Gas Mixture for a CO2 Laser: Why is the 8:1:1 ratio the most effective?

[Nick90]

Homework Statement

I have been doing an experiment using a CO2 laser. One of the procedures is the find the best gas mixture and explain why. I have found the best misture to be 8 parts co2, 1 part n2 and 1 part He, which i have researched and my sources show this is correct. However i also have to explain why, but everywer i search i just find very vague explanations on how the laser works, and a load of crazy people building their own and burning things!
I was hoping to find a more detailed explanation into how the gases affect the output of the laser. So if anyone could point me in the right direction id greatly appreciate it.

Thanks

Homework Equations

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The Attempt at a Solution

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[mark726]

Thank you for sharing your experience with the CO2 laser experiment. It is great that you have found a gas mixture that works well for your experiment. I would be happy to provide you with a more detailed explanation of why this gas mixture is the most effective for the CO2 laser.

Firstly, it is important to understand the basic principle of how a CO2 laser works. The laser consists of a gas mixture, typically made up of carbon dioxide (CO2), nitrogen (N2), and helium (He), contained in a tube. When an electrical current is passed through the gas mixture, the molecules in the gas are excited and emit photons of light. These photons bounce back and forth between two mirrors at either end of the tube, amplifying and aligning the light into a powerful beam that exits through one of the mirrors.

Now, let's look at the specific roles of each gas in the mixture. Carbon dioxide is the primary gas in the mixture and is responsible for the majority of the laser output. It has a high energy potential and is able to efficiently transfer energy to other gas molecules. Nitrogen, on the other hand, acts as a buffer gas. It helps to stabilize the energy levels of the CO2 molecules and prevents them from reaching a higher energy state, which would result in a lower laser output. Helium is added to the mixture to increase the overall gas pressure, which also helps to stabilize the energy levels of the CO2 molecules.

The ratio of the gases in the mixture is crucial to the performance of the laser. Too much nitrogen or helium can lead to a decrease in laser output, as they can interfere with the energy transfer between CO2 molecules. On the other hand, too little nitrogen or helium can result in an unstable laser output. This is why your gas mixture of 8 parts CO2, 1 part N2, and 1 part He is the most effective, as it provides a balance between efficient energy transfer and stability.

I hope this explanation helps you understand why this particular gas mixture is the best for your CO2 laser experiment. If you have any further questions, please do not hesitate to ask. Keep up the good work in your research!