THE EFFECT OF WAVE-PARTICLE INTERACTIONS ON THE POLAR WIND O+

The escape of the polar wind plasma is an important element in the ion osphere-magnetosphere coupling. Both theory and observations indicate that the wave-particle interactions (WPI) play a significant role in t he dynamics of ion outflow along open geomagnetic field lines. A Monte Carlo simulation was developed in order to include the effect of the WPI in addition to the factors that are traditionally included in the 'classical' polar wind (i.e. gravity, electrostatic field, and diverge nce of geomagnetic field lines). The ion distribution function (f(j)), as well as the profiles of its moments (density, drift velocity, temp erature, etc.) were found for different levels of WPI, that is, for di fferent values of the normalized diffusion rate in the velocity space (D(perpendicular-to j)). Although the model included O+, H+ and electr ons, we presented only the results related to the O+ ion. We found tha t (1) both the density and drift velocity of O+ increased with the WPI strength, and consequently, the O+ escape flux was enhanced by a fact or of up to 10(5); (2) The O+ ions could be energized up to a few elec tron volts; (3) for moderate and high levels of WPI (D(perpendicular-t o)(O+) > 1), the distribution function f(O+) displayed very pronounced conic features at altitudes around 3R(e). Finally, the interplay betw een the downward body force, the upward mirror force, and the perpendi cular heating resulted in the formation of the ''pressure cooker'' eff ect. This phenomena explained some interesting features of our solutio n, such as, the peak in the O+ temperature, and the formation of ''ear s'' and conics for f(O+) around 2.5R(e).