NONLOCAL HEAT-TRANSPORT IN THE SOLAR-WIND

It is shown that a nonlocal, suprathermal tail originated near the sol ar corona base dominates the conductive energy flux at distances r gre ater than or equal to 2 R(circle dot). A nonlocal analytical expressio n for the electron heat flux in,,weakly collisional plasmas is derived by solving the Fokker-Planck equation in a narrow, tail energy range. A correction to the anisotropy of the distribution function due to th e divergent magnetic field lines was included. This term is essential to recover from the delocalization prescription, in the limit r greate r than or equal to 6 R(circle dot), the well-known Hollweg's Ansatz fo r the ''collisionless'' heat flux. In the intermediate region 2 R(circ le dot) less than or equal to r less than or equal to 6 R(circle dot), the nonlocal convolution smoothly interpolates between the classical Spitzer-Harm's formula and the so-called collisionless regime.