A global model of the self-pulsing regime of micro-hollow cathode discharges

Lazzaroni, C.; Chabert, P.

doi:doi:10.1063/1.3690943

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Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering

The plasma over a magnetron’s erosion “racetrack” is not azimuthally uniform but concentrated in distinct dense ionization zones which move in the E×B direction with about 10% of the electron E×B/B2 drift velocity. The ionization zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each ionization zone has a high plasma density edge, which is the origin of a plasma-generating electron jet le...

Modeling of switching delay in gas-insulated trigatron spark gaps

Based on the gas discharge theory involving distorted E-field enhancement, a physical model is proposed to estimate the switching delay for gas-insulated trigatron spark gaps with a trigger pin inside the main electrode. Two discovered breakdown modes, i.e., fast-breakdown mode (FBM) and slow-breakdown mode (SBM), can be unified in this model. Raether criterion can distinguish these two modes. If the main E-field and enhanced E-field near the trigger pin tip are great enough, FBM forms easily. ...

A global (volume-averaged) model of the self-pulsing regime of micro-hollow cathode discharges working in argon gas is proposed. The power balance is done using an equivalent circuit model of the discharge that allows the current and voltage dynamics to be calculated. The fraction of the total power dissipated in the discharge that contributes to electron heating is deduced from a sheath model previously described. The particle balance is first done in a very simplified reaction scheme involving only electrons, argon atomic ions, and argon molecular ions. In a second step, the excited states (the metastable state Ar*(³P₂) and the resonant state Ar*(³P₁)) are included in the particle balance equations. The models are compared to experiments and several conclusions are drawn. The model without excited states underestimates the electron density and does not capture well the trends in pressure. The model with the excited states is in better agreement which shows that multi-step ionization plays a significant role. The time-evolution of the electron density follows closely that of the discharge current but the excited states density presents two peaks: (i) the first at the early stage of the current peak due to direct excitation with high electron temperature, (ii) the second at the end of the current (and electron density) peak due to large production of excited states by electron-ion recombination at very low electron temperature.

Article Outline

INTRODUCTION
THE GLOBAL MODEL
1. Power balance
2. Particle balance without excited states
3. Particle balance with excited states
RESULTS AND DISCUSSION
1. Electron density in the stationary regime - Model without excited states
2. Electron density in the self-pulsing regime - Model without excited states
3. Electron density in the self-pulsing regime - Model with excited states
4. Dynamics of excited states
CONCLUSIONS

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KEYWORDS and PACS

Keywords

argon, excited states, glow discharges, ion recombination, ionisation, metastable states, plasma collision processes, plasma density, plasma temperature, plasma transport processes, resonant states

PACS

52.80.Hc

Glow; corona
52.20.Fs

Electron collisions
52.20.Hv

Atomic, molecular, ion, and heavy-particle collisions
52.25.Fi

Transport properties
52.25.Jm

Ionization of plasmas

ARTICLE DATA

Digital Object Identifier

http://dx.doi.org/10.1063/1.3690943

PUBLICATION DATA

ISSN

0021-8979 (print)

1089-7550 (online)

Publisher

$abstract.society.value is a Member of CrossRef

American Institute of Physics

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