Nonlocal heat transport in the solar wind 2

CANULLO, M. V.; COSTA, A.; FERRO FONTAN, C.

JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS

R.J. Strangeway Inst. of Geophysics and Planetary Physics, Earth and Space Sciences Dept., University of California at Los Angeles (UCLA), 405 Hilgard Ave. Los Angeles, CA 90095-1567, USA

Lugar: Califormia; Año: 1995 vol. 462 p. 1005 - 1009

0021-9169

A nonlocal analytical expression for the electron heat flux in low collisional plasmas, which reproduces known results at high, low and intermediate ion charge number Z is derived by solving the Fokker-Planck equation in a narrow, tail-energy range. The solutions involve an external magnetic field. A correction to the anisotropy of the distribution function due to the divergent magnetic field lines was included. It is shown that the heat flux can be expressed taking into account a delocalization function for the suprathermal particles. The convolution formula leads in a physically relevant way to the delocalization of the heat flux. The theory is applied to the lower solar corona, showing that a non-local, ballistic suprathermal tail originated near the coronal base dominates the energy flux at distances r approximately equal to 4 solar radius. The further development of the anisotropy of the distribution function has been studied through a test-particle model, revealing that particles with v(parallel) greater than 5v(e), will eventually run away due to the magnetic pumping effect. The scaling with v(parallel) of the parallel distribution function and of the perpendicular temperature is also derived.