Static Theory of a Discharge Column at Intermediate Pressures

Self, S. A.; Ewald, H.

doi:10.1063/1.1761642

Cited by 246 publications

(132 citation statements)

References 6 publications

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“…Figure 5 compares the radial pressure profiles calculated on the midplane and the divertor plate to show their corre- Figure 6 presents a plot of the pressure loss factor versus the target electron temperature in comparison with an analytic two-point model given by Self and Ewald. 2,33 The analytic curve shows qualitative agreement with the results from our two-dimensional hybrid simulation but tends to underestimate the pressure drop at low temperatures less than 20 eV. We consider that this discrepancy is due to the inclusions of the cross-field diffusion and the parallel temperature gradient within the recycling zone in addition to the momentum transfer by charge-exchange interactions in the present fluidparticle simulation.…”

Section: ͑15͒supporting

confidence: 74%

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Kim

Hong

2005

Physics of Plasmas

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A two-dimensional simulation modeling that has been performed in a self-consistent way for analysis on the fully coupled transports of plasma, recycling neutrals, and intrinsic carbon impurities in the divertor domain of tokamaks is presented. The numerical model coupling the three major species transports in the tokamak edge is based on a fluid-particle hybrid approach where the plasma is described as a single magnetohydrodynamic fluid while the neutrals and impurities are treated as kinetic particles using the Monte Carlo technique. This simulation code is applied to the KSTAR ͑Korea Superconducting Tokamak Advanced Research͒ tokamak ͓G. S. Lee, J. Kim, S. M. Hwang et al., Nucl. Fusion 40, 575 ͑2000͔͒ to calculate the peak heat flux on the divertor plate and to explore the divertor plasma behavior depending on the upstream conditions in its base line operation mode for various values of input heating power and separatrix plasma density. The numerical modeling for the KSTAR tokamak shows that its full-powered operation is subject to the peak heat loads on the divertor plate exceeding an engineering limit, and reveals that the recycling zone is formed in front of the divertor by increasing plasma density and by reducing power flow into the scrape-off layer. Compared with other researchers' work, the present hybrid simulation more rigorously reproduces severe electron pressure losses along field lines by the presence of recycling zone accounting for the transitions between the sheath limited and the detached divertor regimes. The substantial profile changes in carbon impurity population and ionic composition also represent the key features of this divertor regime transition.

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Section: ͑15͒supporting

confidence: 74%

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Kim

Hong

2005

Physics of Plasmas

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“…SELF and EWALD [4] pointed out, that by taking into account the inertia term, the Schottky theory can also be applied for low pressures and leads to results which are in good agreement with those of the free fall theory. Thus, the Self-Ewald approach represented a transition between the two older theories and provided results also for intermediate pressures.…”

Section: Introductionsupporting

confidence: 68%

Numerical Modeling of the Non‐Isothermal Positive Column of an Ar⁺‐Laser

Zech

Ertl

Herold

et al. 1992

Contrib. Plasma Phys.

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A hydrodynamic description of the positive column is used to study the radial variation of particle densities, drift velocities, temperatures and heat fluxes of electrons, singly-charged ions and neutral atoms and the radial electric field. Elastic collisions between the plasma particles and neutrals as well as Coulomb collisions between ions and electrons are taken into account. The relevant equations to solve are the balance equations of particle densities, momentum, energy and the equations for the heat fluxes for each of the three studied particle types; the Poisson equation has to be added for closure. They form a system of 13 nonlinear differential equations with critical points. One singularity occurs when the ions reach the ion sound velocity which is the case inside the positive column. Therefore, a numerical method for multipoint boundary value problems was used which can also successfully handle removable singular points. The applied relaxation method is an iterative method which demands some preliminary knowledge of the solution looked for. The necessary knowledge can be retrieved from the quasineutral model and from a simplified two-fluid model.

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“…Since both the neutral and plasma pressures in the vicinity of the targets in the high-recycling regime are significantly lower than P up , it is widely assumed that P recyl is related to the effective ion-neutral drag force. This idea is usually illustrated by the results following from the paper by Self & Ewald (1966), where an isothermal plasma flow to a material surface through a cloud of a cold, stationary neutral gas was analysed. This model is based on the balance equations of the plasma momentum and particle fluxes: 12a,b) where is the coordinate along the magnetic field, T = const.…”

Section: Recycling Regionmentioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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The basic physics of the processes playing the most important role in divertor plasma detachment is reviewed. The models used in the two-dimensional edge plasma transport codes that are widely used to address different issues of the edge plasma physics and to simulate the experimental data, as well as the numerical schemes and convergence issues, are described. The processes leading to ultimate divertor plasma detachment, the transition to and the stability of the detached regime, as well as the impact of the magnetic configuration and divertor geometry on detachment, are considered. A consistent, integral physical picture of ultimate detachment of a tokamak divertor plasma is developed.

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Static Theory of a Discharge Column at Intermediate Pressures

Cited by 246 publications

References 6 publications

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Numerical Modeling of the Non‐Isothermal Positive Column of an Ar⁺‐Laser

Physics of ultimate detachment of a tokamak divertor plasma

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Static Theory of a Discharge Column at Intermediate Pressures

Cited by 246 publications

References 6 publications

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

Numerical Modeling of the Non‐Isothermal Positive Column of an Ar+‐Laser

Physics of ultimate detachment of a tokamak divertor plasma

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Numerical Modeling of the Non‐Isothermal Positive Column of an Ar⁺‐Laser