Plasma Magnetics / Electromagnetic Radiation / Forums

Forums

4hv.org :: Forums :: Electromagnetic Radiation

« Previous topic | Next topic »

Plasma Magnetics

1 2 next

Move Thread

LAN_403

Ryan

Thu Feb 26 2009, 05:10PM

Registered Member #1606 Joined: Fri Jul 25 2008, 02:40PM
Location:
Posts: 71

I was reading an article in wikipedia regarding plasma magnetics, see quote below.

"Magnetization
A plasma in which the magnetic field is strong enough to influence the motion of the charged particles is said to be magnetized. A common quantitative criterion is that a particle on average completes at least one gyration around the magnetic field before making a collision (ie. Ï‰ce / Î½coll > 1 where Ï‰ce is the "electron gyrofrequency" and Î½coll is the "electron collision rate"). It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are anisotropic, meaning that their properties in the direction parallel to the magnetic field are different from those perpendicular to it. While electric fields in plasmas are usually small due to the high conductivity, the electric field associated with a plasma moving in a magnetic field is given by E = -v x B (where E is the electric field, v is the velocity, and B is the magnetic field), and is not affected by Debye shielding."

Questions:
1) What is the difference between a regular plasma field and magnetized plasma field? And how are they created and can they be created through a tesla coil?
2) It said magnetic fields are different when perpendicular or parallel to it, do they cancel each other out? Are they opposing?
3) How strong are these fields?

Could somebody elaborate on this for me?

Thanks, Ryan.

Plasma Lover

Thu Feb 26 2009, 06:30PM

Registered Member #1911 Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165

Ryan wrote ...

Questions:
1) What is the difference between a regular plasma field and magnetized plasma field? And how are they created and can they be created through a tesla coil?
2) It said magnetic fields are different when perpendicular or parallel to it, do they cancel each other out? Are they opposing?
3) How strong are these fields?

Could somebody elaborate on this for me?

Thanks, Ryan.

What is the difference between a regular plasma field and magnetized plasma field? And how are they created and can they be created through a tesla coil?

A regular plasma field is the same as a magnetized plasma field, the only difference being that the magnetized plasma field has an external source of magnetism, which causes a redirection of the plasma. They can be created through a Tesla coil, but it would take a trrememendous amount of magnetic force. The current in a Tesla coil's streamer is usually much too little to move using a magnetic field.

It said magnetic fields are different when perpendicular or parallel to it, do they cancel each other out? Are they opposing?

When perpindicular, magnetic fields are either pushing the plasma from one pole, or pushing it with the other pole; when parallel, a magnet will induce a magnetic field in the plasma and one pole will attract the plasma while another repels it.

How strong are these fields?

It depends on the magnetic force needed to pull the plasma - for example, in an evacuated tube, there is no need for a 'giant' magnet with a huge number of gauss, since there's no air in the tube to cause the plasma to 'run away' from the magnet, due to the plasma's heating of the air (just like the air in a Jacob's ladder). For small, evacuated tubes, you can probably use a medium-large ceramic magnet. A fridge magnet will almost definitely not work, but a ceramic magnet taken out of a microwave has worked in the past. A neodymium magnet would be best.

Just as a side note, has anybody attempted to redirect plasma in a tube using a toroidal magnet with its poles being on opposite sides, similar to a microwave oven magnetron magnet? If not, I have a tube that i could fit a magnet around. To be honest, all I need is a vacuum pump. I've been looking to get one off of Cragslist, but it doesn't seem to be working very well.

Ryan

Sat Feb 28 2009, 05:50AM

Registered Member #1606 Joined: Fri Jul 25 2008, 02:40PM
Location:
Posts: 71

Great thanks for the rather extensive reply!

-Ryan

Proud Mary

Sat Feb 28 2009, 08:58AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Is a magnetized plasma necessarily one with an externally applied magnetic field? Isn't current flowing in the plasma the cause of magnetization in the plasma pinch and z-pinch?

See wikipedia articles on pinch (plasma physics) and z-pinch

Conundrum

Sat Feb 28 2009, 10:23AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

You might try looking into using the "plasma" tubes they sell for PC case lighting. the outer bore is small enough to fit most magnetron magnets.

Also may be worth obtaining one of those tag removal magnets as they are pretty strong (IIRC NIB based) and also have an inverted cone shape which makes for some strange field profiles.

regards, -A

btw 600 posts :) (20*30)

Ryan

Sat Feb 28 2009, 11:23PM

Registered Member #1606 Joined: Fri Jul 25 2008, 02:40PM
Location:
Posts: 71

I was under the impression that the plasma field itself gave off a strong magnetic field, does this still hold true?

big5824

Sat Feb 28 2009, 11:40PM

Registered Member #1687 Joined: Tue Sept 09 2008, 08:47PM
Location: UK, Darlington
Posts: 240

I think the plasma itself gives off an electrical field, but when current is flowing through it it also creates a magnetic field.

Plasma Lover

Sat Feb 28 2009, 11:55PM

Registered Member #1911 Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165

Ryan wrote ...

I was under the impression that the plasma field itself gave off a strong magnetic field, does this still hold true?

The strength of the magnetic field is highly dependent upon the current of the plasma. I just realized that I didn't add the current of the arc as a factor in my previous post.

The plasma emits an electromagnetic field which is able to interact with a magnet. Since the electromagnetic field is created by the plasma, the plasma is forced to stay in the center of said electromagnetic field. If you influence a change in the electromagnetic field with a magnet, this will cause the plasma to adhere to its original magnetic field, which is either attracted to or repelled by the magnet.

I'm not sure as to the exact physics, but I understand what is happening in the tube.

May I ask what the application of this knowledge is?

big5824

Sun Mar 01 2009, 10:59AM

Registered Member #1687 Joined: Tue Sept 09 2008, 08:47PM
Location: UK, Darlington
Posts: 240

You can use an electromagnet to extinguish an arc (not quite sure how, i just know it can be done)

Ryan

Sun Mar 01 2009, 07:05PM

Registered Member #1606 Joined: Fri Jul 25 2008, 02:40PM
Location:
Posts: 71

No application in specific, its more for general knowledge of how these things work. I will do some experimenting, thanks for your help everyone. I will post some questions/results in a few weeks.

-Ryan

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob