Experimental investigation of helium gas heat exchangers for vibration and thermal noise control in closed-cycle cryostats.

Closed-cycle cryostats are widely employed in quantum precision measurement and superconducting quantum computing, where vibration and temperature stability critically affect performance. Gifford–McMahon (GM) cryocoolers, widely used as cold sources, suffer from low-frequency mechanical vibrations and cold head temperature fluctuations, which limit their applicability in precision experiments. To address this challenge, a helium gas heat-exchange chamber was proposed, fully enclosing the GM cold head to eliminate the rigid mechanical connection and enable heat transfer through helium. By employing helium as a non-rigid thermal transfer medium, the chamber enables efficient heat conduction while simultaneously attenuating vibration noise. In this study, the vibration isolation and thermal conduction characteristics of the helium gas heat exchange chamber were systematically investigated. Experimental results show that the chamber effectively isolates the 60 μm peak-to-peak vibration of the GM second-stage cold head, reducing the transmitted vibration to about 400 nm, while maintaining efficient thermal conduction. A minimum temperature of 3.4 K was achieved, with temperature fluctuations suppressed to 0.02 K. These results confirm the dual role of the helium gas heat exchange chamber in vibration isolation and thermal stabilization, providing valuable guidance for the design and optimization of low-vibration closed-cycle cryostats.