Evidence for Nanoparticles in Microwave-Generated Fireballs Observed by Synchrotron X-Ray Scattering

The small-angle x-ray scattering method has been applied to study fireballs ejected into the air from molten hot spots in borosilicate glass by localized microwaves [ V. Dikhtyar and E. Jerby Phys. Rev. Lett. 96 045002 (2006)]. The fireball’s particle size distribution, density, and decay rate in atmospheric pressure were measured. The results show that the fireballs contain particles with a mean size of ∼50  nm with average number densities on the order of ∼10⁹. Hence, fireballs can be considered as a dusty plasma which consists of an ensemble of charged nanoparticles in the plasma volume. This finding is likened to the ball-lightning phenomenon explained by the formation of an oxidizing particle network liberated by lightning striking the ground [ J. Abrahamson and J. Dinniss Nature (London) 403 519 (2000)].