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

Technical Report · Sat Sep 01 00:00:00 EDT 1990

DOI:https://doi.org/10.2172/6227661· OSTI ID:6227661

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

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1. Texas Univ., Austin, TX (USA). Inst. for Fusion Studies
2. California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics General Atomics, San Diego, CA (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. Saturated fluctuation spectrum is calculated using the condition of nonlinear saturation. The turbulent transport coefficients are in turn calculated using saturated fluctuation spectrum. Due to the disparity in the three different radial scale lengths of the slab-like eigenmode: {Delta} (trapped electron layer width), x{sub t} (turning point width) and x{sub i} (Landau damping point), {Delta} < x{sub t} < x{sub i}, we find 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}(k{sub {theta}}) {approximately} k{sub {theta}}{sup {minus}{alpha}} ({alpha} = 2 and 3 for the dissipative and collisionless regime, respectively) occurs for k{sub {theta}}{rho}{sub s} < 1 and is heavily damped for k{sub {theta}}{rho}{sub s} > 1. The predicted fluctuation level and transport coefficients are well below the mixing length'' estimate. This is due to the contribution of radial wavenumbers x{sub t}{sup {minus}1} < k{sub r} {le} {rho}{sub i}{sup {minus}1} to the nonlinear couplings, the effect of radial localization of trapped electron response to a layer of width, {Delta}, and the weak turbulence factor {l angle}({gamma}{sub e}{sup l})/({omega}{sub {rvec {kappa}}}){r angle}{sub {rvec k}} < 1, which enters the saturation level. 18 refs., 1 tab.

• Research Organization: Texas Univ., Austin, TX (USA). Inst. for Fusion Studies
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG05-80ET53088
• OSTI ID: 6227661
• Report Number(s): DOE/ET/53088-456; IFSR-456; ON: DE91004302; TRN: 91-000081
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
PLASMA WAVES
TURBULENCE
TOKAMAK DEVICES
TRANSPORT THEORY
TRAPPED ELECTRONS
KINETICS
COMPTON EFFECT
FLUCTUATIONS
KINETIC EQUATIONS
MAGNETIC FIELDS
PLASMA DRIFT
SCATTERING
SHEAR
BASIC INTERACTIONS
CLOSED PLASMA DEVICES
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELECTRONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
INTERACTIONS
LEPTONS
THERMONUCLEAR DEVICES
VARIATIONS
700103* - Fusion Energy- Plasma Research- Kinetics
700108 - Fusion Energy- Plasma Research- Wave Phenomena