ON THE STABILIZATION OF NEOCLASSICAL TEARING MODES BY PHASED ELECTRON-CYCLOTRON WAVES

The stabilization of neoclassical tearing modes by phased electron cyc lotron current drive (ECCD) and electron cyclotron resonance heating ( ECRH) is studied numerically. The dependence of the saturated magnetic island width on the magnitude, width and location of the driven curre nt and the corresponding resistivity perturbation are investigated. Si nce the saturated island size cannot become much smaller than the widt h of the driven current layer, this width is one of the most important parameters. Assuming usual heat transport coefficients, the stabiliza tion by ECRH is found to be more effective than that by BCCD for a lar ge island in a middle-size tokamak, while the stabilization by BCCD sh ould be more effective for a tokamak reactor.