High & Low Magnetic Permeability Materials for UHV Systems

Posted on: April 17, 2017

Mu-Metal and 316LN-ESR Stainless Steel are specialty alloys which offer very different levels of magnetic permeability. Applied Vacuum offers expert fabrication capabilities for these and other specialized materials.

Mu-Metal is a nickel-iron alloy (77 % Ni, 15 % Fe, plus Cu and Mo) with extremely high magnetic permeability at low field strengths.

Stray magnetic fields present a challenging issue for certain vacuum instruments, such as those used for electron spectroscopy. Mu-Metal is an ideal material to reduce the effects of magnetic fields inside these systems.

Certain design criteria must be considered before embarking on the fabrication of Mu-Metal chambers. An alternative to constructing a complete vacuum chamber from Mu-Metal is to install liners or shields inside the chamber. The Mu-Metal shielding helps reduce the effects of magnetic fields within the vacuum system. 316LN-ESR Stainless Steel is produced using an electro-slag refinement process. Flanges manufactured from 316LN material have superior properties when compared to 304 and 316 SS versions, including very low magnetic permeability.

AVT stocks 316LN-ESR bar and standard CF flanges to 6 inches. Larger sizes, other flange types, and custom components can be quickly quoted and manufactured in certified 316LN-ESR material.

Applied Vacuum Technology has more than 25 years experience fabricating custom flanges, assemblies and chambers for specialized vacuum applications. All products are fabricated and inspected to critical UHV standards. Our manufacturing and quality systems are certified to ISO 9001:2008 and Nuclear Quality Assurance (NQA-1).