Two-dimensional particle simulation of plasma expansion between plane parallel electrodes

Patel, Kartik; Mago, V. K.

doi:10.1063/1.359841

Cited by 15 publications

(7 citation statements)

References 12 publications

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“…In an actual experiment where ion would be heavier by many orders, it is expected that fluctuations would be proportionately slower, and less in magnitude. This is what was seen in our simulations using barium, 4 and on Gadolinium by Ogura, Kaburaki and Shibata. 9 The depth of the modulations in the ion current was very much reduced.…”

Section: Issues Related To Experimental Observationsupporting

confidence: 76%

Observation of ion waves in two-dimensional particle simulation of field-assisted plasma expansion

Patel

1997

Journal of Applied Physics

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We report the results of two-dimensional particle simulations (computer experiments) of finite plasma expansion between biased plane parallel electrodes. We show that the simulation produces results consistent with the existing one-dimensional analytical model. While the plasma expansion on the low-potential side is space-charge limited, on the opposite side it is due to ambipolar diffusion. The time-dependent simulated ion current to the electrode exhibits a modulation which has not been experimentally observed. This is identified to be a consequence of the oscillation in sheath front ion density which occurs because of the ion acoustic waves generated during the expansion. This modulation, which is greater at lower ion temperatures and nonuniform with respect to the electrode surface, can be used to estimate the transient number density in the plasma. Modifications to conventional experimental detection circuits which could help in the detection of these waves are presented.

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Section: Issues Related To Experimental Observationsupporting

confidence: 76%

Observation of ion waves in two-dimensional particle simulation of field-assisted plasma expansion

Patel

1997

Journal of Applied Physics

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“…A 2D-PIC code 16 has been developed to simulate studies of photoplasma in an electrostatic field. In this method the large numbers of ions and electrons of the plasma are substituted by lesser number of macroparticles.…”

Section: D-pic Simulationmentioning

confidence: 99%

“…This field is responsible for plasma expansion in all directions. Particle-in-cell ͑PIC͒ simulations [16][17][18] in which both ions and electrons are considered as particles, have been used to describe 2D motion of photoplasma in collisionless and in charge-exchange collision domain.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional expansion of finite-size barium photoplasma in an electrostatic field

et al. 2008

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Two-dimensional evolution of finite-size barium photoplasma, produced using multistep-resonant ionization is experimentally investigated in an externally applied electrostatic field. Several processes like bulk motion, ambipolar diffusion, Coulomb repulsion, Child-Langmuir flux, bounded diffusion, etc. that contribute to its expansion, have been identified. They are quantified with the help of signals recorded by Faraday cups, electrodes and plates and by two-dimensional particle-in-cell simulation. These processes are superimposed and their relative magnitudes decide the evolution of the photoions. When external field is dominant, a significant fraction of ions reach the cathode with negligible vertical spread and the plasma motion can be considered as one-dimensional. However, when plasma collective effects are dominant, then the different mechanisms become comparable and the photoplasma expands in two dimensions. The spread of photoions at different locations in parallel plate geometry is determined as a function of plasma density and compared with simulation.

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“…The entire system is located in an oblique static magnetic field (making angle ~g with the y-axis: ~g = 5~ ~ 60 ~ 90~ ~t = 900, XT = 1). The equations of motion (1) and the Poisson equation (6) The problem of expansion of the plasma between two parallel electrodes was studied in [62]. In a computational region of size 4x 10 cm 2 a 40 x 100 grid was introduced (Ax =Ay = 0.1cm).…”

Section: Ivo(~(t))dt the Inversion Of This Formula Presentsmentioning

confidence: 99%

Application of the particle-in-cell method for numerical simulation of sheath plasma

Filippychev¹

1998

Comput Math Model

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We give a survey of papers on the numerical simulation of the sheath plasma using the particle-in-cell method. We study the problem of the behavior of a plasma bounded in the longitudinal direction of an absorbing wall. The model studied contains charged particles (electrons and ions) 1. Introduction. Under laboratory conditions a plasma is always bounded by surfaces of a suitable device. The study of the processes in the sheath layer occupies a significant place in the studies of plasma physics. The importance of this problem is due to the large number of different applications among which one may mention electrostatic probes, divertor and limiter tokamak plates, thermoemission energy transformers, plasma electrons, and ion particle sources, plasma technology processes, and so forth.In the present paper we study a one-dimensional plasma model consisting of electrons and single-charge ions. In the longitudinal direction the system is bounded by absorbing walls. Due to their greater mobility the electron flux across any section of plasma is so much larger than the ion flux that the condition of approximately equal exit of electrons and ions from the plasma region (the condition of steady state of the system) leads to a plasma potential that is positive relative to the walls. The electrostatic potential varies only weakly in the plasma region, where the ion and electron densities are approximately equal (quasi-neutrality of the plasma). Near the absorbing surface a region approximately several Debye lengths in extent forms, in which the quasi-neutrality of the plasma is significantly violated, and in which a sharp potential drop occurs. The electric field is significantly different from null in this sheath region, which is called the Langmuir (or Debye) region.The basic problem in the theoretical study of a plasma with bounding walls is the study of the very complicated structure of the sheath regions, which to a significant degree is determined (in the absence of an external magnetic field) by the Knudsen number Kn -L/L and the Debye number De =-~.JL. Here ~. is the effective length of free travel of particles, ~-o is the Debye length, and L is the characteristic macroscopic dimension of the problem (the length of the region). A case of practical interest is the case Kn << 1, De << 1. Here the region containing the charged particles can be divided into a quasi-neutral hydrodynamic part and a thin sheath layer of bulk charge. Usually in a gas-discharge plasma the inequalities L >> L >> L D hold. In this case a collisionless protective layer forms around the absorbing wall, to which the strongly nonequilibrium quasi-neutral Knudsen layer is adjacent. Depending on the problem in question we use different models for describing the plasma. Far away from the wall (at distances that exceed several free travel lengths) the plasma is quasi-neutral and collisional, and the distribution function of the velocities of the particles is nearly Maxwell. In this region we use hydrodynamic models or the diffusion approximation to...

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Two-dimensional particle simulation of plasma expansion between plane parallel electrodes

Cited by 15 publications

References 12 publications

Observation of ion waves in two-dimensional particle simulation of field-assisted plasma expansion

Observation of ion waves in two-dimensional particle simulation of field-assisted plasma expansion

Two-dimensional expansion of finite-size barium photoplasma in an electrostatic field

Application of the particle-in-cell method for numerical simulation of sheath plasma

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