# Calculating Electromagnets for 4T Output without Superconductors

• microfracture
In summary, it is not necessary to use bitter magnet equations for creating a 4T electromagnet. A simple solenoid using a buzz box welding unit and materials from a DIY store can easily achieve this. However, for higher field strengths, a bitter magnet may be more suitable, but it requires specialized equipment and careful handling due to high voltages and amperages. It is also possible to modify a MOT to produce a 150 amp current.

#### microfracture

anyone have equations for bitter magnets? or do i use the ones for solenoids?

i need an electromagnet capable of 4T. that doesn't use super conductors >_>

i have access to liquid nitrogen though.

So you are saying that your only problem is not having liquid helium? Or do you care about the bore temperature?

Magnets are a thing that you simply buy, there must be very special reasons to do home brew. If you use copper I think that the permeability is negligible and I assume we are talking about dc. You should be able to use Biot Savart with homogeneous current density and integrate, but the field should be very similar to a normal coil.

But let's talk about the real problems: you will need massive current. This will resistively heat the copper. One of the purposes of the bitter configuration is fighting this heat, first by giving the "wire" a large cross section, and then adding pipes to use liquid coolant. A rough calculation should show that you would need massive amounts of LN2 to cool the magnet, even though the resistivity is decreased. The description I found on line uses deionized water for cooling.
You will need a large cooling setup, a large power supply, then you need to think about mechanical stability...

Why don't you just buy the thing? Otherwise you should probably use some simulation software.

I've never heard of anyone using a nitrogen cooled normal magnet (unless it is the experiment itself that needs to be cooled); most large normal magnets are simply water cooled. You don't really gain much in terms of reduces losses by colling copper wire and LN2 is not really a good coolant anyway.
Hence; water cooling is both more efficient and easier to use.
Moreover, winding a 4T magnet is far from trivial and needs specialist equipment. Unless you know what you are doing you are better off buying one.

Also, as 0xDEADBEEF has already pointed out you need a current source as well. For a 4T normal magnet something like a 50A supply should work (with maybe 20V compliance).
This is more or less a standard piece of kit (you can buy one from e.g. TTI) but they are still pretty expensive, at least a few thousand dollars.

So, if you are asking: is there any way to DIY a 4T magnet without spending a lot of money, the answer is no.

at the moment I am only trying to make a penning trap. sounds trivial but its only part of a bigger project. i was going to use Y123 at first as a plate material, yea not to easy to get made >_> ... yea
then i saw the penning design and how it uses copper and an efficient water cooling system. given the amount of LN2 needed to compensate for water, and the amount of power used in there systems, i though 4T would be a fraction of what they are doing.

im attempting to assemble a bitter magnet, using 50A will generate allot of heat from resistance /cry

i understand... kinda

im making it home brew because i have no funding other than a hobbyist's wages D:
50A sounds doable though. is it possible to get that out of a duel MOT config? reversed ofcorse.

2 points;
You really don't need a bitter magnet to get up to 4T, a simple solenoid can do this easily.
If you want to build a bitter magnet to get up to around 10T this can be done with equipment that is fairly commonly available and won't break an average budget.
A 'buzz box' welding unit can supply around 200 amps at 6v and these are low cost as second hand / car-boot sale equipment.
To produce the 'coil'; aluminium and acryllic sheet, available from your local DIY store, a 'junior' hacksaw, tinsnips and a drill / file plus some time and care will produce this.
Plus a large mild steel bolt (don't use high tensile bolts - the high carbon content causes problems). Try to fit the whole inside a CD tower case (the 100 off style) adapted to take water flow - if you feel you need it. Air cooling generally will do for these relatively low field applications
As for the formula, for a home-brew version, the standard solenoid equations will do best. A rough calculation is ;- Field intensity = (amps x turns)/coil area; ignoring coil length effects

For some info on diy Bitter magnets see:

www.flickr.com/photos/hackerfriendly/3396999204/in/set-72157613645586248/magnets[/URL]

Note that these coils are destroyed when used--but they are subjected to a pulse from 300 microfarads at multiple thousands of volts and with very low inductance.

My usual advice: read, read, read, and then BE CAREFUL. The 'experiment' shown here uses deadly voltages/amperages.

Neil

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IanP2 said:
2 points;
You really don't need a bitter magnet to get up to 4T, a simple solenoid can do this easily.
If you want to build a bitter magnet to get up to around 10T this can be done with equipment that is fairly commonly available and won't break an average budget.
A 'buzz box' welding unit can supply around 200 amps at 6v and these are low cost as second hand / car-boot sale equipment.
To produce the 'coil'; aluminium and acryllic sheet, available from your local DIY store, a 'junior' hacksaw, tinsnips and a drill / file plus some time and care will produce this.
Plus a large mild steel bolt (don't use high tensile bolts - the high carbon content causes problems). Try to fit the whole inside a CD tower case (the 100 off style) adapted to take water flow - if you feel you need it. Air cooling generally will do for these relatively low field applications
As for the formula, for a home-brew version, the standard solenoid equations will do best. A rough calculation is ;- Field intensity = (amps x turns)/coil area; ignoring coil length effects

first off :O!
and second ty for giving me hope sir. i got 150 amps out of a modded MOT and some grounding wire i picked up at home depot. 15 windings is too much, so ill try one large multi-stranded winding insted.

amateur question: when you said "coil area" in the equation did you mean planer? as in i calculate the area of one layer of the conductor and multi by the number of layers

ps i didnt see your post till WAY later. thought the thread died...

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## 1. How do you calculate the strength of an electromagnet without using superconductors?

To calculate the strength of an electromagnet without using superconductors, you will need to use the formula: B = μ0 * N * I / l, where B represents the magnetic field strength, μ0 represents the permeability of free space, N represents the number of turns in the coil, I represents the current, and l represents the length of the coil.

## 2. What is the difference between using superconductors and not using superconductors in an electromagnet?

The main difference between using superconductors and not using them in an electromagnet is the ability to achieve higher magnetic field strengths. Superconductors have zero resistance, which allows for a continuous flow of current without any energy loss, resulting in much stronger magnetic fields compared to traditional conductors.

## 3. Can an electromagnet without superconductors achieve a 4T output?

Yes, it is possible for an electromagnet without superconductors to achieve a 4T (tesla) output. However, it would require a large number of turns, high current, and precise calculations to achieve this level of strength.

## 4. What materials are typically used in an electromagnet without superconductors?

The most commonly used materials in an electromagnet without superconductors are copper wires, iron cores, and power sources such as batteries or power supplies. Other materials such as aluminum, steel, and nickel can also be used depending on the specific requirements of the electromagnet.

## 5. How can I increase the strength of an electromagnet without using superconductors?

To increase the strength of an electromagnet without using superconductors, you can increase the number of turns in the coil, increase the current flowing through the coil, or use a stronger magnetic core material. Additionally, optimizing the design and dimensions of the electromagnet can also help increase its strength.