PROTON TRANSPORT IN A MAGNETIC LOOP AND H-ALPHA IMPACT LINE LINEAR-POLARIZATION

Using a 1-D test particle model with 350 000 numerical protons, we stu dy the evolution of the proton distribution function in a magnetic loo p. A continuous injection of low-energy 200-1500 keV protons with a di stribution function proportional to a E(-3) power-law is considered. T he acceleration region is assumed to be at the top of a flare loop whe re the protons are injected into a cone of pitch angles centered along the loop axis. The computations are made for a static loop of length 20880 km with the parameters in the chromosphere corresponding to the VAL-C model of the solar atmosphere. Coulomb collisions, mirroring, an d Alfven wave scattering in an intermediate regime (W-a(tot) = 10(-1) ergs cm(-3)) relative to prior analyses corresponding to saturated sca ttering are taken into consideration. The proton distribution function in the chromosphere at the H alpha formation layer is computed. The r esulting anisotropy of the proton distribution function in a quasi-sta tionary state of proton bombardment is analyzed from the point of view of its expected effects on the impact linear polarization of chromosp heric lines.