PROTON TRANSPORT MODEL IN THE IONOSPHERE .1. MULTISTREAM APPROACH OF THE TRANSPORT-EQUATIONS

The suprathermal particles, electrons and protons, coming from the mag netosphere and precipitating into the high-latitude atmosphere are an energy source of the Earth's ionosphere. They interact with ambient th ermal gas through inelastic and elastic collisions. The physical quant ities perturbed by these precipitations, such as the heating rate, the electron production rate, or the emission intensities, can be provide d in solving the kinetic stationary Boltzmann equation. This equation yields particle fluxes as a function of altitude, energy, and pitch an gle. While this equation has been solved through different ways for th e electron transport and fully tested, the proton transport is more co mplicated. Because of charge-changing reactions, the latter is a set o f two-coupled transport equations that must be solved: one for protons and the other for H atoms. We present here a new approach that solves the multistream proton/hydrogen transport equations encompassing the collision angular redistributions and the magnetic mirroring effect. I n order to validate our model we discuss the energy conservation and w e compare with another model under the same inputs and with rocket obs ervations. The influence of the angular redistributions is discussed i n a forthcoming paper.