Stirling cooler magnetic interference measured by a high-Tc SQUID mounted on the cold tip

H.J.M. Brake, ter, H.J. Holland, H. Rogalla

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review


    Small Stirling-type cryocoolers are available on the market mainly for cooling IR detectors, but they can also be used to cool high-Tc superconducting devices, like SQUIDs. Because SQUIDs are extremely sensitive magnetic sensors it is questionable whether these devices can be mounted directly on the cold tip of the cooler. To investigate this the authors attached a high-Tc SQUID to the tip of a representative split Stirling-cycle cryocooler (Signaal Usfa type 7058), and operated it in a magnetically shielded room. The SQUID that they used for the test expts. was one of the first high-Tc SQUIDs that were manufd. in our group and had a noise level of 0.7 pT/?Hz at about 77 K. With the SQUID attached to the tip of the cold head and the cooler running, the noise appeared to have increased dramatically: at the driving frequency of 50 Hz and at the harmonics by roughly 5.105, and at other frequencies by about a factor 103. The expts. indicated that the noise coupled into the SQUID was dominated by contributions originating from the cold head, and not by compressor interference. The expts. are discussed, and the consequences with respect to the cooling of SQUIDs with std. cryocoolers are briefly considered. [on SciFinder (R)]
    Original languageEnglish
    Title of host publicationCryocoolers 9
    EditorsR.G. Ross
    Place of PublicationNew York
    PublisherPlenum Press
    ISBN (Print)0-306-45511-0
    Publication statusPublished - 1997
    Event9th International Cryocooler Conference (Cryocoolers 9) - Waterville Valley, NH, United States
    Duration: 25 Jun 199627 Jun 1996


    Conference9th International Cryocooler Conference (Cryocoolers 9)
    Abbreviated titleCryocoolers 9
    CountryUnited States
    CityWaterville Valley, NH

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