1.8THz receiver development for the TELIS instrument

Abstract

A new state-of-the-art balloon borne three channel (500GHz, 625GHz, 1.8 THz) cryogenic heterodyne spectrometer will allow enhanced limb sounding of the Earth's atmosphere within the submillimeter and far-infrared spectral range. The instrument, called TELIS (TErahertz and submm LImb Sounder), is being developed by a consortium of major European institutes that includes the Space Research Organisation of the Netherlands (SRON), the Rutherford Appleton Laboratory (RAL) in the United Kingdom and the Deutschen Zentrum für Luft- und Raumfahrt (DLR) in Germany (lead institute). TELIS will utilise state-of-the-art superconducting heterodyne technology and is designed to be compact and lightweight, while providing broad spectral coverage, high spectral resolution and long flight duration. Target species are key atmospheric short-lived radicals such as OH, HO2, ClO, BrO together with stable constituents such as O3, HCl and HOCl. TELIS will consist of a common front end with a cassegrain based pointing telescope, common transfer optics and a digital autocorrelator spectrometer for each channel. One of the three receiver channels (developed by DLR) will focus on the measurement of the OH-triplett at 1.8 THz. Low noise NbN based Hot Electron Bolometers will be acting as heterodyne mixing elements. A Martin Puplett Interferometer designed for cryogenic operation in the cryostat is used to interfer signal- and LO radiation generated by a solid state based local oscillator unit. Recently athe laboratory DSB version of the TELIS heterodyne receiver (using a far infrad laser as preliminary LO source) has been set up and tested successfully. In this paper the current status of the THz-channel design and development in the framework of the TELIS project will be presented.