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Title: On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region

Abstract

The use of the standard approaches for evaluating a neoclassical radial electric field Er, i.e., the Ampere (or gyro-Poisson) equation, requires accurate calculation of the difference between the gyroaveraged electron and ion particle fluxes (or densities). In the core of a tokamak, the nontrivial difference appears only in high-order corrections to a local Maxwellian distribution due to the intrinsic ambipolarity of particle transport. The evaluation of such high-order corrections may be inconsistent with the accuracy of the standard long wavelength gyrokinetic equation (GKE), thus imposing limitations on the applicability of the standard approaches. However, in the edge of a tokamak, charge-exchange collisions with neutrals and prompt ion orbit losses can drive non-intrinsically ambipolar particle fluxes for which a nontrivial (Er-dependent) difference between the electron and ion fluxes appears already in a low order and can be accurately predicted by the long wavelength GKE. As a result, the parameter regimes where the radial electric field dynamics in the tokamak edge region is dominated by the non-intrinsically ambipolar processes, thus allowing for the use of the standard approaches, are discussed.

Authors:
 [1];  [1];  [2];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1248311
Report Number(s):
LLNL-JRNL-609355
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 20; Journal Issue: 8; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; tokamaks; electric fields; charge exchange reactions; Maxwell equations; orbital dynamics

Citation Formats

Dorf, M. A., Cohen, R. H., Simakov, A. N., and Joseph, I. On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region. United States: N. p., 2013. Web. doi:10.1063/1.4818777.
Dorf, M. A., Cohen, R. H., Simakov, A. N., & Joseph, I. On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region. United States. https://doi.org/10.1063/1.4818777
Dorf, M. A., Cohen, R. H., Simakov, A. N., and Joseph, I. 2013. "On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region". United States. https://doi.org/10.1063/1.4818777. https://www.osti.gov/servlets/purl/1248311.
@article{osti_1248311,
title = {On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region},
author = {Dorf, M. A. and Cohen, R. H. and Simakov, A. N. and Joseph, I.},
abstractNote = {The use of the standard approaches for evaluating a neoclassical radial electric field Er, i.e., the Ampere (or gyro-Poisson) equation, requires accurate calculation of the difference between the gyroaveraged electron and ion particle fluxes (or densities). In the core of a tokamak, the nontrivial difference appears only in high-order corrections to a local Maxwellian distribution due to the intrinsic ambipolarity of particle transport. The evaluation of such high-order corrections may be inconsistent with the accuracy of the standard long wavelength gyrokinetic equation (GKE), thus imposing limitations on the applicability of the standard approaches. However, in the edge of a tokamak, charge-exchange collisions with neutrals and prompt ion orbit losses can drive non-intrinsically ambipolar particle fluxes for which a nontrivial (Er-dependent) difference between the electron and ion fluxes appears already in a low order and can be accurately predicted by the long wavelength GKE. As a result, the parameter regimes where the radial electric field dynamics in the tokamak edge region is dominated by the non-intrinsically ambipolar processes, thus allowing for the use of the standard approaches, are discussed.},
doi = {10.1063/1.4818777},
url = {https://www.osti.gov/biblio/1248311}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 20,
place = {United States},
year = {Tue Aug 27 00:00:00 EDT 2013},
month = {Tue Aug 27 00:00:00 EDT 2013}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 5 works
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Works referenced in this record:

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Works referencing / citing this record:

Continuum kinetic modeling of the tokamak plasma edge
journal, May 2016