Magnetohydrodynamic Research Into Uber Magnets...

[Spacescifi]

I think the future of uber magnetic manmade fields lies in advanced magnetohydrodynamics.

For example, the massive magnetic field of earth is said to be caused from the rotating molten iron core.

And magnetars (uber magnetic neutron stars) are theorized to generate their fields from as follows below from wikipedia:

Origins of magnetic fields edit

The dominant theory of the strong fields of magnetars is that it results from a magnetohydrodynamic dynamo process in the turbulent, extremely dense conducting fluid that exists before the neutron star settles into its equilibrium configuration.[16] These fields then persist due to persistent currents in a proton-superconductor phase of matter that exists at an intermediate depth within the neutron star (where neutrons predominate by mass). A similar magnetohydrodynamic dynamo process produces even more intense transient fields during coalescence of pairs of neutron stars.[17] But another theory is that they simply result from the collapse of stars with unusually strong magnetic fields.[18]

Questions:

1. Has anyone tried to generate a magnetic field by rotating molten iron?

2. Do you think we could develop uber magnetic fields with magnetohydrodynamics, or is it simply a matter of mass, meaning more mass applied allows for stronger fields etc as in the case of magnetars.

Interestingly in pulse pure fusion detonation research, uber magnetic fields have been created, albeit only momentarily. So it seems you either need a ton of mass or a lot of energy, because mass and energy are two sides of the same coin and are interchangeable and convertible.

 

 

Thoughts?

[RCgothic]

My 4th year project at university was research on the subject of generating ultra-high strength magnetic field with electromagnets.

Firstly, it needs a lot of windings. The more loops for a particular current, the higher the magnetic field. It doesn't seem to me that molten iron is especially condusive to compact windings.

Secondly, resistance tends to go with temperature, and specifically drops to zero in certain materials at ultra-low temperatures.There's a reason super-high power magnets are generally cooled with liquid gasses. Molten iron, again, is not condusive to a low conductive resistance.

Thirdly, the hoop-stress in the material is key factor. Magnets want to disassemble themselves and fly apart under extreme tension. Molten iron contributes nothing to the tensile strength of the material. The research found hoop stress was related to the thickness of the coil. Nesting multiple small coils could potentially keep the stress down. Again, Molten iron a pretty poor choice.

Finally, the reason planets can generate enormous magnetic fields is because they themselves are enormous. Just having rotating iron isn't sufficient, you'd need to seed the iron with charge and/or a starting magnetic field somehow, and see above for all the reasons solid cold materials are a better choice for that.

For all the power of planetary magnetic fields, they're pretty inefficient for the masses involved. The right combination of eddy currents and movements eventually create a self-sustaining feedback loop that generates steady magnetic fields. But even sunspots are only ~3000 Gauss (Jupiter is about 4 Gauss). MRI machines regularly generate 70,000 Gauss, and we can create 450,000 Gauss steady state magnets in labs.

Edited March 10 by RCgothic

[kerbiloid]

A poorly cooled electromagnet becomes molten iron on its own.

[farmerben]

 

[AckSed]

1 hour ago, farmerben said:

 

Important science to be sure, but... All I could see was the Dinosaur Comics strip in the background.

[kerbiloid]

19 hours ago, RCgothic said:

Finally, the reason planets can generate enormous magnetic fields is because they themselves are enormous. Just having rotating iron isn't sufficient, you'd need to seed the iron with charge and/or a starting magnetic field somehow

Afair, the magnetic field appears at the very core/mantle border, where the sinking amounts of iron oxides and sulfides decay into the elements, releasing iron (sinks down) and oxygen/sulfur (surfacing as oxygen and sulfur oxides).

As the compounds are compounded from ions, and the whole mass is dissolved in the conductive metallic matter of the upper iron core, the charges of ions and electrons temporarily get distributed not uniformly and move in different directions at different speeds, so the spherical whirlpool around the core works as dynamo machine.

Thus, when all iron oxides get dissipated (+1.5 Gy or so), the magnetosphere will get weak, and then disappear.

This will cause the chain of the atmosphere and hydrosphere changes, turning Earth into Venus.
Also, this limits any evolution and local biolife at all with several billion years of existence, regardless of the star lifespan, and makes red dwarves lifeless.

Edited March 11 by kerbiloid