Scattering of lower-hybrid waves by drift-wave density fluctuations: solutions of the radiative transfer equation

Journal Article · Thu Sep 01 04:00:00 EDT 1983 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.864443· OSTI ID:5860894

Andrews, P L; Perkins, F W

The investigation of the scattering of lower-hybrid waves by density fluctuations arising from drift waves in tokamaks is distinguished by the presence in the wave equation of a large, random, derivative-coupling term. The propagation of the lower-hybrid waves is well represented by a radiative transfer equation when the scale size of the density fluctuations is small compared to the overall plasma size. The radiative transfer equation is solved in two limits: first, the forward scattering limit, where the scale size of density fluctuations is large compared to the lower-hybrid perpendicular wavelength, and second, the large-angle scattering limit, where this inequality is reversed. The most important features of these solutions are well represented by analytical formulas derived by simple arguments. Based on conventional estimates for density fluctuations arising from drift waves and a parabolic density profile, the optical depth tau for scattering through a significant angle, is given by tauroughly-equal(2/N/sup 2//sub parallel/) (..omega../sub p/i0/..omega..)/sup 2/ (m/sub e/c/sup 2//2T/sub i/)/sup 1/2/ (c/..cap alpha..(..cap omega../sub i/..cap omega../sub e/)/sup 1/2/ ), where ..omega../sub p/i0 is the central ion plasma frequency and T/sub i/ denotes the ion temperature near the edge of the plasma. Most of the scattering occurs near the surface. The transmission through the scattering region scales as tau/sup -1/ and the emerging intensity has an angular spectrum proportional to cos theta, where sin theta = k/sub perpendicular/xB/sub p//(k/sub perpendicular/B/sub p/), and B/sub p/ is the poloidal field.

• Research Organization: Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5860894
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 26:9; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101 -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
CLOSED PLASMA DEVICES
DRIFT INSTABILITY
FLUCTUATIONS
HEATING
HIGH-FREQUENCY HEATING
INSTABILITY
LOWER HYBRID HEATING
PLASMA
PLASMA DENSITY
PLASMA HEATING
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
PLASMA WAVES
SCATTERING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VARIATIONS