Effect of E x B flows on global linear ion temperature gradient modes

Strong electric fields generate an ExB rotation of the equilibrium plasma. Experiments have shown that this effect could lower the anomalous transport in tokamaks. The study of the effect of these flows on the linear stability of ion temperature gradient (ITG) modes has therefore been undertaken. The question is addressed solving the spectrum of the gyrokinetic equation in the full two-dimensional poloidal plane for a large aspect ratio tokamak with concentric circular magnetic surfaces. Results show a strong stabilizing effect of ExB flows on the ITG modes. Study with respect to different profiles of the flow shows that the so-called curvature of flow (second derivative) has no effect, while the intensity of flow itself produces the strongest effect. Study with respect to different magnetic shears did not allow the discovery of any particular behavior of the negative magnetic shear cases. Eventually, an experimental comparison was conducted. (C) 2001 American Institute of Physics.