Active suppression of temperature oscillation from a pulse-tube cryocooler in a cryogen-free cryostat: Part 2. Experimental realization

Changzhao Pan (1) , Jiangfeng Hu (1) , Haiyang Zhang (1) , Yaonan Song (1) , Dongxu Han (1) , Wenjing Liu (1) , Hui Chen (1) , Mark Plimmer (2) , Fernando Sparasci (2) , Ercang Luo (1) , Bo Gao (1) , Laurent Pitre (2)

1 CAS - Chinese Academy of Sciences [Beijing]
2 LCM - Laboratoire commun de métrologie LNE-CNAM

A cryogen-free cryostat cooled by a closed cycle cryocooler is compact, can provide uninterrupted long-term operation (up to ten thousand hours) and is suited to temperatures from 3 K to 300 K. Its intrinsic temperature oscillation, however, limits its application in experiments requiring high thermal stability at low temperature (below 77 K). Passive suppression methods are effective but all suffer from drawbacks. We describe a novel, active suppression scheme more efficient than traditional proportional-integral (PI) control. The experimental results show that it can reduce the standard deviation of the temperature oscillation by a further 30% compared with PI feedback. To the best of our knowledge, this is the first time such active suppression of temperature oscillations has been implemented with the cryogen-free cryostat. The results also show, however, that an unwanted lower frequency thermal noise will be generated, which appears to be the limit of the method. Nevertheless, the approach could be used to improve the temperature stability in all cryogen-free cryostats.

Mots clés: Pulse tube cryocooler Cryogen-free cryostat Active suppression method Temperature oscillation; Pulse tube cryocooler; Cryogen-free cryostat; Active suppression method; Temperature oscillation

Domaines: Sciences de l'ingénieur [physics]

Changzhao Pan, Jiangfeng Hu, Haiyang Zhang, Yaonan Song, Dongxu Han, et al.. Active suppression of temperature oscillation from a pulse-tube cryocooler in a cryogen-free cryostat: Part 2. Experimental realization. Cryogenics, 2020, 109, pp.103096. ⟨10.1016/j.cryogenics.2020.103096⟩. ⟨hal-04032216⟩