# Altering Magnetic Fields

1. Jan 8, 2014

### rangerellis

Greetings, PF forum members!

I have had a sudden interest in Active Radiation Shielding (ARS), and as such, an increased interest in magnetics. I have had trouble locating any information regarding the possibility/impossibility of altering magnetic fields in such a way that changes the field's shape, strength, size, and gradient (I do not know the proper term; I am referring to how steeply the strength of the field changes as you move away from the source of the field).

And so I ask for any links, knowledge, etc. that could help me understand these things. Thank you for your time!

2. Jan 8, 2014

### thegreenlaser

You'll probably need to be more specific about what exactly you want to do. What magnetic field are you starting with, and what magnetic field do you want to end up with? I don't think there's really a general method (at least not a straightforward one) for making arbitrary alterations to a magnetic field.

3. Jan 8, 2014

### rangerellis

Specifically, I had an idea about making active shielding more efficient (energy-wise) at blocking radiation in space. The conventional idea, not method since it hasn't been used yet, is to have a very powerful superconductor that generates a magnetic field kilometers wide. It is that large because it needs to be strong enough to repel radiation. My idea was to somehow manipulate the field so that its radius isn't as large, hopefully saving energy, but much more powerful. I haven't been able to locate studies to read up on, hence my post.

Example: Instead of having a permanent magnet with a field radius of 1 meter and a magnetic repelling force of 1 newton, create a specialized device that manipulates the field so that the field has a radius of 0.1 meters and a magnetic repelling force of 100 newtons. I hope this helps explain my idea.

I was thinking that if I spun the 'magnet', pulsed its field (for a superconductor), and/or added other magnetic field sources, I could accomplish the goal of a smaller, stronger field.

I hope this helps you help me! Thanks for your time!

4. Jan 8, 2014

### ZapperZ

Staff Emeritus
This is very puzzling.

If you just want a shield, why not just enclose it in a rather good metal? That should be enough to shield it from a lot of the external electromagnetic field. You don't need to generate your own field to do that!

And if you have the money and you want to shield just the magnetic field, then use a mu-metal. If it is good enough to shield the electrons in photoemission experiments from stray external magnetic field, I'd say it should be good enough for you.

Zz.

5. Jan 8, 2014

### davenn

is inferring that he's wanting to use a magnetic field to create a shield from various particles
alpha, beta, gamma, x-ray etc
is that correct, rangerellis ?

it sorta hints of the mythical shields used in star trek etc

we await a confirmation

cheers
Dave

6. Jan 8, 2014

### ZapperZ

Staff Emeritus
That would be even more puzzling. Magnetic field to shield against EM radiation? What existing physics do we use to do this?

Zz.

7. Jan 8, 2014

8. Jan 8, 2014

### ZapperZ

Staff Emeritus
And did you read the section that mentioned the mu-metal that I mentioned?

Zz.

9. Jan 8, 2014

### collinsmark

'Just a guess here, but I read the OP assuming that the radiation in question is in the form of cosmic rays, consisting of mostly high energy protons, and some high energy electrons:charged particles. (And also deflecting the solar wind, while we're at it).

I was assuming that the OP was inquiring about a system to divert cosmic rays (and/or solar wind) similar to how the Earth's magnetic field shields us against cosmic rays (and/or solar wind), except on a smaller scale.

[Edit: Now that I think about it, shielding against solar wind might be the more practical of two (vs. cosmic rays) for things such as extended journeys to the Moon or Mars.]

Last edited: Jan 8, 2014
10. Jan 8, 2014

### ZapperZ

Staff Emeritus
But then why did he/she gave that link? That is a material shielding of magnetic field.

I have a feeling that the OP has a severe misunderstanding of several issues here.

Zz.

11. Jan 8, 2014

### rangerellis

To clear things up, I am not talking about shielding the magnetic field. I am, in fact, talking about using the magnetic field as a shield. I alluded to this when I said 'active radiation shielding', which is the use of the magnetic relationship between a magnetic field and charged particle to block the particles. I did not mean 'passive radiation shielding', which is the use of matter to block charged particles. Sorry for the confusion.

Yes it is similar to the fictional Star Trek shields, but these fictional shields were not actually explained in the show so I cannot say if this is what I want.

The purpose of the magnetic field I envision is to protect astronauts from radiation in space, most specifically CMEs and GCR, however it should perform well in blocking the radiation in the Earth's own Van Allen. Radiation Belts, which consists of Electrons and Protons.

To be more specific, I am looking for sources, links, and equations that can help me figure out how much magnetic force is required to block these forms of radiation and how to manipulate the magnetic field to do so.

Essentially, the idea I have should, hopefully, help to create a smaller sized magnetosphere, much like the one Earth has and the one Mars doesn't, but much smaller, more efficient, and cheap to manufacture (relatively). Thanks for your time!

12. Jan 8, 2014

### ZapperZ

Staff Emeritus
Magnetic field cannot shield against EM radiation, because it doesn't interact with such radiation. So if you have intentions of shielding against x-rays, gamma rays, UV, then this already doesn't work!

Zz.

13. Jan 8, 2014

### rangerellis

I'm not looking to block EM radiation... As I said I am looking to block Galactic Cosmic Radiation, Coronal Mass Ejections, and the charged particles of the Van Allen belts. Please read my posts fully if you want to post. I am essentially trying to create a miniature magnetosphere, similar to Earth's.

But that is not what I asked.............. I would like help finding equations that find the force required to block these particles and information on how to alter magnetic fields. Please stick with the question at hand.