Doppler shift spectroscopy for the measurement of angular divergence and ion species of ion beam

Both the angular divergence and the mixed ion species of the hydrogen-ion beam extracted from a duoplasmatron are simultaneously measured using Doppler shift spectroscopy of the Hα spectral line. Doppler-shifted Hα lines, which originate from several different ions, such as H+, H+2, H+3, and H2O+, are spectrally well resolvable from each other on the measured spectrum. The ratio of mixed species is deduced from the intensity ratio of each peak by using a fully developed emission model which is valid for target thickness of less than 1016 cm-2, and the angular divergence of each ion beam component is determined from the line widths with the measured emission lines fitted to a Gaussian shape