Ion concentrations in spark channels in hydrogen

Ion concentrations in hydrogen spark channels may, it is shown, be found by observing the Stark broadening of the Balmer lines. The line breadths are measured in two ways: by the normal techniques of photography or by plotting the line breadths with a photoelectric electron multiplier, amplifier and cathode-ray oscillograph. The advantages of the latter method is that the light emission/time relation can be studied. Representative oscillograms are shown in the paper. Full account must be taken of the fine structure of the lines in assessing their true breadths, and Holtsmark's theoretical analysis of the Stark effect for inhomogeneous fields is used for that purpose.