Fireball Ejection from a Molten Hot Spot to Air by Localized Microwaves

A phenomenon of fireball ejection from hot spots in solid materials (silicon, germanium, glass, ceramics, basalt, etc.) to the atmosphere is presented. The hot spot is created in the substrate material by the microwave-drill mechanism [ Jerby et al. Science 298 587 (2002)]. The vaporized drop evolved from the hot spot is blown up, and forms a stable fireball buoyant in the air. The experimental observations of fireball ejection from silicate hot spots are referred to the Abrahamson-Dinniss theory [ Nature (London) 403 519 (2000)] suggesting a mechanism for ball-lightning initiation in nature. The fireballs observed in our experiments tend to absorb the available microwave power entirely, similarly to the plasmon resonance effect in submicron wavelengths [ Nie and Emory Science 275 1102 (1997)].