Experimental study on scattering phenomena of both laser beam and electromagnetic wave due to micro dielectric materials

It is noted that one of the most significant problems connected with optically observing the prebreakdown and breakdown phenomena in liquids is a simultaneity between the movement of charged particles and the optically observed disturbance whose size is smaller than the wavelength of light. An experimental study is described in which an electromagnetic wave of 50 GHz, which is called a mm-wave, irradiates a spherical glass whose size is comparable to the wavelength of a mm-wave. The electric field of the scattered wave measured using a doublet antenna whose size is 0.3 cm agrees roughly with that calculated theoretically using the wave optics. In contrast, the intensity distribution of the laser radiation refracted due to the same material, which is measured along the axis of light, agrees completely with that calculated using geometric optics. Finally, it is suggested that the optically observed disturbance might be a cloud of tiny bubbles which is produced by the movement of quasi-free electrons in liquids