Viscous relaxation of drift-Alfvén waves in tokamaks and its applicationfor triggering improved confinement regimes

Viscous damping of the drift-Alfvén modes in tokamaks and its application for triggering improved confinement regimes are considered. It is shown that these waves are effectively damped by the neoclassical viscosity with the upper limit for their frequency ω equal to the collision frequency of slow ions ν i ∕ ϵ , where ϵ is the inverse aspect ratio. Quasistationary plasma poloidal and toroidal velocities and current drive produced by damping of these waves are estimated. Evaluations of the viscosity effects on the Alfvén waves which were induced by the dynamic ergodic divertor in the Tokamak Experiment for Technology Oriented Research tokamak [ K. H. Finken , Phys. Rev. Lett. 94 , 015003 ( 2005 ) ] are made.