Magnetic topology and guiding centre drift orbits in a reversed shear tokamak

The magnetic topology and particle drift orbits are analysed in a monotonic q profile and in a reversed shear TEXTOR equilibrium that is subject to a magnetic perturbation driven by the Dynamic Ergodic Divertor (DED). The mai n results prove that there exists a transport barrier for magnetic field li nes and for circulating particles in the reversed shear case when the DED i s applied. This transport barrier occurs near the surface of minimum q valu e where the KAM theory may be invalid. Moreover, it should be noted that tr apped particles are lost due to the presence of ripple and that the DED doe s not affect their trajectories. To analyse magnetic topology, a symplectic perturbed map is used and the guiding centre orbits are evaluated in Booze r co-ordinates.