fist Co2 Laser (beginner questions)

Hey guys,

Me and a friend who i am going to visit this summer ordered a 40W Co2 Laser tube from Ebay.
At the moment we are trying to figure out what's the best (and easiest) way to power it.
I heard of people using a usual ZVS with a TV-flyback transformer.
But since the tube has a triggering voltage and an operating voltage, we are not sure if this will work.
Is the no-load voltage high enough to ignite the lasertube and will the voltage drop low enough so it will not damage the tube?
Furthermore, what resistance do we need between the supply and the tube in order to get a stable discharge?

I also have another question regarding the cooling system. Our pump is able to push 2l/minute through it. Will that be enough?

Kind regards,

Philipp

Philipp said:

what's the best (and easiest) way to power it.

Click to expand...

Buy a power supply for it.

If by "best and easiest" you actually meant cheapest, Then it depends on what you have lying around. A Flyback works, but it won't feed the tube enough current to reach 40W unless you have a BIG transformer, or more than one transformer. Neon sign transformers are popular. They work better if you can rectify/filter them as well as run them off of a variac.

As far as water, the ~300W heat from the tube is 18kJ/m. That means 2L/m will have a rise of about 2C per pass through the tube. So yes, that seems fine as long as you don't recirculate the water for too long or have an undersized reservoir.

A ZVS and a large flyback should do a good job powering the tube, but you will need a ballast resistor.

As for triggering, the simplest thing to do would be to use a trigger transformer.

Thank you for your answers.

Is the ballast resistor critical? I have heart about people using like 100kohms.

You can wire the output of multiple identical flyback transformers in parallel to get more current. It isn't the most elegant way of powering one of these tubes but it will work. You will want a milliammeter in the cathode (-) side so you know how hard you're driving the tube. You may not need a ballast resistor as typical flyback transformers have a lot of resistance in the secondary winding already and a fair amount of leakage inductance unless you remove the shims.

The best approach is still to buy a proper power supply, but as far as lasers go, CO2 tubes are relatively forgiving.