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Magnetic shielded room made from Al in real magnetic field

Posted Sep 16, 2013, 7:21 a.m. EDT Low-Frequency Electromagnetics Version 4.3 4 Replies

Anca Iftemie
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I need some help, I want to model a 3d shielded room 12mm thick (2mx2mx3m) placed in real magnetic field (geomagnetic, frequency range 0-300Hz). When I select the AC/DC model, magnetic field, frequency domain, I put the parameter B=50e-6T, then in magnetic field I select magnetic field = B/mu0_const, I receive an error after computation. What is the best way to model the ambient geomagnetic field, To put the shielded room in a cube, a sphere? to put the condition for magnetic field source on the walls of the cube? what I am trying to find is the phase shift of the magnetic field when passing the wall of the shielded room with application in biomagnetism.
please give me a help to finish this small model for some, important for me,
4 Replies Last Post Sep 19, 2013, 10:23 a.m. EDT
Lingling Tang
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Posted: 1 decade ago Sep 16, 2013, 8:11 a.m. EDT

I need some help, I want to model a 3d shielded room 12mm thick (2mx2mx3m) placed in real magnetic field (geomagnetic, frequency range 0-300Hz). When I select the AC/DC model, magnetic field, frequency domain, I put the parameter B=50e-6T, then in magnetic field I select magnetic field = B/mu0_const, I receive an error after computation. What is the best way to model the ambient geomagnetic field, To put the shielded room in a cube, a sphere? to put the condition for magnetic field source on the walls of the cube? what I am trying to find is the phase shift of the magnetic field when passing the wall of the shielded room with application in biomagnetism.
please give me a help to finish this small model for some, important for me,


Perhaps you may first read the "submarine" example in AC/DC module, and I think the submarine model which uses the magnetic shielding boundary condition is similar to your magnetic shielding room, for both of them are multi-scaled, ie, the very thin thickness and very large dimensions.
good luck!
[QUOTE] I need some help, I want to model a 3d shielded room 12mm thick (2mx2mx3m) placed in real magnetic field (geomagnetic, frequency range 0-300Hz). When I select the AC/DC model, magnetic field, frequency domain, I put the parameter B=50e-6T, then in magnetic field I select magnetic field = B/mu0_const, I receive an error after computation. What is the best way to model the ambient geomagnetic field, To put the shielded room in a cube, a sphere? to put the condition for magnetic field source on the walls of the cube? what I am trying to find is the phase shift of the magnetic field when passing the wall of the shielded room with application in biomagnetism. please give me a help to finish this small model for some, important for me, [/QUOTE] Perhaps you may first read the "submarine" example in AC/DC module, and I think the submarine model which uses the magnetic shielding boundary condition is similar to your magnetic shielding room, for both of them are multi-scaled, ie, the very thin thickness and very large dimensions. good luck!
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Sep 16, 2013, 8:13 a.m. EDT
Hi Anca,

it is often a matter of taste how to choose the geometry of the outer boundary, I like a sphere because it doesn't have sharp edges and corners. You can use a magnetic field boundary to achieve a uniform field inside the boundary (e.g. the sphere). A few more hints:

- The frequency zero gives an error in a frequency domain study, for zero (static field) choose a static study
- Add the 'gauge fixing for A-field' under the Ampere's law node
- Look at the complex field components inside the shield to find the phase shift.
- Avoid sharp edges and corners in the geometry of the shield.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
Hi Anca, it is often a matter of taste how to choose the geometry of the outer boundary, I like a sphere because it doesn't have sharp edges and corners. You can use a magnetic field boundary to achieve a uniform field inside the boundary (e.g. the sphere). A few more hints: - The frequency zero gives an error in a frequency domain study, for zero (static field) choose a static study - Add the 'gauge fixing for A-field' under the Ampere's law node - Look at the complex field components inside the shield to find the phase shift. - Avoid sharp edges and corners in the geometry of the shield. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology
Anca Iftemie
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Posted: 1 decade ago Sep 16, 2013, 8:21 a.m. EDT
Thank you, I am runing the model now, but about the frequency, In the magnaetic field no currents I can't varry the frequency, and the phase inside the shield varries with the shield thick and frequency of the applied magnetic field....
Thank you, I am runing the model now, but about the frequency, In the magnaetic field no currents I can't varry the frequency, and the phase inside the shield varries with the shield thick and frequency of the applied magnetic field....
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Sep 19, 2013, 10:23 a.m. EDT

Anca,

you have to use the mf. physics for that, mfnc. doesn't offer the frequency domain study.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
Anca, you have to use the mf. physics for that, mfnc. doesn't offer the frequency domain study. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology

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