙气体开关绝缘子寿命

多间隙气体开关绝缘子寿命

火花通道长度对激光触发开关特性的影响

火花通道长度对激光触发开关特性的影响

气体开关抖动对输出峰值功率和前沿的影响

气体开关抖动对输出峰值功率和前沿的影响

多间隙气体开关触发特性

多间隙气体开关触发特性

预电离触发管气体开关特性

预电离触发管气体开关特性

多间隙气体开关电感

多间隙气体开关电感

2MV激光触发气体开关实验研究

2MV激光触发气体开关实验研究