RELAXATION OF TOROIDAL PLASMAS - TOKAMAKS

We do not believe that the minimum energy theory [I] is applicable to driven plasmas. We assume that relaxation occurs towards a state of mi nimum entropy production rate. As the equilibrium Ohm's law cannot be satisfied in peaked-current density states, the final state must be st eadily turbulent. What is new about our theory is, fundamentally: (i) the pressure balance is considered as a relevant constraint upon the r elaxed state and this is expressed as an integral relation; (ii) the e nergy dissipation by turbulence is assumed to be minimal and (iii) ani sotropic resistivity is regarded as the main cause of poloidal current . The numerical calculations of magnetic field and current density rep roduce typical observations in tokamaks.