Shear Alfven waves in tokamaks

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5803696

Kieras, C E

Shear Alfven waves in an axisymmetric tokamak are examined within the framework of the linearized ideal MHD equations. Properties of the shear Alfven continuous spectrum are studied both analytically and numerically. Implications of these results in regards to low frequency rf heating of toroidally confined plasmas are discussed. The structure of the spatial singularities associated with these waves is determined. A reduced set of ideal MHD equations is derived to describe these waves in a very low ..beta.. plasma. Analytic expressions for the continuum are obtained by solving a set of coupled differential equations on each flux surface in an expansion scheme in powers of the small inverse aspect ratio, epsilon = a/R/sub 0/, where a and R/sub 0/ are the minor and major radii, respectively, of the toroid. To lowest order in epsilon, the continuum is given by an appropriate generalization of its counterpart in an infinitely long, axially periodic, cylindrically symmetric screw pinch. First order corrections due to toroidicity induce a coupling of particular poloidal harmonics about rational q surfaces, where q is the safety factor. The coupling leads to the formation of gaps in the continuum. Depending on the structure of the continuum near the gaps, it may not be possible to heat the plasma with certain oscillator frequencies and helicities. Numerical solutions for the shear Alfven continuum of the Tokapole II device at the University of Wisconsin, Madison, are in qualitative agreement with the predictions of the analytic model.

• Research Organization: Wisconsin Univ., Madison (USA)
• OSTI ID: 5803696
• 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
ALFVEN WAVES
ANALYTICAL SOLUTION
ASPECT RATIO
CLOSED PLASMA DEVICES
FLUID MECHANICS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
LOW-BETA PLASMA
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
SHEAR
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TORI