Massimo Materassi - ISC-CNR Firenze #
Gradient Dynamics for Turbulent Space Plasmas #
The local topology of the streamlines and magnetic lines of plasma 
determines important phenomena occurring in space physics. Since the 
local topology 
of those field lines can be transparently described through the gradients 
of fields, it is appealing to reformulate Plasma Dynamics using the gradients of 
the velocity and of the magnetic field as dynamical variables.
<br/>
Here an attempt in this direction is presented: the gradient dynamics, 
well explored in Hydrodynamics where it was applied to kinetic variables, is 
here extended to the MHD magnetic variables. Furthermore, a finite scale 
stochastic dynamics is formulated for the new dynamical variables: 
statistical aspects of topological variable dynamics are indeed expected to be extremely 
relevant in the turbulent regime, where a stochastic field scenario is, in 
practice, taking place, and where making the scale appear explicitly as a variable 
of the problem helps studying inter-scale processes.