Magnetized plasma sheath in the presence of negative ions

Paul, Rupali; Adhikari, S.; Moulick, R.; Kausik, S. S.; Saikia, B. K.

doi:10.1063/5.0004796

Cited by 9 publications

(8 citation statements)

References 38 publications

(53 reference statements)

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“…In previous studies on the properties of the magnetized sheath, the stress tensor in the ion motion equations is often neglected, meaning that the influence of stress on ion motion is not considered [14][15][16][17]. Some studies only consider the effects of thermal pressure and external fields [18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Effect of ion stress on properties of magnetized plasma sheath

CHEN 陈,

CUI 崔,

GAO 高

et al. 2024

Plasma Sci. Technol.

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In the plasma sheath, there is a significant gradient in ion velocity, resulting in strong stress on ions treated as a fluid. This aspect has often been neglected in previous sheath studies. This study is based on the Braginskii plasma transport theory and establishes a 1D3V sheath fluid model that takes into account the ion stress effect. Under the assumption that ions undergo both electric and diamagnetic drift in the presheath region, self-consistent boundary conditions, including the ion Bohm velocity, are derived based on the property of the Sagdeev pseudopotential. Furthermore, assuming that the electron velocity at the wall follows a truncated Maxwellian distribution, the wall floating potential is calculated, leading to a more accurate sheath thickness estimation. The results show that ion stress significantly reduces the sheath thickness, enhances ion Bohm velocity, wall floating potential, and ion flux at the wall. It hinders the acceleration of ions within the sheath, leading to notable alterations in the particle density profiles within the sheath. Further research indicates that in ion stress, bulk viscous stress has the greatest impact on sheath properties.

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Section: Introductionmentioning

confidence: 99%

Effect of ion stress on properties of magnetized plasma sheath

CHEN 陈,

CUI 崔,

GAO 高

et al. 2024

Plasma Sci. Technol.

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“…[12][13][14][15][16][17] The electronegative plasma sheath under different conditions has already been widely explored. [18][19][20][21][22][23] However, with the advent of fusion research, interest has grown to study the electronegative sheath with negative ion emitting wall. [5,9,24,25] It has been shown earlier [5,14,26] that if the temperature ratio of the electrons and volume negative ions exceed a value of 5 + √ 24, the sheath edge electric potential becomes multi-valued with respect to the electronegativity.…”

Section: Introductionmentioning

confidence: 99%

Plasma sheath with multi‐species of positive ions and surface produced negative ions

Samanta

Moulick

Bhuyan

et al. 2023

Contrib. Plasma Phys

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The structure of a plasma sheath has been investigated in front of a caesium‐coated metallic plate, using a simple theoretical model. Along with the electrons, the plasma is composed of multi‐species of positive ions, and surface and volume produced negative ions. While the volume produced negative ions are common in many plasma processing chambers, the surface produced negative ions are of critical importance, especially to the Neutral Beam Injection (NBI) systems. The surface negative ions are produced via the coated metallic plate. With a single species of positive ion, the Bohm criterion, which determines the sheath edge potential, is multi‐valued for a specific range of electronegativity (). The width of the multi‐valued region has been reported to increase with the surface production yield (). Calculations are done for hydrogen plasma with a slight admixture of a second gas such as argon. Besides discussing the differences brought in by the mere presence of a second ion, the paper highlights the importance of the positive ion current density in determining the Bohm criterion. In addition, the effect of three species of positive ions in the surface production process has been discussed.

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“…[2][3][4] The sheath structure of electron-ion plasma has been well documented in the plasma physics literature. [5][6][7][8] In addition to electrons and ions, enormous, highly charged micro-sized dust grains are contained in dusty plasmas, which are widely found in space and the laboratory. [9][10][11] Electrons and ions hit and attach onto the surface of the dust grain, making it charged.…”

Section: Introductionmentioning

confidence: 99%

Effects of trapped electrons on the sheath at the boundary of a dusty plasma

Yang¹,

Chen²,

Chen

et al. 2023

Jpn. J. Appl. Phys.

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In the present paper, the characteristic behaviors of the sheath in an unmagnetized dusty plasma contained trapped electrons, cold ions and variable-charged dusts are investigated based on the Sagdeev potential approach. The result shows that both the formation and structure of the sheath are modified by the trapped electrons. At the sheath edge, the critical ion Mach number decreases as the trapping parameter β increases. It is noted that the effect of electron trapping on the ion-entering-sheath-velocity is indirect, and closely related to the dust charge variation. In the sheath, the increased β leads to the enlargement of the sheath thickness and absolute value of electrostatic potential which results in the redistribution of particles densities. Moreover, the results of the Maxwellian case are essentially recovered when β = 1. As expected, the present results would give more insight into the interaction processes happened on the plasma-wall interface.

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Magnetized plasma sheath in the presence of negative ions

Abstract: Influence of ionization on sheath structure in electropositive warm plasma carrying twotemperature electrons with non-extensive distribution Physics of Plasmas 27, 063515 (2020);

Cited by 9 publications

References 38 publications

Effect of ion stress on properties of magnetized plasma sheath

Effect of ion stress on properties of magnetized plasma sheath

Plasma sheath with multi‐species of positive ions and surface produced negative ions

Effects of trapped electrons on the sheath at the boundary of a dusty plasma

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