排序方式: 共有32条查询结果,搜索用时 0 毫秒
31.
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. 相似文献
32.
In this communication we report the synthesis, structural and preliminary physical characterisation of a new layered oxyselenide Ce(2)O(2)FeSe(2). This material, containing a 1D portion of the structure of the layered FeSe-related superconductors, is a semiconductor with a band gap of around 0.64 eV and orders antiferromagnetically at low temperatures. 相似文献