Theoretical and simulation research on self-stabilizing secondary electron emission process across solid dielectrics in vacuum

Zhan, Jiasui; Mu, Hai‐Bao; Huang, Xiaona; Zhang, Guanjun

doi:10.1063/1.4772965

Cited by 14 publications

(5 citation statements)

References 19 publications

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“…By contrast, the δ max and corresponding A max of the CuO@PI/SrO@PI/MgO@PI/Al 2 O 3 @PI coated films are 1.59/1.58/1.71/2.02 and 400/300/200/300 eV, respectively. It has been demonstrated that the SEE plays a dominant role in determining the flashover discharge development process, and the reduction of SEY is usually favorable for flashover mitigation. ,, This is because lower SEY inhibits the formation of the SEEA and hence the subsequent desorbed gas breakdown. Analytical flashover theory suggests that the flashover voltage increases with lower SEY, with the voltage approximately proportional to the square root of the term A max δ max A 0 − 1 .…”

Section: Resultsmentioning

confidence: 99%

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Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Yang,

Sun,

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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High-voltage and high-power devices are indispensable in spacecraft for outer space explorations, whose operations require aerospace materials with adequate vacuum surface insulation performance. Despite persistent attempts to fabricate such materials, current efforts are restricted to trial-and-error methods and a universal design guideline is missing. The present work proposes to improve the vacuum surface insulation by tailoring the surface trap state density and energy level of the metal oxides with varied bandgaps, using coating on a polyimide (PI) substrate, aiming for a more systematical workflow for the insulation material design. First-principle calculations and trap diagnostics are employed to evaluate the material properties and reveal the interplay between trap states and the flashover threshold, supported by dedicated analyses of the flashover voltage, secondary electron emission (SEE) from insulators, and surface charging behaviors. Experimental results suggest that the coated PI (i.e., CuO@PI, SrO@PI, MgO@PI, and Al2O3@PI) can effectively increase the trap density and alter the trap energy levels. Elevated trap density is demonstrated to always yield lower SEE. In addition, increasing shallow trap density accelerates surface charge dissipation, which is favorable for improving surface insulation. CuO@PI exhibits the most remarkable increase in shallow trap density, and accordingly, the highest flashover voltage is 42.5% higher than that of pristine PI. This study reveals the critical role played by surface trap states in flashover mitigation and offers a novel strategy to optimize the surface insulation of materials.

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Section: Resultsmentioning

confidence: 99%

“…It has been demonstrated that the SEE plays a dominant role in determining the flashover discharge development process, and the reduction of SEY is usually favorable for flashover mitigation. 22,63,64 This is because lower SEY inhibits . 21 Here A 0 is a known constant.…”

Section: Experimental Validation Of Trap Modulation and Flashover Mit...mentioning

confidence: 99%

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Yang,

Sun,

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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“…Since numerous existing simulations and theories of SEEA are 2D2V, a simplified 2D angular distribution function were more frequently adopted in a range of studies: f 0 (α 0 ) = 0.5cos(α 0 ), with α 0 ∈(−0.5π, 0.5π), as shown in Figure 3a [18,32,33]. The two different treatments will be further compared below to show their influences on the expression of tan(θ).…”

Section: D3v Saturated Secondary Electron Emission Modelmentioning

confidence: 99%

Integrated modelling of vacuum flashover development: Above‐surface processes and breakdown threshold analyses

Sun,

Yao,

Yang

et al. 2023

High Voltage

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The flashover in vacuum is a rapid interfacial discharge across the insulator surface when subjected to high applied voltage. Here a theoretical model covering above‐surface processes is introduced. The model calculates the flashover threshold in vacuum, with revised secondary electron emission avalanche theory and improved desorbed neutral transport model. The model serves as the first part of an integrated flashover model, aiming for consistent treatment of both above‐surface and subsurface processes during the entire flashover development. The flashover threshold is obtained by combining the desorbed neutral pressure at given applied voltage and the gas breakdown criterion dictated by the Paschen's law. An analytical formula for threshold estimation containing physical parameters, and a simplified formula consisting of empirical coefficients are introduced, catering for both conceptual understanding and practical application. The derived formulae are validated by experimental data for a variety of insulator materials. The theory generalisation for non‐uniform electric field distribution is further discussed.

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“…Since numerous existing simulations and theories of SEEA are 2D2V, a simplified 2D angular distribution function were more frequently adopted in a range of studies: 𝑓 ′ (𝛼 ′ ) = 0.5cos (𝛼 ′ ), with 𝛼 ′ ∈ (−0.5π, 0.5π), as shown in Figure 3(a) [18,32,33]. The two different treatments will be further compared below to show their influences on the expression of tan(𝜃).…”

Section: • D𝛺mentioning

confidence: 99%

Integrated modeling of vacuum flashover development: above-surface processes and breakdown threshold analyses

Sun

2023

Preprint

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<p>The flashover in vacuum is a rapid interfacial discharge across the insulator surface when subjected to high applied voltage. Here a theoretical model covering above-surface processes is introduced. The model calculates the flashover threshold in vacuum, with revised secondary electron emission avalanche theory and improved desorbed neutral transport model. The model serves as the first part of an integrated flashover model, aiming for consistent treatment of both above-surface and subsurface processes during the entire flashover development. The flashover threshold is obtained by combining the desorbed neutral pressure at given applied voltage and the gas breakdown criterion dictated by the Paschen’s law. An analytical formula for threshold estimation containing physical parameters, and a simplified formula consisting of empirical coefficients are introduced, catering for both conceptual understanding and practical application. The derived formulae are validated by experimental data for a variety of insulator materials. The theory generalization for nonuniform electric field distribution is further discussed.</p>

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Theoretical and simulation research on self-stabilizing secondary electron emission process across solid dielectrics in vacuum

Cited by 14 publications

References 19 publications

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Integrated modelling of vacuum flashover development: Above‐surface processes and breakdown threshold analyses

Integrated modeling of vacuum flashover development: above-surface processes and breakdown threshold analyses

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