Influence of equilibrium magnetic shear on the double tearing modes for different rational surface spacing

Based on the two-dimensional geometric model, the influence of equilibrium magnetic shear on the double tearing modes for different rational surface spacing is numerically simulated. We find that when the spacing is small, the saturation time of unstable mode decreases with the increase of the equilibrium magnetic shear. With the spacing increases, the saturation time will gradually change from decreasing with the increase of the equilibrium magnetic shear to increasing with the increase of the equilibrium magnetic shear. When the spacing is large, the saturation time increases with the equilibrium magnetic shear.