A Study of Hydrogen Diffusion in the Earth's Upper Atmosphere Near the Critical Level

Abstract

An attempt is made in this paper to formulate the transport of hydrogen in the earth's upper atmosphere as a Monte Carlo problem. The relevant details of the technique adopted are given. The capability of the technique to provide useful answers to the following questions is demonstrated. How is the flux of hydrogen atoms, possessing enough kinetic energy to escape from the earth's gravitational field, influenced by the fact that the escape takes place not from a particular atmospheric level (the critical level) but from a layer of finite thickness? What is the law of variation of hydrogen density in this finite layer? More specifically, does the hydrogen gas maintain a Maxwellian distribution while diffusing through the layer? If not, how does the distribution change with height inside the layer? The answers obtained are discussed with reference to their statistical validity, and compared with some of the conclusions of earlier investigations.