Dear Cassio Alvarenga your, at first sight, net technical issue raises the main deep questions of the nature (or God).

We will give some, most known examples on this, the subject touched by you, from various areas.

1. All devil sits in trifles.

2. Fly in the ointment.

3. Small additional additives very strongly change taste of tea. The ingenious English physicist Michael Faraday paid attention to it and invented alloyed and stainless steels by entering of small additives in iron of other metals, for example, of molybdenum.

4. The washing capability of anion detergents raises in case of small additives cationic surfactant that contradicts logic. As mixed among themselves in an identical proportion cationic and anion surfactant is compensated each other and this mix doesn't wash at all, etc.

5. Thus, it is possible to draw a conclusion that efficiency of the active environment depends on a right choice of the main gases of the gas laser and additional small additives. It is a lot of work, to touch and mix together different gases in big and small proportions.

Sincerely,

Alexander, PHD "Laser Physics", 1992.

Hello Mr Cassio,

From my understanding, the mixture of laser gas is depended on the design of each machine because there are certain co2 laser cutting machine that used 3C (combination of 3 gases) and 4C (combination of 4 gases). I'm using a CO2 laser machine with 4 combination of mixture gases (CO, He, N and CO2).

Your are correct of couse. My e-mfil is [email protected]

Dear Cassio,

You have mentioned Ne2 - does it means N2, of course?

The composition certainly depends on the RF laser type, but it does not mean that one laser will not work with the mixture for another laser. But optimal mixture and preassure will be individual for all laser types. For instance, Rofin-Sinar use 6 component mixture Xe/O2/CO2/CO/N2/He for their multikilowatt DC series lasers, typical composition is 3/3/6/4/19/65.

Mixture H2/Xe/CO2/N2/He = 1/5/18/18/58 was also reported in literature.

Composition you have mentioned first (1CO2/1N2/3He+5%Xe) is treated in the first patents on Synrad low power RF-lasers with a discharge gap of rectangular cross-section. The second mixture (1CO2/1N2/8He +3-6%Xe) seems to be closer to optimal for more powerful slab RF-laser.

Optimal pressure is generally around 70-100 mbar.

You may start with 1/1/3+5%Xe and then add Helium to get 1/1/8+3%Xe. Optimum is probable somewhere between these two mixtures. Then you can optimize pressure.

Admixture of CO, O2 and H2 are generally used for decreasing CO2 decomposition in the discharge plasma and often presume the use of some type of catalyst that may be deposited on the walls of the discharge chamber.

Dear Mikhail,

Is really N2, my digitation erro.

My project is just test a large volume contaminent nano-ceramic catalists for CO oxidation in ambient temperature, will be a auxiliary cilinder instaled in a Rofin SX20, This laser have original power of 120 - 130w, but I rebuild it, make a critical alingment, etc... And try some mixtures, the max I get is 95-105w. You know if those O² + CO, have influence in the output power, or it is only for catalyst propourses? My intention is to test whitout any wall coating or "catalyst gas", only "power gas" to see the influence of my auxiliary catalizator.  

Thanks a lot for you contribuition. Sorry for my bad english.

Cássio.

PS: In my tests H² drasticaly drops the output power in this laser.

Dear Cassio,

We have developed RF laser with gold catalyst. The paper was published in N.A.Generalov, V.P.Zimakov, N.G.Solov'ev, A.N.Shemyakin, M.Yu.Yakimov, N.A.Yatsenko. "Application of a distributed gold catalyst to increase the output power and efficiency of a sealed-off CO2 laser excited by a transverse RF discharge in tubes", Quantum Electronics, 35 (12), 1131-1137, 2005.

We have had only a small amount of CO (about one per cent) added to standard mixture to get advantages from catalyst. In diffusively cooled laser the efficiency of lasing is first increased with power, then drops due to gas heating and CO2 decomposition. The use of catalyst increase the power of diffusively cooled laser when efficiency substantially drops.

As I can presume, the aim of the use both CO and O2 in Rofin mixture is to prepare mixture not being subjected to changes under the discharge - the percentage of CO and O2 seem to correspond typical dissociation of CO2 (50%). 1 excessive per cent of CO indicates the use of some kind of catalyst.

So they pursue two aims - lasing stability in on-off regimes and long-term mixture stability. The increase of output power due to the catalyst is not so great if one use optimal output coupling of the laser resonator. If the resonator is too open, the output coupler reflectivity is lower than optimum, the increase of laser power due to the catalyst will be higher.

Н2 in reactions with oxygen gives the water vapour, that strongly affects the electron density in the discharge, so it should be strictly controlled. So H2 is generally used in slow flowing systems, not in sealed ones. You could read about it in US patents by John Macken on the use of distributed gold catalyst in DC-discharge lasers. The reference is in our paper cited above. You can also find the patent through relevant data bases.

Gold was deposited by means of gold cathode sputtering procedure in the atmosphere of light rare gases at low pressure (moderate vacuum). The details you may find in mentioned above patent and related paper by John Macken, who invented the feasibility of gold catalyst produced through cathode sputtering procedure for CO2 lasers (see his US patent 4,756,000 (1988) and his paper IEEE J. Quantum Electron., 1989, 25(7), p. 1695-1703).

Thanks Mikhail. 

In CO2 Laser, gas mixture depends on the specific application. The optimum mixture can be obtained through the experiment, i.e.,you can try different ratios of CO2, N2, and He until you get the proper ratios.

My Dear

for pulse or CW  CO2 laser the stander mixture gases He:N2:CO2 ,8:1:1 respectevely