Stochastic model for lower hybrid wave scattering by density fluctuations

Journal Article · Sat Jun 01 04:00:00 EDT 1985 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.864921· OSTI ID:5816052

Grossmann, W; Spigler, R

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, k/sub y/M, appearing in the wave equation, where k/sub y/ is the poloidal wavenumber of the incident wave and Mequivalent<..omega../sup 2//sub p/e>/..omega cap omega../sub c/e . 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 P/sub t/ transmitted through the scattering region is given as a function of the usual parameter epsilon/sup 2/LS, where epsilon 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 (epsilon,L/aapprox.0.01--0.1, where a is the plasma radius; k/sub y//k/sub parallel/ approx.0.5--1.0) the present theory predicts a P/sub t/approx.10%: 50% which favorably agrees with Andrews and Perkins' (P. L. Andrews and F. W. Perkins, Phys. Fluids 26, 2537 (1983)) radiative transfer model.

• Research Organization: Courant Institute of Mathematical Sciences, New York University, New York, New York 10012
• DOE Contract Number: AC02-76ER03077
• OSTI ID: 5816052
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 28:6; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101 -- Fusion Energy-- Plasma Research-- Confinement
Heating
&amp; Production
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
CLOSED PLASMA DEVICES
DIFFERENTIAL EQUATIONS
DRIFT INSTABILITY
EQUATIONS
FLUCTUATIONS
HEATING
HYBRID RESONANCE
INSTABILITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLASMA
PLASMA DENSITY
PLASMA HEATING
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RANDOMNESS
REFRACTIVITY
RESONANCE
SCATTERING
STOCHASTIC PROCESSES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VARIATIONS