| Abstract: | The interpretation of cathode behavior in traveling wave tubes is clouded considerably by the uncertainty in both the precision and absolute accuracy of cathode temperature measurements as determined by optical pyrometry. The sensitivity and potential accuracy of optical pyrometry is very good, but many sources of error are possible. Sources of error that were experimentally measured in this study can be classified in three categories: (a) instrument and calibration errors; (b) operator (subjective) errors; and (c) errors caused by obstacles or geometrical variations in the optical path. Possible methods of avoiding or correcting sources of errors are recommended, including the use of an in-house primary standard blackbody. The design and use of this device are described in detail. When the primary standard is used and coupled to cathode measurements through secondary blackbodies optical pyrometry is an extremely reliable method for cathode temperature determination. |
