The effect of sheared diamagnetic flow on turbulent structures generated by the Charney-Hasegawa-Mima equation

The generation of electrostatic drift wave turbulence is modeled by the Cha rney-Hasegawa-Mima equation. The equilibrium density gradient n(0) = n(0)(x ) is chosen so that dn(0)/dx is nonzero and spatially variable (i.e., v(*e) is sheared). It is shown that this sheared diamagnetic flow leads to local ized turbulence which is concentrated at max(del n(0)), with a large dv(*e) /dx inhibiting the spread of the turbulence in the x direction. Coherent st ructures form which propagate with the local v(*e) in the y direction. Move ment in the x direction is accompanied by a change in their amplitudes. Whe n the numerical code is initialized with a single wave, the plasma behavior is dominated by the initial mode and its harmonics. (C) 1999 American Inst itute of Physics. [S1070-664X(99)00510-8].