Transport bursts in simulations of edge-localized modes (ELMs) in tokamaks are suppressed by increasing the magnetic shear. As the magnetic shear becomes larger, the magnitude of the bursts is reduced and the frequency of the bursts decreases. The suppression of the ELM bursts by magnetic shear is very similar to the suppression of the bursts by resonant magnetic field perturbations. However, increasing the magnitude of resonant magnetic field perturbations can lead to the destruction of magnetic flux surfaces and magnetic field line stochasticity. In contrast, magnetic flux surfaces are preserved when the magnetic shear is increased in an axisymmetric tokamak magnetic field.
Nonlinear evolution and deformation of driven magnetic islands in rotating plasmas