Cathode spot dynamics on pure metals and composite materials in high-current vacuum arcs

Chaly, A.M.; Logatchev, A.A.; Shkol'nik, S.M.

doi:10.1109/27.640666

Cited by 66 publications

(17 citation statements)

References 11 publications

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“…[65] Aiming at predicting the behavior of vacuum arc, it is crucial to explore how cathode spots contribute to the melting of electrode as cathode spots are centers of plasma production. [1][2][3][4][5][6][7]106] It is believed that the size of electrode and the amount of imposed electric current significantly influence the behavior of cathode spots and consequently, the distribution of arc plasma in the vacuum region. [107,108] The distributions of arc and the self-induced magnetic field are interdependent.…”

Section: Discussionmentioning

confidence: 99%

“…Modeling VAR process is very challenging and controversial as the process involves a wide range of physical phenomena and their interactions. Modeling activities are required to study each phenomenon including formation and movement of cathode spots at the tip of electrode, [1][2][3][4][5][6][7] the vacuum plasma, [4,5,[8][9][10][11][12][13][14][15][16][17][18][19][20] the electric current transferred directly between the electrode and mold, known as ''side-arcing,'' [12,18,[21][22][23][24] the thermal radiation in the vacuum region, [21,25,26] melting of the electrode, [8,[27][28][29][30][31][32][33][34][35][36][37][38] the influence of electromagnetic field on the flow known as magnetohydrodynamics (MHD) in the molten pool, [39][40]…”

Section: Introductionmentioning

confidence: 99%

“…[65] The probability of the formation of a constricted arc increases as the gap length increases. [1] Furthermore, an external magnetic field can significantly influence the behavior of the arc including the arc radius and speed. [11,16] Research attempts to model plasma generation and expansion in VAR process are minimal.…”

Section: Introductionmentioning

confidence: 99%

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A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side-Arcing, and Gas Cooling

Karimi-Sibaki

Kharicha

et al. 2019

Metall Mater Trans B

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Main modeling challenges for vacuum arc remelting (VAR) are briefly highlighted concerning various involving phenomena during the process such as formation and movement of cathode spots on the surface of electrode, the vacuum plasma, side-arcing, the thermal radiation in the vacuum region, magnetohydrodynamics (MHD) in the molten pool, melting of the electrode, and solidification of the ingot. A numerical model is proposed to investigate the influence of several decisive parameters such as arc mode (diffusive or constricted), amount of side-arcing, and gas cooling of shrinkage gap at mold-ingot interface on the solidification behavior of a Titanium-based (Ti-6Al-4V) VAR ingot. The electromagnetic and thermal fields are solved in the entire system including the electrode, vacuum plasma, ingot, and mold. The flow field in the molten pool and the solidification pool profile are computed. The depth of molten pool decreases as the radius of arc increases. With the decreasing amount of side-arcing, the depth of the molten pool increases. Furthermore, gas cooling fairly improves the internal quality of ingot (shallow pool depth) without affecting hydrodynamics in the molten pool. Modeling results are validated against an experiment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side-Arcing, and Gas Cooling

Karimi-Sibaki

Kharicha

et al. 2019

Metall Mater Trans B

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“…This is due to the fact that for contact separation at higher current the duration of the high density arc is longer, and therefore the effect of the arc on the contact surface is higher. The other effect as explained in [1] is that the dimension of the high density arc (cathode spots group) depends on the gap distance and arc current, i.e. for smaller gap distances and higher currents the dimensions of the arc are smaller and therefore its influence on the contact surface is higher.…”

Section: Discussionmentioning

confidence: 99%

Effect of short circuit switching on dielectric properties of vacuum interrupters

et al. 2010

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Short circuit current interruption may change the dielectric properties of vacuum interrupters during their service life. Therefore, in this work effects of the current interruption on the dielectric properties and contact erosion of the interrupters have been investigated. Contact material's evaporation during the flow of the vacuum arc before current zero may change the contact surface and cause some erosion after each operation. With the help of field electron emission current measurement the surface conditions of the interrupter contacts are compared between the new vacuum interrupters and interrupters which were previously subjected to interruptions with different arc current amplitudes and arcing time. With the help of Fowler-Nordheim diagram, surface parameters i.e. field enhancement factor β and emission area A e are calculated and compared for each case. Field electron emission current inception voltage and breakdown voltage are compared for these cases as well.

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“…Currently, research on the spot characteristics of high‐current vacuum arc cathode mainly focuses on the influencing factors of the motion characteristics of the cathode spot under flat contacts and axial magnetic field (AMF) contacts without external magnetic field and the influence of external AMF and transverse magnetic field (TMF) on cathode spot under flat contacts. Agarwal and Chaly et al studied the initial diffusion velocity of large‐current vacuum arc cathode spots under the action of external AMF. It was found that increasing AMF would significantly reduce the reverse velocity of cathode spots.…”

Section: Introductionmentioning

confidence: 99%

Investigation of unstable motion characteristics of vacuum arc cathode spots between transverse magnetic field contacts

Pang

Yang

Jing

et al. 2019

Contributions to Plasma Physics

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With the improvement of the current level of power grids, the requirements of the opening level of the vacuum switches are also increasing. Vacuum arc cathode spots provide steam and electrons and, to a certain extent, determine the opening capacity of the vacuum switch. In this paper, a vacuum arc cathode spot research platform based on the de-mountable vacuum chamber is constructed. The characteristics of the vacuum arc cathode spots under the transverse magnetic field (TMF) contacts are assessed by a high-speed charge coupled device. The experimental results show that the cathode spot diffusion process can be divided into three processes through cathode spot distribution, arc voltage and current: initial diffusion stage of cathode spots, unstable motion stage of cathode spots, and extinguishing stage. The motion mode of cathode spots during unstable motion stage can be divided into cathode spots group stagnation (CSGS) to multi-cathode jet (MCJ) switch mode, cathode spots group motion (CSGM) to MCJ switch mode, CSGM mode, and MCJ mode.The effects of peak current and contact diameter on unstable motion mode were analysed. K E Y W O R D Scathode spot, transverse magnetic field contacts, unstable motion mode, vacuum arc 1 Abbreviations: AMF, axial magnetic field; CSGM, cathode spots group motion; CSGS, cathode spots group stagnation; MCJ, multi-cathode jet; TMF, transverse magnetic field.

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Cathode spot dynamics on pure metals and composite materials in high-current vacuum arcs

Cited by 66 publications

References 11 publications

A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side-Arcing, and Gas Cooling

A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side-Arcing, and Gas Cooling

Effect of short circuit switching on dielectric properties of vacuum interrupters

Investigation of unstable motion characteristics of vacuum arc cathode spots between transverse magnetic field contacts

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