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There are many considerations to make when designing the perfect shield, one of which is the thermal environment in which the shield will be used. Some applications of magnetic shielding may take place at temperatures below −180 °C or −292.00 °F or 93.15 K. The magnetic permeability of a material has a temperature dependence, meaning that there is an optimal temperature range in which the permeability peaks.

The permeability of MuMetal® begins to drop below -40 °C, making this material unsuitable in low temperature applications. In these cases, we suggest an alternative cryogenic alloy to manufacture such shields, CRYOPHY®. CRYOPHY® is nickel-iron soft magnetic alloy (81% Ni, 5% Mo, and balance Fe) suitable for constructing magnetic shields for use at cryogenic temperatures, typically down to 4K.


Contact our Technical Sales Team for assistance.

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In recent years Nickel Iron manufacturers have worked to produce high permeability grades of material suitable for magnetic shielding that can maintain good levels of permeability down to 4 degrees Kelvin. This development is very significant in high energy physics and other superconductor applications. It means that a functioning shield can be inserted inside the cryogenic system, improving functionality and providing economical reductions in both space and cost.

Magnetic Shields Limited have been constructing shields using CRYOPHY® for a number of years and have developed considerable expertise in the special heat treatment required to develop the optimal low temperature magnetic properties. Our specialised pure and dry hydrogen furnace program heat treats CRYOPHY® for over 36 hours within a varying temperature range of 200°C to 1150°C with a long cooling time in order to achieve a typical permeability of 70,000 at 4K (applied field 0.4 A/m or ~ 5mOe).

Headcorn Road  |  Staplehurst  |  Tonbridge  |  Kent  |  TN12 0DS  |  UK

Tel : +44 (0) 1580 891521  Fax : +44 (0) 1580 893345

® MuMetal is a registered trademark of Carpenter Technology Corporation
® MuRoom is a registered trademark of Magnetic Shields Limited
® Cryophy is a registered trademark of Aperam Alloys

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