On the numerical simulation of the diffuse arc in a vacuum interrupter

Langlois, Y.; Chapelle, Pierre; Jardy, Alain; Gentils, François

doi:10.1063/1.3587180

Cited by 30 publications

(23 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fig. 5b shows the radial profile of the energy flux density transferred to the anode P a for different gap lengths, which has been calculated according to the relations detailed in [10]. The profile of P a strongly depends on the axial current density profile and exhibits thus similar variations as those observed in Fig.…”

Section: A Resultsmentioning

confidence: 63%

“…• Because the Debye length is very small in front of the typical length scale of the system [10], the plasma may be considered as quasi-neutral.…”

Section: A Physical Modelmentioning

confidence: 99%

“…Recently, their work was combined with a thermal model of the anode to consider particles emitted at the anode [14]. One should mention also the work of Langlois et al [10] having strong similarities with the model reported in [6] and which was used to investigate in detail the various components of the energy flux density transferred to the anode for both supersonic and subsonic flow conditions. Finally, using a significantly different approach from all above works, Londer and Ulyanov [7] have developed a semianalytical model of the VA.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Study of the Current Constriction in a Vacuum Arc at Large Contact Gap

Montcel

Chapelle

Creusot

et al. 2019

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

A classical two temperature magnetohydrodynamic modelling approach is used to study the influence of a large contact gap (up to 40 mm) on the behaviour of a diffuse vacuum arc controlled by a 5 mT/kA uniform external axial magnetic field between two copper electrodes with a 20 mm radius. The current constriction and energy flux density at the anode surface are more particularly analyzed, considering both supersonic and subsonic flow conditions. In the case of a supersonic arc, simulations show that the constriction of the current develops in the whole interelectrode region, but the constriction level at the anode surface does not evolve monotonically with the contact gap. The constriction is partly correlated to the radial compression of the plasma. In the case of a subsonic arc, the current constriction is related to the presence of the anode sheath. It occurs only close to the anode (from a constant distance from the anode of around 15 mm). Whereas the current constriction at the anode surface increases when the gap length goes from 10 mm to 20 mm, it no longer evolves when increasing the gap length from 20 mm to 40 mm. For both flow conditions, the evolution with the gap length of the radial profile of the energy flux density transferred by the plasma to the anode is similar as that followed by the current constriction at the anode.

show abstract

Section: A Resultsmentioning

confidence: 63%

“…• Because the Debye length is very small in front of the typical length scale of the system [10], the plasma may be considered as quasi-neutral.…”

Section: A Physical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Study of the Current Constriction in a Vacuum Arc at Large Contact Gap

Montcel

Chapelle

Creusot

et al. 2019

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

show abstract

“…Proposed mechanisms have included field emission of electrons from surface imperfections, the growth of whiskers that enhance field emission of electrons, emission of ions from surfaces, and the acceleration of electrically charged clumps, presumably of oxide, from one electrode to the other. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The clump model yields the best agreement with the generally observed scaling of voltage holding with the vacuum gap distance, namely, but suffers from the fact that oxides are tightly bound to their surfaces, and thus not easily detachable for acceleration.…”

mentioning

confidence: 74%

Experimental test of whether electrostatically charged micro-organisms and their spores contribute to the onset of arcs across vacuum gaps

Grisham¹,

Halle²,

Carpe³

et al. 2013

Physics of Plasmas

View full text Add to dashboard Cite

Recently it was proposed [L. R. Grisham et al. Phys. Plasmas 19, 023107 (2012)] that one of the initiators of vacuum voltage breakdown between conducting electrodes might be micro-organisms and their spores, previously deposited during exposure to air, which then become electrostatically charged when an electric potential is applied across the vacuum gap. This note describes a simple experiment to compare the number of voltage-conditioning pulses required to reach the nominal maximum operating voltage across a gap between two metallic conductors in a vacuum, comparing cases in which biological cleaning was done just prior to pump-down with cases where this was not done, with each case preceded by exposure to ambient air for three days. Based upon these results, it does not appear that air-deposited microbes and their spores constitute a major pathway for arc initiation, at least for exposure periods of a few days, and for vacuum gaps of a few millimeters, in the regime where voltage holding is usually observed to vary linearly with gap distance. V C 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4858895]Although the voltage gradient which can be reliably sustained across a vacuum gap between two metallic conductors without arcing is the most significant constraint in the design of electrostatic accelerators and in related applications, the physical mechanisms responsible for the onset of electrical arcs between electrodes have remained unclear. Proposed mechanisms have included field emission of electrons from surface imperfections, the growth of whiskers that enhance field emission of electrons, emission of ions from surfaces, and the acceleration of electrically charged clumps, presumably of oxide, from one electrode to the other. 2-16 The clump model yields the best agreement with the generally observed scaling of voltage holding with the vacuum gap distance, namely, but suffers from the fact that oxides are tightly bound to their surfaces, and thus not easily detachable for acceleration.Recently, it was proposed 1 that some or all of the "clumps" of the clump model might be microbes such as bacteria, bacterial spores, fungi, and fungal spores. They are ubiquitous in air, and thus constantly being deposited upon exposed surfaces, they are appropriately sized, 17,18 with dimensions of microns, they are in most cases only weakly attached, if attached at all, to the surfaces on which they land, and they readily acquire an electrostatic charge, especially as spores.If microbes and their spores deposited from air, as hypothesized, play a significant role in initiating at least some electrical arcs between metallic electrodes in vacuum, then one way to test this hypothesis would be to explore whether changes in the timing of the final cleaning of the electrodes comprising a high voltage vacuum gap relative to when the electrodes are put under vacuum is associated with changes in the number of high voltage conditioning shots required to reach the nominal operating voltage for the vacuum gap. The results of thi...

show abstract

“…When B z decreases, the contraction of the electron current increases, and the electron current density on the axis of SHCVA approaches the saturation current density j sat . Usually the Langmuir formula (1) is used in the theory of SHCVA to determine the negative anode drop value [3][4][5]. The dependence φ a (j e ) is used as a boundary condition on the anode when solving 2D-problems.…”

Section: Application To a Vacuum Arcmentioning

confidence: 99%

Theory of anode region of high-current vacuum arc

Londer

Ul’yanov

2012

2012 25th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV)

View full text Add to dashboard Cite

A model of the anode region of high-current vacuum is developed that explicitly takes into consideration the ratio of the drift velocity of the electrons in plasma v 0 to their thermal velocity v T as a parameter of the electron velocity distribution function in the anode sheath. A transcendental equation for determining the value of the negative anode drop as a function of the ratio v 0 /v T is obtained. It is shown that in contrast to the well-known Langmuir formula the anode drop remains negative for any value of v 0 /v T relation. For small values of v 0 /v T << 1 the expression obtained passes asymptotically into the Langmuir formula. The dependence of the anode drop value on the current density is used as a boundary condition at the anode in solving the two-dimensional problems in the theory of short vacuum arc. In accordance with the Langmuir formula a region with a positive anode drop is formed at the anode when the current density increases. The results of present work show that the region with a positive anode drop is absent.

show abstract

On the numerical simulation of the diffuse arc in a vacuum interrupter

Cited by 30 publications

References 16 publications

Numerical Study of the Current Constriction in a Vacuum Arc at Large Contact Gap

Numerical Study of the Current Constriction in a Vacuum Arc at Large Contact Gap

Experimental test of whether electrostatically charged micro-organisms and their spores contribute to the onset of arcs across vacuum gaps

Theory of anode region of high-current vacuum arc

Contact Info

Product

Resources

About