Existence of subsonic plasma sheaths

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

doi:10.1103/physreve.83.016406

Cited by 33 publications

(33 citation statements)

References 28 publications

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“…In this situation, the ion and electron velocities at the sheath edge were recently derived in the limit of cold ions. 15 We now extend the results to the case of finite ion temperature.…”

Section: A Ion Sheathsmentioning

confidence: 99%

“…Equation (1) results from computing the first moment of the electron distribution function, which is a truncated Maxwellian in the proximity of a perfectly absorbing wall. 15 Notice that the spatial dependence of V e is contained in the potential g. We now consider the continuity equations for ions and electrons and the momentum equation for ions, which in steady state are…”

Section: A Ion Sheathsmentioning

confidence: 99%

“…III, we perform numerical simulations with the ODISEE (one-dimensional sheath edge explorer) code, 15 a fully kinetic, electrostatic PIC code akin to previous simulations. 16,17 We simulate an one-dimensional plasma bound between two absorbing walls at x ¼ 0 and x ¼ L, where L is much larger than the sheath scale, L ) k D .…”

Section: Numerical Simulationsmentioning

confidence: 99%

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Potential of a plasma bound between two biased walls

et al. 2012

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An analytical study is presented for an one-dimensional, steady-state plasma bound between two perfectly absorbing walls that are biased with respect to each other. Starting from a description of the plasma sheaths formed at both walls, an expression relating the bulk plasma potential to the wall currents is derived, showing that the plasma potential undergoes an abrupt transition when currents cross a critical value. This result is confirmed by numerical simulations performed with a particle-in-cell code.

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“…In this situation, the ion and electron velocities at the sheath edge were recently derived in the limit of cold ions. 15 We now extend the results to the case of finite ion temperature.…”

Section: A Ion Sheathsmentioning

confidence: 99%

Section: A Ion Sheathsmentioning

confidence: 99%

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Potential of a plasma bound between two biased walls

et al. 2012

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“…We then derive the condition defining the MP entrance by following an approach similar to that described in Ref. 22 in the case of a magnetic field normal to the wall.…”

Section: Derivation Of the Magnetic Presheath Entrance Conditionmentioning

confidence: 99%

“…II and III, we perform numerical simulations with the ODISEE (One-DImensional Sheath Edge Explorer) code, 22,26 a fully kinetic, electrostatic particle-incell (PIC) code akin to previous simulations, 27,28 which solves the Vlasov-Poisson system in one dimension in real space and three dimensions in velocity space. ODISEE is used to simulate a one-dimensional plasma bound between two absorbing walls at s ¼ 0 and s ¼ L, being the size of the system much larger than the sheath scale, i.…”

Section: Particle Simulations Of the Magnetic Presheathmentioning

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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Comments on the Bohm Criterion and on the Determination of the Ion Velocity at the Sheath Edge in Non‐Maxwellian Plasma

Jauberteau

2011

Contrib. Plasma Phys.

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International audienceThis work is devoted to the study of the Bohm criterion in the general case of the electron energy distribution function (EEDF). Investigations are performed by means of a Monte Carlo integration method. We resolve the cold fluid equation system describing the ion motion within the sheath, assuming collisionless conditions, singly charged and mono kinetic incoming ions (BOHM model). Results confirm that the limit ion velocity at the sheath edge to assure a monotone electric field with a positive charge over the entire sheath is vi ≥ (kTe/Mi) or εi ≥ 1/3 <εe > in the case of Maxwellian electrons. We show that in the case of a Druyvesteyn electron energy distribution, this limit is larger, it is εi ≥ 0.6 <εe >. The study is also extended to other distributions functions. Because of the large controversy in recent publications, concerning the boundary conditions at the sheath entrance, we discuss the collisionless conditions at the sheath edge according to the plasma parameters. It is shown that in a collisionless sheath, the condition ni(χ) ≥ ne(χ) can be used to determine the limit ion velocity at the sheath edge of the negatively biased collector (Langmuir probe for instance)

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Existence of subsonic plasma sheaths

Cited by 33 publications

References 28 publications

Potential of a plasma bound between two biased walls

Potential of a plasma bound between two biased walls

Boundary conditions for plasma fluid models at the magnetic presheath entrance

Comments on the Bohm Criterion and on the Determination of the Ion Velocity at the Sheath Edge in Non‐Maxwellian Plasma

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