The gasses quit combining properly as the tube age, at least in layman terms. This can be from shelf time to operational times. I don’t know of any specific time frames and I suspect from my time around them, it’s more of how it was manufactured (accuracy) than anything else.
These commonly go out of TEM00 mode or resonance. This effects how the beam is formed or it’s quality.
They can resonate correctly but still start loosing power because of degraded gas mixture.
My understanding of the placard is that rated power, is the tubes 100% power rating, whereas the maximum peak is the do not exceed power limit. So these are really 150W tubes… at least IMHO. I spoke with a number of people that should know.
Most tubes of this size are generally warranted for 10k hours. They are also analog devices, so they run longest at mid-range. You can run 150W, but anything that’s analog and you drive it at 100%, it generally shortens the devices life. If it’s measurable or not, I don’t know.
I run my tubes at 20C (68F), I think temperature being cooler helps keep everything working.
I’ve spoken to people with 150W machines that failed out of the box as a bad tube and I’ve been told by someone who has had the same machine for over 10 years running 5 days/week 8 to 10 hours a day.
Many of the smaller consumer co2 don’t seem to make 10k hours. One of the guys has a K40, expected life in best case according to OMTech is 700 hours, he’s run his for 7 years.
I assume you have mA meters on these and that the lps is set at the proper current limit for your device… If you don’t do this you may get more current through the tube than desired. If you adjust the lps for your tube current limit it will synchronize with power settings in Lightburn (or other software package).
Good luck
