ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Recent tokamak experiments have shown the presence of drift-wave-induced random density fluctuations localized near the plasma edge. These fluctuations may be treated as a random perturbation of the refractive index that appears in the scalar wave equation obeyed by the electrostatic potential. The treatment here includes the additional effect on density gradient fluctuations through a term, kyM, appearing in the wave equation, where ky is the poloidal wavenumber of the incident wave and M≡〈ω2pe〉/ωΩce . This additional term is shown to have non-negligible consequences in several cases of physical interest. By invoking the modern theory of stochastic differential equations, various statistics of particular functionals of the potential may be computed. An explicit calculation of the fractional power Pt transmitted through the scattering region is given as a function of the usual parameter ε2LS, where ε is the relative density fluctuation amplitude, L is the scale width of the scattering region, and S is the power spectral density of the fluctuations. For typical tokamak parameters (ε,L/a∼0.01–0.1, where a is the plasma radius; ky/k(parallel) ∼0.5–1.0) the present theory predicts a Pt∼10%—50% which favorably agrees with Andrews and Perkins' [P. L. Andrews and F. W. Perkins, Phys. Fluids 26, 2537 (1983)] radiative transfer model.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.864921
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