This progress report covers continuing work to develop a temperature probe for a coal gasifier. A workable probe design requires finding answers to crucial questions involving the probe materials. We report on attempts to answer those questions. We designed, assembled, and tested a portable test fixture that can give relative quantitative data on the condition of phosphors. It needs a more-sensitive detector for optimum performance. We ordered an appropriate detector. An experimental test of the survivability of thermographic phosphor in an ambient environment similar to that in a slagging gasifier showed no substantial deterioration of the phosphor. We consider this result so important that we delayed the date of publication of this report by one month to accommodate it. We assembled the first version of a prototype probe and were preparing to test it at the time of this report.

This progress report covers continuing work to develop a temperature probe for a coal gasifier. A workable probe design requires finding answers to crucial questions involving the probe materials. We report on attempts to answer those questions. We attempted to measure the laser-input power at a wavelength of 355 nm that would damage the ends of sapphire fiber optics. We were surprised and pleased to learn that they survived an input power density of about 3 x 10{sup 9} W/cm{sup 2}, which greatly exceeds the best that fused-silica fibers can do. During a run of our new simulator to obtain an upgraded calibration curve for the improved YAG:Dy phosphors, we found that the phosphor appeared to form a eutectic, with the fused-silica cuvette used to hold the phosphor, when the temperature exceeded 1450 C. This result could have substantial ramifications in this and other high-temperature applications. Our new proprietary detector package that replaced the original photomultiplier tube gave excellent results, with much better signal-to-noise ratio at a given temperature than the old package. Our new plasma-spraying operation has succeeded in spraying YAG, which we think may be a technological breakthrough.

This progress report covers continuing work to develop a temperature probe for a coal gasifier. A workable probe design requires finding answers to crucial questions involving the probe materials. We report on attempts to answer those questions. We previously reported an apparent anomaly in the high-temperature behavior of fused-silica optical components. This time, we report on further anomalies in other components. These unexpected results impede or prevent acquiring data related to the project. The commercial manufacturer of gasifier probes had agreed to lend us three ceramic inner sheaths and one outer sheath for experimentation. He subsequently sent us one inner sheath. We designed a test fixture to be used in a proposed test of phosphor material in a reducing environment at a power company's test facility. Funding delays outside our control caused a related project to be put on hold. Because the two projects shared travel funds, we are unable to continue experimental work until funding resumes. Meanwhile, we are doing some of the labor-intensive data reduction for our recent calibration curves.

This progress report covers continuing work to develop a temperature probe for a coal gasifier. A workable probe design requires finding answers to crucial questions involving the probe materials. We report on attempts to answer those questions. We received and studied new samples of an important thermographic phosphor, YAG:Dy. We studied the brightness as a function of dopant concentration and the relative brightnesses of the pertinent thermographic emission lines, both with respect to each other and among the phosphors. With the previously reported failure of the binder method for coatings, we are setting up a plasma-spray facility in cooperation with a subcontractor. We have been forming a network of people and organizations that may help us with various aspects of the problems at hand. This period, we approached a company with commercially successful probes, met with Tennessee Valley Authority staff (codes and coatings), and added a new faculty member to the team with materials expertise.