Destabilization of global Alfven eigenmodes and kinetic Alfven waves by alpha particles in a tokamak plasma

Journal Article · Fri May 01 04:00:00 EDT 1987 · Phys. Fluids; (United States)

OSTI ID:6561110

Li, Y M; Mahajan, S M; Ross, D W

Alfven wave instabilities in a reacting tokamak plasma are calculated both analytically and numerically. Two distinct classes of eigenmodes are considered, global Alfven eigenmodes and kinetic Alfven waves, each driven unstable by the free energy associated with the alpha particle density gradient. The growth rates of the global Alfven eigenmodes are given for the first time. These are basically magnetohydrodynamic (MHD) modes, whose resonances with electrons and alpha particles are calculated using kinetic theory. The calculation of kinetic Alfven wave growth rates is improved from earlier treatments. These modes depend on electron inertia and finite ion gyroradius for their existence and have no counterpart in MHD theory. In both sets of calculations toroidal coupling of the alpha particle response to sidebands in the poloidal mode number is fully taken into account. Global modes with small parallel phase velocity are identified as the most dangerous, both because of their substantial growth rates and the expected ineffectiveness of quasilinear stabilization. The kinetic waves, on the other hand, are likely to be stabilized easily by quasilinear flattening of the alpha particle profile. Calculations using both Maxwellian and slowing-down alpha distributions are performed, showing that, for the same alpha density and energy density, the slowing-down distribution yields somewhat larger growth rates.

• Research Organization: Fusion Research Center, The University of Texas at Austin, Austin, Texas 78712
• OSTI ID: 6561110
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 30:5; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ALFVEN WAVES
ALPHA PARTICLES
ANALYTICAL SOLUTION
ANNULAR SPACE
CHARGED PARTICLES
CHEMICAL REACTIONS
CLOSED PLASMA DEVICES
CONFIGURATION
COUPLING
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
EQUATIONS
FERMIONS
FLUID MECHANICS
FREE ENERGY
HYDRODYNAMICS
HYDROMAGNETIC WAVES
INSTABILITY
INSTABILITY GROWTH RATES
KINETIC EQUATIONS
LEPTONS
MAGNETOHYDRODYNAMICS
MECHANICS
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
PLASMA
PLASMA INSTABILITY
RESONANCE
SPACE
THERMODYNAMIC PROPERTIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TOROIDAL CONFIGURATION