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Capacitive Shielding
Posted 15.08.2013, 12:40 GMT-4 Low-Frequency Electromagnetics 3 Replies
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Hi everyone,
I'm trying to model a capacitive shield made of aluminium. The shield function is to interrupt the capacitive coupling between un helical coil and a charge inside the coil. Our objective is to evaluate the thickness of the shield in order to maximize magnetic field penetration while minimizing capacitive coupling.
The problem i'm dealing with is that the working frequency is about 2.7MHz. At this frequency, the skin depth of the aluminium is 45um. So shield thickness must at less 3times lower then 45um. The scale of my model is in centimeters. Since i didn't succeed to mesh a cylinder of 45um diameter, i would like to know if there is a boundary condition i can use to model this effect ?
The impedance boundary condition is not suitable for me because it will simulate a perfect magnetic screen. I see that there is a "Transition boundary condition" but i would to know how valid this condition is ?
Thank you very much.
I'm trying to model a capacitive shield made of aluminium. The shield function is to interrupt the capacitive coupling between un helical coil and a charge inside the coil. Our objective is to evaluate the thickness of the shield in order to maximize magnetic field penetration while minimizing capacitive coupling.
The problem i'm dealing with is that the working frequency is about 2.7MHz. At this frequency, the skin depth of the aluminium is 45um. So shield thickness must at less 3times lower then 45um. The scale of my model is in centimeters. Since i didn't succeed to mesh a cylinder of 45um diameter, i would like to know if there is a boundary condition i can use to model this effect ?
The impedance boundary condition is not suitable for me because it will simulate a perfect magnetic screen. I see that there is a "Transition boundary condition" but i would to know how valid this condition is ?
Thank you very much.
3 Replies Last Post 15.08.2013, 15:18 GMT-4
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Posted:
1 decade ago
Hi,
I haven't used the transition BC so far, but from what I read in the documentation it should exactly do your job.
Cheers
Edgar
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Edgar J. Kaiser
emPhys Physical Technology
I haven't used the transition BC so far, but from what I read in the documentation it should exactly do your job.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
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Posted:
1 decade ago
Thank you Edgar for your respons. In fact it seems that this condition do the job, but i would like to have user experience with this BC.
I already tried it but the results are not satisfactory. I made a simulation at 10*skin_depth and another at skin_depth/10. Then i calculated the surface electromagneting heating of the my charge (modeled with an impedance boundary condition). The difference is very small (<5%) compared with what we can obtain experimentally.
Regards.
I already tried it but the results are not satisfactory. I made a simulation at 10*skin_depth and another at skin_depth/10. Then i calculated the surface electromagneting heating of the my charge (modeled with an impedance boundary condition). The difference is very small (<5%) compared with what we can obtain experimentally.
Regards.
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Posted:
1 decade ago
Christian,
would you mind uploading your model? Clear solutions and meshes to get it small enough.
Cheers
Edgar
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Edgar J. Kaiser
emPhys Physical Technology
would you mind uploading your model? Clear solutions and meshes to get it small enough.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology