Analysis on discharge process of a plasma-jet triggered gas spark switch

MV pulsed switch plays a key role as the transfer switch in large electromagnetic pulse simulators. To broaden the range of self-triggering time, a novel spark-discharge pre-ionization switch, in which the main gap electric field is superposed at the trigger gap to let the electrons in its spark channel also become initial electrons, is proposed and tested. The design idea is: as electrons in the spark channel of the trigger gap always exist after its breakdown, the injection time of pre-ionization should have a more negligible effect on reducing the switch jitter. The experiment results under pulses with a rise time of ∼100 ns support the above assumptions. When the operating voltage is from ∼300 to ∼800 kV and the self-triggering time is ∼45% to ∼75% of the peak time, the breakdown time delay jitter is less than 2 ns, and the breakdown voltage jitter is smaller than 1.25%. Under specific self-triggering time, the breakdown time delay jitter is less than 1.5 ns, and the breakdown voltage jitter is smaller than 0.8%.

Section: Introductionmentioning

confidence: 99%

A low-jitter self-triggered spark-discharge pre-ionization switch: primary research on its breakdown characteristics and working mechanisms

Wang

Chen

2021

“…In terms of experimental studies, a large number of studies have been carried out on the spatial and temporal evolution of the plasma jet process and the propagation mechanism. Dong et al [17] and Tie et al [18] used a highspeed camera to observe the plasma jet process, and the experiments showed that the plasma was approximately axisymmetrically distributed. The energy of the applied pulse was increased, and the transition of the plasma jet from 'bullet' to 'surge' propulsion was accelerated.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation and experimental verification of plasma jet development in gas gap switch

Dong

Guo

Zhang

et al. 2023

Plasma jet triggered gas gap switch has obvious advantages in fast control switch. The development of the plasma in the ambient medium is the key factor affecting the triggering conduction of the gas switch. However, the plasma jet process and its characteristic parameters are complicated and the existing test methods cannot fully characterize its development laws. In this work, a two-dimensional transient fluid calculation model of the plasma jet process of the gas gap switch is established based on the renormalization-group (RNG) k-ε turbulence equation. The results show that the characteristic parameters and morphological evolution of the plasma jet are basically consistent with the experimental results, which verifies the accuracy of the simulation model calculation. The plasma jet is a long strip with an initial velocity of 1.0 km/s and develops in both axial and radial directions. The jet velocity fluctuates significantly with axial height. As the plasma jet enters the main gap, the pressure inside the trigger cavity drops by 80%, resulting in a rapid drop in the jet velocity. When the plasma jet head interacts with the atmosphere, the two-phase fluid compresses each other, generating a forward-propelled pressure wave. The plasma jet heads flow at high velocity, a negative pressure zone is formed in the middle part of the jet, and the pressure peak decreases gradually with the height. As the value of the inlet pressure increases, the characteristic parameters of the plasma jet increase. The entrainment phenomenon is evident, which leads to an increase in the pressure imbalance of the atmospheric gas medium, leading to significant Coandǎ effect. Compared with air, the characteristic parameters of plasma jet in SF6 are lower, and the morphological evolution is significantly suppressed. The results of this study can provide some insight into the mechanism of action of the switch jet plasma development process.

“…Atmospheric pressure gas discharges have been used in widespread applications, including spark gap switch [1], combustion ignition [2,3], material preparation [4,5], environmental pollution control [6], and biomedicine [7]. A stable discharge is an essential basis for its applications.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal control of femtosecond laser filament-triggered discharge and its application in diagnosing gas flow fields

Zhu¹,

Li²,

Gao³

et al. 2022

Precise control of the discharge in space and time is of great significance for better applications of discharge plasma. Here, we used a femtosecond laser filament to trigger and guide a high-voltage DC pulse discharge to achieve spatiotemporal control of the discharge plasma. In space, the discharge plasma is distributed strictly along the channel generated by the femtosecond laser filament. The breakdown voltage threshold is reduced, and the discharge length is extended. In time, the electrical parameters such as the electrode voltage and the electrode gap affect discharge delay time and jitter. By optimizing the parameters, we can achieve sub-nanosecond jitter of the discharge. Based on the spatiotemporal control of the discharge, we applied filament-triggered discharge for one-dimensional composition measurements of the gas flow field. Besides, the technique shows great potential in studying the spatiotemporal evolution of discharge plasma.