Author/Authors :
Caldas، نويسنده , , I.L. and Viana، نويسنده , , R.L. and Szezech Jr.، نويسنده , , J.D. and Portela، نويسنده , , J.S.E. and Fonseca، نويسنده , , J. and Roberto، نويسنده , , M. and Martins، نويسنده , , C.G.L. and da Silva، نويسنده , , E.J.، نويسنده ,
Abstract :
We review symplectic nontwist maps that we have introduced to describe Lagrangian transport properties in magnetically confined plasmas in tokamaks. These nontwist maps are suitable to describe the formation and destruction of transport barriers in the shearless region (i.e., near the curve where the twist condition does not hold). The maps can be used to investigate two kinds of problems in plasmas with non-monotonic field profiles: the first is the chaotic magnetic field line transport in plasmas with external resonant perturbations. The second problem is the chaotic particle drift motion caused by electrostatic drift waves. The presented analytical maps, derived from plasma models with equilibrium field profiles and control parameters that are commonly measured in plasma discharges, can be used to investigate long-term transport properties.
