Laser power decreases after some minute

[Jefferybarf]

Something strange happen in my laser cutting machine.
I have a 150w laser tube, it works fine but after some minutes of cutting at any power, it seems to lose about 30% of power, so I need to reduce speed or increase the power.
Someone experimented that? any suggestion?
Hope this is the right section

[melvads18]

I am not sure what's wrong with your laser tube, but based on our testing, 150 watt laser tube is not stable, its power lose a lot after show time using.
so we don't suggest our customers choose 150 watt laser tube, your supplier don't remind you this matter?

[Hierro]

Have you a chiller?
Keep the temperature is very important.
Around 18 degrees