Features of spherical particle dynamics near a plane electrode of vacuum gap in an increasing electric field

Nefyodtsev, E. V.

doi:10.1109/tdei.2013.004032

Cited by 10 publications

(7 citation statements)

References 19 publications

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“…Under certain conditions, these microparticles will leave the electrode surface and carry a certain amount of charge. The charge carried by the microparticle is related to the electric-field strength of the gap, which can be expressed as [4,8,26]:…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Breakdown phenomena that are triggered by microparticles in gas and vacuum insulation are widely reported both numerically and experimentally [1][2][3][4][5][6][7][8][9]. Understanding these phenomena is important for many prospective gas-switch applications, including those in pulsed-power technology [10,11], electrical insulation equipment [4,5], and medical science [12].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Sun

Zhou

Yang

et al. 2021

Plasma Sources Sci. Technol.

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This paper studies microparticle-triggered breakdown phenomena in mm-scale nitrogen gaps based on theoretical analysis and numerical simulation. Secondary electron and field emission contributions are both considered when predicting the microparticle-initiated breakdown voltage. In the present model, the ionization coefficient of the microscale discharge is modified to recognize the significant reduction in the number of collisions that occurs when a microparticle is present. The theoretical analysis indicates that small particles have little influence on the gas-gap breakdown voltage unless field-emission effects are dominant. However, when large microparticles (radius 50 μm) are present, a significant decrease (more than 20%) in the minimum breakdown voltage can be observed regardless of the particle position in the gas gap. Therefore, one should endeavor to exclude large microparticles from the discharge process. A fluid model is then used to simulate the microparticle-initiated breakdown process in a gas switch. The microparticle radius is 10 μm and the distance between the microparticle and cathode is 1 μm. It can be found that the electrode–particle microdischarge generates regions of high-density plasma that finally trigger main-gap breakdown when a voltage of 2.5 kV–3.5 kV is applied. The calculated results are consistent with our theoretical analysis. This paper provides a quantitative research method to evaluate the influence of microparticles on gas breakdown and contributes to improving gas-switch insulation performance.

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Section: Mathematical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Sun

Zhou

Yang

et al. 2021

Plasma Sources Sci. Technol.

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“…If the gas gap distance is d , the radius of microparticle is R , and the uniform electric field E 0 is taken as 3 × 10 6 V/m, the field‐induced charge carried by a spherical microparticle is related to its radius and local electric field, expressed by [ 1,9,15,16 ]

q = A {π ϵ}_{0} R^{2} E_{0},

where A is a geometry constant.…”

Section: Theory and Calculationmentioning

confidence: 99%

Microparticle‐initiated electron emission and subsequent gas breakdown

Zhong

Shi

et al. 2021

Contributions to Plasma Physics

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Microparticle‐initiated breakdown phenomena in gas gap have obtained extensive research interest and micro‐gap discharge is convinced to play a key role. To illustrate this, this paper focused on microparticle‐initiated electron emission and subsequent gas breakdown process in a nitrogen gap. Analytic results of the electric field distribution between the charged microparticle and electrode surface are obtained by using the image method first. Results indicate that for the typical microparticles (R < 20 μm) from electrode erosion, when the micro‐gap distance h is lower than 2 μm, the maximum enhanced field strength could exceed 3 × 107 V/m. Based on this, a two‐dimensional axis‐symmetry numerical model is calculated by using the particle‐in‐cell coupling with Monte Carlo method and the charged microparticle is positioned near anode and cathode separately. In both cases, the local enhanced electron emission between microparticle and electrode surface is the key to initiate the final gas breakdown. The breakdown near cathode is electron‐dominated, which could accomplish in several nanoseconds. The breakdown near anode is ion‐dominated, which needs stronger field enhancement factor or longer breakdown time and would be harder to occur in reality.

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“…Based on conventional theory, most studies have suggested that free particles could facilitate microdischarges at the electrodes, which further triggered a breakdown across the whole gap [7,23,24]. Moreover, the FE effect was thought to be mainly responsible for microdischarges [13,35]. However, when the particle size decreases sufficiently, their capability to enhance the local field can be weakened, and they cannot cause significant FE.…”

Section: Effect Of Small Metal Particles On the Breakdown Processmentioning

confidence: 99%

“…They also found that charged particles tended to move toward high-electric-field areas. Nefyodtsev [13] calculated the field-emission current caused by a particle departing from the electrodes. Their results indicated that there was an abrupt increase in field enhancement between the electrode and the particles during their escape process.…”

Section: Introductionmentioning

confidence: 99%

Effect of metal-submicron-particle accumulation on the stability of consecutive high-pulse-power breakdowns in compressed N₂

Yan¹,

Wang²,

Chen³

et al. 2021

J. Phys. D: Appl. Phys.

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Pulse-power technology has been widely used in inertial-confinement fusion, electron-beam accelerators, and the aeronautics and astronautics fields. However, particle contamination can reduce operational stability by altering the breakdown process. The objective of this paper is to study the effects of large numbers of metallic submicron particles on the breakdown characteristics. Particles were spontaneously generated via consecutive high-pulse-power breakdowns in compressed N2. In this paper, we adopted a plasma-diagnosis system that combines a laser scattering technique with laser shadow photography to detect particles originating from different materials. To distinguish the specific effects of particles, a double-electrode/double-pulse method was used to eliminate the unwanted effects of electrode erosion. After thousands of consecutive breakdowns, numerous particles were unexpectedly found to suspend and accumulate in the inter-electrode gap rather than fall to the bottom. These particles mainly stemmed from the anode and were identified as either metallic conducting nanoparticles or submicron particles. Furthermore, their density continuously increased and remained at a high level for a long time. This converted the insulating medium from a pure gas to a mixture with numerous metallic particles. In this case, the probability of breakdowns involving particles increased and their mean breakdown voltage showed a downward trend. According to our analysis of the field-enhancement process, these small particles alone can neither cause field emission nor trigger a microdischarge. However, their collective effects could be significant if they were involved in the breakdown channel.

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Features of spherical particle dynamics near a plane electrode of vacuum gap in an increasing electric field

Cited by 10 publications

References 19 publications

Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Microparticle‐initiated electron emission and subsequent gas breakdown

Effect of metal-submicron-particle accumulation on the stability of consecutive high-pulse-power breakdowns in compressed N₂

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Features of spherical particle dynamics near a plane electrode of vacuum gap in an increasing electric field

Cited by 10 publications

References 19 publications

Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Theoretical and numerical studies of breakdown phenomena triggered by microparticle in nitrogen gaps

Microparticle‐initiated electron emission and subsequent gas breakdown

Effect of metal-submicron-particle accumulation on the stability of consecutive high-pulse-power breakdowns in compressed N2

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Effect of metal-submicron-particle accumulation on the stability of consecutive high-pulse-power breakdowns in compressed N₂