2-DIMENSIONAL TRANSPORT AND WALL EFFECTS IN THE THERMAL-DIFFUSION CLOUD CHAMBER .1. ANALYSIS AND OPERATIONS CRITERIA

In this paper we present results of a two-dimensional (z,r) treatment of the mass and energy transfer processes that occur during the operat ion of a thermal diffusion cloud chamber. The location of the wall is considered in solving the mass and energy transport equations, in addi tion to the vertical distance, z, between the upper and lower plate su rfaces, We examine the effect of aspect (diameter to height) ratio on chamber operation; the effects of operation with either a dry or a wet interior chamber wall on temperature, supersaturation, nucleation rat e, and total density profiles in the chamber; the effect of overheatin g the interior of the chamber wall on these conditions within the clou d chamber; and the effects associated with using different density bac kground gases on the operation of the chamber. In a second paper, imme diately following, we apply the formalism and the solutions developed in this paper to address the important problem of buoyancy-driven conv ection that can accompany (seemingly normal) operation of thermal diff usion cloud chambers in nearly all ranges of total pressure and temper ature. (C) 1997 American Institute of Physics.