Laser-induced fluorescence saturation effects on ion velocity distribution functions in the vicinity of reflecting surfaces

Pigeon, V.; Claire, N.; Arnas, C.; Doveil, Fabrice

doi:10.1063/1.5077047

Cited by 3 publications

(2 citation statements)

References 38 publications

(46 reference statements)

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“…Often, the rate of ionization and charge-exchange collisions is sufficiently rapid in the presheath that the ion velocity distribution function (IVDF) is not simply a flowing Maxwellian, but also consists of a "slow tail" associated with ions born within the Sheaths, double layers and fireballs 20 presheath [73,102,103,104,105]. This tail is an important part of the IVDF in many models of the plasma-boundary transition, including in the classical Tonks-Langmuir model [33,106,107].…”

Section: Plasmas With One Ion Speciesmentioning

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: Plasmas With One Ion Speciesmentioning

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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show abstract

“…However, the online version of record will be different from this version once it has been copyedited and typeset. optical pumping saturation 22,23 . The maximum diode laser power is 150 mW.…”

Section: A Plasma Discharge and Lif Systemmentioning

confidence: 99%

Plasma sheath material induced dependence due to secondary electron emission

et al. 2020

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Plasma sheaths in front of six different materials samples (BN, BNSiO 2 , Al 2 O 3 , SiO 2 , stainless steel and silicon) used in various experiments and devices (Hall thrusters, plasma discharge, microelectronics) are studied using the Laser Induced Fluorescence diagnostic. The specific Secondary Electron Emission (SEE) yield of each material is expected to induce differences in the sheath structure from one sample to another. The experiments are carried out in two different plasma discharges (multipolar device and ECR device), exhibiting distinct electron distribution functions: bi-maxwellian and maxwellian. The agreement between the two experiments is good and allow to classify the materials in a consistent way regarding their SEE yields. The multipolar experiments results are compared to a 1D kinetic sheath model and a 1D-1V kinetic sheath simulation code. The predictions of the model are discussed and are in good agreement with previous theory. The influence of the low energy impinging electrons on the SEE yield and emissive sheaths is investigated with the code.

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Three-dimensional cross-field flows at the plasma-material interface in an oblique magnetic field

et al. 2020

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This article describes experimental evidence that the magnetic presheath is a fully three-dimensional structure modified by ion–neutral collisions. Velocity distributions of both ions and neutrals, obtained via laser-induced fluorescence, show that cross field ion drifts do not result from entrainment of ions in a flowing neutral background. Ion flows parallel to E×B arise and accelerate to as much as 0.2cs within several ion gyroradii of the boundary surface, where cs is the sound speed. Within measurement resolution, the onset of the E×B aligned flow occurs at the same distance to the surface that ions begin to deflect from travel along magnetic field lines. Collisional fluid and particle-in-cell simulations of the boundary region are compared to the experimental measurements. We find that, in contrast to the classical collisionless Chodura model, collisional effects between the ions and the non-flowing neutral population are essential to quantitatively predict the observed ion drift velocities. No momentum coupling between ions and neutrals, separable from noise and other effects, is observed in either signal. We discuss several explanations and implications of this observation.

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Laser-induced fluorescence saturation effects on ion velocity distribution functions in the vicinity of reflecting surfaces

Cited by 3 publications

References 38 publications

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

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

Plasma sheath material induced dependence due to secondary electron emission

Three-dimensional cross-field flows at the plasma-material interface in an oblique magnetic field

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