Effects of flow shear on the ion-temperature-gradient-driven instability (ITG mode) is reported. The variable flow shear is created by controllable nonuniform radial electric field. The experimental results show that large flow shear is capable of suppressing the ITG mode but the strength of the required shear is significantly larger than that predicted by most theories.

• Received 14 September 1993

DOI:https://doi.org/10.1103/PhysRevLett.72.92