A millimeter (mm) wave broadband video detecting system based on high temperature superconducting (HTS) junction and compact pulse tube cryocooler (PTC) has been studied. The lowest attainable temperature of the PTC is 42 K and the operating temperature (T) can be adjusted by changing the pressure difference in the compressor. By measuring the linewidth of the Josephson oscillation as well as the dynamic range of the Josephson detector, it is found that the PTC has no excess noise compared with other kinds of cryostats such as liquid helium cryostats, and is very suitable for the applications in the mm wave detecting system. Furthermore, to improve the sensitivity of the system, the coupling efficiency of the system has been studied in detail. It is found that the coupling efficiency increases with the increase of RN linearly, and is better than 1% for RN of 1.7 Ω. A sensitivity of about 318 V/W has been obtained for the system based on the PTC and a junction with RN = 1.7 Ω and ICRN = 1 mV.
|Number of pages||6|
|Journal||Chinese Journal of Physics|
|Issue number||4 II|
|Publication status||Published - 2004 Aug|
ASJC Scopus subject areas
- Physics and Astronomy(all)