Potential of a plasma bound between two biased walls

Loizu, Joaquim; Dominski, J.; Ricci, Paolo; Theiler, C.

doi:10.1063/1.4745863

Cited by 10 publications

(13 citation statements)

References 20 publications

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“…This work also shows consistency with measured IVDFs. The predictions of equation (32) have also been tested using PIC simulations of biased electrodes [155,161]. In this case, the modification from the fluid Bohm criterion arises due to the non-local kinetic character of the electron distribution.…”

Section: Weak Ion Sheaths and The Transition To Electron Sheathmentioning

confidence: 99%

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Baalrud

Scheiner

Yee

et al. 2020

Plasma Sources Sci. Technol.

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Biased electrodes are common components of plasma sources and diagnostics. The plasma-electrode interaction is mediated by an intervening sheath structure that influences properties of the electrons and ions contacting the electrode surface, as well as how the electrode influences properties of the bulk plasma. A rich variety of sheath structures have been observed, including ion sheaths, electron sheaths, double sheaths, double layers, anode glow, and fireballs. These represent complex self-organized responses of the plasma that depend not only on the local influence of the electrode, but also on the global properties of the plasma and the other boundaries that it is in contact with. This review summarizes recent advances in understanding the conditions under which each type of sheath forms, what the basic stability criteria and steady-state properties of each are, and the ways in which each can influence plasma-boundary interactions and bulk plasma properties. These results may be of interest to a number of application areas where biased electrodes are used, including diagnostics, plasma modification of materials, plasma sources, electric propulsion, and the interaction of plasmas with objects in space.

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Section: Weak Ion Sheaths and The Transition To Electron Sheathmentioning

confidence: 99%

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Baalrud

Scheiner

Yee

et al. 2020

Plasma Sources Sci. Technol.

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“…The y coordinate labels the position along the magnetic field line. Sheath boundary conditions are applied to the boundaries in y by setting the parallel current J || to the current at the entrance to the magnetic pre-sheath J sh [50,51] where…”

Section: Mast Geometrymentioning

confidence: 99%

Numerical investigation of isolated filament motion in a realistic tokamak geometry

et al. 2015

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This paper presents a numerical investigation of isolated filament dynamics in a simulation geometry representative of the scrape-off layer (SOL) of the Mega Amp Spherical Tokamak (MAST) previously studied in [N.R.Walkden et.al, Plasma Phys. Control. Fusion, 55 (2013) 105005]. This paper focuses on the evolution of filament cross-sections at the outboard midplane and investigates the scaling of the centre of mass velocity of the filament cross-section with filament width and electron temperature. By decoupling the vorticity equation into even and odd parity components about the centre of the filament in the bi-normal direction parallel density gradients are shown to drive large velocities in the bi-normal (approximately poloidal) direction which scale linearly with electron temperature. In this respect increasing the electron temperature causes a departure of the filament dynamics from 2D behaviours. Despite the strong impact of 3D effects the radial motion of the filament is shown to be relatively well predicted by 2D scalings. The radial velocity is found to scale positively with both electron temperature and cross-sectional width, suggesting an inertially limited nature. Comparison with the two-region model [J. R. Myra et.al, Phys. Plasmas, 13 (2006) 112502] achieves reasonable agreement when using a corrected parallel connection length due to the neglect of diamagnetic currents driven in the divertor region of the filament.Analysis of the transport of particles due to the motion of the filament shows that the background temperature has a weak overall effect on the radial particle flux whilst the filament width has a strong effect.

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“…(17), (21), (22), (23), (24), and (26), in the GBS code, 6 a global three-dimensional fluid code based on the drift-reduced Braginskii equations with T i ( T e and the Boussinesq approximation. GBS evolves the plasma dynamics with no separation between equilibrium and fluctuating quantities, as a balance between density and heat sources, the turbulent cross-field transport produced by plasma instabilities, and the losses at the sheaths, where the magnetic field lines terminate on the walls.…”

Section: Fluid Simulations With Boundary Conditions At the Magnetimentioning

confidence: 99%

Boundary conditions for plasma fluid models at the magnetic presheath entrance

et al. 2012

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The proper boundary conditions at the magnetic presheath entrance for plasma fluid turbulence models based on the drift approximation are derived, focusing on a weakly collisional plasma sheath with Ti≪Te and a magnetic field oblique to a totally absorbing wall. First, the location of the magnetic presheath entrance is rigorously derived. Then boundary conditions at the magnetic presheath entrance are analytically deduced for v||i, v||e, n, ϕ, Te, and for the vorticity ω=∇⊥2ϕ. The effects of E × B and diamagnetic drifts on the boundary conditions are also investigated. Kinetic simulations are performed that confirm the analytical results. Finally, the new set of boundary conditions is implemented in a three-dimensional global fluid code for the simulation of plasma turbulence and, as an example, the results of a tokamak scrape-off layer simulation are discussed. The framework presented can be generalized to obtain boundary conditions at the magnetic presheath entrance in more complex scenarios.

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Potential of a plasma bound between two biased walls

Cited by 10 publications

References 20 publications

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Numerical investigation of isolated filament motion in a realistic tokamak geometry

Boundary conditions for plasma fluid models at the magnetic presheath entrance

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