Modeling of Cathode Plasma Flare Expansion

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

doi:10.1109/tps.2013.2244921

Cited by 31 publications

(52 citation statements)

References 16 publications

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“…Equa tions (6) were written for Ti n and Al n components with n = 0, 1, …, 4. Despite the simplified approach to describing ionization, these calculations of the com position of the ionized arc plasma give results that are quite consistent with the experimental data [7,10,13] and with detailed kinetic calculation data [14]. This allows us to hope that the proposed simple method will also yield at least qualitatively correct results for a dis charge plasma with a composite cathode.…”

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confidence: 63%

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Model calculation of the charge composition of a plasma in a vacuum-arc discharge with a composite cathode

2015

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Composite cathodes manufactured by mixing (sin tering or melting) various components in the desired proportion are widely used to obtain various func tional coatings by electric arc spraying. In particular, titanium-aluminum composite cathodes are used to deposit wear resistant and heat resistant coatings on cutting tools [1]. During spraying of a composite cath ode in a vacuum arc source material for multicompo nent ion deposition (implantation), the main task is to form a near surface layer with a certain stoichiometric composition on the processed substrate (target). For this reason, it is an important to know how the charge composition of ions of the initial components entering the vacuum discharge plasma changes as compared to the relative yield of these components from the cath odes of corresponding pure materials.The present Letter proposes a simple model for cal culating changes in the charge composition of a vac uum arc plasma in discharge with a composite cath ode. The results of model calculations are compared to recent experimental data [2,3]. Zhirkov et al.[2] pre sented the results of an experimental study of the mass and charge composition in a vacuum arc discharge plasma with a Ti 1 -x Al x (x = 0.16-0.7) composite cathode operating in a continuous mode. In [3], the mass and charge composition in a vacuum arc dis charge plasma had a cathode with a similar composi tion (Ti 0.67 Al 0.33 ), but operating in a pulsed discharge regime.The proposed model is based on the ecton mecha nism of vacuum arc cathode spot operation [4]. According to this mechanism, a vacuum arc plasma is formed as a result of the operation of separate cells (explosive emission centers) in the cathode spot of the vacuum arc. The arc current buildup is accompanied by an increase in the number of simultaneously oper ating cells of the cathode spot. For this reason, the ion flux parameters (the distribution of ion velocities and charges, ion erosion rate, ion current fraction) are independent or weakly depend on the arc current up to the kiloampere level [4][5][6][7].It was shown [8] that the elemental composition of the vacuum arc plasma almost coincides with the ele mental composition of the composite cathode. For this reason, the proposed model assumes that compo nents in the cathode spot of the composite electrode (in this case, Al and Ti) erode simultaneously and the relative rate of their erosion corresponds to their rela tive content and does not change with time. In addi tion, the results of Zhirkov et al. [2,9] show that ions of various sputtered components have almost identical velocities. The results of our recent model calculations [10] for a three component plasma showed that the drift velocities of ions with even significantly different masses (zirconium and deuterium) exhibit leveling as a result of strong ion-ion interaction in a dense near cathode plasma. For this reason, the proposed model assumes that ions of different components have the same velocity and, hence, the plasma can be described using the two temperat...

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confidence: 63%

“…The electron temperature at the cathode boundary was assumed to be 1.5 eV and the ion tem perature was 1 eV. These values were adopted by anal ogy with the kinetic model [14], according to which these temperatures were calculated directly. At the outer boundary of the cone, the conditions were supersonic and there was no electron heat flux.…”

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Model calculation of the charge composition of a plasma in a vacuum-arc discharge with a composite cathode

2015

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“…Roughly, it can be assumed that the probability increases with the density, n e and n e / 1=r 2 . The choice of this relation was dictated by that the probability of initiation of a new ecton during the interaction of the cathode plasma with the cathode surface is substantially determined by the plasma density [27][28][29] and that the plasma expansion from the cathode spot region is nearly spherically symmetric. 30 Here, we assume that the new cathode spot cell is initiated by the interaction of the erosion plasma with the surface of the electrode in contrast to Refs.…”

Section: B Modelmentioning

confidence: 99%

Arc spot grouping: An entanglement of arc spot cells

Kajita

Hwangbo

Ohno

et al. 2014

Journal of Applied Physics

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Articles you may be interested inA model of reaction field in gas-injected arc-in-water method to synthesize single-walled carbon nanohorns: Influence of water temperatureIn recent experiments, clear transitions in velocity and trail width of an arc spot initiated on nanostructured tungsten were observed on the boundary of the thick and thin nanostructured layer regions. The velocity of arc spot was significantly decreased on the thick nanostructured region. It was suggested that the grouping decreased the velocity of arc spot. In this study, we try to explain the phenomena using a simple random walk model that has properties of directionality and selfavoidance. And grouping feature was added by installing an attractive force between spot cells with dealing with multi-spots. It was revealed that an entanglement of arc spot cells decreased the spot velocity, and spot cells tend to stamp at the same location many times. V C 2014 AIP Publishing LLC.

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“…These values were obtained from the solution based on the kinetic model [15], in which these temperatures are calculated directly. The bound ary conditions on the outer boundary of the cone were ultrasonic, and the electron heat flux was zero.…”

Section: Model For Estimating the Deuterium Concentration In The Vacumentioning

confidence: 99%

Generation of hydrogen isotope ions in a vacuum arc discharge with a composite zirconium deuteride cathode

et al. 2015

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The mass and charge composition of the plasma of a vacuum arc with thick and film type zirco nium cathodes containing deuterium and hydrogen is investigated experimentally and theoretically. For a thick cathode, it is shown that such a system ensures effective generation of deuterium ions with an integral fraction per arc current pulse of approximately 60%; the maximal concentration of deuterium is observed at the initial stage of the arc operation. In the case of the film cathode, such a concentration of hydrogen iso topes can be attained for currents exceeding 400 A and for an arc duration at a level of a few tens of microsec onds. Occlusion of deuterium in the cathode leads to additional energy expenditures for its ionization and, as a consequence, a decrease in the average charge of ions of the cathode material in the arc plasma. Deuterium in the cathode spot is ionized completely, and the drift velocity of its ions almost coincides with the velocity of ions of the cathode material due to the high frequency of ion-ion collisions in the cathode region. The inter action of a dense (~10 20 cm -3 ) cathode spot plasma with microinhomogeneities of the cathode surface leads to the development of thermal instability in them over time intervals that do not exceed tens of nanoseconds.

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Modeling of Cathode Plasma Flare Expansion

Cited by 31 publications

References 16 publications

Model calculation of the charge composition of a plasma in a vacuum-arc discharge with a composite cathode

Model calculation of the charge composition of a plasma in a vacuum-arc discharge with a composite cathode

Arc spot grouping: An entanglement of arc spot cells

Generation of hydrogen isotope ions in a vacuum arc discharge with a composite zirconium deuteride cathode

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