"Is there no plasma in ball lightning?" CWI researcher Ute Ebert comments recent experiments on lightning balls. These experiments were done by Antônio Pavão and Gerson Paiva of the Federal University of Pernambuco in Brazil, who published their findings in the Phys. Rev. Lett. 98, 048501 of January 2007. In a rather simple laboratory experiment, the Brazilian group evaporated silicon with strong electrical currents just as they occur in lightning. In a movie can be seen how the silicon is bursting into fragments. Sometimes glowing ping-pong sized balls are being formed, surviving for up to 8 seconds. It looks as if the balls have their own life: they move, jump and turn before they fade.
"The experiment suggests that there is no plasma in this phenomenon, only chemical combustion," Ebert says. She is an expert on the theory of lightning. Ute Ebert is head of the Multiscale Modelling and Nonlinear Dynamics (MAS3) research group at CWI and a professor at the Technische Universiteit Eindhoven.
In the Netherlands in the 1980s, a company called Convectron, tried to make plasma in lightning balls in order to start nuclear fusion - without success. Ebert will publish her remarks on the recent Brazilian experiments in the March issue of the magazine of the German Physical Society.
More information can be found on an article in New Scientist, the Dutch Wikipedia page on lightning balls, the German Wikipedia page on lightning balls or Ute Ebert's homepage
