Alfven's hypothesis of the ionizing critical velocity is investigated on the basis of observations with rotating plasma devices. The experimental fact is that the relative velocity between a neutral gas and a plasma perpendicular to a magnetic field does not exceed a critical velocity vc=√2eVi/m(eVi and m, the ionization energy and the atomic or molecular mass of the gas, respectively). It is interpreted from the standpoint of a current which generates in a process of plasma polarization. A final interpretation on the hypothesis is not given, but the structure and elementary process of the ionizing interaction is clarified.
A high spectral resolution laser radar system using a cesium vapor blocking filter was constructed. A method for measuring the Mie/Rayleigh scattering ratio by scanning the laser wavelength was developed and tested by an experiment. As a result, we are confirmed that this method is very effective for measuring a scattering parameter.
Authors developed a reflection acoustic microscope using liquid nitrogen as the coupling liquid. The resolution of a sample surface is better than 0.4μm when the instrument is operated at 1.5 GHz. This system is more practical than any ever developed, because it is easy to change a sample and to select an observation area. In this paper, authors report the concrete structure of this system and some images of IC's, and discuss the properties of these images qualitatively.