Shearless bifurcations in particle transport for reversed-shear tokamaks

Some internal transport barriers in tokamaks have been related to the vicinity of extrema plasma equilibrium profiles. This effect is numerically investigated by considering guiding-center trajectories particles undergoing ExB drift motion, that electric field has a stationary nonmonotonic radial profile and an electrostatic fluctuation. In addition, configuration safety factor profile. The numerical integration equations motion yields symplectic map with shearless barriers. By changing parameters profile, appearance, breakup these curves are observed. successive recovering explained using concepts from bifurcation theory. We also present sequences associated creation multiple curves. Physical consequences scenarios discussed.