Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can magnets control fire?

  1. Jun 29, 2009 #1
    I was told by my teacher that fire is plasma and that plasma can be controlled by magnets. Does that mean it is possible to effectively use magnets to control fire?
     
  2. jcsd
  3. Jun 29, 2009 #2

    negitron

    User Avatar
    Science Advisor

    No. Even in fires which are hot enough to produce plasmas, the flames are essentially neutrally charged--although the electrons are separated from their nucleii, they are still more or less homogeneously mixed with them, so the net charge is zero. Only plasmas which have had their charges separated (such as by an electric field, as in a plasma TV) can be affected by electric or magnetic fields on a macroscopic scale.
     
  4. Jun 29, 2009 #3
    That's not true. Electric and magnetic fields will induce dipoles in a plasma just as they do in a neutral solid (but to an even greater degree). However, the net effect of dipole interactions, I imagine, would do significantly less to control the path of the flame then the fuel aspect (i.e. it will spread to areas rich in oxygen and fuel).
     
  5. Jun 29, 2009 #4
    I suppose if you got a really strong magnet, you could attract oxygen and control which direction the fire burned in. That has nothing to do with it being plasma though.
     
  6. Jun 29, 2009 #5

    berkeman

    User Avatar

    Staff: Mentor

    Okay folks, the next post better have some pointers to some peer-reviewed journal articles on this, or the responses will be deleted as unsubstantiated claims. It shouldn't be that hard to look up...
     
  7. Jun 29, 2009 #6

    negitron

    User Avatar
    Science Advisor

    Well, it looks as though I'll have to partially retract my earlier post, at least for the case of very strong B fields:

    http://ieeexplore.ieee.org/Xplore/l...065242.pdf?arnumber=1065242&authDecision=-203

    Note, however, that it appears to be the oxygen that is affected by the B field, rather than the flame itself.
     
    Last edited: Jun 29, 2009
  8. Jun 30, 2009 #7
    Yeah, that's what I was saying. Oxygen is paramagnetic.
     
  9. Jun 30, 2009 #8
    It should be noted that in a 2 Tesla magnetic field you'd be ripping nails out of walls and such and would require a giant superconducting magnet (MRI's are around 3 Tesla). Which makes it pretty useless for any form of 'fire fighting'
     
  10. Jul 23, 2009 #9
    Great idea ! controlling fire by a magnet ! First of all, I would like to know whether fire should be considered as 'plasma phase' of matter ?
     
  11. Jul 23, 2009 #10

    negitron

    User Avatar
    Science Advisor

    Nearly all ordinary fires aren't hot enough to be plasmas. What you see as flame is simply ordinary gas heated to incandescence.
     
  12. Jul 23, 2009 #11

    Borek

    User Avatar

    Staff: Mentor

    Flame is conductive and as such will be reacting to magnetic fields - that's what magnetohydrodynamics is about. How strong the interaction will be is completely different question - but it looks to me like it is so weak that we are outside of the realm of practical applications.
     
  13. Dec 21, 2011 #12
    I signed up just to post my results to the questions above,

    Some time back I was trying to make my own solar flares in the lab.

    https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/198578_10150137123923291_519458290_6399092_828389_n.jpg [Broken]

    https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/200686_10150137123883291_519458290_6399090_6825074_n.jpg [Broken]

    Those are pictures I took from my tests with Fire and very large high voltage fields.

    In this experiment I have a 15,000 Watt X ray transformer running at 50KV DC through the fire to the ring of the burner as ground.

    I was able to manipulate the shape of the fire by changing the voltage and current characteristics.

    So this is an interesting result, What do you all think is going on?

    Happy to answer any questions about my rig.
     
    Last edited by a moderator: May 5, 2017
  14. Dec 21, 2011 #13
    Also the gas used for the experiment was Propane
     
  15. Dec 22, 2011 #14

    Drakkith

    User Avatar

    Staff: Mentor

    I'd say you were ionizing the air and fire due to the 50,000 volts.
     
  16. Dec 22, 2011 #15
    This whole "is fire plasma" thing turns up repeatedly. I think a thread stickyed on it would be useful.
     
  17. Dec 22, 2011 #16

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    The only practical way to control fire with magnets is that if you can pour enough magnets on a fire, eventually you will snuff it out.
     
  18. Dec 22, 2011 #17

    cmb

    User Avatar

    I think it would be interesting if you can post a better write-up of the test, kit layout, controls, images with flow rates (albeit arbitrary units like 'angle of valve setting', if you aren't using a mass flow device), &c.. Also more info on your power supply and how you come to conclude you have a 50kV discharge. Are we looking at a PSU pulled down to quite low volts with a 'high' current, or otherwise how does the presence of the flame affect the conductance/arcing in that region.

    The second image does look interesting, but not enough 'control' information here to begin making second guesses at what we are looking at.
     
  19. Dec 22, 2011 #18
    Bingo, that is what I was thinking as well. You can even hear it slightly.

    As for an experiment, I set up the rig again last night and this time I went with a large coil mounted fixed with a deflection shield, I then ran 10KV DC to a cap bank, and sent an Directed EMP at the flame, and sure enough it would 'poof' on impact. like explained above, it was not a huge effect but noticeable.

    Also interesting effect, while the caps where charging the fire would 'list' or slightly lean as if attracted to the coil, then on fire, it would move abruptly in the opposite direction.

    I would love to test this in a vacuum, the only problem is getting fire to burn with no oxygen :P
     
  20. Dec 22, 2011 #19
    You got it! Let me work on a sketch,

    As for my power supply,

    DSC_1679-1.jpg

    It is a 15,000 Watt X-Ray transformer. The above pic is with it removed from the oil. the full wave bridge is on the left side.

    The output voltage was first calculated by the arc distance I was getting consistent arcing at 0.787" so for AC that is about 47KV being that I was using DC my best guess was 50KV

    I then grabbed my High voltage probe,
    Mine looks just like this,
    Product-200442420185-2.jpg

    And verified my output.

    Now with the fire on, all bets are off, for it shortened the arc distance as well as introduced a dynamic load.


    the fire was being fed from a large Lab bunsen burner, similar to this,
    41oOf9WRwaL.jpg

    And was fed an constant stream of propane. As for the flow, I was not worried about this, for all I needed was a consistent height flame for the tests.


    and for my EMP tests last night I used my Glassman,

    im.php?id=216838.png

    I have much more consistent control over current and voltage.




    Now you asked about control, I can not bend the fire and hold it there, the pictures abaove where after many takes to get right, the effect is pulsed, for once the fire conducts the full force of the current it deflects drops the connection and repeats,

    so the effect is a fast oscillating almost chaotic experience. I did find through pictures I was able to effect the shape of the fire for only milliseconds at a time. for the reasons stated above.

    When I get some free time, I will try to recreate my original setup and get some video to explain as well
     
  21. Dec 22, 2011 #20
    Also I will mention the 15,000Watt X-Ray transformer I had to current limit to 600Watts for the test, for at full power, the fire ball that was formed at full flame deflection got to be many feet in length!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook