Helium spark spectrum

For Z=2 we obtain the spectrum of ionised helium (the spark spectrum of helium). In this spectrum the lines which correspond to even quantum numbers (w=2N),... 

This similarity between the spark spectrum of helium and the spectrum of hydrogen was responsible for the fact that the former used to be written in the form... 

The value of C, as has been explained, depends upon the nuclear charge less the screening effect of other electrons. For the K series of X-ray frequencies it varies nearly as Z. As the degree of ionization of the atom increases with more intense methods of spectral excitation, for example, passage from flame spectra to spark spectra, G increases. For the spectrum of ionized helium (nuclear charge 2, one electron) it is four times the value for hydrogen (nuclear charge... 

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