Theory of neoclassical pressure-gradient-driven turbulence

Journal Article · Thu Feb 01 00:00:00 EST 1990 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859238· OSTI ID:6992383

Kwon, O J ^[1]; Diamond, P H; Biglari, H ^[2]

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1. Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (USA)
2. Department of Physics, University of California, San Diego, La Jolla, California 92093 (USA) General Atomics, Inc., San Diego, California 92138 (USA)

The nonlinear evolution and saturation of neoclassical pressure-gradient-driven turbulence (NPGDT), evolving from linearly unstable bootstrap-current modes, are investigated. The theoretical model is based on neoclassical magnetohydrodynamic (MHD) equations'' that are valid in the banana-plateau regimes of collisionality. Modes with poloidal wavelengths shorter than radial wavelengths are shown to be suppressed. From nonlinear saturation conditions, the turbulent pressure diffusivity is determined as an eigenvalue of the renormalized equations. Levels and radial scales of turbulence are determined from the pressure diffusivity and are shown to exceed mixing-length estimates by powers of a nonlinear enhancement factor. The problem of the electron heat transport resulting from stochastic magnetic fields driven by NPGDT is revisited. The reconsideration of the radial structure of magnetic flutter leads to estimates of the electron heat transport and magnetic fluctuation levels that differ qualitatively and quantitatively from previous calculations.

• DOE Contract Number: FG05-80ET53088; FG03-88ER53275
• OSTI ID: 6992383
• Journal Information: Physics of Fluids B; (USA), Vol. 2:2; ISSN 0899-8221
• Country of Publication: United States
• Language: English

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