Three-fluid model of the plasma-sheath region for a planar probe immersed in an active oxygen discharge. Validity of the Boltzmann relation.

The method of matched asymptotic expansions is used to examine the structure of the plasma sheath of the positive column at low pressure in electronegative gases using the fluid model to describe the positive-ion motion. It is shown that at low negative-ion concentrations, and at high concentrations, the structure is that of a plasma joined to a thin sheath, but that for the electron/negative-ion temperature ratio Te/Tn ≡ ε > 5 + √24, and for a well-defined range of A ≡ nn0/ne0 (the central negative ion to electron density ratio) and for small Debye length, there is a more complex structure with a central negative-ion-dominated plasma surrounded by a quasiplasma in which density oscillations may occur before joining to a sheath. This is in agreement with recent computations using the same model.

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Plasma sheath evolution from perturbed electrodes in a negative-ion plasma. Part 2. Experiment and PIC simulation

Journal of Plasma Physics ◽

10.1017/s0022377897006065 ◽

1997 ◽

Vol 58 (3) ◽

pp. 455-466 ◽

Cited By ~ 4

Author(s):

SEUNGJUN YI ◽

YASSER EL-ZEIN ◽

KARL E. LONNGREN ◽

TERENCE E. SHERIDAN

Keyword(s):

Fluid Model ◽

Negative Ions ◽

Plasma Sheath ◽

Negative Ion ◽

Pic Simulation ◽

Particle In Cell ◽

Model Code ◽

Positive Ions ◽

Ion Plasma ◽

Quasineutral Plasma

The two-dimensional spatial and temporal evolution of a plasma surrounding an electrode whose potential is suddenly decreased is experimentally investigated. The electrode contains a localized convex or a localized concave perturbation. The quasineutral plasma consists of positive ions and various proportions of negative ions and electrons. The results are compared and contrasted with those that are obtained numerically using a particle-in-cell (PIC) simulation and those that had previously been obtained using a fluid-model code.

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Influence of ion temperature on plasma sheath transition

Journal of Plasma Physics ◽

10.1017/s0022377809990304 ◽

2009 ◽

Vol 76 (2) ◽

pp. 247-255 ◽

Cited By ~ 25

Author(s):

HAMID GHOMI ◽

MANSOUR KHORAMABADI

Keyword(s):

Lower Limit ◽

Fluid Model ◽

Elastic Collision ◽

Plasma Sheath ◽

Ion Temperature ◽

Transition Velocity ◽

Two Fluid Model ◽

Lower Limits ◽

Two Fluid

AbstractUsing a two-fluid model, the ion transition from plasma sheath boundary is investigated taking into account the effect of the finite ion temperature. It is shown that by considering the effects of neutral-ion elastic collision on the sheath, there will be an upper as well as a lower limit for the ion transition velocity into the sheath. The dependency of upper and lower limits of the ion transition velocity on the ion temperature is investigated, and it is shown that the finite ion temperature only affects lower limits in non-hot plasmas.

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FDTD study of the effects of the doubly ionized ions on the plasma immersion ion implantation process

Journal of Plasma Physics ◽

10.1017/s0022377813001219 ◽

2014 ◽

Vol 80 (2) ◽

pp. 215-223

Author(s):

M. Sharifian ◽

Y. Sadeghi

Keyword(s):

Ion Implantation ◽

Plasma Polymerization ◽

Potential Distribution ◽

Density Ratio ◽

Plasma Sheath ◽

Sheath Region ◽

Implantation Process ◽

Plasma Immersion Ion Implantation

AbstractThe plasma sheath dynamics adjacent to the cathode in the presence of electrons, ions, and doubly ionized ions have been simulated in this work. The aim of the present investigation is, therefore, to study the effect of the doubly ionized ions on the characteristics of the plasma sheath dynamics such as potential distribution, sheath length, and ions dose and velocity near the surface (cathode). It was shown that the presence of the doubly ionized ions can increase the normalized potential of all positions in sheath region, sheath length, and ion/doubly ionized ions density ratio on the target. Obtained results may be helpful for analyzing the practical results of the surface operations such as ion implantation and plasma polymerization, etc.

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Temporal Ion Velocity Variation with Obliqueness in Magnetized Plasma Sheath

Journal of Nepal Physical Society ◽

10.3126/jnphyssoc.v7i2.38634 ◽

2021 ◽

Vol 7 (2) ◽

pp. 138-143

Author(s):

B. R. Adhikari ◽

R. Khanal

Keyword(s):

Magnetic Field ◽

Plasma Sheath ◽

Magnetized Plasma ◽

Velocity Variation ◽

Physical Parameters ◽

Sheath Region ◽

Narrow Region ◽

Force Equation ◽

Ion Velocity ◽

External Oblique Magnetic Field

A narrow region having sharp gradients in physical parameters is formed whenever plasma comes into contact with a material wall. In this work, the temporal velocity variation of ions in such a sheath has been studied in the presence of an external oblique magnetic field. The Lorentz force equation has been solved for the given boundary conditions using Runge-Kutta method. In order to satisfy the Bohm criterion, ions enter the sheath region with ion acoustic velocity. It is observed that all components of the velocity waves are damped in plasma in the time scale of one second. The computed oscillatory part of ion velocity match with the equation of the damped harmonic oscillator. Thus obtained damping constants as well as the frequency of all three components are nearly equal for obliqueness less than 600 after which they are distinctly different. This is due to the fact that the magnetic field becomes almost parallel to the wall. In earlier studies, only the final velocity profiles are reported and hence this study is useful in understanding how the ion velocities evolve in time as they move from sheath entrance towards the wall.

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Plasma sheath region near a boundary with positive ion backscattering

10.2172/6559854 ◽

1981 ◽

Author(s):

J.N. Brooks

Keyword(s):

Plasma Sheath ◽

Sheath Region ◽

Ion Backscattering ◽

Positive Ion

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Numerical simulation of pulsed plasma sheath dynamics around a micro-sized tip

Journal of Plasma Physics ◽

10.1017/s0022377813000433 ◽

2013 ◽

Vol 79 (5) ◽

pp. 759-764

Author(s):

H. GHOMI ◽

A. MAHMOODPOOR ◽

H. GOUDARZI ◽

A. R. NIKNAM

Keyword(s):

Cross Section ◽

Temporal Evolution ◽

Fluid Model ◽

Rectangular Cross Section ◽

Early Time ◽

Plasma Sheath ◽

Two Dimensional ◽

Pulsed Plasma ◽

Ion Density ◽

Density Distributions

AbstractIn this paper the spatial and temporal evolution of pulsed plasma sheath around a micropatterned surface is investigated using two-dimensional fluid model. The simulation region is considered as a micro-sized tip with rectangular cross section. The effects of rise time on electric field, ion density distributions, and dose of ions impacting the target are studied. It is shown that the plasma sheath has a balloon-like behavior in the early time stages.

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