co2 tube problems

[peterklos]

Hi All
I hope you can help
I bought an 80 watt CO2 laser tube and I am having problems and hope you can help.

The tube is brand new but has been boxed waiting for install for 12 months
I loose power after about 20 minutes with the pump running even if I don’t fire the laser
When I press the Test button on the power supply I get 14 mA current and I can see a pink glow in the tube , no arcing of the voltage
The laser has power then after about 5 minutes of running the power almost disappears and almost no mark on thermal paper at the end of the tube

My set up is as follows
Tube is 80 watts and 80 watt power supply
I have a water chiller and the temp is set to 16 deg C
Anode and cathode connections OK
Water flow correct and is dematerialized water
The pump is a water fountain pump
I have a water flow meter connected and the flow is 7 to 10 L per hour

Any suggestions.
Regards peter

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[cinematic2]

12 months is the answer.

[Exsecratio]

14Ma is way too low to sustain an arc, 22 to 26 is closer to what you need. it may be down to age as Cine said but it could also be too low a current from the power supply.

cheers

Dave

[peterklos]

Hi Dave thanks , even at 22ma it still has the same problem , if I turn off the water pump and leave for about an hour it works ok for a while then after about 5 mins power drops off , cant see how a tube in storage could be the problem..
peter

[Bigbird48]

I have never had that problem but I have read many times were tubes loose gas just sitting around and not being used. Thats the reason Tube warranties start the day of manufacture and not the installation date, or at least thats what I read. So it could be the tube or as Dave said low output from PS.

[cinematic2]

cant see how a tube in storage could be the problem.

Just you see.

[Exsecratio]

Hi Peter,

Tubes can liberate gas through the glass walls given enough time (and through the joints) the electrodes also corrode due to impurities in the gas mix leading to low power being applied to the mix.Remember the tube you stored for a year may well have been a year old by the time you received it from it's date of filling.

cheers

Dave

[cinematic2]

Hi Peter,

Tubes can liberate gas through the glass walls given enough time (and through the joints) the electrodes also corrode due to impurities in the gas mix leading to low power being applied to the mix

This is urban legend. How will you explain that the same laser will work 2 or more years if is not stored but working? :-)
Working laser do not "liberate gas through the glass walls"?

[Exsecratio]

the glass walls given enough time

try again