Reduction of the chaotic transport of impurities in turbulent magnetized plasmas

The control of transport in magnetically confined plasmas is of major importance in the long way to achieve controlled thermonuclear fusion. Two major mechanisms have been proposed for such a turbulent transport: transport governed by the fluctuations of the magnetic field and transport governed by fluctuations of the electric field. There is presently a general consensus to consider, at low plasma pressure, that the latter mechanism agrees with experimental evidence [1]. In the area of transport of trace impurities, i.e. that are sufficiently diluted so as not to modify the electric field pattern, the E×B drift motion of test particles should be the exact transport model. The possibility of reducing and even suppressing chaos (combined with the empirically found states of improved confinement in tokamaks) suggest to investigate the possibility to devise a strategy of control of chaotic transport through some smart perturbations acting at the microscopic level of charged particle motions. Chaotic transport of particles advected by a turbulent electric field with a strong magnetic field is associated with Hamiltonian dynamical systems under the approximation of the guiding center motion due to E×B drift velocity. For an appropriate choice of turbulent electric field, it has been shown that the resulting diffusive trans-