Effect of Plasma Shape on the Double‐Tearing Mode

ABSTRACT The influence of plasma shaping on the stability of the double‐tearing mode (DTM) is examined using a hybrid gyrokinetic‐ion/fluid‐electron model. In the cold‐ion limit, both triangularity and elongation enhance the geometric drive of the DTM, although they do so through different modifications to magnetic shear, curvature, and flux‐surface compression. Finite‐temperature ions introduce stabilizing radial magnetic‐drift effects, but the associated damping becomes less effective as the shaping strength increases. The results indicate a competition between geometric and kinetic contributions to DTM stability and may support the interpretation of shaping‐dependent tearing behavior in advanced tokamak configurations.