Numerical Simulation of Plasma Near the Cathode Spot of Vacuum Arc

Shmelev, D. L.; Barengolts, S. A.; Tsventoukh, M. M.

doi:10.1109/tps.2017.2754541

Cited by 34 publications

(35 citation statements)

References 28 publications

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“…The plasma ion kinetic energy E kin ≈ 100 T cr (equation ( 1)) can be directly estimated from the critical state of matter during the explosion, while a coefficient about '100' corresponds to additional plasma acceleration as the cathode flame expands, and fully agrees with the results of MHD and kinetic calculations [13][14][15][16][17].…”

supporting

confidence: 67%

“…The empirical ratios for the average charge [9] and for the cathode potential fall-'cohesive energy rule' [10] were obtained. At the theory progress and numerical simulation, the initiation conditions of explosive pulses were determined [11,12], as well as hydrodynamic and kinetic of the expanding plasma was described in detail [13][14][15][16][17] etc. However, there is still no explanation of these ratios.…”

mentioning

confidence: 99%

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Determination of the critical temperature of Nb–Al alloys from the plasma parameters of a vacuum arc cathode spot

Tsventoukh¹

2022

J. Phys. D: Appl. Phys.

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The plasma of pulsed-periodic splashes of explosive electron emission forms a vacuum arc cathode spot. The average parameters of the plasma can be evaluated from the parameters of the critical state of a metal for different materials. According to the measurements [Siegfried Zöhrer et al 2020 Plasma Sources Sci. Technol. 29 025022] of the average charge and the kinetic energy of plasma ions, the critical temperature and cohesive energy for Nb-Al alloys was evaluated within our model. It was close to the value corresponding to pure aluminum for all component ratios Nb/Al = ¼, ⅔, ¾. We have described the experimentally measured values of the cathode potential fall using the obtained magnitudes of critical temperature in the empirical “cohesive energy rule” and have reproduced the observed deviation from linearity in form of U or V shaped dependencies. The obtained results make possible to evaluate the critical temperature and cohesive energy from the parameters of the vacuum arc plasma.

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supporting

confidence: 67%

mentioning

confidence: 99%

Determination of the critical temperature of Nb–Al alloys from the plasma parameters of a vacuum arc cathode spot

Tsventoukh¹

2022

J. Phys. D: Appl. Phys.

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“…As an example, the densities of the energy flux and electric current from the atmospheric-pressure argon plasma to the surface of a tungsten cathode, given by this model, are shown in figure 2 for three values of the near-cathode voltage drop. The bell-shaped dependence of q p on T w , seen in this figure, is well known for both high-pressure and vacuum arcs (see [12] and references therein for high-pressure arcs and [13][14][15] for vacuum arcs) and represents the root reason of appearance of spots on arc cathodes. Without discussing this dependence in detail, we only note that the bell shape stems from a competition between the heating of the cathode surface by the ions coming from the plasma and the electron emission cooling.…”

Section: Numerical Modelmentioning

confidence: 63%

Simulating changes in shape of thermionic cathodes during operation of high-pressure arc discharges

Cunha¹,

Kaufmann²,

Santos³

et al. 2019

J. Phys. D: Appl. Phys.

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A numerical model of current transfer to thermionic cathodes of high-pressure arc discharges is developed with account of deviations from local thermodynamic equilibrium occurring near the cathode surface, in particular, of the near-cathode space-charge sheath, melting of the cathode, and motion of the molten metal under the effect of the plasma pressure, the Lorentz force, gravity, and surface tension. Modelling results are reported for a tungsten cathode of an atmospheric-pressure argon arc and the computed changes in the shape of the cathode closely resemble those observed in the experiment. The modelling has shown that the time scale of change of the cathode shape during arc operation is very sensitive to the temperature attained by the cathode. The fact that the computed time scales conform to those observed in the experiment indicate that the model of non-equilibrium near-cathode layers in highpressure arc discharges, employed in this work, predicts the cathode temperature for a given arc current with adequate accuracy. In contrast, modelling based on the assumption of local thermodynamic equilibrium in the whole arc plasma computation domain up to the cathode surface could hardly produce a similar agreement.

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“…Some of the observed highfrequency oscillations, with typical periods of 5-10 ns, probably originate from the interaction between the intense electron jets and the expanding plasma vacuum boundary. This plasma instability is predicted to occur for high current-density rise rates, around 10 9 A/cm 2 /ns, by kinetic current numerical simulations of plasma near the cathodic spots [20]. The maximum current was reached quite reproducibly for different gate capacities within the next 40±3 ns.…”

Section: A Electron Emission From Laser-induced Ectons and Low-densimentioning

confidence: 88%

Emission of charged particles from laser-induced germanium ecton, vacuum spark, and vacuum arc

Porshyn

2020

Physics of Plasmas

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The highly resolved temporal evolution of laser-induced micro-explosions on a germanium surface is studied in a triode configuration for various gate charge levels and cathode currents. Electron emission from individual spots is directly imaged with a luminescence screen, showing that the opening angle of the source is about 30°. Electron bunches of several nanocoulombs per pulse in a time interval of about 150 ns are directly extracted to the anode without vacuum breakdown in the cathodic gap. When breakdown occurs, a remarkable change in the arc behavior of a threshold gap potential of around 1 kV is observed, which hints at two different evaporation mechanisms that depend on the cathodic fall of an individual spot. Therefore, for voltages well above the threshold, a fast gate discharge is observed within the first 100-200 ns, followed by fundamental plasma oscillations and an electron emission of several µC per pulse from the plasma boundary. Additionally, highly efficient emission of germanium ion clusters occurs, evidencing a stable twofold electron multiplication in the plasma, with a charge of several µC per pulse below the threshold.

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Numerical Simulation of Plasma Near the Cathode Spot of Vacuum Arc

Cited by 34 publications

References 28 publications

Determination of the critical temperature of Nb–Al alloys from the plasma parameters of a vacuum arc cathode spot

Determination of the critical temperature of Nb–Al alloys from the plasma parameters of a vacuum arc cathode spot

Simulating changes in shape of thermionic cathodes during operation of high-pressure arc discharges

Emission of charged particles from laser-induced germanium ecton, vacuum spark, and vacuum arc

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