Kinetic Nonequilibrium Signatures in the Distribution Function of Earth-Escaping Hydrogen Atoms

The lightest atmospheric gas constituents, like H- and He- atoms, are known to escape from planetary gravitational fields open space. Hereby it counts that not only the uppermost layer, so-called exobase, contributes this escape, but layers below do contribute as well, especially since a nonthermal character of final particle outflow is induced.We consider H - atoms lower levels oxygen-dominated upper atmosphere, stratified by planet‘s field given in case Earth. terrestrial H-atom locally modified elastic collisions upwards flying H-atoms with heavy major background constituent. This causes collision–induced velocity-modulation directed flow induces kinetic signatures local ˗ atom distribution function. An important, hitherto unrespected point hereby angle-integrated O collision cross sections velocity-dependent, falling off increasing velocity v (1/v). Consequently modulation influences low stronger than high-velocity ones, which changes profile escaping deviations classic Jeans escape. Deeply down thermosphere H-atoms, well O-atoms, indeed thermodynamical equilibrium characterized Maxwell distributions common temperature TH = TO. Nevertheless, at exobase border atmosphere resulting turns out be a, non-equilibrium non-thermal escape-relevant properties. Here we describe collisional modification H-escape quantify upcome features power laws wings H-distribution via velocity-dependent cross-sections acts typical process convert into kappa-like functions. On basis theoretical approach stabilizing type "iso-baric Kappa functions" all represent same atom- pressure can calculate effective flux space its difference respect classical value. While finding again formula slightly overestimates actual flux, now for first time taking account influence modulations show value even enhanced factors 2 3.