Rotating structures in low temperature magnetized plasmasâ€”insight from particle simulations

Boeuf, Jean-Pierre

doi:10.3389/fphy.2014.00074

Cited by 100 publications

(102 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We additionally show a potential jump at the head of the zone, which makes the system consistent with the requirement that the plasma potential needs to return to the same value when the path over the racetrack is closed (at same radius r and height z): Ð ðV p ðnÞ À hV p iÞ r;z dn ¼ 0, where hV p i designates the plasma potential averaged of the racetrack. In PIC-MCC (ParticleIn-Cell Monte Carlo Collisions) simulations, Boeuf 65 investigated several E Â B discharge geometries and found that for low pressure discharges, like those investigated here, significant deviations from quasi-neutral conditions can occur suggesting that electron and ion space charge regions are not specific but an essential feature of E Â B discharges.…”

Section: E Comparison Of Potential Measurements With Simulations Fromentioning

confidence: 77%

Plasma potential of a moving ionization zone in DC magnetron sputtering

Panjan

Anders

2017

Journal of Applied Physics

View full text Add to dashboard Cite

Using movable emissive and floating probes, we determined the plasma and floating potentials of an ionization zone (spoke) in a direct current magnetron sputtering discharge. Measurements were recorded in a space and time resolved manner, which allowed us to make a three-dimensional representation of the plasma potential. From this information we could derive the related electric field, space charge, and the related spatial distribution of electron heating. The data reveal the existence of strong electric fields parallel and perpendicular to the target surface. The largest E-fields result from a double layer structure at the leading edge of the ionization zone. We suggest that the double layer plays a crucial role in the energization of electrons since electrons can gain several 10 eV of energy when crossing the double layer. We find sustained coupling between the potential structure, electron heating, and excitation and ionization processes as electrons drift over the magnetron target. The brightest region of an ionization zone is present right after the potential jump, where drifting electrons arrive and where most local electron heating occurs. The ionization zone intensity decays as electrons continue to drift in the Ez × B direction, losing energy by inelastic collisions; electrons become energized again as they cross the potential jump. This results in the elongated, arrowhead-like shape of the ionization zone. The ionization zone moves in the –Ez × B direction from which the to-be-heated electrons arrive and into which the heating region expands; the zone motion is dictated by the force of the local electric field on the ions at the leading edge of the ionization zone. We hypothesize that electron heating caused by the potential jump and physical processes associated with the double layer also apply to magnetrons at higher discharge power, including high power impulse magnetron sputtering.

show abstract

Section: E Comparison Of Potential Measurements With Simulations Fromentioning

confidence: 77%

Plasma potential of a moving ionization zone in DC magnetron sputtering

Panjan

Anders

2017

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…In the nonlinear regime the perturbed electric field develops into a robust quasi-coherent mode with a pri- mary wave vector around the fundamental cyclotron resonance. 26 The growing mode is driven by the energy input from the few lowest order cyclotron resonances with k 0 providing the dominant contribution, as seen in Fig. 4.…”

Section: Nonlinear Dynamics and Formation Of The Long-wavelengthmentioning

confidence: 94%

Nonlinear structures and anomalous transport in partially magnetized E×B plasmas

et al. 2017

View full text Add to dashboard Cite

Nonlinear dynamics of the electron-cyclotron instability driven by the electron E × B current in crossed electric and magnetic field is studied. In nonlinear regime the instability proceeds by developing a large amplitude coherent wave driven by the energy input from the fundamental cyclotron resonance. Further evolution shows the formation of the long wavelength envelope akin to the modulational instability. Simultaneously, the ion density shows the development of high-k content responsible for wave focusing and sharp peaks on the periodic cnoidal wave structure. It is shown that the anomalous electron transport (along the direction of the applied electric field) is dominated by the long wavelength part of the turbulent spectrum.

show abstract

“…Alongside these theoretical efforts, computational modelling has become increasingly important in extending present understanding of the spoke. Amongst the many numerical approaches available [31][32][33][34] , simulations employing Particle-in-cell (PIC) codes 33,35 have lately gained relevance, including simulations of real sized devices 36 . Indeed, 'spoke-like' structures have been shown to appear in such recreated devices even in the simplest formulations, such as in the abscence of ionisation or collisions.…”

Section: Introductionmentioning

confidence: 99%

Boundary-induced effect on the spoke-like activity in E × B plasma

et al. 2019

View full text Add to dashboard Cite

The spoke instability in an E × B Penning discharge is shown to be strongly affected by the boundary that is perpendicular to B field lines. The instability is the strongest when bounded by dielectric walls. With a conducting wall, biased to collect electron current from the plasma, the spoke becomes faster, less coherent and localised closer to the axis. The corresponding anomalous cross-field transport is assessed via simultaneous time-resolved measurements of plasma potential and density. This shows a dominant large-scale E×B anomalous character of the electron cross-field current for dielectric walls reaching 40-100% of the discharge current, with an effective Hall parameter β eff ∼ 10. The anomalous current is greatly reduced with the conducting boundary (characterised by β eff ∼ 10 2 ). These experimental measurements are shown to be qualitatively consistent with the decrease of the E field that triggers the collisionless Simon-Hoh instability.

show abstract

Rotating structures in low temperature magnetized plasmasâ€”insight from particle simulations

Cited by 100 publications

References 84 publications

Plasma potential of a moving ionization zone in DC magnetron sputtering

Plasma potential of a moving ionization zone in DC magnetron sputtering

Nonlinear structures and anomalous transport in partially magnetized E×B plasmas

Boundary-induced effect on the spoke-like activity in E × B plasma

Contact Info

Product

Resources

About