TEMPERATURE COEFFICIENTS OF TOPCON RADIATION THERMOMETERS
− The ambient or instrument temperature affects the outputs of a standard radiation thermometer through various parts such as a detector, a feedback resistance and an interference filter. Usually the output was corrected by one coefficient assuming the linear dependence. If the filter wavelength changes, the dependence is different at each target temperature. We measured the temperature coefficients of Topcon radiation thermometers at different target temperatures and found the target temperature dependence as well as the feed back resistance dependence. Therefore a high stability radiation thermometer requires controlling the detector, filter and amplifier temperatures.
Long-Term Stability of 0.65-μm Radiation Thermometers at NMIJ
Narrow-band radiation thermometers with center wavelengths near 0.65 μm are frequently used as standard thermometers at high temperatures. The long-term stability of ten Topcon 0.65-μm radiation thermometers was assessed at NMIJ by using fixed-point blackbodies and spectral responsivity measurements. Most of the changes are due to shifts in the center wavelength of the interference filters to longer wavelengths. Even when the center wavelengths shifted, the filter widths and transmittances remained quite stable for some radiation thermometers, but one was found for which the bandwidth increased from 15.7 to 17.2 nm and the transmittance decreased by 6%. Three Barr filters were found to be very stable in wavelength. The output signals of 0.65-μm Topcon radiation thermometers were within 2% · year−1 without correcting for the wavelength change and within 0.2% · year−1 after the correction. Keeping the objective lens clean is very important for radiation thermometers. Large output decreases were observed in early 2000 for many radiation thermometers at NMIJ. The output changes were as large as 1% and were recovered by cleaning the objective lens.
Long Ceramic Beam Tubes for Accelerator Magnets
The ceramic beam tubes for the fast and abort kickers and the bucker and pinger magnets used at Fermilab must meet a number of exacting requirements. The tubes must be long and sufficiently straight so as not to limit magnet design. They must have wall strength capable of withstanding the atmospheric and mechanical forces encountered during construction and operation. Vacuum tight ceramic to stainless steel transitions must be of reasonable cost; they must also withstand high temperature processing and remain vacuum tight to the 10/sup -9/ Torr range. To remove the possibility of static charge buildup each tube must have a surface coating of indium oxide applied to the inner wall. This thin coating is difficult to achieve and requires the most careful attention to detail. The methods used at Fermilab to achieve these goals are presented in this paper.