Flashover strength improvement and multipactor suppression in vacuum using surface charge pre-conditioning on insulator

Sun, Guangyu; Guo, Bao-Hong; Mu, Hai‐Bao; Song, Bai‐Peng; Zhou, Run-Dong; Shu, Zhang; Zhang, Guanjun

doi:10.1063/1.5048063

Cited by 25 publications

(16 citation statements)

References 44 publications

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“…Finally, it rises by 25% when the energy of irradiated electrons reach 25 keV, which is consistent with the results of Pan et al [13]. Sun et al [164] impulse surface flashover voltages as a function of preset negative charge. They found surface charge accumulation greatly affects DC surface flashover.…”

Section: Polarities Of Surface Charge and Applied Voltagesupporting

confidence: 90%

Surface flashover in 50 years: Theoretical models and competing mechanisms

Liu

Ohki

et al. 2023

High Voltage

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Surface flashover is a devastating electronic avalanche along the gas–solid interface when a high electric field is applied, which is a potential issue that threatens the safe operations of advanced power electronic, electrical, and spacecraft applications. However, the underlying physical mechanisms for surface flashover development are still under investigation owing to the complex charge transport processes through the gas phase, solid phase, and gas–solid interface. In this study, the history of surface flashover theory in the last 50 years is introduced, and several key questions are reviewed from the perspective of the competing mechanisms of charge transport: the role of each phase in a surface flashover, the origin of surface charging, and effects of traps in solid on surface flashover. Then, some suggestions involve charge transport processes in each phase, and their correlations are put forward, and a predictable ‘charge transport competitive flashover model’ is proposed by clarifying the competing mechanisms of charge transport processes through multiple phases. This study summarises the history and hot topics of physical mechanisms of surface flashover proposed based on classic and recent progress and offers promising routes for developing a more precise surface flashover theory and improving surface flashover performances.

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Section: Polarities Of Surface Charge and Applied Voltagesupporting

confidence: 90%

Surface flashover in 50 years: Theoretical models and competing mechanisms

Liu

Ohki

et al. 2023

High Voltage

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“…When Q = 0.5 mm, the SEEA is almost entirely suppressed. The mean surface charge density behaviours in accordance with the SEEA process, as the SEEA theory predicts that the negative charges of electrons in SEEA are equal to the accumulated positive surface charges on dielectric [6].…”

Section: Resultsmentioning

confidence: 99%

“…Solid insulator is widely adopted in a range of electrical devices using vacuum as the insulating medium or operating in vacuum ambient, including pulsed-power devices, vacuum interrupters, satellites, and many other electrovacuum devices designated to separate conductors and provide mechanical support [1][2][3][4][5]. However, the breakdown will preferentially occurs over the vacuum-dielectric interface (i.e., flashover) under high electric field (E-field) due to the fact that the insulation strength of the vacuum-dielectric interface is much weaker than pure vacuum and bulk insulator, leaving the interface the weakest link in vacuum insulation system [6]. This has become a major concern affecting the reliability, minimisation and operation longevity of above electrical devices, falling significantly short of the ever-increasing demands for more robust vacuum insulation systems [7].…”

Section: Introductionmentioning

confidence: 99%

Design and 3D printing of porous cavity insulation structure for ultra‐high electrical withstanding capability

et al. 2023

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Vacuum‐dielectric interface is the most vulnerable part of vacuum insulation systems where surface electrical breakdown is prone to happen, hence severely restricts the development of advanced electro‐vacuum devices with large capacity and its miniaturisation. Generally, a direct and effective way to improve vacuum surface insulation is to alleviate the initiation and development of multipactor phenomena. Inspired by this approach, the authors report a 3D‐printed insulation structure designed with a millimetre‐scale surface cavity covered by periodic through‐pore array via stereolithography, exhibiting remarkable multipactor suppression and flashover threshold improvement, well outperforming the conventional flashover mitigation strategies. Experiments and simulations demonstrate that electrons in the multipactor region pass through‐pores and are unlikely to escape from the cavity, hence no longer participate in the above‐surface multipactor process, and eventually improve flashover threshold. The proposed approach provides new inspiration for the design of advanced insulators featuring ultra‐high electrical withstanding capability and brings up new insight into pertinent industrial applications.

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“…Some examples of the SEY curve are given in Fig. 1, where A 1 is the energy where SEY is 1 (the smaller one) [38].…”

Section: Theory and Model Set-upmentioning

confidence: 99%

Modelling vacuum flashover mitigation with complex surface microstructure: mechanism and application

Zhang

Sun

et al. 2020

High Voltage

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The vacuum discharge along the dielectric surface, also called surface flashover, brings significant damages to the vacuum-solid insulation system. Here the authors implement shape-flexible, complex surface groove microstructures on the dielectric to mitigate the initiation of vacuum flashover. A particle-in-cell simulation is employed to reveal the real-time discharge development considering the blockage of the multipactor propagation as well as the space field distortion in the presence of specific surface microstructures. Electron trajectories within barriers are theoretically analysed to present how the barrier shape affects the discharge process, showing consistent results with the simulation. By analysing three parameters, namely the anode current, the surface average charge density and the flashover threshold, it is found that the effect of suppressing surface flashover remarkably augments when the groove number and depth rise up, while such effect gradually saturates when the groove depth reaches a critical value. Theoretical analyses are also provided for the decay factor as well as the optimal shape and trapezoid grooves are proved as the optimal shape distribution of microstructures. Furthermore, different secondary emission yield (SEY) distributions are considered with two kinds of structures, including the material with low-SEY inside and on the top surface of grooves.

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Flashover strength improvement and multipactor suppression in vacuum using surface charge pre-conditioning on insulator

Cited by 25 publications

References 44 publications

Surface flashover in 50 years: Theoretical models and competing mechanisms

Surface flashover in 50 years: Theoretical models and competing mechanisms

Design and 3D printing of porous cavity insulation structure for ultra‐high electrical withstanding capability

Modelling vacuum flashover mitigation with complex surface microstructure: mechanism and application

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