[SOLVED] Sodium vapor lamp spectra

[darkseid]

Hi

I dont know if this is the best forum to post this query.

In a sodium vapor lamp, there is 99% inert gas (Penning mixture of Argon and Neon) and 1 % Sodium, but in the spectrum, we can see only sodium lines (despite of low concentration) and no argon or neon lines. Why?

 

[albbg]

As far as I know, in high pressure lamp type, the Penning mixture is roughly 1% of total, so the lines due to Neon and Argon are present but Sodium D line dominates over them. Penning mixture is used only to lower the ionizing voltage.

 

[darkseid]

Thanks, I also checked some IES and IEEE papers. In a high pressure Sodium Vapor lamp, The role of inert gas is to lower the ionization voltage and increase the sodium vapor temperature.