Integrated superconducting spectrometer for atmosphere monitoring

Abstract

The results of the development of sub-mm Superconducting Integrated Receiver (SIR) for monitoring of the Earth’s atmosphere from high-altitude balloons are presented. The microchip of the superconducting integrated receiver comprising local oscillator based on the long Josephson junction (flux flow oscillator, FFO) is developed and successfully tested. The receiver noise temperature as low as 200 K is measured at a frequency of 650 GHz. The possibility to phase-lock FFO to the reference oscillator, which is vitally important for spectrometer operation, is demonstrated. To ensure the possibility of remote tuning of a phase-locked (PL) SIR onboard a balloon, a number of approaches for the PL SIR automatic computer control are developed and tested. New modifications of the superconducting local oscillator (FFO) are developed, fabricated and tested. The FFO design is optimized for the integrated spectrometer. The FFO linewidth is studied at frequencies of up to 700 GHz using a specially developed technique. A free-running linewidth between 9 and 2 MHz is measured in the frequency range from 500 to 700 GHz. As a result, the spectral ratio of the phased-locked FFO ranges from 35 to 90%. The effect of FFO linewidth imperfections on the retrieval procedure of the atmosphere gas spectra is studied.