On the applicability of the standard approaches for evaluating a neoclassical radial electric field in a tokamak edge region
The use of the standard approaches for evaluating a neoclassical radial electric field E _{r}, i.e., the Ampere (or gyroPoisson) 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 highorder corrections to a local Maxwellian distribution due to the intrinsic ambipolarity of particle transport. The evaluation of such highorder 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, chargeexchange collisions with neutrals and prompt ion orbit losses can drive nonintrinsically ambipolar particle fluxes for which a nontrivial (E _{r}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 nonintrinsically ambipolar processes, thus allowing for the use of the standard approaches, are discussed.
 Authors:

^{[1]};
^{[1]};
^{[2]};
^{[1]}
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Publication Date:
 Report Number(s):
 LLNLJRNL609355
Journal ID: ISSN 1070664X; PHPAEN
 Grant/Contract Number:
 AC5207NA27344
 Type:
 Accepted Manuscript
 Journal Name:
 Physics of Plasmas
 Additional Journal Information:
 Journal Volume: 20; Journal Issue: 8; Journal ID: ISSN 1070664X
 Publisher:
 American Institute of Physics (AIP)
 Research Org:
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION; tokamaks; electric fields; charge exchange reactions; Maxwell equations; orbital dynamics
 OSTI Identifier:
 1248311
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.,
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. doi: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.
doi: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 gyroPoisson) 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 highorder corrections to a local Maxwellian distribution due to the intrinsic ambipolarity of particle transport. The evaluation of such highorder 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, chargeexchange collisions with neutrals and prompt ion orbit losses can drive nonintrinsically ambipolar particle fluxes for which a nontrivial (Erdependent) 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 nonintrinsically ambipolar processes, thus allowing for the use of the standard approaches, are discussed.},
doi = {10.1063/1.4818777},
journal = {Physics of Plasmas},
number = 8,
volume = 20,
place = {United States},
year = {2013},
month = {8}
}