MRI magnetic shielding room

Here is an example of the calculation of a magnetic shielded room. A coil resembling an MRI (magnetic imaging device) that performs tomography of the human body is located in the center of the room. Since it is a linear calculation, this calculation has scalability in which the magnetic field value is completely proportional to the current value. However, in reality, MRI has a large current value (electromotive force is several Tesla), and nonlinear calculations are required using a high permeability material such as permalloy as a shielding material.

In this example, for simplicity, we use a linear calculation that normalizes the magnetic permeability and aeromotive force. If you want to analyze the real thing, please contact us.

Analytical Models

Chamber and coil

  • Room 5m×7.5m×2.5m (without open part) 1cm thick iron plate
  • Hollow center thick winding coil

Physical property data

  • Current value 1 AT
  • Permeability of iron plate 1000
  • Changed the parameters of ferromagnetic cells (QMn) to 0.096, 0.1, 0.005.

Shape input file

Create a T108_SRoom_02.pin as the main input file for the 3D preprocessor P. 

Please refer to the T108_SRoom_02.Pin file included with the package. Omit the list. The T108_SRoom_01.Pin file is a model that makes it easy to see what the joints in the corners of the room look like. If the junction is not properly modeled, magnetoresistance will be generated as in real life, and the shielding effect will be poor.

State before thickening the iron plate and dividing it into mesh

Analysis results

Magnetic field around the room (contour diagram)
Magnetic flux density generated in the magnetic field around the room and the shielding material (vector diagram)
Magnetic flux density generated by the magnetic field around the room and the shielding material
Magnetic flux density generated in the magnetic field around the room and the shielding material (vector diagram)

Analysis model (door opening)

It was removed from the T108_SRoom_02 model with 8 iron plates as doors and 4 as windows.

Analysis result (door opening)

Magnetic field slightly leaking from the open part (contour diagram)
Magnetic field slightly leaking from the open part (vector diagram)
Magnetic field slightly leaking from the open part (contour diagram)
Magnetic field slightly leaking from the open part (vector diagram)

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