This research will develop a high pressure diffusion cloud chamber for measurement of nucleation rates at modest supersaturation. The chamber will be designed to operate at pressures up to 10,000 K Pa and temperatures up to 600 K greatly expanding the range heretofore available. Thus nucleation kinetics will be measurable for some substances near their critical points. The theory of operation will be expanded to account for non-idealities, vapor depletion, and latent heat release. Nucleation kinetics will be measured for ethanol and nonane as functions of temperature and pressure. Nucleation is an important phenomena in the environment and in engineering applications. The kinetics are extremely sensitive to temperature, supersaturation, and material properties. The expected data should help in the selection of improved theories for nucleation.
