Abstract
Most SQUID systems for biomagnetic measurements use liquid helium as a cryogen. To reduce operating costs and to eliminate the need for handling liquid helium, SQUID systems cooled by small closed-cycle cryocoolers have been developed and have been used to successfully measure MCGs and MEGs [1–4]. Those systems were single-channel systems. We have developed a cryogen-free 32-channel MCG system cooled by a Gifford-McMahon/Joule-Thomson (GM/JT) cycle cryocooler. Other advantages for cryocooled systems include excellent S/M ratio becauseof the small clearancebetween the pickup coil and the subject [5], and the high degree of freedomin the tilt of the cryostat On the other hand, two disadvantagesare the magnetic noise producedby movement of the magnetic and metallic parts in the cryocooler and the mechanical Vibration. To reduce this noise and the Vibration, we have been improving the cryocooler in the system.
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References
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Fujimoto, S. et al. (2000). A 32-Channel MCG System Cooled by a GM/JT Cryocooler. In: Aine, C.J., Stroink, G., Wood, C.C., Okada, Y., Swithenby, S.J. (eds) Biomag 96. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-1260-7_11
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DOI: https://doi.org/10.1007/978-1-4612-1260-7_11
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