This Brief Communication investigates the influence of toroidal effects (due to the coupling of various poloidal harmonics) on the nonlinear saturation of the m = 1 island. Bounds are obtained relating the aspect ratio, the shear at the q= 1 surface, and the saturated island width. Provided these bounds are satisfied, it is then found that the cyli…
09The thin beam model of an axis-encircling relativistic electron beam in a uniform, constant, external magnetic field in a cylindrical waveguide is used to develop a unified theory of the various interactions of such a beam with the electromagnetic field. The model includes the gyrotron interaction (longitudinal displacement of the beam) and the p…
The question of the influence of nonaxisymmetric field perturbations on tokamaks is investigated. Recent experiments in the COMPASS-C tokamak [in Proceedings of the 15th Symposium on Fusion Technology, Utrecht (North-Holland, Amsterdam, 1989), Vol. 1, p. 3611 with externally applied helical fields reveal that magnetic islands do not appear until th…
