Scattering and beam trapping in laser-produced plasmas in gases

Experimental evidence is presented to verify that the laser light scattered at 90° from laser-induced breakdown plasmas in air is not due to Thomson scattering from free electrons as has been generally assumed. The scattering appears to be dominated by reflections from the interfaces of minute localized regions of high electron density. The geometry of the scattering regions indicates that self-focusing may occur in the plasmas generated in some gases.