3-1p
Jeanne Treuttel
Observatory of Paris - LERMA
Submillimeter Wave Instrument (SWI)
The Submillimeter Wave Instrument (SWI) is a spectrometer/radiometer instrument build for the Jupiter Icy Moon (JUICE) ESA-L1 spacecraft planned to flight in September 2022. The SWI instrument will measure and map temperatures, Doppler winds and chemical species (e.g. CO, CS, HCN, H2O) of Jupiter’s stratosphere, perform a characterisation of the tenuous atmospheres/exospheres of Galilean satellites in a unique and unprecedented manner, in terms of their horizontal distribution and vertical structure. It will also measure thermophysical and electrical properties of satellite surface/subsurfaces and correlate them with atmospheric properties and geological features.
SWI measures spectra and continuum emissions in two bands between 530 – 625 and 1080 – 1275 GHz (around 530 and 255 µm). The signal is down-converted by multiplication with a tunable local oscillator (LO) signal to an intermediate frequency band (IF) from 4 to 8 GHz using passively cooled subharmonically pumped mixers (SHM). The LO consists of K-band synthesizers, frequency controlled against an Ultra Stable Oscillator E-band triplers and Power Amplifiers (PA) and cascaded doublers based on III-V Schottky diodes. The final frequency doubling takes place in the III-V Schottky diodes sub-harmonic mixers for both 600 GHz and 1200 GHz channels. After amplification using a Low Noise Amplifier (LNA) the IF-signal feeds high resolution Chirp Transform Spectrometers (CTS) broadband Autocorrelation Spectrometers (ACS) and continuum channels (CCH).
Observatory of Paris - LERMA is responsible for the fabrication, delivery and calibration of critical sub-systems of the two channel front- ends, including its 1200GHz mixer, DC bias voltage regulator and last frequency stage local oscillator at 300 GHz and 600 GHz. LERMA responsibility also includes 1200 GHz channel LNA, USO and Ka-band synthesizer developed respectively by Miteq, Rakon and Syrlinks. This developement features a 1200 GHz system noise temperature well below the initial 4000K DSB requirement and better than the 3000K goal over the full bandwidth, thanks to the stable and strong signal power achieved at the output of the LERMA 600 GHz doubler. In this talk we will present achieved sub-system specifications (OCXO, synthetizer, local oscillator, mixer) for the delivery of viable flight models. These subsystem features space-qualified hardware that can be adapted to next future instrumentation up to 1.9 THz.
