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« on: April 11, 2012, 03:16:50 AM »
Hi Josh,
As you have seen I am using a ‘closed loop’ water cooling system with a forced air radiator as the heat exchange element. This type of system will only cool the tube to ambient air temperature but, for me, works just fine within the UK where our (ambient air) temperature rarely exceeds 25 deg.C.
From tests carried out (with a glass tube CO2 laser) the maximum efficiency is achieved with a tube temperature of around 7 to 8 deg.C so in some circumstances it may be an advantage to consider active cooling with a refrigerated device such as a ‘beer chiller’ or purpose built cooling unit. The down side to this is that relative humidity has to be taken into account because condensation forming on the output coupler lens can cause premature failure just as condensation on the outside of the glass tube could compromise the electrical insulation of the high voltage electrode connection (as an example - the condensation that forms on the outside of glass of a cold beer).
In reality, it should never be necessary to drive a CO2 laser at it’s absolute maximum power output but I think you should be aiming to maintain a nominal water temperature between 10 to 20 deg.C during operation.
Hope this helps.
Tweakie.
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but perhaps that's the way luck goes sometimes.