An Airborn Condensation Nuclei Counter.

摘要

Stratospheric measurements of particles smaller than 0.1micrometer are clearly necessary. For this reason a new type of counter for detecting these small particles has been designed and built. For purposes of this report,particles smaller than 0.1micrometer diameter will be referred to as condensation nuclei (CN) because this name reflects the method by which the concentration is measured. The CN are grown in a thermal gradient diffusion cloud chamber. This consists of a temperature controlled center rod kept moist with the working fluid. The outer wall is kept at constant temperature by an ice bath. The difference in temperature between the two walls and the vapor coming from the working fluid produces a degree of supersaturation in the TGDCC depending on the temperature of the center rod. After the sampled air has passed through the TGDCC,the enlarged particles are detected by a photoelectric particle counter. Testing and performance are described.