Electromagnet Question
Electromagnet Question
(OP)
At this point I have a cylindrical dipole electromagnet with a 1008 steel core and encasement (no exposed copper wire, just a steel cylinder). I imagine the magnetic field looks like what I have depicted in Figure A below. My question is this: Is there a way to reconfigure the magnet so that is remains a dipole but to produce a field similiar to Figure B (note the elongated N pole field)?

(if the image doesn't show go here: http://www.proverbsllc.com/images/electromagnet.jpg)
Would removing the steel plating from the North end accomplish this? Or perhaps cupping (parabolic) the ends: S ( ( N ?
Any help is greatly appreciated.
-Andrew

(if the image doesn't show go here: http://www.proverbsllc.com/images/electromagnet.jpg)
Would removing the steel plating from the North end accomplish this? Or perhaps cupping (parabolic) the ends: S ( ( N ?
Any help is greatly appreciated.
-Andrew





RE: Electromagnet Question
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RE: Electromagnet Question
RE: Electromagnet Question
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RE: Electromagnet Question
I also remember a discussion about using parabolic shaped ends might produce an extended field. So those are my two ideas for this, but I am looking for either confirmation or alternates.
Thanks,
-Andrew
RE: Electromagnet Question
RE: Electromagnet Question
http://en.wikipedia.org/wiki/Halbach_array
This should work just as well for an electromagnet.
RE: Electromagnet Question
see:
http://www.etel.ch/cms/default.asp?Id=372
versus:
http://en.wikipedia.org/wiki/Halbach_array
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RE: Electromagnet Question
a magnetic dipole (remember that magnetic monopoles do not exist) is just like, in electrical terms, a battery: the load (e.g. a lamp in the electrical parallel) is represented by the air gap between the poles, whilst any ferromagnetic component added to the flux path is like a conductor wire.
By reasoning in this way you'll easily understand that there is no way for a simple dipole to increase the flux on one pole at the expense of the flux on the other one: just like the current in a circuit is the same near the positive lead and the negative one, the flux will be the same.
And as I told your colleague Greavis on another thread, if you don't explain the purpose of your magnet assembly, you'll not be able to receive more help on how to achieve your goal.
prex
http://www.xcalcs.com : Online tools for structural design
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads
RE: Electromagnet Question
Having a core and then a backbar on one end will project the field in one direction. The bigger the diameter of the core and the bigger the backbar the further the field will be projected.
A starting thickness for the backbar is to provide the same cross section as the core at their intersection.
Some dimensions and detail would make this analysis much easier.
Mike
RE: Electromagnet Question
I refer to the magnets at dipole only in that I can't do a configuration to U shape the electromagnets. Space is limited, as is the voltage that can be supplied to the magnets (about a 6 volt source).
The electromagnets each have the following dimensions:
Core Diameter: 0.125"
Core/Coil Length: 0.25"
Coil Diameter: 0.375"
Currently using 30awg wire for the coil.
My understanding of magnetics stems from my electronics background, that is to say I know electronics just never specialized into magnetics. That said, I have always understood that any force (electrical, light, etc) can be focused to some degree. We use lenses and parabolic mirrors to focus light. We use magnets to focus lasers or partical accelerators. We use low resistance wiring to focus electricity (as opposed to a big hunk of metal that has eddies all throughout). Etc.
My thought with this is that by using a material with high permeability on the sides and one end of the electromagnet, the "juice" would flow more readily to the other end, providing more (or less reduced?) flux at the open end. Sort of like reducing the resistance before a light bulb so you get max energy at the bulb.
Mike, by "backbar" do you mean the end of the magnet facing away from the other (in my picture above) such as the S pole on the bottom electromagnet?
Hope this all explains some of what I am trying to do and can help everyone out there shed some ideas on ways to accomplish this.
Thanks,
-Andrew
RE: Electromagnet Question
The backbar is what you describe on the S pole and extended to the sides.
The coil you describe given a perfect lay will be about 260 turns of wire. 20 watts of power is required at 6 VDC. This gives you about 880 ampturns. Not much to work with. A 0.125 dia core will have very little projection. Even conserving all the flux possible.
Mike
RE: Electromagnet Question
The core of 1010 steel is saturated thru about 3/4 of it's length.
Mike
RE: Electromagnet Question
RE: Electromagnet Question
You need bigger core and more ampturns for a pound force.
Mike