Thermal management design and key technology validation for PandaX underground experiment.

The scale of liquid xenon experiments aimed at searching for rare events is expanding, with plans to reach up to fifty tons. These detectors and the accompanying distillation towers require a reliable cooling source that can deliver large cooling power in the liquid xenon temperature range. Previously utilized pulse tube refrigerators and GM refrigerators have the disadvantages including small cooling power, large space occupation, and non-standby mutuality, which become significant challenges to scaling up experiments. In this study, an autocascade refrigerator was developed using ethanol as a coolant, with improved heat transfer effect achieved by adopting a concentric shaft heat exchanger and an after-pumping heat transfer scheme. This system provides a stable cooling power of 2.5 kW at 155 K. Further, the feasibility and key technology of the centralized cooling system of 5 kW at 160 K is discussed. This study promises to simplify liquid xenon experimental auxiliary devices, thereby benefiting the PandaX-xT experiment scheme.