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Show injection rate of 3 lbs/hr (corresponding to 50% carryover) a particle number density of ~2 x 10^ cm-^ is calculated from these measurements. These results rely on an assumed value for the complex index of refraction for the slag particles and could vary significantly should this value be found in error. If the Mie theory efficiency for extinction of light is assumed to be 2 and a NASA chemical equilibrium code (23) is used to calculate the particle volume concentration, a "Sauter mean" diameter can be calculated using one-color transmissometer data. This technique gives similar results (24). Seed-slag injection caused the gas stream to become so bright that it was painful to observe visually near the combustor. Emission spectra of the gas stream between 400 and 900 nm for clean, slag injected and seed + slag injected conditions were taken. Blackbody radiation, the potassium lines at 766 and 770 nm, and the sodium D lines at 589 nm, are the principal features. Weaker emission lines attributed to lithium and rubidium can also be identified. Spectral scans of the gas stream when only flyash is injected indicate that strong band emissions between 610 and 650 nm are due to the coal residue. Many band systems also become prominent in the 400-580 nm spectral region when the seed-slag mixture is introduced into the combustor. Identification of these features is underway. III. Experimental Technique To make CARS temperature measurements in this environment, provisions were made to relay the pump and Stokes laser beams to the test chamber located one floor be?_ow the CARS laboratory. To minimize problems associated with relative beam alignment, the three beams (for BOXCARS phaseraatching) were transferred by single, right angle prisms (5 cm x 5 cm clear aperature). Figure [3] shows the laser sources, the signal processing optics and electronics. Characteristics of similar systems have been described in the literature (1). Briefly, the output of Quanta Ray Nd:YAG laser (DCR-2A) was doubled to produce -350 mj of pulsed energy at 532 nm. The residual fundamental radiation was passed through a second doubler (KD*P type II) to produce a pulse of 35 mj energy which was used to pump a broadband dye laser oscillator. This 9 |