CA1159938A

CA1159938A - Method for generating laser beams in the 16-1m wavelength range

Info

Publication number: CA1159938A
Application number: CA000395660A
Authority: CA
Inventors: Hans-Jurgen Cirkel; Klaus-Joachim Schmatjko
Original assignee: Kraftwerk Union AG
Current assignee: Kraftwerk Union AG
Priority date: 1981-02-06
Filing date: 1982-02-05
Publication date: 1984-01-03
Also published as: EP0057762A2; EP0057762A3; AU8022382A; DE3104229A1; JPS57176787A

Abstract

ABSTRACT OF THE DISCLOSURE
Method for generating laser beams in the 16-µm wavelength range, especially for the U235 isotope separation, using a first CO2 gas laser, the CO2 molecules of which are lifted to the (00°1) energy level by supplying pumping energy, and using a high intensity radiation source radiated into the laser tube, especially a second CO2 laser serving as an injection laser, with the transition (00°1) (02°0) for occupying the upper laser level for the 16-µm radiation of the first laser to be stimulated on the bending mode transition (02°0) (0110), characterized by the following features:
a) The laser gas mixture of the first laser is deep-cooled in a manner known per se, and the laser pumping process is carried out by means of an electric high-energy gas discharge according to the TEA (transversely excited atmospheric pressure laser) principle with at least one TEA-CO2 laser module as element of a 16-µm laser;
b) the emission line of the injection laser is tuned in a range which covers the exact transition (00°1) (02°0) to a rotation level of the (02°0) level as well as virtual levels (02°0)' at a freely selectable distance from the line center of the exact transition;
c) for tuning to a virtual level (02°0)', the emission line of the injection laser is shifted by a fraction of a wave number from the line center of the corresponding transition, and the injection laser is preferably operated as a high-pressure TEA-CO2 laser;
d) the injection laser pulses with a leading edge as short as possible, detuned in this manner, are coupled into the 16-µm resonator of the first laser, so that its transition from the (00°1) level takes place to a virtual energy level (02°0)' thus resulting, which is likewise removed by a fraction of a wave number from the real (02°0) level of the CO2 molecules, so that, due to non-linear scattering at this virtual energy level in the transition to the lower (0110) laser level, the CO2 molecules emit light quanta, the wavelengths of which are shifted again by the same fraction of a wave number (the amount of detuning) of the real transition (02°0)

Description

J 1599~8 _ackground of the Invention Field of the Inven_ion The invention relates to a method for generating laser beams in the 16-~m wavelength range, especially for U235 isotope separation, using a first C02 gas laser, the C02 molecules of which are lifted to the (00l) energy level by supplying pumping energy, and using a high intensity radiat-ion source radiated into the laser tube, especially a second C02 laser serving as an injection laser, with the transition (00~l) ~(020) for occupying the upper laser level for the 16-Jum radiation of the first laser to be stimu-lated on the bending mode transition (020) ~(01 0).
Description of the Prior Art A suitable 16~1m laser is of particular importance for the laser isotope separation of UF6 because it is possible with such a laser to excite substantially only the molecules which contain U235.
It is known in laser technology that the C02-molecule can be ex-cited to laser emission in the 16-J~m range on the transition (020)--~(0110).
By a suitable pumping method, the CO2-molecule is lifted for this purpose into the (00l) state and the upper laser level is occupied for the laser radiation by a suitable high-intensi~y radiation source, for instance, a C02-laser with the transition (00l) `(020). The kinetics of this laser transition is described in detail in the journal "J. Chem. Phys." 71, 1 September 1979, pages 2299 to 2312.
Several methods are known for obtaining laser emission in the 16-~m range of C02, for instance, by optical pumping of HBr in an HBr/C02 gas mixture with an HBr laser and the following energy transfer: HBr >
CO2, see the journal "Applied Physics Letters", vol. 28, No. 6, March 15, 1976, pages 342 to 345. Corresponding laser transitions are also obtained by direct optical excitation of the C02 with an HF laser, see the journal l 1599~8 "Applied Physics Letters", vol. 29, No. 5, September 1, 1976, pages 300 to 302. The important disadvantage of the last-mentioned two methods is the need for an additional expensive pumping laser; it can be avoided by direct electric excitation.
On this principle is based an electrically excited gas-dynamic C02 laser which, through modification, can also emit in the 16-J~m wave range, see the Journal "Applied Physics Letters" vol. 29, No. 6, September 25, 1976, page 360 to 362. It is a disad~antage of this gas-dynamic laser that the electric excitation must take place in a nitrogen-helium mixture which then flows through the nozzles of the laser, and only there can the C02 be admixed. If for economic reasons the same gas is to be reused, the individual components must first be separated again from the laser gas mixture. This requirement and the extremely high specific gas through~ut burden the laser system with hardly justifiable costs.
Direct electric excitation of the C02-molecule, circumventing the elaborate gas~dynamic laser principle, is des~ribed for a C02-laser radiating in the 14-~m wavelength range in the already repeatedly mentioned journal "Applied Physics Letters", vol. 31, No. 2, July 15, 1977, pages 82 to 84.
There, a C02-laser tube is arranged in a cold bath at about 140 K, such as is used in longitudinally excited CW (continuous wave) CO lasers, and the elec-tric excitation of the C02 within a gas mixture C02:N2:He = 1:2:25 at a pressure of about 5 to 18 Torr is accomplished via a current pulse several microseconds long. The upper laser level is occupied by stimulated emission from the (00l) level of the cooled-down C02 gas, and the radiation of a con-ventional TEA-C02 laser is injected as the transfer pulse into the cooled laser tube. However, only small output energies can be generated in the frequency range of interest by this method, which must be considered as in-sufficient for an isotope separation process of technical interest.

l 159938 The low gas pressure (about 10 Torr) demanded by the longitudinal excitation principle especially determines the low output energies. The described design causes a large self-inductance of the electric excitation system and therefore does not allow current pulses, being shorter than a few ~sec. Through those relatively long current pulses the respective vibration temperature of the cold CO2 is increased, and this also has an adverse effect on the kinetics for the 16-J~m laser which is the sub~ect of the present in-vention because then, among other things, the lower laser level t0110) is more heavily occupied. The invention therefore should make it possible to operate a laser system radiating in the 16-Jlm wave range at a higher gas pressure and substantially shorter current excitation pulses, so that the energy yield can be increased substantially as compared to the above-mentioned known laser system.
Summary of the Invention With the foregoing and other objects in view, there is provided in accordance with the invention a method for generating laser beams in the 16-Jlm wavelength range, especially for use in separation of the U235 osotope from a mixture containing U235 and U238 isotopes comprising supplying pumping energy to lift CO2 molecules of a first gas laser having a C02 laser gas mixture to the (00l) energy level, and radiating from a high intensity radiation source as an injection laser into the laser tube of the first gas laser to stimulaee the ~ransition (00 1) ~ (020) for occupying the upper laser level for the 16-L~ radiation of the first laser on the bending mode transition (020) (01 0), the combination therewith of a) cooling the laser gas mixture of the first laser and effecting said pumping by an electric high-energy gas discharge according to the TEA
(transversely excited atmospheric pressure laser) principle with at least one TE~-C02 laser module as an element of a 16-J1m laser of the first laser, 1 159g38 b) tuning the emission line of the in~ection laser in a range which covers the exact transition (00l) `(020) to a rotation level of the (020) level as well as virtual levels (020)' at a freely selectable distance from the line center of the exact transition, c) shifting the emission line of the injection laser by a fraction of a wave number from the line center of the corresponding transition, for tuning to a virtual level (02 0)', d) coupling injection laser pulses with a leading edge as short as possible, tuned as above, from the injection laser into the 16-~m resonator of the first laser, to cause the transition in the first laser from the (00l) level to a virtual energy level ~020)' located apart from the real level (020) and removed from the real level (020) of the CO2 molecules by a fraction of a wave number, and due to non-linear scattering at this virtual energy level in the transition to the lower (0110) laser level, ~he CO2 mole-cules emit light quanta, the wavelengths of which are again shifted by the same fraction of a wave number of the real transition ~02 0) > t0110).
Other features which are considered as characteristic for the in-vention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for generating laser beams in the 16-~m wavelength range, it is nevertheless not intended to be limited to the details shown, since ~arious modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
Brief Description of the Drawin~s ; The invention, however, together with additional objects and advantages thereof will be bes~ understood from the following description when read in connection with the accompanying drawings, in which:
FIGURE l diagrammatically illustrates in an isomeric fractional 1 1599~8 view, the deep-cooled TEA C02 module of the first laser;
FIGURE 2 is a top view, greatly simplified, of the overall arrange-ment of the first and the second laser which latter serves as an injection laser;
FIGURE 3 is an energy level diagram for the energy transition taking place in the laser chamber of the first and the second laser;
FIGURE 4 is a diagram in a qualitative presentation for illustrat-ing how the 235-UF6 absorption can be optimized by wave-number tuning of the laser emission; the wavelength is chosen as the dimension for the abscissa axis, and the dimension for the ordinate axis is the intensity or power density I (W/m2); and FIGURE 5 schematically illustrates a 16-Jum laser chain with a common injection laser.
Detailed Description of the Invention A TEA laser transversely excited atmospheric pressure laser is understood here and in the following to be a laser which can be operated with gas pressure of some tens of mbar to the over-pressure range of several bar;
and with which excitation pulses with half-amplitude widths of less than 1~0 ns can be achieved. Due to their high peak power and short pulse durations, such TEA lasers have acquired particular importance.
The method according to the invention will be explained in greater detail in the following with reference to the drawings shown in schematic, simplified presentation.
The laser system L shown in FIGURE 2 realizes a method for genera-ting laser beams in the 16-Jum wavelength range. These laser beams serve in particular for the isotope-specific (selective) excitation of 235-UF within a UF6-isotope mixture. The laser system L has a first laser Ll, designed as a TEA-C02 gas laser, the C02 molecules of which are lifted to the (00 1) 1 15g938 energy level by supplying pumping energy (see FIG. 3), where the pumping energy is supplied by an electric high-energy gas discharge within the laser module LMl.
The corresponding resonator Rel is constructed along the optical axis aa and con-tains a grating G and a partially transparent mirror Spl. The 16-~m radiation Sl is coupled out via the mirror Spl. The grating G closes the resonator Rel under a suitable angle c~ and serves at the same time for coupling the radiation of the laser L2 used as an injection laser into the laser Ll at the angle R.
The optical axis of the second laser L2, preferably a TEA-C02 laser, is designated bb, and its laser module is designated LM2~ Resonator Re2 of the second laser L2 has a 100% reflecting mirror Sp2 which, for tuning the injection laser L2, can be replaced by a grating, and a partially transparent mirror Sp3, via which the 10-J~m injection radiation S2 is coupled out of the laser L2.
Between the in;ection laser L2 and the laser Ll, the radiation passes through the pulse former PF which it triggers itself and which provides for a steep leading edge of the pulse S2.
The arrangement of the components for the electric digcharge in the laser modules LMl and LM2 corresponds to the form generally customary in TEA lasers.
In the embodiment example shown, the first laser Ll comprises one, i.e., at least one, TEA-C02 laser module LMl which is cooled to a temperature not lower than 150 K,~ where the required CO2 vapor pressure limits the temperature downward. The electrodes of the laser module LMl are designated Ell and E12, and the fast high-voltage discharge circuit connected thereto designated Zl. The laser L2 al~o contains a corresponding discharge circuit Z2 and electrodes E21 and E22. The electronic delay circuit V between the two firing devices Zl and Z2 takes care that the injection pulses of the second laser L2 are coupled into the resonator Rel of the first laser Ll with a ~; -6-l 159938 defined delay of up to 100 ~s relative to the electric excitation pulses of the first laser Ll.
FIGURE 1, in an enlarged fractional view, shows an example of a design of a TEA-C02 laser module LMl. Gas pressures of several lOs of mbar up to the bar range can be obtained with such a module, and excitation pulses with half-amplitude widths of less than 100 ns. The discharge space 3 of the laser module LMl is enclosed by a tubular body 4 which is customarily called - a laser tube. The laser electrodes Ell and E12 of approximately mushroom-shaped cross section are elongated and extend parallel to the optical axis aa and are opposite each other and at a spacing al. The TEA module can be design-ed in known manner, in particular as found in commercially available TEA
lasers (for instance, from the firm Lumonics). The laser electrodes Ell and E12 are made, for instance, of alloy steel or aluminum. The one electrode Ell is connected to chassis ground M of the discharge circuit Zl, and the other electrode E12 to its high-voltage potential HV. The gas-tight stub-shaped electrode feedthroughs are designated 5. Of the elements of the discharge circuit Zl, only the two charging capacitors Cl are indicated~ To deep-cool the discharge space 3, i.e. cool to a low temperature, preferably be-low 200K, the latter is surrounded by a cooling ~acket which can take the form of a cooling canal 6 arranged in spiral-fashion in the outer regions of the body 4 as indicated by dashed lines, with inflow nozzles 6a for intro-duction of coolant at one end and outflow nozzles 6b for discharge of ccolant at the other end. The laser gas which flows in the discharge space 3 and may be, in particular, a gas mixture of C022,and He, for instance, in the mixing ratio 1:2:25j is pumped according to the arrows fl along a flow path through the discharge space 3 which extends, as can be seen, in the direction of the ; optical axis aa, and between the oppositely disposed laser electrodes Ell and E12. This laser gas is pumped through an external cooling and gas processing .~

l 159938 device (not shown) and enters the discharge space 3 with the already mentioned temperature of minimally l50K. For high laser pulse frequencies it is advis-able to pump the laser gas long flow paths f2 through the discharge space 3 and the laser chamber, which paths f2 extend approximately perpendicularly to the optical axis aa and perpendicularly to the discharge direction between the laser electrodes Ell and E12. To effect~his alternative, gas inlet and out-let nozzles 7a and 7b are disposed diametrically opposite each other on the circumference of tubular body 4 and are connected to nozzle strips 8a and 8b for uniform distribution of the laser gas. These strips have nozzle holes 8.2 which cut into a longitudinal canal 8.1 in their interior and open into the discharge space 3, where the longitudinal canals 8.1 of the nozzle strips are again in communication with the canals 7.1 of the respective stubs 7a and 7b.
The nozzle strips 8a and 8b are inserted into corresponding recesses at the inside circumference of the body 4. Thereby, a transversal flow for the laser gas in the discharge space 3 is obtained, marked by the arrows f2. The latter laser gas flow can be used, before it flows into the discharge space 3, first as a coolant for the cooling system 6a, 6, 6b and then introduced into the discharge space 3 according to the arrows fl and the arrows f2. Then, a single loop for the laser gas and the coolant is sufficient.
To further explain the method according to the invention, reference is made in the following to FIGURES 2 and 3. It is of special importance for the kinetics of the 167~m laser that (FIGURE 3) the upper laser level (02 o?
is filled up as fast as possible in order to prevent, due to deactivation processes, the excitation energy (020) flow off into the adjacent states (10O) of the symmetrical vibration and (o220) of the bending mode vibration prior to the start of the laser emission; and the lower laser level (011) is occupied appreciably. For this reason, the rise time of the laser pulse of the injection laser L2 is set to a value as small as possible under 50 ns.

'~

l 159~38 the power density being above the saturation power density of the transition (00l) (020) in the cooled-down TEA-C02 module LMl of the first laser L]L. To this end, the pulse forming by the pulse former PF according to FIGURE 2 of the injection laser L2 is carried out by methods known from the literature, for instance, Pockels cells or mode locking. The laser pulse from the injection laser is coupled into the 16-~m resonator Rel with a de-fined delay of up to 100 ~us relative to the electric excitation pulse of the laser module LMl of the first laser Ll.
It is now of particular importance for the method according to the invention that the emission line of the injection laser can be tuned in a range so that the exact transition (00l) , (020) to a rotational level of the (020) level as well as transitions to virtual levels (02 0)' at a freely selectable distance from the line center of the exact transition are covered. For the special case of exact tuning, the rotation line of interest of the (020) level is therefore exactly occupied by the injection laser pulse. If then a higher pressure is used in the injection laser L2 than in the 16-~m laser Ll, better coincidence can be achieved by the method known per se for the frequency stabilization of the TEA-C02 laser L2. In the described special case of exact tuning, a number of relatively narrow-band laser lines, which, however, lie relatively far apart, can be excited in the 16-Jum range. However, a certain tuning range about one of these laser lines is of special importance for the isotope separation of U235.
The tunability can be achieved by resonance scattering at the rotation levels of interest of the (02 0) vibration which, of course, is a molecular bending mode vibration of the C02. For this purpose, the emission line of the injection laser L2, which in this case is preferably a high-pressure TEA-C02 laser, is shifted by methods known per se from the literature, by a fraction of the wave number from the center of the line. A pulse of l 159;~8 this laser with steep leading edge and sufficient power density is coupled into the 16~um resonator Rel of the first laser Ll, which comprises the cooled TEA-C02 module LMl of sufficient length, as explained in principle in con-nection with FIGURE 1.
Through this injection laser pulse, the virtual level (02 O)', drawn in dashed lines in FIGURE 3, is reached in the laser Ll, which is, for instance, removed by a fraction of a wave number above the real level (020) is reached. Which virtual level is most advantageous for the 235-U excitat-ion, i.e., the greatest isotope-specific excitation can be reached, is found from the optimization of the overall separation process. Through nonlinear scattering at such a virtual level of the C02, a light quantum is produced, the wavelength of which is shifted by the fraction of a wave num~er, the amount of detuning, of the real transition. The lower laser level for this scattering process is again the (0110) level of the C02 molecule. To expand the tuning possibilities, a gas mixture consisting of different isotope com-pounds of the C02 can be used as the laser gas and the composition and/or the mixing ratio of the mixture components can be varied.
For better understanding, the 10.6-J~m transition from the (00l) level to the (10O) level and the 14-,um transition from the last-mentioned level to the (0110) level are also shown in FIGURE 3, and further, the (o220) level. Below the lowest bending mode vibration level (0110), the (00O) level corresponding to the not excited state is shown.
Tunability of the TEA-C02 injection laser (fine tuning) is known per se, see the journal "Optics Communications", Vol. 30 of September, 1979, pages 414 to 418, and the journal "Applied Physics Letters", vol. 35 of December 1, 1979, pages 835 to 838.
T~ithin the scope of the invention, the tunability of the 167um wavelength is utilized to achieve optimum selectivity of the excitation pro-l 159938 cess under the conditions of the chosen technical process. This may mean, in particular, exact coincidence between a laser line and the absorption of the UF6 isotope to be excited. These relationships are shown in FIGURE 4 quali-tatively and schematically. If the transfer pulse of the in~ection laser Ll is tuned exactly to the energy level (020), then the first laser Ll emits according to the emission line shown by the heavy line in FIGURE 4. If the transfer pulse is detuned by fractions of wave numbers once in the direction toward smaller wavelengths, once in the direction toward greater wavelengths, then the two emission lines shown dashed in FIGURE 4 are obtained, with which upper and lower virtual levels (020)' of FIGURE 3 can be associated. If the transfer pulse is tuned to lower virtual level (02 0)', good resonance is obtained, as can be seen, with the absorption line of the 235 UF6, so that excitation resonance between the enclosed light quanta and the 235-UF6 mole-cules, i.e., their v3-vibration form takes place. Outside the tuning range, the absorption line of the 238-UF6 molecule (v3-vibration) is further shown below the abscissa axis.
A substantial increase in power of the 16~m pulses delivered by the first laser Ll can be achieved by using as the cooled TEA-CO2 laser module one of the basic stack designs disclosed in Published German Patent Appli-cation P 29 32 781.9, in which, for a capacitor discharge in the gas space as homogeneous as possible and free of arcing, a low-inductance high-voltage switching circuit extending between at least two laser electrodes which extend parallel to the optical axis of the laser module and are opposite each other with spacing, is provided, consisting of the TEA CO2 laser module, an associ-ated fast high-voltage switching gap, ohmic resistors and associated circuit connections, where the electrodes of the first and the second stripline capacitors and their dielectric layers in between are stacked substantially normal to the optical axis of the laser module to form a capacitor stack and ~.

1 1599~8 are connected via contact lugs brought out laterally to the electrodes of the laser module. It is furthermore particularly advantageous for a capacitor discharge as homogeneous as possible and free of arcing in the gas space between the electrodes of the cooled TEA-C02 laser module, to use the basic mushroom electrode design with preionlzation rods disclosed in Canadian Patent Application 386,280, where at least one of the electrodes protrudes with a mushroom stem serving as a current lead and a mushroom cap serving to dîstri-bute the current, into the discharge space, and where, for pre-ionizing the discharge space between or ad~acent to the electrodes, at least one rod-shaped auxiliary electrode consisting of an inner conductor and a dielectric sur-rounding the same, is arranged parallel to the axis and with sparking distance from one of the electrodes. The two above-mentioned basic designs, namely on the one hand, the stack design and on the other hand, the mushroom elect-rode design with pre-ionization rods, can also be used to advantage for the injection laser, if high in~ection power and a capacitor discharge as homo-geneous as possible and free of arcing are to be achieved.
If in a technical separation process several 16~1m lasers Ll.l Ll.n are required, only one independent in;ection laser L2 is nevertheless necessary, since each 16-~m laser Ll acts at the same time as an amplifier of the 107~m radiation S2. The so amplified radia~ion S2 can then be used again, after separation of Sl, in the next 16-Jum laser in a respective prism Pr, as is shown in FIGURE 5. In another embodiment, also part of the 16-Jum radiation of the respective preceding laser Ll can be coupled into the next one together with the lO~m radiation so as to lower the threshold for starting up the laser emission therein. By using light delay lines for the 10-J~m radiation S2 in this chain of lasers Ll.l... Ll.n, a time delay of the 16~um laser pulses is then possible at the same time. In FIGURE 5 deflection mirrors 5 together with the prisms Pr provide a zig-zag-shaped ray path S2.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Method for generating laser beams in the 16-µm wavelength range, especially for use in separation of the U235 isotope from a mixture containing U235 and U238 isotopes, comprising supplying pumping energy to lift CO2 mole-cules of a first gas laser having a CO2 laser gas mixture to the (00°1) energy level, and radiating from a high intensity radiation source as an injection laser into the laser tube of the first gas laser to stimulate the transition (00°1) (02°0) for occupying the upper laser level for the 16-µm radiat-ion of the first laser on the bending mode transition (02°0) (01°0), the combination therewith of a) cooling the laser gas mixture of the first laser and effecting said pumping by an electric high-energy gas discharge according to the TEA
(transversely excited atmospheric pressure laser) principle with at least one TEA-CO2 laser module as an element of a 16-µm laser of the first laser, b) tuning the emission line of the injection laser in a range which covers the exact transition (00°1) (02°0) to a rotation level of the (02°0) level as well as virtual levels (02°0)' at a freely selectable distance from the line center of the exact transition, c) shifting the emission line of the injection laser by a fraction of a wave number from the line center of the corresponding transition, for tuning to a virtual level (02°0)', d) coupling injection laser pulses with a rising pulse flank as short as possible, tuned as above, from the injection laser into the 16-µm resonator of the first laser, to cause the transition in the first laser from the (00°1) level to a virtual energy level (02°0)' located apart from the real level (02°0) and removed from the real level (02°0) of the CO2 molecules by a fraction of a wavelength, and due to non-linear scattering at this virtual energy level in the transition to the lower (0110) laser level, the CO2 molecules emit light quanta, the wavelengths of which are again shifted by the same fraction of a wave number of the real transition (02°0)(0110).

2. Method according to claim 1, wherein the injection laser is a second CO2 laser.

3. Method according to claim 2, wherein the injection laser is operat-ed as a high pressure TEA-CO2 laser.

4. Method according to claim 1, wherein a pulse width of ? 50 ns with a leading edge as steep as possible of the injection laser is used and the power density of the injection laser radiation is above the saturation power density of the process for the desired 16-µm transition in the cooled-down TEA-CO2 laser module.

5. Method according to claim 1, wherein the injection laser pulse is coupled into the 16-µm resonator of the first laser with a defined delay of up to 100 µs relative to the electric excitation pulse of the first laser.

6. Method according to claim 1, wherein for the purpose of expanding the tuning possibilities, a gas mixture containing different isotopes of CO2 is used and the composition or the mixing ratio of the gas mixture components are varied.

7. Method according to claim 1, wherein the laser gas is pumped through the laser module along a flow path which runs in the direction of the optical axis and between oppositely disposed laser electrodes.

8. Method according to claim 1, wherein the laser gas is pumped especially for high laser pulse frequencies through the laser module along a flow path which is approximately perpendicular to the optical axis and per-pendicular to the discharge direction between oppositely disposed laser electrodes.

9. Method according to claim 1, wherein the cooled TEA-CO2 laser module has a basic stack design in which, for a capacitor discharge as uniform as possible and free of arcing, there is provided in the gas space between at least two laser electrodes which extend parallel to the optical axis of the laser module and with spacing from each other, a low-inductance high-voltage switching circuit, consisting of the TEA-CO2 laser module, an associated fast high-voltage switching gap, first and second stripline capacitors, ohmic resistors and associated circuit connections, where the electrodes of the first and second stripline capacitors and their dielectric layers in between extend substantially normal to the optical axis of the laser module and are stacked substantially parallel to the optical axis of the laser module to form a capacitor stack and are connected, with contact lugs brought out lat-erally, to the electrodes of the laser module.

10. Method according to claim 9, wherein for a capacitor discharge as homogeneous as possible and free of arcing in the gas space between the electrodes of the cooled TEA-CO2 laser module, a basic mushroom electrode design with pre-ionization rods is used therefor, in which at least one of the electrodes protrudes with a mushroom stem serving as a current lead and a mushroom cap serving to distribute the current into the discharge space, where, for pre-ionizing the discharge space between or adjacent to the electrodes, at least one rod-shaped auxiliary electrode consisting of an inner conductor and a dielectric surrounding the latter, is arranged parallel and at a sparking distance from one of the electrodes.

11. Method according to claim 9, wherein the injection laser has the same basic design with stripline capacitor electrodes stacked in the axial direction of the laser and dielectric layers with mushroom-shaped electrodes and with pre-ionization rods as used for the first laser.

12. Method according to claim 10, wherein the injection laser has the same basic design with stripline capacitor electrodes stacked in the axial direction of the laser and dielectric layers with mushroom-shaped electrodes and with pre-ionization rods as used for the first laser.

13. Method according to claim 1, wherein the 10-µm radiation of the independent injection laser is coupled into the ray path of a laser chain which consists of at least two 16-µm lasers (L1.1, L1.2, ... L1.n) which are optically connected in series with respect to the 10-µm radiation of the injection laser.

14. Method according to claim 11, wherein the 10-µm radiation of the independent injection laser is coupled into the ray path of a laser chain which consists of at least two 16-µm lasers (L1.1, L1.2, ... L1.n) which are optically connected in series with respect to the 10-µm radiation of the injection laser.

15. Method according to claim 12, wherein the 10-µm radiation of the independent injection laser is coupled into the ray path of a laser chain which consists of at least two 16-µm lasers (L1.1, L1.2, ... L1.n) which are optically connected in series with respect to the 10-µm radiation of the injection laser.

16. Method according to claim 13 or claim 14 or claim 15, wherein 16-µm radiation is at least partially coupled-out at the output of the respective 16-µm laser by means of ray deflection devices, but 10-µm radiation at the output is coupled into the ray path of the next-following 16-µm laser.

17. Method according to claim 13 or claim 14 or claim 15, wherein 10-µm radiation of the injection laser is conducted through light delay lines within the ray path of the laser chain (L1.1, L1.2, ... L1.n), to delay the 16-µm laser pulses of the chain of lasers relative to each other.