Collisional modification to the exospheric theory of solar wind halo electron pitch angle distributions

A theoretical model of suprathermal halo or strahl solar wind electrons, including both binary collisions and conservative force fields, is proposed. From this model we derive the collisionally modified electron pitch angle distribution and compare it with relevant measurements made in the solar wind at 1 AU by using the Los Alamos IMP 8 plasma analyzer. Although the collisionally modified distribution is more isotropic than that predicted by simple exospheric theory, it is not isotropic enough to describe the measurements