AC Electric field in the conducting media

[ali hemmati]

Hello,

I have simulated AC electric field in multiple (in fact 3) media with COMSOL, a multiphysic solver.

The simulation took place with different frequencies of applied electric potential. Media have different conductivities. At lower frequencies, every thing is ok, I mean, electric potential is approximately equal in domain of high conductive medium and does not enter the low conductive ones. On the other hand, with increasing frequency, at a specific frequency, the potential "flows" into the low conductive medium.

This phenomenon is a little strange for me, as I am not completely familiar with the electromagnetics. Does anyone know what is happening here?

I have attached my pictures...

 

[ZapperZ]

You might want to look into what is known as "skin depth", and see its frequency dependence on the conductivity of the medium.

Remember, the conduction electrons react to the oscillating field. Something with higher conductivity can naively be thought of having "better moving electrons" than something with a lower conductivity.

Zz.

 

[ali hemmati]

Thank you Zapper,

I have already assessed the skin depth of my model. Considering the conductivity and permittivity of the materials, skin depth is in order of tens of meters. The entire dimension of my model does not exceed millimeters! So, the skin depth may not have important role.

Bests,
Ali

 

[ZapperZ]

Thank you Zapper,

I have already assessed the skin depth of my model. Considering the conductivity and permittivity of the materials, skin depth is in order of tens of meters.

Whoa! Are you sure? What kind of a conductor is this that has THAT long of a skin depth? Have you benchmarked your codes to see if a similar material has the same parameters?

Zz.

 

[the_emi_guy]

Which module are you using?

 

[ali hemmati]

Hi,

I used AC/DC module and used "frequency study".

 

[the_emi_guy]

Use the RF module for 1GHz. The AC/DC model does quasi-static analysis.

Consider joining the Comsol discussion forum if you are going to be doing a lot if this.

Cheers.

 

[ali hemmati]

Whoa! Are you sure? What kind of a conductor is this that has THAT long of a skin depth? Have you benchmarked your codes to see if a similar material has the same parameters?

Zz.

Hi,

I have checked it again. It does not seem irrational! Conductivities are about 1e-13 S/m, 0.01 S/m, and 1 S/m. These conductivities bring about a high skin depth.