Diagnostic Instrumentation And Analysis Laboratory Research Articles

Laser optogalvanic detection of airborne uranium particles

Laser optogalvanic spectrometry (LOGS) is being developed at the Diagnostic Instrumentation and Analysis Laboratory (DIAL) to measure the concentration of uranium present in the off-gases of mixed hazardous waste thermaltreatment systems, where metal species occur as airborne metal oxide and/or metallic particles rather than as free, single atoms. Limits of detection for uranium and selected volatile, toxic trace metal particles are reported. This study demonstrates the feasibility of using LOGS to detect uranium in off-gases at concentrations significantly lower than can currently be achieved using other real-time, on-line technologies, such as radioactive disintegration counting methods or air inductively coupled plasma-atomic emission spectrometry (air ICP-AES).

Comparative study of temperature measurement with folded BOXCARS and collinear CARS

A theoretical model has been developed to simulate temperature profile measurements performed with Coherent Anti-Stokes Raman Spectroscopy (CARS) using collinear and BOXCARS phase matching geometries. Spatial averaging is a more serious problem for collinear geometry in which the observed spectra have CARS signal contributions generated outside the focal volume. The shape of the extracted temperature profile close to the boundary of a gas stream is quite sensitive to the temperature gradient at the boundary for both collinear and BOXCARS measurements. Based on the modeling results, collinear CARS phase-matching optics have been modified to reduce the contribution of the CARS signal from the cold region. The error in the temperature extracted from a spectrum generated in a bimodal temperature distribution medium has been studied. Temperature and temperature profile measurements have been performed with both collinear and folded BOXCARS geometries in a CH 4/air, flat flame burner and the Diagnostic Instrumentation and Analysis Laboratory (DIAL)/MSU test stand to compare the results of these two phasematch geometries. Collinear CARS data taken with the usual and modified collinear CARS in the DIAL test stand have been compared to study the application of collinear CARS in practical combustion. A temperature profile obtained from the measurements with modified collinear CARS and folded BOXCARS phase matching technique is in agreement with the theoretically predicted results. The studies also show that BOXCARS is the best choice for the temperature profile measurement. However, collinear CARS can be used with a modified optics arrangement and an expanded laser beam to improve the spatial resolution whenever folded BOXCARS is not able to provide a sufficient signal.