Abstract
An investigation is made into the effect of particle dragging, which occurs when toroidal plasmas are r.f. heated by travelling waves. A generalized quasi-linear relaxation theory in a collisional plasma is developed, including the effect of the conservation of the longitudinal component of momentum. The dependence of the toroidal current on the amplitude of the r.f. field and on the plasma parameters is obtained and a saturation effect for this current is found at strong r.f. fields.