A general theoretical approach has been formulated for analyzing two-dimensional structures of high-n toroidal Alfvén eigenmodes (TAE) in large aspect-ratio, finite-β tokamaks. Here, n is the toroidal wave number and β is the ratio between plasma and magnetic pressures. The present approach generalizes the standard ballooning-mode formalism and is capable of treating eigenmodes with extended global radial structures, as well as finite coupling between discrete and continuous spectra. Employing the well-known (s,α) model equilibrium and assuming a linear equilibrium profile, the present approach has been applied to the calculation of the resonant continuum damping rate of TAE modes. Here, s and α denote, respectively, the strengths of magnetic shear and pressure gradients. In particular, it is found that there exists a critical α value, αc(s), such that, as α→αc, the continuum damping rate is significantly enhanced and, thus, could suppress the potential TAE instability. © 1993 American Institute of Physics.
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Physics and Astronomy(all)
- Fluid Flow and Transfer Processes