A kinetic theory of trapped-electron-driven drift wave turbulence in a sheared magnetic field

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859957· OSTI ID:6390064

Gang, F Y ^[1]; Diamond, P H; Rosenbluth, M N ^[2]

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1. Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (US)
2. Department of Physis B-019, University of California, San Diego, La Jolla, California 92093 (USA) General Atomics, Inc., San Diego, California 92186-9784 (USA)

A kinetic theory of collisionless and dissipative trapped-electron-driven drift wave turbulence in a sheared magnetic field is presented. Weak turbulence theory is employed to calculate the nonlinear electron and ion responses and to derive a wave kinetic equation that determines the nonlinear evolution of trapped-electron mode turbulence. The saturated fluctuation spectrum is calculated using the condition of nonlinear saturation. The turbulent transport coefficients ({ital D}, {chi}{sub {ital i}}, {chi}{sub {ital e}}), are, in turn, calculated using the saturated fluctuation spectrum. Because of the disparity in the three different radial scale lengths of the slab-like eigenmode: {Delta} (trapped-electron layer width), {ital x}{sub {ital t}} (turning point width), and {ital x}{sub {ital i}} (Landau damping point), {Delta}{lt}{ital x}{sub {ital t}}{lt}{ital x}{sub {ital i}}, it is found that ion Compton scattering rather than trapped-electron Compton scattering is the dominant nonlinear saturation mechanism. Ion Compton scattering transfers wave energy from short to long wavelengths where the wave energy is shear damped. As a consequence, a saturated fluctuation spectrum {vert bar}{phi}{vert bar}{sup 2}({ital k}{sub {theta}}){similar to}{ital k}{sup {minus}{alpha}}{sub {theta}} ({alpha}=2 and 3 for the dissipative and collisionless regimes, respectively) occurs for {ital k}{sub {theta}} {rho}{sub {ital s}}{lt}1 and is heavily damped for {ital k}{sub {theta}} {rho}{sub {ital s}}{gt}1. The predicted fluctuation level and transport coefficients are well below the mixing length'' estimate.

• OSTI ID: 6390064
• Journal Information: Physics of Fluids B; (USA), Vol. 3:1; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COLLISIONLESS PLASMA
TURBULENCE
COMPTON EFFECT
DAMPING
DRIFT INSTABILITY
ELECTRONS
ENERGY LOSSES
ENERGY TRANSFER
FLUCTUATIONS
KINETIC EQUATIONS
MAGNETIC FIELDS
NONLINEAR PROBLEMS
SATURATION
TRAPPING
BASIC INTERACTIONS
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
INSTABILITY
INTERACTIONS
LEPTONS
LOSSES
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
SCATTERING
VARIATIONS
700103* - Fusion Energy- Plasma Research- Kinetics