Optimization of a microprocessor-based line reversal system for temperature measurements in coal combustion plasmas

The absolute, radiometric, plasma temperature measurement method of modified line reversal (MLR) is reviewed briefly with respect to its components and use at the U.S. Department of Energy Coal-Fired Flow Facility (DOE CFFF) at The University of Tennessee Space Institute. Performance of the existing system is discussed. A survey of the existing electronics, physical layout and operations of the instruments, including the data acquisition and analysis equipment concludes that the existing system is severely limited in its ability to address additional anticipated plasma temperature measurement needs at the CFFF. Many of the existing system's limitations are due to dependence on the CFFF mainframe minicomputers for data acquisition and processing. To address many of the limitations, a general-purpose, commercially available microcomputer was chosen as the base of the new, stand-alone data system. Several hardware devices were assembled with the microcomputer: a data acquisition/multifunction board, a DMA card, a GPIB standard interface bus, and a 45 MB removable hard disk drive. The software environment for the acquisition, calculation and data management were programmed using a graphical programming language based on principles of dataflow processing. The microprocessor-based, stand-alone MLR system was subsequently developed and was tested using prerecorded, analog MLR signals.