Features of plasma structure observed in high-current quasi-stationary magnetron discharge

Kaziev, Andrey V.; Kharkov, M. M.; Khodachenko, G. V.; Tumarkin, Alexander V.

doi:10.1016/j.surfcoat.2015.12.074

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…Similar findings were reported by Hecimovic et al [5]. Different spoke number and shapes in very long pulses (more than 1000 µs) were reported by Kaziev et al [49]. In very short HiPIMS pulses (12 µs long), Velicu et al [50] noticed a change in the shape of spokes from triangle-like to rhomboidal-like with increasing current and explained this by metal-rich plasma.…”

Section: Plasma Self-organization Analysissupporting

confidence: 81%

Plasma dynamics of individual HiPIMS pulses: imaging study using high-frame-rate camera

Panjan

2024

Plasma Sources Sci. Technol.

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A high-frame-rate camera with microsecond-level time resolution was used to make systematic investigations of plasma self-organization and spoke dynamics during individual HiPIMS pulses. The plasma was imaged for a range of argon pressures (0.25-2 Pa) and peak discharge currents (10-400 A) using an Al target. The experiments revealed that plasma evolves through three characteristic stages as the discharge current increases. In stage I, which is present from the current onset and up to ~25 A, spokes are azimuthally long and rotate in the -E×B direction. The spoke behavior is similar to the one observed in DCMS discharges. The number of spokes depends on pressure and the current growth rate. At the lowest pressure (0.25 Pa) a single spoke is present in discharge, while at higher pressures (1-2 Pa) two spokes are most often observed. The spoke velocity depends on the number of spokes, current growth rate and pressure. A single spoke rotates with velocities in the 4-15 km/s range, while two spokes rotate in the 1-9 km/s range depending on the pressure and growth rate. Following stage I, the plasma undergoes a complex reorganization that is characterized by aperiodic spoke patterns and irregular dynamics. In stage II spokes are less localized, they merge, split and propagate either in the retrograde or prograde direction. After chaotic plasma reorganization, more ordered spoke patterns begin to form. Spokes in stage III are azimuthally shorter, typically exhibit a triangular shape and rotate in the E×B direction. In general, the spoke dynamics is less complicated and is only influenced by the pressure. Spokes rotate faster at higher pressures than at lower ones; velocities range from 9 km/s at 0.25 Pa to 6 km/s at 2 Pa. The spoke velocity in stage III is largely unaffected by the discharge current or number of spokes. Stage III can be further divided into sub-stages, which are characterized by different current growth rates, spoke sizes and shapes. In general, the spoke evolution is highly reproducible for pulses with similar discharge current waveforms.

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Section: Plasma Self-organization Analysissupporting

confidence: 81%

Plasma dynamics of individual HiPIMS pulses: imaging study using high-frame-rate camera

Panjan

2024

Plasma Sources Sci. Technol.

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“…These papers cover a wide range of discharge current, gas type, and gas pressure, and report direct measurement of plasma properties and ion distributions at the cathode surface for two different crossed-field geometries. Rotational motion at 2-10 kHz is attributed to gas-phase ionization instabilities [30]. These papers sometimes mention an important role for oxide films, cathode metals that readily form oxide films, and the effect of oxygen or oxygen-bearing molecules in the gas [3,31].…”

Section: Cathode Emission Process and Dot Motionmentioning

confidence: 99%

Voltage and cathode emission mechanisms of a magnetized, constricted, orbiting plasma in helium 6.7–850 Pa

Smith

Sommerer

Lawler

et al. 2021

J. Phys. D: Appl. Phys.

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We present a semiquantitative description of several important properties of a magnetized cold-cathode plasma in helium over a wide pressure range 6.7–850 Pa. We focus on the ‘constricted orbiting’ mode where the plasma attaches to the cathode as a moving ‘dot’ and the voltage and rate of cathode erosion are both unusually low. We propose that the low plasma voltage and observed motion of the plasma adjacent to the cathode can be attributed to field emission as the source of electrons from the cathode, a process that is aided by the charging of an oxide film by ions. We find that the observed dependence of plasma voltage on pressure is consistent with the assumption that the axial electric field must increase in regions of strong crossed magnetic field to maintain current continuity.

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Glows, arcs, ohmic discharges: An electrode-centered review on discharge modes and the transitions between them

Anders

2024

Applied Physics Reviews

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Ever since they have been studied, gas discharges have been classified by their visual appearance as well as by their current and voltage levels. Glow and arc discharges are the most prominent and well-known modes of discharges involving electrodes. In a first approximation, they are distinguished by their current and voltage levels, and current–voltage characteristics are a common way to display their relations. In this review, glow discharges are defined by their individual electron emission mechanism such as secondary electron emission by photons and primary ions, and arcs by their respective collective mechanism such as thermionic or explosive electron emission. Emitted electrons are accelerated in the cathode sheath and play an important role in sustaining the discharge plasma. In some cases, however, electron emission is not important for sustaining the plasma, and consequently we have neither a glow nor an arc discharge but a third type of discharge, the ohmic discharge. In part 1 of this review, these relationships are explained for quasi-stationary discharges, culminating with updated graphical presentations of I–V characteristics (Figs. 15 and 16). In part 2, further examples are reviewed to include time-dependent discharges, discharges with electron trapping (hollow cathode, E×B discharges) and active anode effects.

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Features of plasma structure observed in high-current quasi-stationary magnetron discharge

Cited by 4 publications

References 17 publications

Plasma dynamics of individual HiPIMS pulses: imaging study using high-frame-rate camera

Plasma dynamics of individual HiPIMS pulses: imaging study using high-frame-rate camera

Voltage and cathode emission mechanisms of a magnetized, constricted, orbiting plasma in helium 6.7–850 Pa

Glows, arcs, ohmic discharges: An electrode-centered review on discharge modes and the transitions between them

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