Shielding for Low Temperature
Amuneal Manufacturing Corporation was established
in 1965 in response to the growing demand for
low frequency magnetic shielding. Today, the company
is a world leader in the supply of magnetic shield
components and assemblies for scientific, medical,
and commercial applications. The majority of shields
that are designed for these industries are constructed
from Amumetal, a high permeability shielding
alloy developed for room temperature applications.
However, the performance of Amumetal and other
high permeability materials is degraded at cryogenic
temperatures and is therefore not an appropriate
material selection to yield high shielding performance
at very low temperatures.
Cryoperm 10®, a high nickel content shielding alloy, was
developed in response to the growing need for higher
performance magnetic shielding at cryogenic temperature
applications. Cryoperm’s magnetic properties at low
temperatures are similar to those of standard shielding
alloys such as Amumetal at room temperature. Figure 1
compares the permeability of Cryoperm 10® and Amumetal
as a function of ambient temperature.
Amuneal maintains an inventory of Cryoperm in 0.020”
(0.5mm), 0.040”(1.0mm) and 0.060”(1.5mm) thick sheets.
Our standard width is 10.23” (260mm). This selection
allows us to work with our customers to design the
most cost-effective shielding for their specific application.
Once the proper thickness and geometry have been
calculated, Amuneal employs cutting-edge technology
to fabricate each shield ensuring that it conforms to all
specified dimensional and magnetic requirements.
After fabrication, each Cryoperm 10® shield is hydrogen
annealed using a specific cycle developed to provide
optimal performance for its application temperature
(4.2K or 77.3K).
Magnetic and Physical Properties
Table 1 lists the typical properties of Cryopperm 10® at
4.2K and 77.3K, based on measurement of fully annealed
0.1mm (0.004”) toroids.