High pressure sodium lamp phosphorescence

[MechatEng2023]

I noticed that high pressure sodium lamp arc tubes exhibit fluorescence and even phosphorescence when  the lamp is excited at low power.
When the sodium is not vaporized, the Xe-Hg plasma generates a significant amount of UV light but not all HPS lamp have fluorescent and phosphorescent arc tubes.
Philips MASTER SON-T PIA Plus lamp have them.
I made some videos of the phenomenon:

/>www.youtube.com/watch?v=bKaBvIwCUH0
https://www.youtube.com/shorts/ISq_K2TWQIo

Did anyone else try this? Now I have to get some cermic metal halide lamps to see if they also have fluorescent and phosphorescent arc tubes.

[klugesmith]

That's fascinating.  Thank you for reporting it and making a nice video.

I found some old discharge lamps while cleaning out a storage tent. Will be fun to check for phosphorescence.   Any guesses about whether there's anything like that in a low-pressure sodium vapor lamp? (SOX type)?

This forum isn't the greatest place for getting discussions about lamps and optics, but a few people pay attention and comment once in a while.

[MechatEng2023]

Low pressure sodium lamps just produce a neon glow when cold, no phosphorescence. The arc tube of some high pressure sodium lamps contains rare earth metal ions.