A Continuous 100-mK Helium-Light Cooling System for MUSCAT on the LMT

TL;DR

This paper presents a helium-light, continuous cooling system for the MUSCAT instrument on the LMT, achieving sub-Kelvin temperatures efficiently and cost-effectively using innovative sorption and dilution refrigeration technologies.

Contribution

It introduces a novel helium-light cryogenic cooling system combining continuous sorption and miniature dilution refrigerators for large-scale millimeter-wave instruments.

Findings

Successful operation of continuous sorption coolers and miniature dilution refrigerator.

Achieved 100 mK cooling with only 9 liters of helium-3.

Demonstrated viability for future large-scale cryogenic experiments.

Abstract

The MUSCAT instrument is a large-format camera planned for installation on the Large Millimeter Telescope (LMT) in 2018. MUSCAT requires continuous cooling of several large-volume stages to sub-Kelvin temperatures, with the focal plane cooled to 100 mK. Through the use of continuous sorption coolers and a miniature dilution refrigerator, the MUSCAT project can fulfil its cryogenic requirements at a fraction of the cost and space required for conventional dilution systems. Our design is a helium-light system, using a total of only 9 litres of helium-3 across several continuous cooling systems, cooling from 4 K to 100 mK. Here we describe the operation of both the continuous sorption and the miniature dilution refrigerator systems used in this system, along with the overall thermal design and budgeting of MUSCAT. MUSCAT will represent the first deployment of these new technologies in a science-grade instrument and will prove the concept as a viable option for future large-scale experiments such as CMB-S4.