IMPROVED FIBER-OPTIC TEMPERATURE SENSORS FOR PROPULSION SYSTEMS

METHODS WILL BE INVESTIGATED TO IMPROVE ON THE UPPER TEMPERATURE LIMIT, RESPONSE, AND DURABILITY OF FIBER-OPTIC SENSORS FOR HIGH TEMPERATURES. PRESENT HIGH-TEMPERATURE, FIBER-OPTIC SENSORS (BOTH COMMERCIALLY AVAILABLE PRODUCTS AND LABORATORY PROTOTYPES) USE SAPPHIRE RODS, TUBES, OR FIBERS THAT BECOME SIGNIFICANTLY LESS RESISTANT TO THERMAL SHOCK AND PHYSICAL STRESSES AT THE UPPER END OF THEIR USEFULTEMPERATURE RANGE (1950 DEGREES CENTIGRADE). A WAY TO INCREASE THE TEMPERATURE LIMIT INVOLVES USING REFRACTORY WAVEGUIDES, INCLUDING CARBIDES, NITRIDES, AND CERTAIN METALS PLUS THEIR ALLOYS. RESPONSE AND ACCURACY CAN BE IMPROVED THROUGH INCREASES IN THE EMISSIVITY OF THE PROBE TIP AND DECREASES IN THERMAL MASS. DURABILITY MAY BE IMPROVED WITH SPECIAL COATINGS OR BY EMBEDDING PROBES IN OTHER REFRACTORY MATERIALS. THIS PROJECT WILL IDENTIFY SEVERAL VIABLE MATERIALS AND METHODS TO BE USED IN FABRICATING PROBES THAT CAN NOT ONLY SURVIVE A LONG TIME AT HIGH TEMPERATURES IN HARSH ENVIRONMENTS, BUT ALSO PROVIDE HIGHLY ACCURATE TEMPERATURE DATA IN A FIBEROPTIC SENSING SYSTEM. IN ADDITION TO PROVIDING ACCURATE TEMPERATURE MEASUREMENT IN ROCKET ENGINES, A FIBER-OPTIC SENSOR USING THESE PROBES WILL BE OF GREAT VALUE IN FIELDS SUCH AS METALLURGY, SEMICONDUCTOR PROCESSING, AND COMBUSTION RESEARCH. METHODS WILL BE INVESTIGATED TO IMPROVE ON THE UPPER TEMPERATURE LIMIT, RESPONSE, AND DURABILITY OF FIBER-OPTIC SENSORS FOR HIGH TEMPERATURES. PRESENT HIGH-TEMPERATURE, FIBER-OPTIC SENSORS (BOTH COMMERCIALLY AVAILABLE PRODUCTS AND LABORATORY PROTOTYPES) USE SAPPHIRE RODS, TUBES, OR FIBERS THAT BECOME SIGNIFICANTLY LESS RESISTANT TO THERMAL SHOCK AND PHYSICAL STRESSES AT THE UPPER END OF THEIR USEFULTEMPERATURE RANGE (1950 DEGREES CENTIGRADE). A WAY TO INCREASE THE TEMPERATURE LIMIT INVOLVES USING REFRACTORY WAVEGUIDES, INCLUDING CARBIDES, NITRIDES, AND CERTAIN METALS PLUS THEIR ALLOYS. RESPONSE AND ACCURACY CAN BE IMPROVED THROUGH INCREASES IN THE EMISSIVITY OF THE PROBE TIP AND DECREASES IN THERMAL MASS. DURABILITY MAY BE IMPROVED WITH SPECIAL COATINGS OR BY EMBEDDING PROBES IN OTHER REFRACTORY MATERIALS. THIS PROJECT WILL IDENTIFY SEVERAL VIABLE MATERIALS AND METHODS TO BE USED IN FABRICATING PROBES THAT CAN NOT ONLY SURVIVE A LONG TIME AT HIGH TEMPERATURES IN HARSH ENVIRONMENTS, BUT ALSO PROVIDE HIGHLY ACCURATE TEMPERATURE DATA IN A FIBEROPTIC SENSING SYSTEM. IN ADDITION TO PROVIDING ACCURATE TEMPERATURE MEASUREMENT IN ROCKET ENGINES, A FIBER-OPTIC SENSOR USING THESE PROBES WILL BE OF GREAT VALUE IN FIELDS SUCH AS METALLURGY, SEMICONDUCTOR PROCESSING, AND COMBUSTION RESEARCH.