Calculation of electromagnets with a hollow core

[curious_science]

TL;DR

Hello everyone, I wrote here, I did not find a topic on electromagnetism.
An interesting point, I searched, but did not find information related to the calculation of magnets with hollow cores, and this is not about a toroid, where we wind on a ring, but specifically as a hollow cylinder, over which the winding is wound.
A few questions, how are magnets with such cores calculated?
What shape will the magnetic field be in this case?
What will happen to the characteristics of the magnet when forei

 

[marcusl]

This is a poor geometry because most of the flux will be concentrated in the core. What is your application? Why are you choosing this geometry?

 

[kuruman]

Can you do the calculation for a solenoid with no core? If so, then the calculation with the core would proceed the same way except that you should apply the usual boundary conditions at the core-vacuum interface that the normal component of $\mathbf B$ and the tangential component of $\mathbf H$ be continuous at the boundary.

As @berkeman noted, you will find that the magnetic field in the vacuum inside is practically zero because what you have described is magnetic shielding. Try it with an infinite solenoid first to see how this works.

 

[berkeman]

As @berkeman @marcusl noted,

Fixed that for you.

(although in fairness, we do look a lot alike)

 

[Baluncore]

Is the coil wound as a solenoid, onto the outside of the tube?
Is the core made from an electrical insulator material such as iron powder or ferrite, or from an iron conductor, like a water pipe?
If a conductor, cut a thin slot along the pipe through into the hole, to break the shorted electrical turn.

 

[curious_science]

This is a poor geometry because most of the flux will be concentrated in the core. What is your application? Why are you choosing this geometry?

Initially, the idea was to introduce ferromagnetic materials into the center of the core as a “sandwich” of materials of different magnetic permeability and electrical resistivity.
There was an idea, but it was probably big from chemistry, how the magnetic field behaves if crystallized metal salts (iron) are used as the core base.

 

[curious_science]

Can you do the calculation for a solenoid with no core? If so, then the calculation with the core would proceed the same way except that you should apply the usual boundary conditions at the core-vacuum interface that the normal component of $\mathbf B$ and the tangential component of $\mathbf H$ be continuous at the boundary.

As @berkeman noted, you will find that the magnetic field in the vacuum inside is practically zero because what you have described is magnetic shielding. Try it with an infinite solenoid first to see how this works.

I'll try to calculate it like this

 

[curious_science]

Is the coil wound as a solenoid, onto the outside of the tube?
Is the core made from an electrical insulator material such as iron powder or ferrite, or from an iron conductor, like a water pipe?
If a conductor, cut a thin slot along the pipe through into the hole, to break the shorted electrical turn.

this is cool, I have to try it

 

[curious_science]

This magnet is part of the project, so that I can initiate it and get permission to implement the project, the boss must see calculations that the device can work.

 

[Baluncore]

If you want to study the magnetic effect of crystallised salts in the core, then throw out the metal tube and replace it with glass. A metal outer core will dominate the field, and hide the inner core.

To study crystal samples, you should make a toroidal core, but with a slot or gap cut across it. Then place the sample in the gap.

 

[berkeman]

This magnet is part of the project, so that I can initiate it and get permission to implement the project, the boss must see calculations that the device can work.

Do you understand how high-mu materials deflect magnetic field lines? That is at the core (sorry for the pun) of our comments on your question. If you are not familiar with that concept, please let us know so we can try to give you some learning resources to help you do the calculations you want to do.

https://www.kjmagnetics.com/blog.asp?p=magnetic-shielding-materials

 

[curious_science]

Do you understand how high-mu materials deflect magnetic field lines? That is at the core (sorry for the pun) of our comments on your question. If you are not familiar with that concept, please let us know so we can try to give you some learning resources to help you do the calculations you want to do.

View attachment 354745
https://www.kjmagnetics.com/blog.asp?p=magnetic-shielding-materials

I would be very grateful if you provide materials

 

[berkeman]

I would be very grateful if you provide materials

In addition to the previous link, this is a good resource: https://www.magnetic-shield.com/all-about-shielding-faqs/

 

[curious_science]

В дополнение к предыдущей ссылке, это хороший ресурс: https://www.magnetic-shield.com/all-about-shielding-faqs/

Thank you