Effects of Shafranov shift on the ballooning mode in negative shear

In negative shear tokamak discharges, an excessively large Shafranov shift (Delta') destabilizes the MHD (magnetohydromagnetic) ballooning mode. A kin etic model, local to a flux surface and which employs the ballooning mode r epresentation of the gyrokinetic equations, also predicts the existence of the instability as does two-fluid theory.