Development of a System for Measurement of Properties of Flow is the CVD Apparatus Using LIF

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As a system for measurement of properties of flow in the CVD apparatus, a method for quantitative imaging of temperature in the rarefied gas flow has been developed. The flow field is visualized by planar laserinduced fluorescence (PLIF) of iodine molecules seeded in carrier gas. Iodine molecules have many absorption lines in visible region and radiate intense fluorescence. The fluorescence intensity is proportional to the number of molecules in the energy level excited by the laser beam. From the dependence of this number on the temperature, the local temperature can be decided from the ratio of the fluorescence intensities of two visualized images which are obtained by irradiations of laser beams with different wave length. This method allows to image the two-dimensional temperature distribution of the flow field by means of a laser sheet and a high sensitive CCD camera. This method is applied to the temperature measurement of the flow field of a supersonic free jet in which temperature varies drastically. It is found that the temperature distribution of the jet measured by P(16)/R(18)[514.720 nm] and P(26)/R(28)[514.942 mn] absorption lines in the transition of B(v'=43) X(v"=0) agrees well with the theoretical one.This system was applied to an interacting flow field between a supersonic free jet and a Si wafer. From the result, the propriety and the effectiveness of the system are verified.