Modeling of magnetized collisional plasma sheath with nonextensive electron distribution and ionization source

Chen, Long; Yang, Yehui; An, Yuhao; Duan, Ping; Sun, Shaojuan; Cui, Zuojun; Kan, Zi-chen; Gao, Weifu

doi:10.1088/2058-6272/aca502

Cited by 6 publications

(4 citation statements)

References 71 publications

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“…q 层的研究中通常采用统计力学的方法描述电子, 通常借助Boltzmann-Gibbs(BG)统计, 假设鞘层中电子、离子都处于热平衡状态, 电子服从麦克斯韦分布, 但经典统计力学并不适用于所有情况, 当系统的熵不等于子系统熵函数的和, 那么熵函数的广延性就被破坏. 如长程相互作用、一维耗散系统、纯电子等离子体系统等 [13][14][15][16][17] 超出了统计力学的适用范围, 对于上述的情况, 1988年, Tsallis [18,19] 在熵的概念中引入一个非广延参量 , 其数学表达式为 Tsallis统计在近年来得到了广泛的应用, 如等离子体不稳定性、尘埃离子声波以及碰撞热等离子体等等诸多领域 [20][21][22] , 针对具有不同物理条件的鞘层特性也进行了大量的研究 [23][24][25][26][27][28] . Hatami [23] 数值研究了正离子温度对电子非广延鞘层特性的影响, 研究表明, 随着正离子温度的升高, 鞘层厚度和带电粒子的密度减小, 此外, 非广延参量对鞘层区域特性的影响随着正离子温度的升高而减小.…”

Section: 等离子体鞘层由大量带电粒子组成在以往鞘unclassified

Multi-ion magnetized sheath properties with non-extensive electron distribution

Chen,

Tan,

Cui

et al. 2024

Acta Phys. Sin.

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Plasma magnetized sheath plays an important role in semiconductor processing, material surface modification, film deposition and so on. In plasma experiments and discharge applications, multi-ion plasmas consisting of more than two kinds of ions often exist. For long range interacting plasma systems, non-Maxwellian electrons can be described by the non-extensive distribution of Tsallis. In this paper, a fluid model with one-dimensional spatial coordinates and three-dimensional velocity coordinates is established for the multi-ion plasma sheath. It is assumed that the electron velocity in the sheath follows a non-extensive distribution, and the background helium ions and different kinds of impurity ions are magnetized in a magnetic field with a certain tilt Angle. The effects of non-extensive parameters, impurity ions and oblique magnetic field on the number density, velocity, wall potential and kinetic energy of ions in the multi-ion magnetic sheath were investigated by numerical simulation. The results show that in the helium-hydrogen or helium-argon mixed plasma sheath, the ionic velocity along the vertical wall direction decreases with the increase of the non-extensive parameters, the number density of ions and electrons in the sheath decreases, the sheath thickness decreases, and the kinetic energy of ions at the wall decreases. When the concentration of impurity ions increases, the kinetic energy of ions on the wall is independent of the type of ions. With the increase of magnetic field intensity, the number density of helium ions and the velocity along the vertical wall fluctuate along the sheath edge, and the fluctuation amplitude increases with the decrease of non-extensive parameters, while the heavy ions have no obvious fluctuation. In addition, the effects of the types and concentrations of impurity ions on the related properties of the sheath were also analyzed. With the increase of the magnetic field intensity, the number density and the velocity along the vertical wall direction fluctuate at the sheath edge, and the fluctuation amplitude increases with the decrease of the non-extensive parameter, whereas there are no significant fluctuations for heavy ions. In addition, when impurity ions are heavy ions, the absolute value of wall potential increases with the increase of impurity ion concentration and the decrease of non-extensibility parameters, and the kinetic energy of background ions increases at the wall surface. When the impurity ion is a light ion, the absolute value of the wall potential decreases with the increase of the impurity ion concentration and the decrease of the non-extensibility parameter, and the kinetic energy of the background ion at the wall decreases.

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Section: 等离子体鞘层由大量带电粒子组成在以往鞘unclassified

Multi-ion magnetized sheath properties with non-extensive electron distribution

Chen,

Tan,

Cui

et al. 2024

Acta Phys. Sin.

Self Cite

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“…Therefore, these two types of viscous stresses should be studied together as a unified entity. In previous studies, the electric drift velocity of ions at the sheath edge has commonly been used as the boundary condition for their transverse velocity [24,[38][39][40][41][42]. However, there exists a weak gradient in ion density within the presheath actually.…”

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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“…In the presence of a magnetic field and ion-neutral collisions, the flow of positive ions at the sheath boundary decreases with the increase in the obliqueness of the magnetic field and collisions [21,22]. In addition, the presence of an ion generation term affects the unmagnetized collisional plasma sheath characteristics, and the source term causes a decrease in the ion flow at the sheath boundary [23,24]. When ion-neutral collisions are taken into account in the sheath region, this region has three different regimes: a collision dominated regime, a collisionless regime, and a transition region that exits in between them.…”

Section: Introductionmentioning

confidence: 99%

Ion flow and dust charging at the sheath boundary in dusty plasma with an electron-emitting surface: applications to laboratory and lunar dusty plasmas

Basnet,

Patel,

Bikram Thapa

et al. 2024

Plasma Phys. Control. Fusion

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In laboratory and space plasmas, the emission of electrons from the surface significantly affects the characteristics of plasma sheath formed at that surface, which is crucial to understanding the overall plasma-wall interaction mechanism. In this work, the collisional fluid model is used for laboratory dusty plasma, whereas collisionless model is used for lunar dusty plasma. We have extended the Bohm sheath criterion for the formation of stable plasma sheath in account of electron emission from the surface, loss of ion flux, and gas pressure for the collisional laboratory dusty plasmas. It is found that ion flow at the sheath boundary is considerably influenced by the concentration of electron emission, ion loss term, and gas pressure. The evolution of dust charge explicitly determines the magnitude of ion flow at the sheath boundary. The plasma parameters adopted in the present case are reliable in laboratory and space dusty plasmas, especially dusty plasma environment on the lunar surface. The lunar surface and dust grains on the Moon become electrically charged as a result of the interaction between solar-wind plasma and photoemission electrons emitted from the lunar surface. In addition, the lunar plasma sheath characteristics, dust charging process, and stable dust levitation on the sheath region have been studied.

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Modeling of magnetized collisional plasma sheath with nonextensive electron distribution and ionization source

Cited by 6 publications

References 71 publications

Multi-ion magnetized sheath properties with non-extensive electron distribution

Multi-ion magnetized sheath properties with non-extensive electron distribution

Effect of ion stress on properties of magnetized plasma sheath

Ion flow and dust charging at the sheath boundary in dusty plasma with an electron-emitting surface: applications to laboratory and lunar dusty plasmas

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