Strato-Mesospheric Ozone Monitoring System Using an SIS Mixer (Special Issue on Toward Digital and Analog Applications of Superconductors)

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We have developed a strato-mesospheric ozone monitoring system with a low noise SIS mixer, which receives 110.836 GHz millimeter-wave emission due to the rotationaltransition of ozone molecules (J=6_<1,5>-6_<0,6>). The system is completely standalone. We derived the altitude profile of ozone density between 25 km and 80 km from the observed spectrum.The receiver noise temperature was as low as 17 K (DSB) , so that the altitude profile could be obtained every 3-10 minutes.The monitoring system can operate continuously over one year without any maintenance work, because it utilizes a 4 K closed cycle helium refrigerator and reliable Nb/AlO_x/Nb SIS junctions. We used two acousto-optical spectrometers (AOSs) as real-time spectrometers because of their high resolution and simple construction. In an up-to-date system, one AOS would have a band-width of 65 MHz and the other, a band-width of 250MHz, with resolutions of 40 kHz and 250 kHz, respectively. A computer controls the entire system and is also used to analyze measured data. In this paper, we present the principles of system operation, the latest performance and the construction of the system, and some observed data.
社団法人電子情報通信学会の論文
1996-09-25