Solar flare Hα impact polarization from high energy electrons?

In this paper we investigate the possibility of obtaining Hα line linear polarization in solar flares following the excitation of neutral hydrogen by energetic electron beams with a large initial pitch angle. We compare the factors affecting the sign, magnitude and intensity of polarized radiation collisionally excited by electron and proton beams and present a calculation of the polarization which could be observed from an electron beam, using a stochastic simulation to solve the Fokker-Planck evolution equation for the electron beam in the collisionally thick chromosphere, in the presence of a converging magnetic field. We find that polarization from electron beams is possible but requires extreme energy fluxes which are unlikely to be present for any length of time during solar flares