Hi, as far as I know the spectral distribution of emitted light is a variable of the gas mixture. This allows to effectively "design" the emission spectrum of the light source. And this means that each plasma light source will have a particular emitted spectrum that you would either have to measure or get (and believe in) from the manufacturer. As mentioned above, plasma light sources are employed in some applications because it is possible to achieve UV emission, so I would recommend to get the "real" data of the source you are interested in rather than some generic assumptions.