Using fireballs to uncover the mysteries of ball lightning

“People have been pondering ball lightning for a couple of centuries,” says James Brian Mitchell, a scientist the University of Rennes in France. Mitchell says that different theories of how it forms, and why it burns in air, have been considered, but until now there were no experimental indications of what might be happening as part of the ball lightning phenomenon.

Now, working with fellow Rennes scientist LeGarrec, as well as Dikhtyar and Jerby from Tel Aviv University and Sztucki and Narayanan at the European Synchrotron Radiation Facility in Grenoble, France, Mitchell can prove that nanoparticles likely exist in ball lightning. The results of the work by Mitchell and his colleagues can be found in Physical Review Letters: “Evidence for Nanoparticles in Microwave-Generated Fireballs Observed by Synchrotron X-Ray Scattering.”

“A group in New Zealand came up with this idea of ‘dusty plasma,’” Mitchell tells PhysOrg.com. “They thought that nanoparticles burning in air could cause ball lightning to remain for seconds, rather than disappearing after milliseconds. This was an attractive model.” But the model couldn’t be proved without detecting the nanoparticles.

Mitchell says that he saw a paper by Jerby describing the creation of a fireball in controlled conditions. “These fireballs floated in air,” Mitchell explains. “They resemble ball lightning.” This provided an opportunity to study whether or not nanoparticles were likely to exist in this natural phenomenon, shedding light on a scientific mystery.

Video of a floating fireball: WMV (610KB)

The work was done at the European Synchrotron Radiation Facility in Grenoble. The facility uses an x-ray that is 10 billion times more powerful than a typical x-ray found in a hospital. Additionally, Mitchell explains, the accelerator for the synchrotron is more than a kilometer in circumference: “We can get measurements here that we couldn’t get in many other places.”

“We passed an x-ray beam through the fireball we made, and saw that it was scattered. This indicated that there were particles inside the fireball.” Not only were Mitchell and his peers able to determine that nanoparticles must exist in fireballs similar to ball lightning, but they were also able to take measurements. “Particle size, density, distribution and even decay rate were measured using this technique,” he says.

Mitchell’s work with fireballs isn’t finished. When PhysOrg.com spoke to him for this article, he was back in Grenoble taking more measurements. “This is interesting from a fundamental standpoint,” he insists, “and right now we are more interested in size and structure.” Additionally, he says that some of the particles will be trapped and sent to Tel Aviv in order to study them for composition.

Mitchell hopes that this work will have more practical applications as well. “We are working with coupling the nanoparticles with microwave energy,” he says. “They heat up very quickly. This could be a way of producing catalysts for other experiments.”

Right now, it looks as though one of the mysteries of ball lightning has been solved. This experiment has provided a strong case for the presence of nanoparticles in ball lightning. The next step is discovering what scientists can do with the information.

More videos can be found at http://www.eng.tau.ac.il/~jerby/Fireballs.html

Copyright 2007 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

   

• vivcollins - Feb 18, 2008
  • Rank: 3.7 / 5 (3)
  Now thats incredibly exciting news!
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• Nikola - Feb 18, 2008
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  Nice! For the longest time many people, including scientists, insisted that this phenomena was not real. I wonder what else will be discovered in the coming decades that will overturn foregone scientific conclusions.
  
  Hopefully new energy applications will come out of this demonstration of ball lightning.
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• deatopmg - Feb 18, 2008
  • Rank: 4.5 / 5 (2)
  so there are nanoparticles.
  Has anyone calculated what the total energy flux of this man made ball lightning is? Where did these nanoparticles come from? Were they put there on purpose to get the plasma to form? What are they made of? Can the oxidation of that quantity of nanoparticles supply the energy needed to maintain the plasma for several seconds? Why don't the particles release all their energy in an "instant" as one would expect from pyrophoric materials? MAYBE nanoparticles explain man made fire ball but where do the nanoparticles come from in reported long lived natural ball lightning? SOMETHING IS MIGHTY FISHY HERE!!
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• fleem - Feb 18, 2008
  • Rank: 3.7 / 5 (3)
  This is just silly. When they find the particles are pieces from the particular alloy of the electrodes used to create the plasma, will they exclaim, "Voila', we have discovered that ball lightning is made of a nickel-copper plasma!"
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• earls - Feb 18, 2008
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  The particles are made of glass.
  
  They energized a borosilicate glass rod with microwaves that shot burning particles into the air.
  
  "Ball lightning appears after lightning strikes soil"
  
  http://www.scienc...fob3.asp
  
  http://link.aps.o.../e065001
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• merlrennes - Feb 26, 2008
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  The proposed ball lightning theory is that a lightning strike to earth creates nanoparticles that glow as they re-oxidize. The soil consists largely of silicon dioxide and this is also the constituent of glass, hence the use of glass in these experiments. Lightning is of course is millions of times more powerful that the microwave generator used in this experiment and so we cannot hope to reproduce the phenomenon exactly in the laboratory. We can only test aspects of the theory. This experiment showed that a microwave discharge can liberate nanoparticles from a solid surface and that these particles can be levitated in the electrical field of the microwave waveguide much as ball lightning seems to be a phenomenon involving levitation. Microwaves generated in a lightning storm have been proposed as one of the factors involved in the appearance of the phenomenon. The electrical field structure seems to be able to interact with the dusty plasma to keep the ball elevated. At this stage one of the important goals of the project is to understand this interaction and the heating mechanism that can raise the temperature of these nanoparticles so that they glow so brightly. Why is it important that these laboratory produced fireballs contain particles? Because particles have the possibility of staying excited for long periods through combustion like reactions. This has not been demonstrated in this experiment but it may be possible in larger scale experiments or withe different substrates. Gas plasmas on the other hand containing molecular ions, recombine with electrons and neutralize much too rapidly to easily explain ball lightning and this is a major reason for the enigma that has bewildered researchers for decades if not centuries.
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