Vacuum arc plasma jet interaction with neutral ambient gas

Gidalevich, E.; Goldsmith, S.; Boxman, R.L.

doi:10.1088/0022-3727/33/20/312

Cited by 16 publications

(16 citation statements)

References 16 publications

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“…The shock wave is characterized by a sharp increase of plasma density at the shock front, a decrease of directed ion velocity to beneath the sound velocity behind the shock front, and transfer of directed ion energy to thermal energy [20]. Shock formation for a vacuum arc plasma jet entering a background gas was described in the theoretical research by Gidalevich et al [21]. Meunier et al [22,23] observed a boundary between the regions of the metal vapour plasma jet and a background gas.…”

Section: Shock Front Formationmentioning

confidence: 99%

Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

Zarchin¹,

Zhitomirsky²,

Goldsmith³

et al. 2003

J. Phys. D: Appl. Phys.

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The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of a vacuum arc plasma source, a straight plasma duct, and a multi-probe consisting of a removable disc obstacle and a set of ring probes for measuring the radial ion flux. A dc arc discharge was ignited in vacuum between a truncated cone-shaped Cu cathode and an annular anode. The plasma jet produced by cathode spots passed through the anode aperture into the straight plasma duct. An axial magnetic field guided the plasma jet in the duct. The multi-probe consisted of a removable disc obstacle and a set of five ring probes for measuring the radial plasma flux as a function of distance from the disc obstacle. The rings and the disc probes were coaxially arranged on the multi-probe assembly and positioned so that plasma from the source passed through the ring probes and then encountered the disc. The influence of the obstacle was determined by measuring the ring ion currents, both in the presence of the obstacle, and when the disc obstacle was removed. The difference between the measured ion currents with and without the obstacle was interpreted to be the contribution of reflected or sputtered particles from the obstacle to the radial ion flux. The ring probes were biased by −60 V with respect to the grounded anode, to collect the saturated ion current. The multi-probe was connected to a movable stem, and positioned at different distances from the plasma source.A plasma density of ∼6 × 1017 m−3 was estimated in this study based on the ion current to the obstacle. The radial ion flux collected by the ring probes increased by 20–25% due to the presence of the obstacle. As the calculated mean free path for collisions between the plasma ions and sputtered or reflected particles is much larger than the plasma path length, the plasma jet should not be affected by returning particles. Hence, the increase of the radial flux is most probably due to ion reflection from the obstacle and ionized neutral atoms sputtered from the obstacle.

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Section: Shock Front Formationmentioning

confidence: 99%

Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

Zarchin¹,

Zhitomirsky²,

Goldsmith³

et al. 2003

J. Phys. D: Appl. Phys.

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“…The primary ion jet deceleration depends on the secondary ion or atom density. In the stationary the problem, 11 primary jet down to subsonic velocities such that a shock front appears. 16 In contrast, low secondary ions/atoms density causes only slightly decelerates the primary jet, and the plasma motion from the cathode remains continuous.…”

Section: Description Of the Problemmentioning

confidence: 99%

“…These values correspond to Mach number Mϭ13, thus the vacuum arc plasma jet ͑VAPJ͒ is considerably supersonic. The hydrodynamic description of the VAPJ was discussed previously, [7][8][9] as was the necessity of shock front formation, in multicathode VAPJs, 10 in the interaction with an ambient gas, [11][12][13] and in the interelectrode gap. 14 The VAPJ interacts with an obstacle in several practical devices, e.g., in vacuum arc plasma coating apparatus and circuit breakers.…”

Section: Introductionmentioning

confidence: 99%

Shock front formation at vacuum arc anodes

Gidalevich

Goldsmith

Boxman

2002

Journal of Applied Physics

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A vacuum arc plasma jet between copper electrodes is considered as a supersonic hydrodynamic jet (the primary plasma jet) that bombards the anode and sputters and/or reflects ions (secondary plasma). An initial primary ion jet velocity of v0=1.5×104 m/s is assumed. The time-dependent interaction between primary and secondary ions is considered for primary ion concentrations of n0=1018 and 1019 m−3 and for a Cu-Cu self-sputtering yield coefficient of β=0.2. It is found by numerical calculation that the primary jet is decelerated by the collisions with the secondary ions. In the case where the mean free path in the primary plasma is much less than the interelectrode gap (l11≪L) and the mean free path for the primary-secondary ion collision is much more than the interelectrode gap (l12≫L), the primary jet decelerates, but initially remains supersonic, while at a later time the deceleration is to a subsonic value, and a shock front appears. For a primary ion concentration of n0=1018 m−3 and an initial secondary ion velocity ≈0.1×v0, a shock front appears at time t≈245×L/v0 while for n0=1019 m−3, at t≈135×L/v0.

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“…Some of them were mainly related to the study of elastic interactions between metallic ions and neutrals. [8][9][10][11][12] Other studies referred to inelastic interactions in the interelectrode region. From photon and ion emission studies, [13][14][15] it was concluded that charge-exchange reactions were the main channel for metallic ion losses, in a gas pressure ͑p͒ range of 10 −6 -10 −2 mbar.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic model for a vacuum arc operated with background gas: Theory and experimental validation

Grondona

Kelly

Minotti

2006

Journal of Applied Physics

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Differences in the metallic plasma-neutral gas structure in a vacuum arc operated with nitrogen and argon J. Appl. Phys. 96, 3077 (2004) A stationary, one-dimensional fluid model is presented to describe the interelectrode region of a nonfiltered vacuum arc operated with a background gas. The model includes the electron energy equation and the main elastic and inelastic atomic processes among metallic ions, electrons, and gas particles. To validate the model predictions an experimental study of the plasma-neutral gas structure, using a titanium ͑Ti͒ cathode and argon ͑Ar͒ as the background gas, is presented. The measured electron temperature and the experimental dependence on the pressure of neutral Ti and Ar spectroscopic emission lines are well reproduced, using a simple atomic model to interpret the plasma radiation emission.

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Vacuum arc plasma jet interaction with neutral ambient gas

Cited by 16 publications

References 16 publications

Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

Shock front formation at vacuum arc anodes

Hydrodynamic model for a vacuum arc operated with background gas: Theory and experimental validation

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