Spectral distribution of the scattered laser light from high pressure arcs and its application to electron density measurement

The presence of a satellite peak on the wavelength axis was shown in the spectral distribution of scattered laser light due to electrons in high pressure arcs. The method of direct electron density measurement only from its location in the wavelength axis was thus contrived. Its features are as follows. (1) There is no need of obtaining the absolute intensity of scattered light. (2) The satellite peak being sharp, only this limited portion needs to be oserved, no need for the overall spectral distribution. (3) The satellite peak is over several nm away from the central laser wavelength, so the stray light in the vicinity presents no problem. The detection apparatus is simple in configuration, being of optical fiber, PMT, coaxial cable and synchroscope. (Mori, K.)