FR2529721A1 - ATMOSPHERIC PRESSURE CO2 GAS LASER WITH ELECTRIC TRANSVERSE FIELD - Google Patents

Abstract

THE INVENTION RELATES TO A CO GAS LASER AT ATMOSPHERIC PRESSURE, WITH A TRANSVERSAL ELECTRIC FIELD. THIS LASER INCLUDES A GAIN AGENT 13, A WATERPROOF ENVELOPE 12 WHICH CONTAINS THE GAIN AGENT, A CATALYST 30 IN THE ENCLOSURE AND A DEVICE 40 FOR PROTECTING THE CATALYST AGAINST ELECTRIC FIELD AND SHOCK WAVES IN THE ENVELOPE, AND CONSISTING OF A CONDUCTIVE CONTAINER 26, 28 OF WHICH AT LEAST PART OF THE SURFACE IS PERMEABLE TO THE GAINING AGENT AND IMPERMEABLE TO THE CATALYST. APPLICATION TO LASER TECHNOLOGY.

Description

The present invention relates to a gas laser

  Co 2 at atmospheric pressure, with a trans-

versal.

  In a CO 2 gas laser, the active agent is a

  gaseous mixture of carbon dioxide, nitrogen, helium and in some cases other gases such as carbon monoxide or xenon When an electric discharge is produced

  in the gas to excite the active agent, some of the

  In this way, the stituents of the mixture dissociate.

  carbonic acid dissociates into carbon monoxide and oxygen Dissociation of the gas results in a reduction of

  volume of active agent and is one of the main reasons

  failures of hermetically sealed C 02 lasers.

is lying.

  Attempts to reduce the harmful effects

  detrimental effects of gas have implemented

  such as the use of large volumes of

  serve as gas, and catalyze the dissociated constituents.

  The technique most often used in C 02 lasers

  consists in using a catalyst that accelerates the recombination

  Dissociated constituents carbon monoxide and oxygen do not recombine at room temperature; but under certain conditions they can combine in

  presence of certain catalysts Platinum is the catalyst

  best known lyser; but it imposes a functioning of the

  laser at high temperatures, which is not pos-

  sible in a hermetically sealed C 02 laser Hopcalite, a mixture of magnesium oxide (Mn O 2) and copper oxide

  (Cu 0), commercially available, is sometimes

  As the main problem is that the catalyst powder is dispersed in the

  laser and therefore degrades performance, especially when

  part of the catalyst powder is deposited on the

optical elements.

  An article titled "Sealed Multia Tmosphere C 02 TEA Laser: Seed-Gas Compatible System Using Unheated Oxide Catalyst" by R B Gibson et al, Appl Phys.

  Letters 32 (11), June 1, 1978, describes a laser that

  the catalyst powder outside the main envelope of the laser and requires a pump

  circulate the gas on this catalyst powder.

  The invention therefore relates to a container for

  lyser which isolates the catalyst powder from the elec-

  intense pulses present in the laser envelope and which protects the shock wave catalyst produced

  by an electric discharge between two electrodes

  to excite the laser gain agent, while

  putting enough contact for the catalysis to take place.

  The container is made of a fully conductive casing, with a conductive lid that is permeable to gaseous Eent and impervious to the catalyst present therein The container is placed in the main casing of the laser in a neighboring region from the discharge area which ensures

  sufficient contact between the dissociated constituents

  the discharge and the catalyst.

  container is in contact with one of the electrodes With this arrangement, the heat produced in the electrode by the electric discharge is transferred by the container

  to the catalyst, which increases the speed of recom-

bination.

  Other features and advantages of the invention

  will appear in the following description.

  of an exemplary embodiment and with reference to the appended drawings in which:

  Figure 1 A is a section of an embodiment of

  1 is a section along the line 11B-1B of FIG. 1A and FIG. 1C is a top view of the catalyst container used in the embodiment of FIG. 1A. A. T Figures 1A to 1C therefore represent a laser

  hermetically sealed, with C 02 gas at atmospheric pressure

  The envelope 12 is intended to contain a gas axle 13 and two main electrodes 14 and 16. The electrode 14 is fixed on a wall of the envelope 12 and is

  separated by screws 20 and spacers 18

  trode 16 is fixed on the opposite wall of the casing 12, also with screws 20 and is spaced from this wall by the combination of the spacers 22 and the catalyst container 40 The relative dimensions of the spacers 18 and spacers 22 and catalyst vessel 40 determines the spacing of the electrodes 14 and 16, and are selected to obtain

  a predetermined distance in order to meet the conditions

  specific application of the container.

  The lyser 40 is constituted by a casing 26 in the form of a trough with an end cap 28. The casing 26 is made of a solid conductive material, for example made of

  aluminum and the cover 28 is made of a material

  ductor with openings of a pre-dimension

  determined, for example a stainless steel grid

  predetermined frame value The function of the

  28 will be described in more detail later and it suffices for the moment to indicate that this cover 28 must allow the free passage of the gaseous agent 13 or its constituents while pocketing that even the most

  small catalyst particles are coming out

  The catalyst container 40 is assembled into the laser envelope 12 by fixing the base

  box 26 on the back surface of one of the elec-

  trodes and fixing on the rim of the casing 26, the neck

  28 and the spacers 22 This is done for example with screws 20 screwed by corresponding openings of the laser casing 12, the casing 26, the cover

  28 and the electrode 16 spacers 24 are also

  used to increase the stiffness between the neck and

  28 and the inner surface of the casing 26 and

  to close the screw openings relative to

  to the contents of the container 40 spacers 22 are

  Between the cover 28 and the wall of the casing 12 to maintain a sufficient space or volume in which the gain agent or amplifying medium 13 can flow in front of and through the cover 28 A catalyst 30 is placed 3 in the casing 26 and the cover 28 A mixture of manganese oxide and copper oxide, such as Hopcalite can be used as a catalyst It can be

  used in the form of a powder whose grains do not adhere

  do not go between them, or be compressed into pellets

  appropriate size The volume between the container

  lyser 40 and the electrode 16 allows the gain agent 13 to circulate and to be in contact with the lid 28 of the catalyst container 40.

  catalyst container 40 has an imperfec-

  However, the gain agent 13 can penetrate by way of the catalyst, but is permeable to the gain agent.

  cover 28 and come into contact with the cat-

  30-but the smaller catalyst particles can not pass through the cover 28 and therefore can not contaminate the gain agent 13 and deposit free particles on the critical optical elements of the laser In general, a frame size of 40 microns

is used.

  A discharge control device 60 is preferably

  seen to produce a discharge between the electrodes 14 and 16, used to excite the gain agent 13 and thereby produce a laser pulse In the case of use

  in the resonator mode, a reflection mirror 50 is

  tale is placed on the optical axis of the laser 10 at one end.

  mite of the envelope 12 and a mirror 52 transmission

  partial is placed on the optical axis at the end Opp O

  In other applications, the mirrors 50 and 52 can be replaced by windows.

  optical output whose planes can be positioned-

  born under the Brewster angle with respect to the optical axis to control the polarization of laser pulses

  of output, as is well known.

  During the operation of the laser, the intense electric fields which are present cause the breaking of the catalyst pellets 30 and have an effect

  3 dispersion on the catalyst powder, which de-

  grade the operation of the laser, especially when the

  sew is deposited on the optical elements in the

  laser tread 12 electric discharge produced

  being the electrodes 14 and 16 also causes a wave

  shock which has the same adverse effects on the catalytic-

  However, those mentioned above, the casing 26 and the cover 28 form in fact a conductive cage, which may be called a Faraday cage, and it turns out that

  this cage protects the catalyst 30 against ef-

  scattering effects of the intense electric fields pre-

  The container 40 also protects the catalyst 30 against the shock wave produced by the discharge between the main electrodes 14 and 16 and prevents catalyst particles from forming.

  escape from the interior volume of the container 40.

  It turned out that the turbulence of the gas,

  by the electric discharge between the main electrodes 14 and 16 are sufficient to establish contact

  between the gain agent 13 and the catalytic agent

  30, when placed in the vicinity of the discharge region. The position of the elongated container 40 between

  one of the side walls of the envelope 12 and the elec-

  trode 16 also provides the advantage of simplifying the montazge of the container 40 Through the use of the screws 20 and the spacers 22 and 24, a solid mounting and

s & r of the container 40 is obtained.

  The discharge control device 60 provides

  the energy for the electric discharge between the electrodes 14 and 16 and controls at will its repetition frequency The repetition frequency of the electric discharges is one of the variables which determine

  the temperature in the envelope of the laser, the constitution

  killing MnO of the catalyst powder is more effective in the lower temperature range occurring in the operation of the low frequency repetition laser while the Cu O component is more efficient.

  in the range of higher temperatures

  in the high-frequency operation of

  petition In combination, they ensure a catalytic ef-

  the dissociated gases in a wider range of temperatures, allowing flexibility in

  choice of repetition frequency of the pulses.

  Of course, the repetition frequency is also limited by the fact that the dissociation rate of the gases

  resulting from the discharge can not exceed the recovery rate

combination of Catalysis.

  As shown in Figures 1A-1B, the recital

  This arrangement allows the heat from the electrode 16 to be transferred to the container 40 and thence to the catalyst agent. This actually increases the temperature of the catalyst. , thus increasing

  the efficiency of catalysis on the speed of recombination

  The discharge between the electrodes 14 and 16

  heat in these electrodes.

  DC load is used, it turns out that the cathode is developing more heat than the anode.

  to obtain a maximum recombination rate, the

  Catalyst container 40 must be in contact with the cathode, such as electrode 16 of FIG. 1A. For non-continuous discharge, the position of the container is not critical to the extent that it is thermally coupled, for example by conduction, with one

electrodes.

  It is understood that various modifications

  may be made to the embodiment of the

  invention, for example, the actual position and the particular shape of the container 40 may be modified to

  respond to a particular design of the envelope.

  It is not necessary for the catalyst container 40 to be in the vicinity of the discharge region and coupled with

  preferably thermally with one of the electrodes.

Claims (8)

  A laser, characterized in that it comprises a gain agent or amplification medium (13), a sealed laser envelope (12) surrounding said gain agent, a catalyst (30) in said envelope and a device ( 40) for protecting said catalyst from the electric field and shock waves present in said laser envelope and comprising a conductive container (26, 28) at least a portion of which   of the surface is permeable to said gain agent and imper- said catalyst.   2 Laser, characterized in that it comprises a   gain agent (13) comprising at least one predefined compound   terminated subject to dissociation into at least two components, a discharge region (14, 16) for stimulating said agent   gain, a catalyst (30) for facilitating recombination   of said two constituents and a conductive container   (26, 28) for said catalyst, part of which: the surface is permeable to said gain agent and impervious to said catalyst, said container being positioned against said discharge region.   3, characterized in that it comprises a gain agent (13) subject to dissociation, a device (14, 16) for producing a discharge in said gain agent and a device (40) for recombining the constituents   dissociated from said gain agent comprising a powder of   a particle size analyzer (30) having a predetermined particle size and a container (26, 28) having apertures of a size smaller than said particle size and greater than the size of said dissociated components,   to contain said powder in a region close to the said discharge.   4 Laser according to claim 3, characterized in that it further comprises a device (60) for   controlling the temperature of said gain agent in order to   maintain an optimum temperature in the region of   sor. Laser according to claim 3, characterized in that it comprises a device (60) for controlling   at will the frequency of said discharge.   Laser, characterized in that it comprises a sealed laser envelope (12), a gain agent (13), two electrodes (t 4, 16) for producing a discharge in said gain agent, a catalyst (30) and a conductive container (26, 28) for containing said catalyst, at least a portion of which is permeable to said surface   gain agent and impervious to said catalyst, said resistor   container being disposed between one of said electrodes and said envelope, with the permeable portion of the   gain in contact with said gain agent.   Laser according to claim 6, characterized in   it further comprises a device (60) for   the frequency of repetition of said discharge.   8 Laser according to claim 6, characterized in that said container (26, 28) is thermally coupled   with one of said electrodes (14, 16).   9 Laser according to claim 6, characterized in that said container is in thermal contact with   one of said electrodes (14, 16).   Laser according to claim 9, characterized in   what said two electrodes (14, 11) form a   a thode and an anode, said container (26, 28) being tact with said cathode.