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XEUS Technology. Milli-Kelvin Refrigerator for the XEUS Cryogenic Detectors Adiabatic Demagnetisation Refrigerator I Hepburn Mullard Space Science Laboratory. Adiabatic Demagnetisation Refrigerator - ADR. XEUS Cryogenic Detectors require cooling to milli-Kelvin temperatures
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XEUS Technology Milli-Kelvin Refrigerator for the XEUS Cryogenic Detectors Adiabatic Demagnetisation Refrigerator I Hepburn Mullard Space Science Laboratory
Adiabatic Demagnetisation Refrigerator - ADR • XEUS Cryogenic Detectors require cooling to milli-Kelvin temperatures • ADR is the ESA system of choice • System to be cooled via space cryo-coolers • No liquid helium
ESA Engineering Model XEUS ADR • End 2001 ESA announced ITT for the XEUS Engineering Model ADR system • Designed for flight (Ariane V qualification) • System to could ultimately be cooled via a space cryo-cooler. • Designed to be accommodated within a spacecraft • i.e. complete control of stray magnetic fields • Designed to accommodate both STJ and TES detectors in the magnetically shielded focal plane unit.
ESA Engineering Model XEUS ADR • Mid 2002 MSSL + EADS Astrium (Stevenage) won the contract to build the XEUS EM ADR. Completion of construction due in next few months
MSSL + Astrium XEUS EM ADR • First world wide attempt to construct a flight cryogen free (i.e. space cryo-cooler cooled) ADR. • Rational was to identify key developments for the full system. • Driver was to demonstration a working flight system within a short time scale. • Expense of mass.
MSSL + Astrium XEUS EM ADR • Massive system • 45kg • 1/3 due to magnetic shielding material for large FPU • 1/3 due to superconducting magnet wire (300 km of 0.1mm superconducting wire) • Rest is the ADR refrigerants and structure.
Further work • The MSSL + Astrium XEUS EM ADR is a building block for the development of the real XEUS ADR. • Tandem system (comprising two ADR systems) gives continuous operation • Reduces mass by factor 5 – 10 • Heat switches • To improve cooling power (magnetoresistive heat switch) • Need to work closely with the detector groups • Optermisation of system • e.g. provide low mass magnetic shielding for the detector (first attempt = 12 kg due to the require large FPU) • Need to work closely with spacecraft in order to have realistic magnetic shielding for the spacecraft.
Conclusion • Milli-kelvin cooler in good situation (testing hopefully successful!) • We have a qualified system. • More work is required • Reduce the mass • Increase detector operation time (currently modelled to be ~16 hours) to continuous