Note: Sub-Kelvin refrigeration with dry-coolers on a rotating system

Abstract

We developed a cryogenic system on a rotating table that achieves sub-Kelvin conditions. The cryogenic system consists of a helium sorption cooler and a pulse tube cooler in a cryostat mounted on a rotating table. Two rotary-joint connectors for electricity and helium gas circulation enable the coolers to be operated and maintained with ease. We performed cool-down tests under a condition of continuous rotation at 20 rpm. We obtained a temperature of 0.23 K with a holding time of more than 24 h, thus complying with catalog specifications. We monitored the system's performance for four weeks; two weeks with and without rotation. A few-percent difference in conditions was observed between these two states. Most applications can tolerate such a slight difference. The technology developed is useful for various scientific applications requiring sub-Kelvin conditions on rotating platforms.

GroundBIRD: Observing Cosmic Microwave Polarization at Large Angular Scale with Kinetic Inductance Detectors and High-Speed Rotating Telescope

“…We developed a series of two rotary joints for high-pressure helium gas and electricity lines, which enables connecting helium gas and power supply line between the cryocooler on the table and the compressor on the ground. We have already achieved cold conditions of 0.23 K with a hold time of more than 24 h under continuous rotation at 20 rpm [14].…”

Superconducting photon detectors

“…The sorption cooler can be used to provide a low temperature of 300 mK or it can be used as an intermediate stage to provide temperature lower than 1 K heat sink for either adiabatic demagnetisation refrigerators or dilution refrigerators. Single-stage helium sorption coolers were widely used with a superfluid 4 He tank as the heat sink in astronomical applications but limited hold times and the rapid development of cryogenic detector technology with higher cooling requirements prompted the development of multistage sorption coolers [91]. This configuration extends holding times and increases the thermal efficiency of the end stage to over 95%.…”