CA1203312A - Method and apparatus for operating a co.sub.2 gas laser - Google Patents

Abstract

Abstract In electrically pumped CO2 gas lasers, there take place widely different chemical and physical process which lead, at least partially, to undesirable interactions of the gases among themselves, and/or of the gases with the electrical and/or the optical field and/or with the materials used in the gas-filled chambers. Bodies that are equipped with surface area-enlarging structures are included in the discharge or resonator chamber or in adjacent secondary chambers. The secondary chambers by themselves act as reservoirs or as carriers of reservoirs for suitable catalysts and gas components and/or the heating of the catalysts, and have a predetermined influence over the conditions of volume and/or pressure and/or temperature.
The inclusion of such secondary chambers and such structures which enlarge surface area inside the chambers make possible the attainment of at least an approximate state of equilibrium, which leads to uniformly good discharge and long life with high laser efficiency.

Description

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Technical Field The invention relates to a method for operating a CO2 gas laser ~ithin a closed housing which is equipped with electronic means for causing an electrical discharge, a power supply, a discharge or resonator chamber and, if suitable, additional chambers that communicate with the discharge or resonator chamber~
The invention further relates to an apparatus for carrying ou~ the aforementioned method.
Background of the Invention In the typical gas discharges of electrically pumped CO2 lasers of this kind, there occur several, partly independent chemical and physical processes that may lead to changes in the operation of the laser. Such effects may be caused, for example, by the adsorption of ions, atoms or mo:Lecules at interior surfaces, by outgassing from surfaces and electrodes, by surface reactions, exchange reactions involvinq ions, atoms, molecules 7 and UV-photons, in the electrical discharge or else by diffusion processes across wallsO Inasmuch as very complex reactions of this kind take place during gas discharges in lasers of the type described above, for example, the achievement of a state of stable equilibrium is relatively difficult. Therefore, the reactions have heretofore been more or less uncontrolled.
Summary of the Invention Accordingly, it is an object of the present invention to provide a highly stable laser function, i.e., to achieve ~' ~

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_ -2-l a state of equilibrium, ideally with respect to all interactions of the gases with the electrical and optical fields, materials of the gas volumes and chambers, as well as all interactions of the gases wi-th one another. This 5 object is attained, according to the inven-tion, by using spaces which have the form of chambers or tubs or are embodied in -the manner of channels of a waveguide laser; or by using materials with surface-enlarging structures which are disposed in the laser spaces to serve as storage lO reservoirs or as carriers of such storage reservoirs and/or as carriers of catalysts; or by using storage reservoirs and/or carriers for Eurther laser gas components having solid, liquid, or gaseous consistency and/or for catalysts;
or by adjusting the total pressure or the partial pressures 15 of the individual laser gas components in the laser chambers with the aid of pressure vessels having a defined leakage rate and/or with the aid of changes in pressure and/or volume and/or with the aid of temperature changes;
or, during each charging or discharging process of the electrical energy storage device, by heating the catalyst, for example, by using a portion of the charging energy or causing the heating to take place in conjurlction wi-th one or more of the above characteristics.

In this way, it is possible to give the laser, and especially its interior, an uncontaminated operational state which facilitates electrical discharge even at extreme temperatures (especially low temperatures) under special requirements of power, energy, efficiency, pulse shape and wavelength; when using gas mixtures having an unfavorable chemistry; at high pressure and rapid pulse rates; as well as when operating without additional preionization or without other additional steps, such as the admixture of specific gases. This method also achieves long laser life.

~2~33~L2 In one broad aspect the present invention relates to a C~2 gas laser comprising: (a) a housing with at least a first chamber having mutually opposed endfaces at least a portion of the internal surface of the housing being lined with a lining material adapted -to permit the laser to operate at a state of equilibrium;
(b) electrically powered means, connected to an insulated voltage supply for producing gas discharge in said housing; (c) means for producing resonation in said first chamber along the longitudinal axis thereof; wherein said lining material is provided with a surface enlarging structure, and is capable of serving as a storage element or carrier for catalys-ts, at least a portion of said lining material being activated by CO, 2 or a combination of CO and 2 In another broad aspect the present invention relates to a method for operating a CO2 gas laser at a state of equilibrium comprising the following steps: (a) placing a predetermined mixture of gas inside said gas laser; (b) applying a voltage -to means ~or produc.ing gas discharge in said gas mixture; and (c) maintaining a stabla composition of said gas mixture during laser operations by: (i) removing dissociation products and contaminants from said gas mixture by absorption or adsorption; or (ii) accelerating the rate of specific reverse reac-tions by adding at least one catalyst; or (iii) adding at least one desired laser component to said gas mixture; or (iv) combining any of steps (c) ~ (iii), wherein steps (c) (i) - (iv) are achieved by exposing said gas mixture to the surfaces of a layer oE material -2a-~033~

covering portions of the internal surfaces of said gas laser and consisting of absorbent, or an adsorbent, or a catalyst, or a laser component disposed inside or at the surface oE said layer, at least a portion of said material being ac-tivated by 2~ CO or a combination of 2 and CO. ~

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3~.~2 1 A further development of the invention provides that the materials having surface-enlarging structures are highly porous solids or materials with high specific surface areas with or without grooves, notches, grids, tubes or holes, 5 the function of wh.ch can also be improved by changes in pressure and/or temperature.

In the aforementioned context, a number of especially favorable features are achieved. Such reservoirs or 10 carriers or at least the surfaces thereof that are to be activated consist of ceramic, quartz, (quartz-) glass, metal, sintered materials, clay, porcelain, alumina or aluminum silicate of sufficiently large specific surface.

lS ~hese reservoirs, carriers or their effective surfaces are equipped with, for example, diffused-in, chemically bound or burned-in catalysts or laser components or with such catalysts or laser components that have been applied by vapor deposition, flame spraying or plasma spraying or by 20 providing further storage reservoirs. Further reservoirs or catalysts of noble metals (for example, palladium or platinum), metals ~for example, titanium), metal oxides (for example MnO2 and/or CuO), carbon hydroxides (for example, palladium hydroxide), carbonates (for example, 25 silver carbonate), or combinations of noble metals and metal oxides may be provided. At least a part of the activated surfaces may be provided with CO and another part with 2~ water (hydrogen), carbon monoxide, formaldehyde, alcohol, carbonyl, copper, nickel, platinum, titanium, 30 palladium or a mixture of MnO2/CuO may be used as a catalyst.

Surfaces of Cu, Ni or Pt exhibit the advantage of permitting higher temperatures during the gas discharge.

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_ -4-1 If it is desired to carry out or even only to accelerate reverse reactions (which usually have low rates), it is suitable to adjust the hydrogen to approximatel~ 0.2 to 15% by volume by gas mixing or by storage in, for example, 5 palladium or titanium, and to adjust -the water vapor pressure -to approximately 0.1 to 10 torr. Alternatively, one may add carbon monoxide from 1 to 20 vol.% and/or wa-ter vapor from approximately 0.1 to 10 vol.% and/or methane and/or eth~me and/or higher hydrocarbon compounds together 10 up to about 10 vol.% and/or carbonates and/or carbonyls and/or formaldehyde in polymerized form, e.g., embedded in ceramic.

Other rneaningful measures, especially for restraining the 15 yeneration of negative ions that are harmful to the discharge as well as for keeping the concentrations of 2 and 03 within acceptable bounds, consist of adding various desirable gases and adjusting the temperature, pressure or volume. The gases can be added by ausing a predetermined

2() rate of leakage of an additive gas from a small pressurized vessel into the laser volume, by adding gas via a valve or nozzle, or by supplying a porous solid body in the laser volume which is permeated with an additive gas. The changes in temperature, volume, and pressure are brough-t 25 about with the aid of heating or cooling systems.

In view of the frequency of dissociation of C02, a further advantageous characteristic of the invention is the use of an e].ement combining a catalyst and an absorber and 30 consisting at least partially of metal, e.g., platinum or nickel, and ceramic, e.g., TiO2/MnO2-CuO. When needed, the element is operated at least for a short time at elevated temperature and, preerably, near the anode electrode of the electric discharge.

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~ --5--1 However, in sorne cases it may also be meaningful to store in the discharge or resonator chamber, and/or in the chamber connected thereto, laser gas or components, gaseous and/or chemically bound and/or physically bouncl gases, 5 e.g., carbon dioxide, hydrogen, water, helium, and to supply -these to the discharge or resonator chamber continuously or in bursts, through diffusion and/or pressure and/or temperature effects.

10 During operation as a laser or amplifier, there are generated products of dissociation and subsequently formed compounds such as CO, H20, 2' 3 or nitrogen oxides.
According to a further characteristic of the invention, these products can be removed continuously or 15 intermittently by means of catalysts/absorbers and/or filters and/or adsorbers and/or they may~be bound chemically and/or physically, and, if needed, other gaseous components, e.g., carbon dioxide, may be admitted.

The apparatus accordin~ to the present invention is also distinguished by the application of material on -the internal surfaces of the walls of one or both chambers wherever these surfaces are free of optically or electrically operative elements. This material has a structure such that its surface area is enlarged. In at least one of the chambers there may be provided the following elements: a catalyst, an absorber, an adsorber, a filter, and/or a membrane with or without a heating or cooling device. The apparatus is also provided with a dosageable gas supply in the form of a gas storage element connected to one of the chambers or else the secondary chamber itself is embodied as a gas reservoir.

Of some further significance is the fact that the heater or the catalyst itself can be embodied as a high-impedance _ -6-1 resistor connected in parallel with the discharge path.
In that case, catalysis is especially initiated only when a discharge actually causes dissocation.

5 Preferred embodiments of the invention will be explained in detail below with the aid of the drawings wherein corresponding elements retain the same reference characters in all of the figures.

Brief Description of the Drawings Figure l is a longitudinal section through a transversely excited laser-amplifier with a gas reservoir or catalyst;
Figure 2 i.5 a laser-amplifier according to F'igure l but with an axially excited laser, which, if appropriately dimensioned~ can also be constructed as a waveguide laser;
Figure 3 is a cross-sectional view of khe embodiment according to Figure l, including an additional (secondary) chamber with an internal wall covering;
Figure 4 is a cross-sectional view of -the ernbodiment according to Figure 3, including a combination of a catalyst/absorber and a heating or cooling device in the secondary charnber;
Figure 5 is a longitudinal sectional view corresponding to that of Figure 2, including a heatable and coolable absorber or catalyst;
Figure 6 is a longitudinal sectional view of the laser-amplifier according to Figure ~, including absorbers, filters or diaphragms that are specific

3 to the individual dissociation products;
Figures 7-9 are circuit diagrams of the electrical internal heater and show the construction and disposition of a catalystO

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1 Description of the Preferred Embodiments Figure 1 is the principal schematic representation of an elongated excited laser-amplifier l which may be operated as a CW (continuous wave), RF (radio Erequency), or pulsed 5 laser and may be suitably adapted to such operation. Its housing 2 consists of a symmetric hollow casing of metal, e.g., a nonmagnetic metal such as aluminum, copper, tungsten, or an alloy of these metals, or of a ferromagnetic metal. The housing is of substantially 10 tub-like form with electrodes 5 and 6 disposed, respectively, at the internal surface at the bottom and the cover 8 of the housing, with the discharge surfaces of these electrodes confronting each other. The internal walls of the housing, the discharge surfaces of the t5 electrodes, and other surfaces define the resonator chamber 17 (i.e., the volume where both resonation and gas discharge take place).

The width of the electrodes and their relative separation may be merely millimeters (when constructed as a waveguide) or may be centirneters, and their length can be as large as several tens of centimeters. The widths of the two electrodes can be equal or different; in the latter case, the widths of the electrodes 6 and 5 may be, for example, in the ratio 4 : 5 and they may be operated at voltages up to 30 kV. This results in field intensities of 10 to 25 kV/cm and energy densities of 0.1 to 0.5, (e.g., 0.25) joules per cm3 of laser gas.

A voltage supply 11 delivers, for example, high potential 3 to the electrodes 5 and 6 so that an electrical discharge may take place in the gas located between the discharge surfaces, thus stimulating the N2 or C02 gas molecules.
The voltage pulse required for this effect has a half-width of, typically, 100 nanoseconds and a leading edge ramp of 3~

less than 20 nanosecond duration. The resonator assembly 15 and 16, attached to the end faces 3 and ~ of housing ~, makes possible the extraction of electromagnetic energy from the housing 2. The electrode 5 and the voltage supply 11 are insulated electrically with respect to the remaining housing by the insulator 12. Between the insulator and the electrode 5, as well as between the electrode 6 and the bottom of the housing, materials 13 are disposed which have a surface area-enlarging struc-ture and can serve as reservoirs or carriers oE reservoirs and/or as carriers of catalysts for solid, liquid, or gaseous laser gas components and/or catalysts.

Figure 2 illustrates an embodiment which differs from that of Figure 1 in that the electrodes 5', 6' and 7' are disposed perpendicular to the longitudinal axis of the housing 2, which also represents the axis of beam extraction. These electrodes are attached in channels 18' which are cast in the housing 2 or drilled later, and serve to excite the laser in the longitudinal direction.

F'igure 3 illustrates a cross-section laser ampliEier 1 according to ~igure 1 with an additional central electrode 7 disposed along the longitudinal axis of the housing 2 and attached, for example, to the cover 8. The discharge surfaces 9 and lO of the additional electrode 7 are disposed to confront the discharge surfaces of electrodes 5 and 6, respectively. This construction results in a once-folded beam path. Multiple beam path folding and correspondingly shor-ter construction would be conceivable in other embodiments not shown in the drawing.
A secondary chamber 1~ has internal walls that are covered with the surface area-enlarging material I3. The covering material 13 has grooves 14 that run parallel to the longitudinal axis and enlarge the total inside surface ~2(~
g 1 area. The secondary chamber 18 is disposed parallel to the resonator or discharge chamber 17 and may be cas-t in place or attached to the housing 2 later. ~f course, other means by which the surface area can be enlarged 9 such as notches, 5 yrids, tubes, holes, and the like, are also conceivable and all of them would serve for improved gas preparation and regeneration. Pcssible materials 13 for -this reservoir or carrier are ceramics, quartz, quartz glass ? metal, sintered materials, clay, porcelain, aluminum oxide, or aluminum 10 silicate having sufficiently large specific surfaces.
Possible catalysts are water, hydrogen, carbon monoxide, formaldehyde, alcohol, carbonyl, copper, nickel, platinum, titanium, palladium, or a mixture of MnO2/CuO. These catalysts or even laser components or further reservoirs 15 made of noble metals (e.g., titanium), or metal oxides (e.g., MnO2 and/or CuO), or carbon, or hydroxides (e.g., palladium hydroxide), or carbonates (e.g., silver carbonate), or combinations of noble metals and metal oxides and/or at least a part of the surfaces that are 20 activated with C0 and another part activated with 2 can all be fixed in the volumes or on the surfaces of the reservoirs or carriers, For example, by diffusion, chemical bonding, or burniny-in, or by vapor deposition, flame spraying, or plasma spraying, respectively. The opening 20 5 provides communication bet~een the two chambers (the resonator or discharge chamber 17 and the secondary chamber 18).

According to Figure 4, different types of absorber 21, combined, if nec~ssary, with a heating and/or cooling device 22, may be disposed in the chamber 18. With the aid of such heating or cooling devices, it is possible to cause short-term or long-term changes in the volume ancl/or temperature, changes of the total pressure in the system or also of partial pressures, e.g., that of hydrogen or I

1 carbon monoxide, independently of the discharge energy.
The pressure, volume, and temperature conditions within the resonator or discharge chamber 17 can also be influenced by the deliberate addition of, e.g., carbon 5 monoxide, water vapor, methane, ethane, higher hydrocarbon compounds, carbonates, carbonyls, or formaldehyde, individually or in combinations of more than one of these substances, through the opening 20.

10 Figure 5 shows an element which is a combinatlon of a catalyst and an absorber 21 in a longitudinally excited laser amplifier 1 and which is located near the anode 7' and its voltage supply 11.

15 ~lowever, the pressure, volume and temperature conditions and the removal of dissociation products can also be influenced by C02 (laser) gas or components, gaseous and/or chemically bound and/or physically bound gases, e.g., carbon dioxide, water, hydrogen, or helium that are stored in the reservoir 19 in the resonator or discharge chamber 17 (as in Figure 6) or in a secondary chamber 1 connected to this chamber 17 ~as in Figures 3 and ~
These materials can be supplied to the resonator or discharge chamber from the reservoir 19 through the nozzle 23, for example, under pressure and/or under the effect of temperature influences and/or by diffusion, either continuously or in bursts, and the dissociation products may be removed in a similar way. The absorbers 21, or adsorbers, filters, or diaphragms, are of highly specific nature relative to the various dissociation products.

Yinally, Fiyures 7 to 9 illustrate a possibility for causing a reverse reaction of C0 and 2' independently of, or in addition to, the gas chemistry described .

--ll--1 hereinabove~ To this end, Figure 7 shows a high-valued coupling resistor Rkop in the form of a wire 24 which extends in parallel with the discharge pa-th formed by the electrodes 5 and 6. In Figure 7, the coupling resistor 24 5 is also the catalyst. In Figure ~, this catalyst is provided, by way of exarnple, in the form of a resis~or Rkat 25, also connected in parallel with the discharge path. In figure 9, in what may be termed an inversion of the scheme of F'igure 7, the catalyst itself is embodied as 10 a coupling resistor. In all of the last three examples, a small portion of the charge energy is used to heat the catalyst during each discharge or charging processO The protective resistor RL 26 can be used in place of the catalyst 25, in a variant of the examples illustrated in 15 Figure 8 or ~. Also shown are a pulse switch 27 and a storage capacitor 28. The circuits shown are given only 'by way of example and, in principle, any circuit (Blumlein circuit and the like) that is customary for controlling lasers would be possible without thereby departing from the ?0 scope o~ the invention.

~y way of example, there will now be given the various reactions of gases that are mixed together in the laser or are generated in the laser, such as He, CO2, N2, CO, 25 H20, OH, C~4, 2' 3~ carbonyls, nitrogen oxides, etc,.
showing the dissociation reaction and the subsequent reactions of the CO2 molecule.

GO~ + e~ - ~ CO ~ O -~ e CO + Ni ~ Ni (CO)4 CO + e- -- - ~ C ~ O

O ~ e ~ - - - ~ ~ O

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1 N2 + 20 ~D 2 NO

H + O~ H20 H20 ~ OH + H

C + 4H- -- CH4 These dissociations and subsequent reactions occur so 10 frequently that they will cletermine the life of a sealed-off laser directly unless special steps are taken for reversing khem. For example, 1016 C02 molecules can dissociate per second per cm3 of volume. Similar reactions also take place for other molecules. The laser according 15 ko the invention was developed in order to prevent the reactions that lead to gas dissociation and demixing. This laser provides, wi-thin the laser chamber or chambers, for bodies having surface area-enlarging configurations and capable of serving as reservoirs or carriers of reservoirs of catalysts that make possible a state of equilibrium of the laser function.

If the C02 laser is used as an amplifier instead of as a generator, then the mirrors 15 and 16 must be replaced by end windows permitting the passage of radiation. In amplifier operation, immediately following the discharge between the electrodes, a pulse is fired through one of these windows into the rnedium in the amplifier; in general this pulse will have a bettPr beam profile and lower power. The total pulse leaving the other window will then be amplified by approximately 3 to 10% per cm.

Claims (29)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A CO2 gas laser comprising:
(a) a housing with at least a first chamber having mutually opposed end faces at least a portion of the internal surface of the housing being lined with a lining material adapted to permit the laser to operate at a state of equilibrium;
(b) electrically powered means, connected to an insulated voltage supply for producing gas discharge in said housing;
(c) means for producing resonation in said first chamber along the longitudinal axis thereof;
wherein said lining material is provided with a surface enlarging structure and is capable of serving as a storage element or carrier for catalysts, at least a portion of said lining material being activated by CO, O2 or a combination of CO and O2.

2. A gas laser as claimed in Claim 1, wherein said layer of lining material is provided with high porosity, high surface specificity, grooves, notches, holes, guides, or similar surface enlarging structures.

3. A gas laser according to Claim 2 wherein said catalyst, and desired laser components are diffused in, chemically bound to, burned in, vapor deposited on, flame-sprayed on, or plasma sprayed on the surface of said layer of lining material.

4. A gas laser according to Claim 3 wherein said housing further defines a second chamber in communication with said first chamber in a manner that allows gas components to travel from one chamber to the other.

5. A gas laser according to Claim 4, wherein a selected one of said chambers contains and is connected to a gas reservoir.

6. A gas laser according to Claim 4, wherein said second chamber is a gas reservoir.

7. A gas laser according to Claim 4, wherein a selected one of said chambers contains means for controlling the temperature in said chambers, thereby to regulate the pressure in said chambers.

8. A gas laser according to Claim 7, wherein said catalyst is disposed in said second chamber, either in or at the surface of said layer of material (d) covering portions of the internal surfaces defining said second chamber, or in the form of an element attached to said means for temperature control, or in the form of an element otherwise disposed within said second chamber.

9. A gas laser according to Claim 7, wherein said means for temperature control operates by heating or cooling either said material (d) or said catalyst.

10. A gas laser according to Claim 4, wherein said layer of lining material comprises absorbing or adsorbing areas, each of said areas being specific to a particular product of gas dissociation.

11. A gas laser according to Claim 5, wherein said gas reservoir comprises a pressurized vessel connected to said first or second chamber via a valve or nozzle.

12. A gas laser according to Claim 9, including a heater comprising a high-impedance resistor connected in parallel to the path of said gas discharge.

13. A gas laser according to Claim 1, wherein said layer of lining material is selected from the group comprising of ceramic, quartz, quartz glass, metal, sintered material, clay, porcelain, aluminum oxide, and aluminum silicate.

14. A gas laser as claimed in Claim 1, 9 or 13 wherein said layer of lining layer of material includes a storage component chosen from the group including palladium, platinum, litanium, manganese dioxide, cupric oxide, carbon, palladium-hydroxide, silica carbonate, and combinations of noble metals and metal oxides.

15. A gas laser according to Claim 1, 9 or 13, wherein said catalyst consists of water, hydrogen, carbon monoxide, formaldehyde, alcohol, carbonyl, copper, nickel, platinum, titanium, palladium, or a combination of MnO2/CuO.

16. A method for operating a CO2 gas laser at a state of equilibrium comprising the following steps:
(a) placing a predetermined mixture of gas inside said gas laser;
(b) applying a voltage to means for producing gas discharge in said gas mixture; and (c) maintaining a stable composition of said gas mixture during laser operations by:
(i) removing dissociation products and contaminants from said gas mixture by absorption or adsorption;
or (ii) accelerating the rate of specific reverse reactions by adding at least one catalyst; or (iii) adding at least one desired laser component to said gas mixture; or (iv) combining any of steps (c) (i) - (iii) , wherein steps (c) (i) - (iv) are achieved by exposing said gas mixture to the surfaces of a layer of material covering portions of the internal surfaces of said gas laser and consisting of absorbent, or an adsorbent, or a catalyst, or a laser component disposed inside or at the surface of said layer, at least a portion of said material being activated by O2, CO or a combination of O2 and CO.

covering portions of the internal surfaces of said gas laser and consisting of absorbent, or an adsorbent, or a catalyst, or a laser component disposed inside or at the surface of said layer, at least a portion of said material being activated by O2, CO or a combination of O2 and CO.

17. A method according to Claim 16 wherein said stable operation comprises the further step of (d) adjusting the temperature or pressure of said gas mixture.

18. A method according to Claim 17 wherein said step (d) for adjusting the temperature comprises supplying electrical energy to a heating or cooling element disposed in said gas mixture.

19. method according to Claim 18, wherein said step for adjusting the temperature comprises heating or cooling said layer of material containing said absorbent or said catalyst.

20. A method according to Claim 17, wherein said step of adding a desired laser components is also carried out by allowing said laser component, which is stored in a pressurized vessel, to pass into said gas mixture via a valve or nozzle at a predetermined rate.

21. A method according to Claim 20 wherein the chemical equilibrium of said gas mixture is displaced toward the CO2 molecule by adding CO to react with H2, or H, or H2O, or OH, or any combination thereof.

22. A method according to Claim 20, wherein the hydrogen concentration in said gas mixture is adjusted to 0.2-15 vol.% by adding hydrogen gas either from a pressurized vessel or from said layer of material in which hydrogen is stored, and the water vapor pressure is adjusted to 0.1-10 torr.

23. A method according to Claim 20, wherein any of the following additional steps are taken:
(e) addition of carbon monoxide so as to attain a carbon monoxide concentration in said gas mixture of 1-20 vol.%;
or (f) addition of water vapor so as to attain a water vapor concentration in said gas mixture of 0.1-10 vol.%; or (g) addition of methane, or ethane, or higher hydrocarbon compounds, or any combination thereof so as to attain a concentration in said gas mixture of 0.1-10 vol.%, or (h) addition of carbonates, or carbonyls, or formaldehyde in polymerized form; or (j) any combination of steps (e) - (h).

24. A method according to Claim 21, wherein carbon and carbon monoxide are transformed into carbon dioxide, and/or nitrogen oxides are transformed into nitrogen by allowing said gas mixture to interact with the surface of said layer of material consisting at least partially of metal (e.g., Pt or Ni) and partially of ceramic (e.g. TiO2/MnO2-CuO), said layer of material acting as a catalyst and an absorber.

25. A method according to Claim 24, wherein said layer of material is heated for short periods of time.

26. A method according to Claim 16, wherein said laser component carried by said layer of material enters said gas mixture by diffusing through said material or by vaporizing at the surface of said layer of material.

27. A method according to Claim 20, wherein said laser component in said pressurized vessel enters said gas mixture continuously or in bursts by means of pressure differential's

28. A method according to Claim 17, wherein said laser component, which is stored in a gas reservoir, enters said gas mixture continously or in bursts by means of temperature differentials.

29. A method according to Claim 16, wherein said dissociation products or said contaminants are removed or physically bound by exposing said gas mixture to said absorbent or said adsorbent, or are chemically bound by adding desired gas components (e.g., CO2) or exposing said gas mixture to said catalyst.