Magnetohydrodynamic flow layer formation in development of resistive double tearing mode

Quasilinear development of double tearing modes induced by plasma resistivity is numerically analyzed. The spatiotemporal characteristics of the modes are analyzed in detail. Magnetohydrodynamic flow layers are demonstrated to merge in the development of the modes. The sheared flows lie just at the boundaries of the magnetic islands in the quasilinear stage. The flows have sufficient levels of shear required for turbulence suppression. Possible correlation between the layer formation and triggering of experimentally observed internal transport barriers, preferentially formed in the proximity of rational flux surfaces of low safety factors, is discussed.