Dual Field Pi Coils

[Aziz]

Magnetic Field Strength Cross-Section Pictures

Hello friends,

is anybody interested on the magnetic field strength (MF) pictures of the compared coil configurations?

I am sure, you will be.
Ok, eat this.

All pictures have the same 3D projection parameters. The x-axis is not shown (going from your eyes into your display). The y-axis shows the longest coil dimension. The z-axis the height/depth above/below coil. The small target is still placed at z=10 cm (can you see it?). The axis length is 40 cm (going from -40 cm .. +40 cm). It is divided every 2 cm for a better comparision. So you can orient at it.

16 MF pictures will follow now ...

Have fun,

Aziz

[Aziz]

to be continued...

to be continued...

[Aziz]

to be continued..

to be continued..

[Aziz]

finally

finally

[Tinkerer]

Thanks Aziz,
These are excellent visualizations.

Tinkerer

[MagnetMan]

Aziz, really cool visualizations! Interesting that the triple coils appear to have a "cold" spot between the two outer coils. It's too bad there isn't a way to reflect a magnetic field so that less energy is expended on the upper side of the coils. Have you tried simulating other shapes that are asymmetrical along the z-axis such as cones?

I'm new to the forum, so I'm curious about the software you use, too!

-Stefan

[Aziz]

Hi Stefan,

Aziz, really cool visualizations!

thanks, it was a long way to achieve this. The coil software is written by me. I am adding as many functionality as I need. I am not giving the coil software away to ensure that coil improvements will be shared in the public domain.

Interesting that the triple coils appear to have a "cold" spot between the two outer coils. It's too bad there isn't a way to reflect a magnetic field so that less energy is expended on the upper side of the coils.

This "cold" spot does not matter. The coil housing won't allow targets to come too close the coil. The one sided exitation of magnetic fields isn't possible.

Have you tried simulating other shapes that are asymmetrical along the z-axis such as cones?

This wouldn't make much sense or get some benefit.

Aziz

[MagnetMan]

Hi Aziz,

I mentioned the asymmetrical shapes because I was curious whether a field could be produced that was larger on one side of the z-axis than the other. I understand that for a given segment of wire the field is symmetrical, but is it possible to change the shape of the field over a collection of turns? That is, does the shape of the field always follow the contour of the wires that generate it?

-Stefan

[Aziz]

Hi Stefan,

Hi Aziz,

I mentioned the asymmetrical shapes because I was curious whether a field could be produced that was larger on one side of the z-axis than the other. I understand that for a given segment of wire the field is symmetrical, but is it possible to change the shape of the field over a collection of turns? That is, does the shape of the field always follow the contour of the wires that generate it?

-Stefan

have a look at the following sites:
http://en.wikipedia.org/wiki/Magnetic_field
http://en.wikipedia.org/wiki/Maxwell%27s_equations
http://en.wikipedia.org/wiki/Gauss%27_law_for_magnetism

The Gauss's law states:

<damn, the formula can't be displayed here>

This law does not allow such wishes. No magnetic mono poles exist.

Answer to question 2:
The coil geometry defines the shape of the whole magnetic field around the coil. Every small part of the coil segment (filament of wire) produces it's own magnetic field lines. At a point of interest (x,y,z) , all magnetic field lines at x,y,z produced by every filament add up together (vector addition).

I am sure, wiki can explain it better.
Aziz

[MagnetMan]

Answer to question 2:
The coil geometry defines the shape of the whole magnetic field around the coil. Every small part of the coil segment (filament of wire) produces it's own magnetic field lines. At a point of interest (x,y,z) , all magnetic field lines at x,y,z produced by every filament add up together (vector addition).

Thanks Aziz. I appreciate your posting those links for me. I'm pretty familiar with the basics of magnetism, but didn't know if things got weird with multiple "mini" fields as is the case with a multiple turn coil. Your mentioning vector addition cleared it up for me. Sounds like fields will always follow the general contours of the coils that produce them.

-Stefan

[Tinkerer]

Hi Aziz,

I mentioned the asymmetrical shapes because I was curious whether a field could be produced that was larger on one side of the z-axis than the other. I understand that for a given segment of wire the field is symmetrical, but is it possible to change the shape of the field over a collection of turns? That is, does the shape of the field always follow the contour of the wires that generate it?

-Stefan

Here is a visualization of a magnetic field that is pushed mostly downward. It is a 5.3Mb video file animation.
the top coil carries 1/3 of the current 180 degrees out of phase from the bottom coil. The 2 magnetic fields interact, that is the top field repels the field of the bottom coil.
The the dots in the 2 coils show the direction of the current.
http://s565.photobucket.com/albums/s...eRepel_640.mp4

Tinkerer

[MagnetMan]

Thanks Tinkerer!

I imagine for our purposes such a coil would be a poor choice for a variety of reasons, especially an increased time delay. But, you certainly got where I was trying to go! Is the upper coil simply canceling out part of the lower coil's field, or is it actually being deflected? I know a bifilar coil with counter wound coils would have a zero net field and be absolutely useless for an MD.

-Stefan

[Tinkerer]

Thanks Tinkerer!

I imagine for our purposes such a coil would be a poor choice for a variety of reasons, especially an increased time delay. But, you certainly got where I was trying to go! Is the upper coil simply canceling out part of the lower coil's field, or is it actually being deflected? I know a bifilar coil with counter wound coils would have a zero net field and be absolutely useless for an MD.

-Stefan

Stefan,

the upper coil repels the magnetic field of the lower coil. The field is deflected. You can make a simple experiment yourself. Take two magnets and approach them. The equal poles will push away, the unequal poles will attract.

If you sprinkle some iron filings or cutup steel wool, over a sheet of paper and mover the two magnets under the sheet of paper, you will see how the repelling of the fields change the shape of the fields around the magnets, concentrate the field in some places and push the field to different places.

You can also Google "Magnetic field visualizations" and find thousands of pages.

Tinkerer

[moodz]

Hey ... not the Corbyn Patent again !

Last week I got the filed application but forgot to post the info here. It's on my desk at work, I'll try to remember to post it tomorrow.

errmmm .... isnt the Corbyn patent a "dual field" coil ?

"1" and "2" are tx coils.

Regards Moodz.

[Aziz]

An induction balance co-planar coil is also a dual field coil!!!
An anti-interference coil (figure-8, double D) is a dual field coil too!!!

Aziz