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 stabilit y of ion temperature gradient (ITG) modes has therefore been undertaken. Th e question is addressed solving the spectrum of the gyrokinetic equation in the full two-dimensional poloidal plane for a large aspect ratio tokamak w ith concentric circular magnetic surfaces. Results show a strong stabilizin g effect of ExB flows on the ITG modes. Study with respect to different pro files of the flow shows that the so-called curvature of flow (second deriva tive) has no effect, while the intensity of flow itself produces the strong est effect. Study with respect to different magnetic shears did not allow t he discovery of any particular behavior of the negative magnetic shear case s. Eventually, an experimental comparison was conducted. (C) 2001 American Institute of Physics.