ANALYSIS OF DIFFERENTIAL ABSORPTION LIDAR TECHNIQUE FOR MEASUREMENTS OF ANHYDROUS HYDROGEN CHLORIDE FROM SOLID ROCKET MOTORS USING A DEUTERIUM FLUORIDE LASER

摘要

The present study evaluates an active optical technique (differential absorption lidar (DIAL)) for detecting, ranging, and quantifying the concentration of anhydrous HC1 contained in the ground cloud emitted by solid rocket motors (SRM). Results are presented of an experiment in which absorption coefficients of HC1 were measured for several deuterium fluoride (DF) laser transitions demonstrating for the first time that a close overlap exists between the 2-1 P(3) vibrational transition of the DF laser and the 1-0 P(6) absorption line of HC1, with an absorption coefficient of 5.64 (atm-cm)-1. These measure¬ments show that the DF laser can be an appropriate radiation source for detecting HC1 in a DIAL technique. Development of a mathematical computer model to predict the sensitivity of DIAL for detecting anhydrous HCI in the ground cloud is outlined, and results that assume a commercially available DF laser as the radiation source are presented. Elements of the computer model consist of a general development of the DIAL equations and calculations of the extinction and scattering coefficients used in the DIAL equations to estimate back-scattered power. A multilayer diffusion model was used to predict cloud growth after stabilization in the atmosphere to obtain typical concentrations of molecular species in the cloud as a function of downwind distance from the launch pad for obtaining ranging information of the DIAL technique.