MICROCANONICAL ENSEMBLE STUDY OF A GAS COLUMN UNDER GRAVITY

The study of a classical ideal gas column of finite height H in a unif orm gravitational field g is made by the microcanonical ensemble at en ergy E. The primary functions of this ensemble, the phase volume and t he density of states, are derived. Related statistical quantities, suc h as the entropy, the temperature and the heat capacity, are also repo rted. The equivalence in the thermodynamic limit between the calculate d microcanonical expressions and those obtained from the canonical ens emble is shown numerically. The expression for the temperature is used to analyze the temperature change when the gas is permitted to expand into an evacuated region increasing the height of the column from H-1 to H-2. The microcanonical single-particle momentum and height distri butions are also reported.