A nitrogen triple-point thermal storage unit for cooling a SQUID magnetometer

A.P. Rijpma, D.J. Meenderink, H.A. Reincke, G.C.F. Venhorst, H.J. Holland, H.J.M. Brake, ter

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    11 Citations (Scopus)
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    In order to achieve turnkey operation, the use is planned of cryocoolers to cool a SQUID magnetometer system. To minimize the magnetical and mech. interference from the coolers, they are switched off during the actual measurements. Consequently, a thermal storage unit (TSU) is required with sufficient capacity at an appropriate temp. (<77 K). In a feasibility study, a load of 0.5 W from the SQUID sensor unit and an operating time of 10 h are considered. To account for an increased load caused by the TSU itself, an overall capacity of 15 Wh is aimed at. The nitrogen triple-point is chosen because of the large latent heat involved in the transition from solid to liq. and the corresponding well-suited temp. (63 K). Furthermore, any safety risks involved with the use of nitrogen are small compared to alternatives. To contain the nitrogen, highly porous alumina is used. A structure was made in which layers of copper and porous material alternate, thus establishing a good thermal contact between the nitrogen and the casing of the TSU. Expts. show an overall capacity of the system around 85% of the expected theor. value. Suggestions for improvements are given so as to arrive at a TSU capacity of 15 Wh. [on SciFinder (R)]
    Original languageEnglish
    Pages (from-to)231-239
    Number of pages9
    Issue number3
    Publication statusPublished - 2005


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