IRREVERSIBLE WALL COLLISIONS AND THERMALIZATION OF A GAS OF INERT ATOMS

Reflection of inert, charge-neutral, spherical atoms from a fixed soli d wall with cubic symmetry at low temperature is considered. Working i n the limit of classical trajectories, a condition is stated for the i rreversibility of reflections, in terms of inelastic energy exchange w ith wall phonons, from which two classes of atomic energies are implie d: I and R. It is found that a monoenergetic low-density confined gas of I-atoms thermalizes due to wall collisions. For a thermal equilibri um low-density confined gas of R-atoms, the model is found to be consi stent with the thermodynamic postulate of the reversibility of an equi librium process undergoing an adiabatic change. In the course of the a nalysis the notion of a purely adiabatic wall is described.