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Toroidal plasmas in RFP configuration: contact points with solar physics.

Martines E.
  Venerdì 30/09   15:00 - 18:00   Edificio Psicologia 2 - Aula 2B   II - Fisica della materia
The Reversed Field Pinch (RFP) is a toroidal configuration for the magnetic confinement of fusion-relevant plasmas. While less performing in terms of confinement properties than the more widespread tokamak configuration, it is interesting because of its potential of giving birth to a technologically simple fusion reactor. From the plasma physics point of view, the RFP offers a spectrum of phenomena which can be of interest to specialists of neighboring fields, in particular to solar physicists. Due to the dominance of the visco-resistive magnetohydrodynamics (MHD) model in determining the magnetic field structure, magnetic reconnection plays an important role in RFP physics, with periodic events giving rise to magnetic field reorganization and transfer of energy to the particles. Furthermore, the occurrence of the so-called Quasi- Single Helicity (QSH) states as the electron temperature increases, with the plasma undergoing a transition from a chaotic state to an ordered one characterized by a helical equilibrium, constitutes a beautiful example of spontaneous emergence of order from chaos. The chaos reduction and consequent local confinement improvement observed in QSH states has recently being related to the concept of a 3D quasiseparatrix layer, developed in solar physics to treat reconnection phenomena without true separatrices. This approach, which extended the concept to a toroidal free-boundary system, while previous applications were in line-tied geometry, builds an additional bridge between the two research fields.