An ultra-low vibration cryostat with split design.

The development of cryogenic technology promotes frontier scientific discoveries, while the device performance is often limited by vibration of cryostats. We present the design and implementation of a split-type, ultra-low vibration cryostat using a pulse tube cryocooler. Methods of gas-liquid helium mixture damping, non-contact heat exchangers, soft connections, and vibration isolating foundation are used together to suppress vibration. These innovations reduce background vibrations at the sample area to 5 × 10-7 m/s2/Hz1/2 (7 × 10-9 m/Hz1/2) @ 1-10 Hz in all directions and effectively suppress vibration harmonics of the pulse tube frequency with a suppression ratio up to 23 dB. In addition, with a low heat leakage design, the 2.2 L large sample area can be cooled down to below 4 K in 36 h, and the temperature fluctuation is 0.03 mK under active control. The performance of ultra-low vibration and fast cooling of a large sample space to below 4 K is outstanding among the reported low-vibration cryostats, which meets the demands of advanced cryogenic applications.