Do you mean velocity filtration, where the corona is simply particles from the tail of the chromospheric distribution function? That theory has been largely discredited.
I'm not sure I agree with this… In any case, the solar wind electron distribution is strongly controlled by the strahl/suprathermals (and the collisions between the core and protons). I believe we see good evidence of the ambipolar electric field (at 1 AU, where it is quite weak).
cheers, Stuart