This project will develop a radiometr speciallytailored for plasma diagnostics. This instrument will havegreater sensitivity and larger dynamic range, about 80 dB, thanbroadband room temperature instruments. The sensor is a thermaldetector based on high temperature superconductor thin films. Ithas been experimentally demonstrated that these thermometers havea noise equivalent temperature (NET) as low as 11 nK/WHz at 87 Kwith a chopper frequency of 10 Hz or higher. This is a fractionaltemperature noise of 1.3 x 10 'ø in a 1 Hz post detectionbandwidth. This detector can be continuously calibrated byelectrical substitution of power, so it is particularly wellsuited to high accuracy measurements. Using this high temperaturesuperconductor thin film technology, we can make radiationdetectors and radiometers for any part of the electromagneticspectrum from radio frequency to xrays, depending on the need. Wepropose consideration of 3 prototype instruments: An instrumentusing rectangular waveguide at frequencies up to 325 GHz, anoptical instrument for frequencies of 1 THz and above, and afiber optic coupled detector for infrared wavelengths shorterthan 10 ,um. The first generation instrument is expected to havea noise equivalent power (NEP) of approximately 1 x 10-11 W/+lHz,and a sub millisecond time constant for the smallest fiber opticcoupled device. Larger devices would be slower. Using broadbandradiation absorbers, such as tapered terminations for waveguide,and optical traps for shorter wavelengths, absolute accuracies of1to are expected to be achieved. Second generation instrumentswould be expected to have improved performance. Our Phase Iproposal is to demonstrate our ability to make state-of-the-artsuperconducting films that we have fabricated.Anticipated Results/Potential Commercial Applications asdescribed by the awarder:The NEP of this instrument will fallmidway between that of the best broadband room temperatureinstruments, 109 W/
