Omniclassical Diffusion in Low Aspect Ratio Tokamaks [electronic resource].
- Published
- Washington, D.C. : United States. Dept. of Energy. Office of Science, 2004.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy. - Physical Description
- 736 Kilobytes pages : digital, PDF file
- Additional Creators
- United States. Department of Energy. Office of Science and United States. Department of Energy. Office of Scientific and Technical Information
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- Restrictions on Access
- Free-to-read Unrestricted online access
- Summary
- Recently reported numerical results for axisymmetric devices with low aspect ratio A found radial transport enhanced over the expected neoclassical value by a factor of 2 to 3. In this paper, we provide an explanation for this enhancement. Transport theory in toroidal devices usually assumes large A, and that the ratio B{sub p}/B{sub t} of the poloidal to the toroidal magnetic field is small. These assumptions result in transport which, in the low collision limit, is dominated by banana orbits, giving the largest collisionless excursion of a particle from an initial flux surface. However in a small aspect ratio device one may have B{sub p}/B{sub t} ≈ 1, and the gyroradius may be larger than the banana excursion. Here, we develop an approximate analytic transport theory valid for devices with arbitrary A. For low A, we find that the enhanced transport, referred to as omniclassical, is a combination of neoclassical and properly generalized classical effects, which become dominant in the low-A, B{sub p}/B{sub t} ≈ 1 regime. Good agreement of the analytic theory with numerical simulations is obtained.
- Report Numbers
- E 1.99:pppl-3935
pppl-3935 - Subject(s)
- Other Subject(s)
- Note
- Published through SciTech Connect.
03/19/2004.
"pppl-3935"
R.B. White; D.A. Gates; H.E. Mynick.
Princeton Plasma Physics Lab., Princeton, NJ (US) - Type of Report and Period Covered Note
- Topical;
- Funding Information
- AC02-76CH03073
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