The dynamics of pre-breakdown cavities in viscous silicone fluids in negative point-plane gaps

Watson, P.K.; Chadband, W.G.

doi:10.1109/14.7346

Cited by 47 publications

(20 citation statements)

References 20 publications

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“…that the onset for charge injection precedes that however, suggests that the forces acting on the liquid are highly directional, and thus that the gas dynamic pressure within the cavity is of limited importance. We believe these observations lend support to the results reported by Watson and Chadband [81] I and further suggest that, from its inception, the growth of the cavity may be described by the electrostatic forces acting on the liquid. B…”

supporting

confidence: 88%

Research for Electric Energy Systems

Anderson¹

1991

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This report documents the technical progress in the four investigations which I make up the project _Support of Research Projects for Electrical Energy Systems", Department of Energy Task Order Number 137, funded by the U.S. Department of Energy and performed by the Electricity Division of the National U Institute of Standards and Technology (NIST). The first investigation is concerned with the measurement of magnetic _elds in support of epidemiogical ,_ and in vitro studies of biological field effects. NIST cohosted a workshop I on exposure and biological parameters that should be considered during in vitro studies with extremely low frequency (ELF) magnetic and electric fields. Additionally, equations were developed to predict the magnetic field in a m parallel plate magnetic field exposure system. An IEEE standard prepared at NIST on measuring dc electric fields and ion related parameters was approved and published. Various site visits were made to characterize the electric and i 1 ELECTRIC FIELD MEASUREMENTS Task O1

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supporting

confidence: 88%

Research for Electric Energy Systems

Anderson¹

1991

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“…No systematic experimental research program on this particular phenomenon has yet been published with the exception of a small number of attempts which have led to very qualitative results. 5,6 Bubble dynamics in liquids has been intensively studied for several decades. The reason for this is the ability of bubbles to be harmful in some situations as, e.g., cavitation in hydraulic machinery, electrical machinery, laser application in medicine ͑ophthalmology͒, etc., and to be useful in other situations ͑as, e.g., in ultrasonic cleaners͒.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of microscopic bubbles in viscous insulating liquids

Jomni¹,

Denat²,

Aitken³

2009

Journal of Applied Physics

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The dynamics of microscopic bubbles in low viscosity insulating liquids has been widely investigated. It has been shown that the bubble motion (growth, collapse, and rebounds) in such liquids is governed by inertial forces. In this paper, the results of an experimental study of the dynamics of microscopic bubbles in viscous liquids (μ≥3 mPl) are presented. It is shown that, according to the conditions (injected energy, liquid viscosity, and applied pressure), the bubble motion is greatly modified. For example, no bubble rebound is observed in the higher viscosity liquids (e.g., Napvis XD110, μ=83.5 mPl) and, for a given injected energy, the ratio of the expansion time of the bubble to its implosion time drops with increasing in liquid viscosity. The bubble dynamics are then governed by liquid viscosity. Moreover, the transition of the bubble dynamics from the inertial regime to the viscous one has been experimentally observed (as far as the present authors are aware) for the first time. This transition can be explained by a refined analysis of the Rayleigh–Plesset model of bubble dynamics. The bubble dynamics regime can be deduced from a Reynolds number (ReTp) versus elasticity number (Σ) diagram, where four zones can be distinguished. Each zone corresponds to a particular regime: inertial regime with only one growth and collapse stage, inertial regime with at least one bubble rebound, viscous regime, and finally, a regime where a jet of hot liquid is produced. All experimental results are well distributed into the good part of this diagram.

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“…Previous work important for this topic includes experimental studies using imaging, broad-band light emission measurements and current measurements [1][2][3][4][5][6][7][8][9][10]. Therefore, a lot is today known about the streamer's appearance, streamer initiation and streamer propagation.…”

Section: Introductionmentioning

confidence: 99%

Spatially and temporally resolved electron density measurements in streamers in dielectric liquids

Barmann¹,

Kröll²,

Sunesson

1997

J. Phys. D: Appl. Phys.

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Abstract. Spatially and temporally resolved spectroscopic measurements of light emitted from positive streamers in transformer oil are presented. Analyses of the measurements performed with a DC needle-plane gap yield electron densities and indications of the atomic excitation temperatures in the streamers. The hydrogen emission reveals an electron density below 10 16 cm −3 during the main part of the streamer propagation time (80-90%). Later the light is also characterized by emission from a high-density plasma with electron densities in the range 10 18 -10 19 cm −3 . The electron density during this time increases approximately linearly with distance from the initiation point and a density factor of four higher has been measured at the streamer tip than at the root. Measurements with high spectral resolution detect both high and low electron densities simultaneously. A tentative model of the interior of the streamer plasma, spatially resolved, is presented.

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The dynamics of pre-breakdown cavities in viscous silicone fluids in negative point-plane gaps

Cited by 47 publications

References 20 publications

Research for Electric Energy Systems

Research for Electric Energy Systems

The dynamics of microscopic bubbles in viscous insulating liquids

Spatially and temporally resolved electron density measurements in streamers in dielectric liquids

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