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Experimental study and modeling cryogenic detectors decoupling within dry cryostat
摘要： The dry cryostat technology is based on pulse tube cryo-coolers and offers a good alternative to wet dilution cryostats. However, the main drawback is the production of vibrations induced by the pulse tube. These vibrations can be transmitted to the cryogenic detectors mounted in the cryostat and cause extra-noises dramatically affecting their performance. A solution to mitigate the impact of these vibrations is to mount the detectors on a suspended tower. For this purpose, vibrations in a dry cryostat were modeled and preliminary prototypes were investigated in the scope of R&D for the EDELWEISS-III experiment.
关键词： Extra-noise,Vibrations,Suspended tower,Dry cryostat,Detector
更新于2025-09-23 15:23:52
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Large Angle Optical Access in a Sub-Kelvin Cryostat
摘要： The development of lens-antenna-coupled aluminum-based microwave kinetic inductance detectors (MKIDs) and on-chip spectrometers needs a dedicated cryogenic setup to measure the beam patterns of the lens-antenna system over a large angular throughput and broad frequency range. This requires a careful design since the MKID has to be cooled to temperatures below 300 mK to operate effectively. We developed such a cryostat with a large opening angle θ = ± 37.8? and an optical access with a low-pass edge at 950 GHz. The system is based upon a commercial pulse tube cooled 3 K system with a 4He–3He sorption cooler to allow base temperatures below 300 mK. A careful study of the spectral and geometric throughput was performed to minimize thermal loading on the cold stage, allowing a base temperature of 265 mK. Radio-transparent multi-layer-insulation was employed as a recent development in ?lter technology to ef?ciently block near-infrared radiation.
关键词： Lens-antenna,Kinetic inductance detectors,Cryogenic optics,Cryostat
更新于2025-09-23 15:21:01
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Accurate Solar Cell Measurements at Low Temperatures using a Cryostat
摘要： Calibrated measurements of solar cells at low temperatures are of specific interest for various space missions, for example to Mars and Jupiter. In the past 15 years, several hundred triple-junction and component solar cells have been measured at the solar cell calibration laboratory at Fraunhofer ISE (CalLab PV Cells), mainly in the frame of the European Space Agency (ESA) programs ExoMars and JUICE. To allow for measurements at temperatures as low as 123 K a specially developed cryostat setup is being used. This paper summarizes the main challenges and findings in respect to measurement low procedures and calibration of solar cells under temperature conditions, including the mounting of the solar cells, control of the correct solar cell temperature, and definition of the correct illumination spectrum and intensity.
关键词： cryostat,low intensity low temperature,space solar cells,LILT,solar cell characterization
更新于2025-09-16 10:30:52
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Cryostat setup for measuring spectral and electrical properties of light-emitting diodes at junction temperatures from 81 K to 297 K
摘要： We introduce a cryostat setup for measuring fundamental optical and electrical properties of light-emitting diodes (LEDs). With the setup, the cryostat pressure and the LED properties of the forward voltage, junction temperature, and electroluminescence spectrum are monitored with temperature steps less than 1.5 K, over the junction temperature range of 81–297 K. We applied the setup to commercial yellow AlGaInP and blue InGaN LEDs. At cryogenic temperatures, the fine structure of the electroluminescence spectra became resolved. For the yellow LED, we observed the phonon replica at 2.094 eV that was located 87 meV below the peak energy at the junction temperature of 81 K. For the blue LED, we observed the cascade phonon replicas at 2.599 eV, 2.510 eV, and 2.422 eV with the energy interval of 89 meV. For both LED types, the forward voltage increased sharply toward the lower temperatures due to the increased resistivity of materials in the LED components. We found significant differences between the temperature dependent behaviors of the forward voltages, spectral peak energies, and bandgap energies of LEDs obtained from the Varshni formula. We also noted a sharp pressure peak at 180–185 K arising from the solid-vapor phase transition of water when the base level of the cryostat pressure was approximately 0.4 mPa.
关键词： spectral properties,light-emitting diodes,electrical properties,junction temperature,phonon replicas,cryostat setup
更新于2025-09-16 10:30:52