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Comments on ECH current drive by asymmetric heating around the median plane (GA Technologies report No. GA-A18656, October 1986) by Tihiro Ohkawa [electronic resource].

Published
Livermore, Calif : Lawrence Livermore National Laboratory, 1987.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
Pages: 12 : digital, PDF file
Additional Creators
Lawrence Livermore National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
In a recent GA report Ohkawa describes a novel electron cyclotron current-drive (ECCD) scheme. Ohkawa finds a net toroidal plasma current driven by ''up-down'' asymmetries in the electron pressure anisotropy, i.e., differences in p/sub perpendicular/ - p/sub parallel/ evaluated at the same absolute value of B between the top and bottom half of the poloidal cross-section. Such up-down asymmetries are associated with the s-dependent, first order in nu/..omega../sub b/ part of the electron distribution function (s is distance along a magnetic field line). The current-drive efficiency estimated by Ohkawa is competitive with other rf current-drive schemes. Ohkawa's scheme is attractive because it appears that this scheme can produce an rf-driven current even when the electron-cyclotron power is dissipated on trapped electrons; and the scheme requires no selectivity in the sign of the parallel velocity of the electrons heated by the electron cyclotron wave. In sections I through III of this memo we analyze the current-drive calculation presented by Ohkawa. We conclude that, in the limit of long mean-free-path appropriate to current tokamak experiments and tokamak reactors, the current Ohkawa attempts to compute from a fluid model is a neoclassical correction to the Fisch-Boozer current. Neoclassical effects that give rise to corrections of this sort were first pointed out by Ohkawa in an earlier paper on ECH current drive. These neoclassical effects (which are associated with magnetic field variations and trapped particles) have been treated more accurately by using a kinetic rather than fluid theory in several recent papers. They are important because they can reduce the ECCD efficiency below the level computed by Fisch and Boozer.
Report Numbers
E 1.99:ucid-21033
ucid-21033
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
03/30/1987.
"ucid-21033"
"DE87008341"
Cohen, R.H.; Nevins, W.M.; Lodestro, L.L.
Funding Information
W-7405-ENG-48
View MARC record | catkey: 14751183