The nonlinear ponderomotive (PM) force due to high-power rf waves is studied as a drive for plasma rotation. It is shown that poloidal rotation may be driven by a radial PM force, in addition to the usual mechanism of direct angular momentum transfer from a poloidal PM force. Here, the effect of a radial PM force producing a radial plasma flow in the presence of viscous damping and neutral collisions is considered. The PM force is produced around an electron cyclotron resonant surface at a specific poloidal location, which naturally creates a poloidally asymmetric steady radial flow, when friction is present. The flow can also arise as a result of poloidal or toroidal PM force components, even in the absence of friction. In toroidal geometry this situation is unstable due to the Stringer spin-up mechanism, for a high enough power of the rf waves. This process is most important near the outer regions of the plasma, where it can then give rise to a high confinement mode (H mode), once a sheared poloidal flow is established. The advantage of this method of driving rotation is that the wave can propagate radially and when it is absorbed at the resonant surface the radial PM force is produced, instead of launching a wave in the poloidal direction. It is shown that this effect may be large enough for electron-cyclotron resonance heating, due to the small width of the resonant surface.

Neoclassical theory provides usable expressions for studying transport in toroidal plasmas and computing the associated radial electric field. An algebraic and three semi-analytical models are used here to study the radial electric field in TJ-II plasmas and compare it with experimental data from a heavy ion beam probe (HIBP) and with DKES calculations. Good qualitative agreement as well as reasonable quantitative agreement is found which allows us to validate the models for describing TJ-II radial electric fields. Furthermore, a simple algebraic formulation (2005 Plasma Phys. Rep. 31 14) provides physical insight for the interpretation of experimental data from the TJ-II heliac in spite of its complicated geometry, like the place of the transition from the electron to the ion root of the radial electric field, which occurs at the maximum value of collisionality, for example.

Poloidal divertors are, more than ever before, a crucial topic for the advancement of magnetic fusion technology. Due to the often non linear and stochastic nature of the plasma edge phenomena, canonical mapping has provided a powerful method at modelling their characteristics, albeit many authors rely on heuristically adapted schemes. Thus, it is reported here a specific and physically consistent map model of the tokamak single null magnetic configuration, assuming plasma-field equilibrium, based on the construction of a fundamental Hamiltonian form. Then, the magnetohydrodynamically non ideal perturbations are introduced through the Rayleigh function of the system. As an illustration, the resulting compact canonical map is applied to the analysis of some of the most relevant features of the edge magnetic topology.

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