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The helium bath cooling becomes more and more expensive and limited and therefore cooling alternatives e.g. conduction cooling or other cryogens have to be used. In the past years, liquid hydrogen or sub-cooled solid nitrogen (at ~ 20 K) were used for superconducting devices. But, liquid H2 needs a special safety conditions and solid N2 may sublimate easily and lost the cooling efficiency. Therefore, behaviour of several MgB2 coils inside the water ice cooled by cryocooler down up to 10 K were studied [1-3]. In addition, I-V characteristics and critical currents versus temperature and external field for coils wound of different wires (Bi-2223, REBCO and Nb3Sn) were measured [4]. Stable and safety behavior of superconducting coils inside sub-cooled water ice have been observed under high DC or pulse currents. The effect of unpleasant volume expansion in water is compensated by double-walls container. Consequently, sub-cooled water ice is promising, cheap and safe cooling medium applicable for He-free systems at temperatures above 10 K.
[1] M. Búran et al Sup Sci and Technology 34 (2022) 105004
[2] P. Kováč et al Sup Sci and Technology 34 (2022) 055001
[3] P. Kováč et al Sup Sci and Technology 34 (2022) 095007
[4] M. Búran et al Supercond. Sci. Technol. 36 (2023) 105013
| Submitters Country | Slovakia |
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