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Working performances of laser-triggered vacuum switch (LTVS) mainly rely on the interactions of laser with target materials. Influences from target configuration, which is one of key factors in the interactions, are neglected so far. The trigger performances of LTVS with different target configurations are studied in this paper. Relevant influence factors about target configurations are discussed briefly based on theoretical analysis about the trigger process. The test prototype is established based on detachable vacuum chamber. The trigger characteristics of LTVS with different target structures, target depths, and laser focal positions are compared. The relationships between target configurations and trigger performances of LTVS are analyzed and discussed. The preferred targets in LTVS are suggested while considering its lifetime. The test results prove that the conical target shows the best trigger performances compared to other targets. Due to the enlarged laser irradiated area and shortened plasma moving distance, the delay time of LTVS reduces with the decrease in conical target angle and the increase in target depth, while the delay time is controlled within 32 ns. Benefited from laser reflection and plasma collision, the trigger performances of conical targets can be enhanced by focusing laser on the target side surface. In particular, the 90° conical target with 1.5 mm depth is suggested to be employed in LTVS products. [ABSTRACT FROM AUTHOR]

The STRETCH meat grinder is one typical inductive pulsed-power supply topology for electromagnetic launch system. It has remarkable current amplification ability as a single unit, but one module cannot provide enough amplitude and width for the load current of the railgun launching. This paper discusses the effects of different triggering delays on the load current with two STRETCH meat grinder modules. To reduce the magnetic field coupling between the two modules, the two main switches are opened simultaneously. To make the load current waveform with no notch, the thyristor of the first module is triggered when its pulse-forming capacitor is fully reversely charged. For the thyristor of the second module, we consider several time points of triggering delay. Because of the practical constraint for the maximum rail current that ensures no rail erosion, the rectangular waveform is the most appropriate load current waveform. Therefore, the comparing criterion can be defined as the ratio of the load current waveform area and its maximum rectangle area at different current levels. Higher ratio means that the current is more like a rectangular wave and is better accordingly. Based on the above criterion and extensive simulation research, we found that the best delay time is the moment when the capacitor is reversely charging the inductor completely. This paper and the result are of great theoretical significance for the further study on the collaborative triggering of multiple STRETCH meat grinder modules. [ABSTRACT FROM PUBLISHER]

With the development of pulsed-power technology, more and more applications require high-voltage and heavy-current pulse switches. Laser-triggered vacuum switch combines laser technology, vacuum switch technology, and three-electrode trigger switch technology, and has the advantages of heavy current capability, good isolation from the main circuit, and short delay time. In this paper, the 1-D thermal conduction model was developed to analyze the influence of laser energy on the velocity of initial plasma. The relationship between the ablation area and the laser energy was derived. The theoretical analysis can be verified by the relationship between the trigger delay time and laser energy and the initial plasma microcurrent curve in the experiments. [ABSTRACT FROM AUTHOR]

Switching time jitter is an important property to consider when selecting closing switches for pulsed-power systems. The corona-stabilized switch (CSS) is identified as an interest for low-jitter systems, in particular for systems where a high-repetition rate is required. In this paper, a commercial CSS is studied and its operating conditions are determined. [ABSTRACT FROM AUTHOR]

Nowadays, the triggered vacuum switch (TVS) is widely used in electromagnetic launcher systems. An important performance of TVS with the six-gap rod electrode system, which has long operating life and maximal switching capacity, has been used in experimental research. The delay time is an important feature of TVS. Therefore, this paper focuses on the effect of trigger circuit and trigger current on the delay characteristics of the TVS. The result shows that, in an indirect trigger circuit, by changing the parameters of the pulse transformer and capacitance C\1, the trigger current can be increased, and the delay time can be decreased simultaneously. In a freewheeling circuit, the rate of the trigger current rise can reach 150 \A/\mu\s, and the delay time is 2–4 \mu\s. Yet, in the trigger circuit, in which the capacitor C\2 is in parallel between the second side of the pulse transformer and the trigger electrode, the rate of the trigger current rise can reach 20 \kA/\mu\s, and the delay time is 2 \mu\s. In a direct trigger circuit without the pulse transformer, the rate of the trigger current rise is greater than 4 \kA/\mu\s, and the delay time shortens to 500 ns, which is the minimum. The delay time can be shortened obviously by changing the trigger circuit. [ABSTRACT FROM AUTHOR]

This paper discusses the development and testing of a low-jitter, high-voltage, high-current, and triggered spark-gap switch, designed as part of an intense electron-beam accelerator (IEBA). The voltage/pressure (V/p) curve of the switch was measured for N2 when the gas pressure is 0.10-0.25 MPa with the main gap spacing of 10 mm. In addition, the operating ranges, delay time, and jitter of the switch were measured during the single trigger experiment when the gas pressures were 0.10, 0.15, 0.20, and 0.25 MPa and the trigger voltage was 80 kV. The experimental results showed that the operating ranges of the switch were 25%-94%, 38%-86%, 40%-88%, and 44%-88% of the switch's self-breakdown voltage, and these results also identified a suitable operating condition for the application of the switch on the IEBA. When the gas pressure was 0.25 MPa, the operating voltage was 40 kV, which was about 88% of the self-breakdown voltage, the delay time was 50 ns, and jitter was 1.28 ns. At last, the repetition rate of the switch was measured when the switch was used as the trigger switch of the IEBA. The pulse repetition rate (PRR) is 10 Hz at the operating voltage of 20 kV and peak currents of 40 kA. The PRR is 5 Hz at the operating voltage of up to 40 kV and the peak currents of up to 80 kA. The switch works steadily and reliably. [ABSTRACT FROM AUTHOR]

Characterization of a corona-stabilized switch in the single-shot regime, including triggering range, delay times, and jitter, is reported over the pressure range 0–3 bar gauge, as a continuation of work from similar characterization with this switch filled with SF6 with different gap spacings. When filled with mixtures of 1,3,3,3-tetrafluoropropene (HFO-1234ze) and N2, the breakdown voltage can be increased by up to ~306% and ~191% under negative and positive polarities, respectively, of that using 100% N2. These results were achieved with gas mixtures consisting of 80% N2 and 20% HFO-1234ze, by pressure. The maximum negative polarity triggering range was 13.6 kV, comparable to that achieved previously using SF6. The measured delay time and calculated jitter were generally found to increase with increasing pressure, and with increasing percentage (from 5% to 20%) of HFO-1234ze in the gas mixtures. von Laue statistical analysis of time-to-breakdown data showed that both the formative time and statistical time increased with increasing pressure, and with increasing percentage of HFO-1234ze in the gas mixtures. The formative time under negative polarity was significantly longer than that for positive polarity. The results indicate that HFO-1234ze may be considered as a suitable candidate to replace SF6 for switching applications, although there are some operational observations that require further investigation. [ABSTRACT FROM AUTHOR]

As one of the critical elements of fast linear transformer driver (FLTD), gas switch directly influences the output parameters, stability, and reliability of generators based on FLTD technology. In this paper, a multigap gas switch with six gaps in series has been investigated to study the proper firing conditions to get better performance for FLTD. The self-breakdown voltage with different gas pressure has been studied to derive the working ratio of the switch. The triggered breakdown delay and jitter with different charge voltage, gas pressure, and working ratio have been studied. The results indicate that when the switch is triggered by a 100-kV trigger voltage pulse under 180-kV charge voltage and 0.325-MPa pure nitrogen (70% working ratio), the delay time and the jitter are 34 and 1 ns, respectively. [ABSTRACT FROM AUTHOR]

This paper gives a numerical model to deal with the thermal effect of field-induced thermal-assisted current passing through the microprotrusion on the cathode surface of a planar high-voltage vacuum diode. The model of protrusion is based on a one-dimensional truncated cone, whose physical and thermal properties have been assumed temperature dependent. The influences of space charge effect and Nottingham effect are included. According to the simulations, the delay times of explosive electron emission of cathodes made of different materials are given and compared with the experimental results, which seems to be in agreement. [ABSTRACT FROM AUTHOR]

In this paper, a dual-electrode gas switch triggered by ejected plasma is proposed to ensure the switch to be triggered reliably under extremely low switching coefficient. The switch has the configuration of dual electrodes, in one of which a microincentive chamber is embedded to develop ejected plasma into the switch gap, leading to the breakdown of the switch. Both the features of ejected plasma and the triggering discharge characteristics of the switch are studied with different types of gas, gas pressures, voltage polarities, gap distances, triggering pulse energies, and so on. The results show that the switch can be triggered reliably in a much wide working voltage range, as the minimum switching coefficient is low to 9% with the delay time of about 10 \mu \texts . With the decrease of gas pressure and the increase of triggering pulse energy, the height of ejected plasma increases while the delay time of the switch reduces. The polarities of charging voltage and triggering voltage both have obvious influence on the delay time of the switch, and the effect of the former is greater. Under the same gas pressure and triggering pulse energy, the delay time in SF6 is much bigger than that in N2. [ABSTRACT FROM PUBLISHER]