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magnetic field due to thin solenoid

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Hi. I'm completely novice in comsol, and I'm trying to simulate magnetic field due to solenoid.

I was wondering how can we simulate "n turn per unit length [m]" in comsol.

Here, I want to have a solenoid of length 50mm and n = 100 turn per m, so I've put 5 for the values of N turn in coil domain, but I'm unsure about the values that I got.

For a single coil, it has approximately 5.52 micro T, and if I extend that into solenoid with 5 turns for total length, it should give around 5.52*5 ~= 25 micro Tesla.

But as you can see from the attached file, it gives around 80 micro T, which seems wrong.

I've attached both single coil and solenoid, with same radius and distance from the point that I'm interested in.

Also, I'm trying to simulate a thin solenoid, which means we can ignore the thickness of the wire. So i've made a geometry of cylinder which has a really small difference between inner and outer radius. Is it valid to do so?



2 Replies Last Post Jul 18, 2019, 6:27 a.m. EDT

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Posted: 5 years ago Jul 18, 2019, 4:05 a.m. EDT
Updated: 5 years ago Jul 18, 2019, 4:02 a.m. EDT

Dear Michael,

     I think you have a problem with the comparison. If you perform a sweep variying number of turns in the "thin solenoid test" you will see the expected behaviour, i.e. B proportional to n (see attacehd fig generated with your model).  You have change the geometry of the solenoid between the 2 cases and that as causing the differences you observe.

     Kind regards,

     Julian
Dear Michael, I think you have a problem with the comparison. If you perform a sweep variying number of turns in the "thin solenoid test" you will see the expected behaviour, i.e. B proportional to n (see attacehd fig generated with your model). You have change the geometry of the solenoid between the 2 cases and that as causing the differences you observe. Kind regards, Julian


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Posted: 5 years ago Jul 18, 2019, 6:27 a.m. EDT
Updated: 5 years ago Jul 18, 2019, 6:26 a.m. EDT

Hi

Thnks for reply.

Then, how can I make a solenoid which has a multiple set of such single coil that I have attached?

Hi Thnks for reply. Then, how can I make a solenoid which has a multiple set of such single coil that I have attached?

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