3
$\begingroup$

My main goal is to magnetize and demagnetize a Mu metal shield. Till now I am using a Helmholtz coils setup and I can generate 10 mT applying 2 A DC. I am using a DRV425 fluxgate and a hall probe sensor to measure the magnetic fields.

To demostrate that my Mu metal shield is being saturated till magnetization: I am measuring the magnetic field on the sensor shielded before and after applying an external field through the Helmholtz coils.

After expose the Mu metal shield 100 seconds at 10mT of uniform field.

  • Without external field applied --->Magnetic field without shield 38uT and after shielding 1,8uT aprox.
  • After applied an external field of 10mT---> Magnetic field after shielding 2,5uT aprox.

I would like to know what would be the maximum magnetic field it is required to saturate the Mu metal shield till magnetization.

If somebody can suggest me a way to calculate it or some literature that touch my point. I would fully appreciate it :).

Thanks!

$\endgroup$
1
$\begingroup$

I can think of two ways to get the answer you looking for. 1) The easy way is to obtain the magnetization specifications from the Mu metal manufacturer. 2) You can make a magnetic amplifier and run some tests. As you magnetically saturate the Mu metal, the amplification decreases. Note: use Wikipedia or Google "magnetic amplifiers" for additional information.

$\endgroup$
  • $\begingroup$ Hi Guill, thank you for your suggestion. Respect to the first solution 1) I have already the specifications from the Manufacturer. It is known that the saturation of my Mu metal shield is 0.8T and the coercitive force is 12,73A/m. I would like to know how can I define this external field H if I know how much field can generate my coils. If I generate for example 15 mT what does mean that in terms of magnetic field strength?. $\endgroup$ – xchange4change May 4 '15 at 15:30
  • $\begingroup$ Respect to the second solution, I have been reading about the magnetic amplifier, I want to run an experiment to determine how much current I am going to amplify using such device and hopefully the power is going up too. I still need to explore the results after using this option. Again thank you so much for your ideas and support! $\endgroup$ – xchange4change May 4 '15 at 15:30
  • $\begingroup$ @xchange4change: Without the external field, you obtained a shielding factor of 38/1.8 = 20, after applying the external field, it was reduced to 38/2.5 = 15. This means you are saturating the shield. You can try to saturate it more by increasing the external field or reducing the uniform field. If the ratio does not change, you reached saturation. One other thing you have to take into account is hysteresis. $\endgroup$ – Guill Apr 16 '17 at 5:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.