Triggering breakdown voltage of a high-current, two-electrode graphite gas switch assisted by ultraviolet pre-ionization

Chen, Li; Yang, Lanjun; Huang, Dong; Liu, Shuai; Lin, Ting

doi:10.1063/1.4997897

Cited by 5 publications

References 10 publications

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Study on the breakdown characteristics of the trigatron spark gap triggered by plasma jet

et al. 2020

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The breakdown characteristics of a trigatron spark gap triggered by a plasma jet are studied in this paper; the development of a plasma jet and the influence of the gap distance, working coefficient, and plasma jet ejection properties on breakdown characteristics are compared. The results show that the plasma jet ejecting process can be divided into expanding, steady, and dissipating phases. The electric field distortion induced by the plasma jet is different during the expanding and dissipating phase, in which the plasma jet length increases and the radius of the curvature of the plasma jet front decreases, respectively. As the two processes have different variation rates, a faster increasing rate of the breakdown delay can be obtained during the dissipating phase. A detailed physical mode that explains the effects on the triggered breakdown process is presented. The shape of a plasma jet induced by polyethylene and ceramic surface discharge changes to a great extent during the dissipating phase; a more stable plasma jet can be obtained when induced only by polyethylene, resulting in a smaller breakdown delay under a low working coefficient. The ultraviolet radiation (UV) generated by the plasma jet is effective in reducing the critical breakdown electric field, while the electric field distortion induced by the plasma jet is the main reason behind the triggered breakdown under different working coefficients; the UV could play a limited role in the triggered breakdown process.

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Study on the breakdown characteristics of the trigatron spark gap triggered by plasma jet

et al. 2020

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Study on the properties of enhanced plasma injection driven by electrical explosion of aluminum wire in PTFE capillary in high-pressure SF6

Li,

Jiang,

et al. 2023

Physics of Plasmas

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Enhanced plasma injection (EPI) driven by the electrical explosion of a metal wire in a microcavity has been proven to be an effective method for triggering 10-cm-magnitude high-pressure SF6 gas gap at very low working coefficients and provides a potential technical routine for ultrafast bypass switches (UFBPSs). In this study, aiming to further promote the EPI strength and improve its triggering ability, the EPI actuator is optimized, and several vital parameters of the actuator structure, including diameter D and length L of the microcavity and nozzle shape, are investigated. EPI with a maximum height of ∼10 cm and an initial velocity of ∼1000 m/s can be realized in 0.5 MPa SF6 when a 600 μm aluminum wire is exploded by a ∼1000 J trigger pulse. The EPI strength vs D curve has an inverted V shape, and 2 mm D results in the most intense EPI, due to the competitive effect of the vent congestion inside a thin capillary and parasitic volume in a fat capillary. As L increases, the EPI strength increases to saturation and then decreases. A 20–23 mm L can yield suitable EPI strength with limited trigger energy. The nozzle shape has a remarkable influence, and a divergent-type nozzle leads to a much stronger EPI than the shrink-type or straight-type nozzle, generating an EPI with a maximum height of 12 cm and an initial velocity of 1600 m/s. This study provides a useful guidance for the EPI actuator design for triggering megavolt UFBPSs at very low working coefficients.

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Design and investigation of a capacitance-coupling pre-ionized sharpening switch

Zhai,

Yin,

et al. 2024

Review of Scientific Instruments

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The sharpening switch is one of the most important elements in the trigger generator, which is used to sharpen the front of the trigger pulse. The breakdown performance of the sharpening switch has an important influence on the output and stability of the trigger generator. In this paper, a novel 200 kV capacitance-coupling pre-ionized sharpening switch, which can realize pre-ionization by dividing voltage through its own structural capacitances, is proposed and investigated. In order to obtain the optimal parameters of the pre-ionized sharpening switch, the influences of the electrode structure, electrode material, main gap distance, and pre-ionized gap distance on the breakdown performance are studied experimentally. The experimental results show that the electrode structure with a circular knife-edged cathode and a plate-shaped anode has the smallest breakdown jitter, followed by the needle-plate structure and the tapered ball-head structure. The stainless steel electrode has the smallest jitter, followed by graphite, aluminum, and brass electrodes. When the gap distances of the main gap and the pre-ionized gap are 13 and 1.5 mm, respectively, the breakdown stability of the pre-ionized sharpening switch is the best. Under an input voltage pulse with a rise time of about one microsecond, the jitter of the capacitance-coupling pre-ionized sharpening switch with the optimal parameters is 6.08 ns, which is about 0.6% of the rise time of the input pulse. The jitter decreases by 44.5% compared to the switch without pre-ionization. The rise time of the output pulse is sharpened to 17 ns, corresponding to a voltage rise rate of more than 11 kV/ns.

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Triggering breakdown voltage of a high-current, two-electrode graphite gas switch assisted by ultraviolet pre-ionization

Cited by 5 publications

References 10 publications

Study on the breakdown characteristics of the trigatron spark gap triggered by plasma jet

Study on the breakdown characteristics of the trigatron spark gap triggered by plasma jet

Study on the properties of enhanced plasma injection driven by electrical explosion of aluminum wire in PTFE capillary in high-pressure SF6

Design and investigation of a capacitance-coupling pre-ionized sharpening switch

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