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I need to create a .7+ Tesla electromagnetic solenoid

  1. Feb 12, 2016 #1
    I am trying to create a solenoid with a high flux density, but I need the specifications (wire gauge, current applied, etc). The diameter of the core would be preferable around 15mm. The length can be pretty much anything reasonable.

    I need this for a project that requires a strong repulsive force between this electromagnet, and a neodymium magnet with dimensions 15mm diameter x 20mm length, at a half centimeter distance between the poles.

    The dimensions of the electromagnet can be flexible. If increasing the diameter substantially increases the strength of the magnet, I am all in for it.

    Thanks in advance.
     
  2. jcsd
  3. Feb 12, 2016 #2

    Vanadium 50

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    Sorry, what you describe cannot be done. Or at least cannot be done safely by amateurs.
     
  4. Feb 12, 2016 #3
    Thanks for your reply. Would you mind explaining why? I suppose I may be able to use anything from .5 Tesla.
     
  5. Feb 12, 2016 #4

    berkeman

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    I think V50 is referring to the need for superconducting coils to get to those field strengths. Plus such strong fields mean a lot of energy is being used to generate them.

    Try playing around with this electromagnet field strength calculator to see what you can get with a non-superconducting coil:

    http://www.calctool.org/CALC/phys/electromagnetism/solenoid

    :smile:
     
  6. Feb 12, 2016 #5

    Vanadium 50

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    You're talking about a huge field. You're going to need of order a kiloamp to do this, and resistive losses will be of order a megawatt. This is unsafe, and is way too much for someone's first magnet. If you go to narrower wire, to get more turns, the current goes down, but the resistance goes up, and you're still trying to shed a megawatt of heat.
     
  7. Feb 12, 2016 #6
    Half a Tesla? There is another thread here where someone tried to reach 1T. I don't believe they mentioned the requirement for such a high current.

    If half a Tesla is unfeasible, what do you believe to be the maximum I can reach given I don't have professional equipment?

    Thanks
     
  8. Feb 12, 2016 #7
    On the point of heat buildup.. how long does it have to run for?. .If you're looking for very low duty cycles and micro or milliseconds of ON time, you can throw a lot more power at it than if you want to run it extensively.
     
  9. Feb 12, 2016 #8
    It will not be continuously running. I only need it to "pulse" a few times a second (anywhere from 2-5 times a second).
     
  10. Feb 12, 2016 #9

    berkeman

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    Can you say what you are trying to do? Maybe there is a better way to do it... :smile:
     
  11. Feb 12, 2016 #10
    Well... I 3D modeled and printed a working (and pretty sturdy) piston-crankshaft contraption. I fitted it with a cylindrical neodymium magnet, and was wondering if there was any way to use an electromagnet to "power" it. There are a few ways of doing it, one is simply placing an electromagnet at the end, and using the repulsive and attractive forces. Another way would be more akin to a railgun.

    I have an identical magnet to the one in the contraption, and I have noticed a very strong repulsive force when I place them near each other. I was hoping to replicate that repulsion using an electromagnet.

    This isn't intended to be a working motor that will power a vehicle, just an interesting hobby.
     

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  12. Feb 12, 2016 #11

    berkeman

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    Nice work! :smile: It would probably be more efficient to use a solenoid arrangement to pull the piston into the solenoid. If you use a magnetized piston, you could get both an attractive and repulsive effect from the coil. Why do you think you need such a high field to make the motor work?
     
  13. Feb 12, 2016 #12
    Thank you.

    As I said, I was hoping to replicate the same repulsive force I found between the two neodymium magnets. I suppose it seemed simpler at the time.

    I suppose now the problem would be to figure out the parameters for solenoid.
     
  14. Feb 12, 2016 #13

    Nidum

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    Last edited: Feb 12, 2016
  15. Feb 12, 2016 #14
    Thanks. This looks interesting.
     
  16. Feb 12, 2016 #15

    Nidum

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  17. Feb 12, 2016 #16

    russ_watters

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    Based on the answers that you have been given and the typical power capacity of a house, I'd say you are probably high by at least a factor of 100.
     
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