Absence of Debye Sheaths Due to Secondary Electron Emission

Campanell, A. Khrabrov and I. D. Kaganovich M.D.

doi:10.2172/1062662

Cited by 3 publications

(3 citation statements)

References 21 publications

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“…This would explain that the CSL is very unstable numerically. Sheath instabilities and the development of an inverse sheath [98] are alternatives to the CSL scenario. Further investigation on these aspects is required.…”

Section: Appendix: the Debye Sheath Modelmentioning

confidence: 99%

Using electron fluid models to analyze plasma thruster discharges

Ahedo

2023

J Electr Propuls

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Fluid models of the slow-dynamics of magnetized, weakly-collisional electrons lead to build computationally-affordable, long-time simulations of plasma discharges in Hall-effect and electrodeless plasma thrusters. This paper discusses the main assumptions and techniques used in 1D to 3D electron fluid models, and some examples illustrate their capabilities. Critical aspects of these fluid models are the expressions for the pressure tensor, the heat flux vector, the plasma-wall fluxes, and the high-frequency-averaged electron transport and heating caused by plasma waves, generated either by turbulence or external irradiation. The different orders of magnitude of the three scalar momentum equations characterize the electron anisotropic transport. Central points of the discussion are: the role of electron inertia, magnetically-aligned meshes versus Cartesian-type ones, the use of a thermalized potential and the infinite mobility limit, the existence of convective-type heat fluxes, and the modeling of the Debye sheath, and wall fluxes. Plasma plume models present their own peculiarities, related to anomalous parallel cooling and heat flux closures, the matching of finite plume domains with quiescent infinity, and solving fully collisionless expansions. Solutions of two 1D electron kinetic models are used to derive kinetically-consistent fluid models and compare them with more conventional ones.

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Section: Appendix: the Debye Sheath Modelmentioning

confidence: 99%

Using electron fluid models to analyze plasma thruster discharges

Ahedo

2023

J Electr Propuls

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“…The sheath above a photoemitting surface in a thermal plasma was studied analytically [ Guernsey and Fu , ]. In the case where Γ > 1, in addition to the SCL sheath solution, a so‐called inverse sheath solution, in which the plasma potential is negative relative to the surface, also exists [ Campanell et al , ; Campanell , ; Taccogna , ].…”

Section: Introductionmentioning

confidence: 99%

Plasma potential in the sheaths of electron‐emitting surfaces in space

Wang

Pilewskie

Hsu

et al. 2016

Geophysical Research Letters

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Sheaths are formed around the surfaces of airless bodies, which both collect and emit electrons. Depending on the ratio of the emitted to collected electron fluxes Γ, the sheath potential structure can be quite different. We present the first experimental measurements of all the three types of the sheath potentials: classical, space‐charge‐limited (SCL), and inverse. A solid surface immersed in plasmas emits secondary electrons. The potential structure changes from a monotonic classical to a nonmonotonic SCL sheath as Γ increases. At the critical electron emission with zero electric field at the surface, the sheath potential is determined by the plasma electron temperature, and Γ approaches but remains smaller than 1, in agreement with the theoretical expectation. The nonmonotonic SCL sheath persists steadily for Γ > 1. When the emitted electron density becomes larger than the plasma electron density, a monotonic inverse sheath forms with a positive surface potential relative to the ambient.

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“…The study of the contact of a plasma with a surface has several applications across a wide variety of technological and scientific areas [1][2][3][4][5][6][7]. On the one hand, a number of surface treatment and functionalization techniques rely on this precise knowledge.…”

Section: Introductionmentioning

confidence: 99%

Use of Computer Experiments to Study the Current Collected by Cylindrical Langmuir Probes

Tejero-del-Caz

Díaz‐Cabrera

Palop

et al. 2016

PPT

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A particle-in-cell simulation has been developed to study the behaviour of ions in the surroundings of a negatively biased cylindrical Langmuir probe. Here, we report our findings on the transition between radial and orbital behaviour observed by means of the aforementioned code. The influence of the ion to electron temperature ratio on the transition for different dimensionless probe radius is discussed. Two different behaviours have been found for small and large probe radii.

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Absence of Debye Sheaths Due to Secondary Electron Emission

Cited by 3 publications

References 21 publications

Using electron fluid models to analyze plasma thruster discharges

Using electron fluid models to analyze plasma thruster discharges

Plasma potential in the sheaths of electron‐emitting surfaces in space

Use of Computer Experiments to Study the Current Collected by Cylindrical Langmuir Probes

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