Nozzle beam technique for mapping low density gas flows

Abstract

A collimated nozzle beam is used to probe the exhaust of a converging nozzle operated at Knudsen numbers ranging from 0.73 to 0.044. The results illustrate the expected transition from free ~nolecular to isentropic flow. The technique is sensitive to densities as low as 3 x lo1' molecules c~I -~.