CO2 & RF Tubes

[willyinaus]

Hey guys can someone explain the difference between a 40w CO2 Tube and a 40w RF tube I am aware of the huge price difference but I really cant find much more information.
Also what is a synrad is this just a brand of laser tube?

Thanks Willy

[lasersafe1]

It's all about how the gas atoms get excited. The DC tube requires a high voltage to ionize the gas. The Rf tube uses rf energy to ionize. It has been said that the RF tube lasts much longer than the DC tube. The other laser forums are usually full of people critisizing the DC tubes. Sometimes I wonder if it is because they were suckered into paying six grand for an RF tube. I have had no problems with my Chinese Tubes and they just passed their second birthday.
Synrad is only a brand name.

You can read all about both types at Sams: http://www.repairfaq.org/sam/lasersam.htm

[willyinaus]

Thanks LS lots of reading to do.

Thanks Willy

[macona]

RF allows initiation of plasma in the tube without any metallic electrodes in the tubes itself. They use a system called inductively coupled plasma. The advantages of this are no feedthroughs for power, making tube construction easier.
Most RF tubes are ceramic which makes a much tougher tube. Also the ceramic tubes handle the high plasma temperatures better and can be fan cooled to much higher powers than a glass tube.
No electrodes me no sputtering which traps gas under deposited metal lowering the pressure.
Sputtering also causes a particle beam effect where particles are accelerated towards the mirrors and slowly etches them.
RF lasers are less electrically noisy. They dont require a HV pulse to start them.
Since there is no pulse needed they have better low end performance.

They are considerably more expensive than glass tubes though. For the extended lifetime I figure I could buy a lot of glass tubes.

It would be interesting to try powering a glass tube though induction. I have a 2.5kw, 450Khz, RF power supply for my sputtering system.