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A two-dimensional integral full-wave model is used to calculate poloidal forces driven by mode conversion in tokamak plasmas. In the presence of a poloidal magnetic field, mode conversion near the ion-ion hybrid resonance is dominated by a transition from the fast magnetosonic wave to the slow ion cyclotron wave. The poloidal field generates strong variations in the parallel wave spectrum that cause wave damping in a narrow layer near the mode conversion surface. The resulting poloidal forces drive sheared poloidal flows comparable to those in direct launch ion Bernstein wave experiments. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

A fully numerical calculation of ion velocity and spatial diffusion coefficients resulting from full wave code electromagnetic fields in tokamak geometry, has been implemented. EM fields are obtained from the TORIC and AORSA-2D codes. The described coefficient calculator integrates the unapproximated Lorentz equation of motion to obtain the change in velocity after one complete transit of the noncircular tokamak flux surfaces. Averaging velocity changes over initial starting gyro-phase and initial toroidal angle of an ion, gives bounce-averaged diffusion coefficients. Performing this operation for an array of initial parallel and perpendicular velocities and radial locations gives the full set of coefficients. Coupling the coefficients to the CQL3D Fokker-Planck code enables calculation of the equilibrium nonthermal ion distribution function resulting from the EM fields and collisions. This calculation is computationally feasible due to the recent rapid advances of computing hardware. Adequate resolution is obtained in 50 CPU hours. Initial results will be presented, and compared with a Fokker-Planck/ray-tracing calculation. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Numerical techniques (windowed Fourier transforms and wavelets) are developed for carrying out a local mode analysis k(x) of ICRF field solutions. It is shown that simultaneous resolution of long- and short-wavelength waves in typical rf mode conversion scenarios requires the use of a modified wavelet transform. The ability to get quantitative information by this technique is assessed and visualization techniques for wave polarization information are illustrated. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We examine the effects on RF wave absorption of two different types of particle wave resonance decorrelations. These two mechanisms are collisions and parallel gradients in the magnetic field. A careful treatment of collisions shows that in the integrand for the plasma dispersion function there is an interaction term which couples both decorrelation mechanisms. In toroidal fusion devices each type of decorrelation dominates in a certain region of space. Of special interest is the region where magnetic field lines intersect the resonant surface with low angle of incidence. In this region neither decorrelation mechanisms dominates over the other, and the combination of the two produces different absorption physics than either mechanism separately. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recent progress on the numerical computation of 2D full-wave field solutions has motivated advances in the nonlinear theory of rf-induced plasma flows for the control of turbulence. Here, an accounting of how momentum is injected into the system by the antenna, and how it can be transferred from waves to plasma flows and to the equilibrium magnetic field coils and walls is given. Equations for both the plasma momentum and the wave momentum are developed. The former is a recapitulation of results from nonlinear flow drive theory. The latter equation yields a generalized form of the Maxwell stress tensor, including plasma dielectric effects. It is shown that momentum is conserved by the plasma-wave-antenna-wall system for poloidal and toroidal flux-surface-averaged flows. In general, however, momentum exchange with the equilibrium magnetic field coils is possible. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]