Momentum interchange between cathode-spot plasma jets and background gases and vapors and its implications on vacuum-arc anode-spot development

Boxman, R.L.; Goldsmith, S.

doi:10.1109/27.131026

Cited by 60 publications

(19 citation statements)

References 14 publications

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“…This decrease with P was explained by cathode erosion rate reduction by cathode material return due to its collisions with background gas atoms in the cathode vicinity [2], [6] and by balancing of the dynamic pressure of the expanding cathode spot plasma jet by the background gas pressure [7].…”

mentioning

confidence: 98%

Measurement of Ion Flux as a Function of Background Gas Pressure in a Hot Refractory Anode Vacuum Arc

Beilis

Shashurin

Boxman

2007

IEEE Trans. Plasma Sci.

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The hot refractory anode vacuum arc (HRAVA) is a metallic plasma source in which plasma expands radially from the interelectrode gap and may deposit substrates circumferentially disposed around the electrode axis. The dependence of copper ion flux expanding from the HRAVA interelectrode gap was determined as a function of background gas pressure. The fraction of the ion flux in the radially expanding plasma flux was obtained by measuring the ion current and the film thickness. Experiments were conducted with arc currents of 145-250 A, a molybdenum anode, and an electrode separation of about 10 mm. The saturation ion current was measured with a circular flat probe with 10-mm diameter biased at −30 V with respect to the anode. It was found that the collected ion current in vacuum was almost constant during the first 30 s of the arc-∼2.5 mA/cm 2 at a distance of 110 mm from the arc axis, with an arc current of 200 A, and increased to a steady-state value in the developed HRAVA (t > 40 s) of ∼5.5 mA/cm 2 . The measured ion current in argon, nitrogen, and helium environments and the deposition rate in nitrogen remained approximately constant with background gas pressure up to some critical pressure and, then, decreased with pressure eventually reaching zero. The critical pressures were 2, 4, and 10 Pa for argon, nitrogen, and helium, respectively. The critical nitrogen pressure for the deposition rate was 2 Pa in contrast with 4 Pa for the ion current. The ion fraction in total deposition flux was 0.6 in vacuum and decreased with nitrogen pressure, except that a local maximum of ∼0.8 was observed at ∼13 Pa.Index Terms-Background gas, degree of ionization, hot refractory anode, ion flux, plasma plume, vacuum arcs.

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mentioning

confidence: 98%

Measurement of Ion Flux as a Function of Background Gas Pressure in a Hot Refractory Anode Vacuum Arc

Beilis

Shashurin

Boxman

2007

IEEE Trans. Plasma Sci.

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“…Later on, Meunier 13 proposed a snow-plow fluid model to study the transient expansion of the plasma jet. Boxman and Goldsmith 14 prea͒ Member of the CONICET. b͒ Electronic mail: kelly@tinfip.lfp.uba.ar sented a zero-order model for the plasma-jet-background-gas interaction, by equating the plasma jet momentum flux with the background pressure.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the ion range was found to be larger than the visible plasma radius 12 or the theoretical predictions based on the balance of the plasmaneutral gas pressure at a sharp boundary. 13,14 The model of Ref. 15 suffered from certain drawbacks: in the first place, it was not possible to obtain the plasma quantities for rϾr* ͑although the neutral gas density and temperature were obtained up to the chamber wall position͒.…”

Section: Introductionmentioning

confidence: 99%

Structure of plasmas generated by the interaction between metallic ions and neutral gas particles in a low-pressure arc

Kelly

Lepone

Minotti

2000

Journal of Applied Physics

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A numerical solution for the metallic-plasma-neutral-gas structure generated in a low-pressure arc is presented. The equations correspond to a spherically symmetric fluid-like steady model, valid for the outer region of the arc, and describe the ion slowing down by elastic scattering with the neutral particles. Technically, the obtention of the profiles of different magnitudes is complicated due to the existence of a critical point in the steady-state system of equations. The proposed approach to overcome this difficulty is to solve instead a pseudotransient system of equations which rapidly and efficiently relax to the stationary state. By employing this numerical method of second-order accuracy in space, the plasma and neutral gas density, the electron and ion drift velocities, the electron and neutral temperatures, and the electrostatic potential profiles are obtained from the border of the arc channel up to the discharge chamber wall. It is found that the value of the neutral gas filling pressure strongly influences the plasma density and plasma potential distributions. An important result is that metallic ions emitted from the arc channel deliver their kinetic energy to the filling gas in a gradual manner, up to a pressure-dependent point beyond which they move to the walls sustained against collisions with the gas by a self-consistent electric field. Near the mentioned point, the metallic ion density presents a peculiar behavior, showing an increase that is more pronounced at high pressures; a pattern also evident in the electrostatic potential.

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“…Vapor evaporated from the hot anode may play a significant role in the discharge process. In some cases, the anodic plasma plume can prevent the cathodic plasma jets from reaching the anode (1), and there are some reports that the cathode spots may even disappear (2). The HAVA is of interest both fundamentally and practically, because it serves as a physical model of the more complex transient anode spot vacuum arc mode which causes rapid electrode destruction and limits the interruption ability of vacuum arcs, and because of its applications in depositing metal vapor coatings (3) and in synthesizing macroscopic diamond crystals (4).…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study of the temperature of a hot-anode vacuum arc

et al. 1994

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Heat transfer to a thermally isolated graphite anode in a long duration vacuum arc was investigated. Anode bulk temperatures were measured as a function of time using two high temperature thermocouples. The anode surface temperature was optically determined. Surface temperatures of 2300 K were obtained in a 340 A arc. A one dimensional non-linear heat flow model for the anode was developed. A solution was obtained using a dynamic numerical method and the effective anode potential was determined to be approximately 6 V.

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Momentum interchange between cathode-spot plasma jets and background gases and vapors and its implications on vacuum-arc anode-spot development

Cited by 60 publications

References 14 publications

Measurement of Ion Flux as a Function of Background Gas Pressure in a Hot Refractory Anode Vacuum Arc

Measurement of Ion Flux as a Function of Background Gas Pressure in a Hot Refractory Anode Vacuum Arc

Structure of plasmas generated by the interaction between metallic ions and neutral gas particles in a low-pressure arc

Experimental and theoretical study of the temperature of a hot-anode vacuum arc

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