JPS61119083A - Sealed type carbon dioxide laser - Google Patents

Abstract

PURPOSE:To contrive the improvement in a laser output and an operating life by forming a cathode electrode out of a perovskite oxide and keeping a temperature of self-heat generation by discharge lower than the redox reaction temperature. CONSTITUTION:A cathode electrode 6 is formed of a pervskite oxice and an anode electrode 7 is formed of a platinum rod. The electrode made of perovskite oxide is actuated in a reduction region of the electrode itself where an oxidizing ability of CO functions and a temperature of a surface of the electrode of self- heat generation due to discharge is kept lower than a redox reaction temperature. Thus reduction of O2 gas in a laser gas during the operation can be prevented and a catalysis of the electrode to CO can be kept good for a long time. A constant quantity of CO2 gas is maintained and a long operating life can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a sealing device for use as a medical surgical scalpel or for non-metal processing, which is simple and small-sized and non-contact processing with an output of 1oOW or less. This relates to a Co2 type laser.

The conventional technology sealed CO□ laser has excellent characteristics of output and energy efficiency, and is a far-infrared laser with a wavelength of 10.6μ. However, 002, which plays a central role in laser gas,
Since the molecules have a low binding energy of 3.75 eV, they are easily dissociated by electron collision in the CO2 laser gas plasma where the average energy of electrons is 3.5@V. As the density of the dissociation products CQ, o2 increases, recombination, which is a reverse reaction, occurs, and the system reaches an equilibrium state. This relationship is expressed by the chemical equation % (1), and the time constant until equilibrium is reached is as short as about 1 second in normal 002 laser gas plasma. The Co2 concentration in this equilibrium state becomes extremely small, and almost no output can be obtained. Therefore, suppressing the dissociation of CQ2 within the laser tube is the most important issue for the output and life of a sealed Co 2 laser.

Conventionally, as a method for suppressing the dissociation of Co2 in a laser tube, there is a catalytic method in which Co generated by dissociation is returned to the original Co2. As the catalyst, a gas catalyst such as a bow and a solid catalyst of a noble metal such as PT or an oxide such as MnO2 or perovskite are used. Gaseous catalysts have low catalytic ability and are difficult to control optimal gas partial pressure, so they are not practical. On the other hand, since solid catalysts generally do not exhibit catalytic activity unless heated to high temperatures, self-caloric heat generated during electrode discharge is utilized. However, in the past, sputtering of the electrode was large and the sputtering product was CO. It has a high gas adsorption/desorption property, and therefore it is difficult to maintain and control the optimum laser gas composition even if the solid catalyst described above is used.

In order to solve this problem, conventional perovskite oxides, such as La1-. 5r
A sealed CO2 laser has been proposed in which an electrode is formed of xCoo3(0,2(x(0,5)) and utilizes its high conductivity.

Problems to be Solved by the Invention However, even when using the above-mentioned highly conductive perovskite oxide layer electrode, the self-heating temperature is 200°C or more.
It has been found that when the temperature reaches 300° C., 0□ gas is released from the electrode, increasing the 02 partial pressure in the laser gas composition, and having a significant impact on the output characteristics and operating life of the sealed Co2 laser. Therefore, even if an electrode made of a highly conductive perovskite oxide layer is simply used, it is still not possible to obtain sufficient output and operational life with good reproducibility. There are 5 reasons for this decline in output.
(1) The 02 gas that brings out the catalytic action of the perovskite oxide electrode decreases and Co2 dissociation increases; @) Perovskite oxide electrode.

An example of this is a decrease in CO2 gas due to adsorption of Co2 gas by the sputtered layer, tube wall, etc. In order to prevent the decrease in O2 gas, which is the first cause, it is necessary for the perovskite oxide to act as an excess oxygen operating electrode that releases O2 gas.

Therefore, the present invention aims to provide a sealed Co2 laser in which gas can be released from the electrode formed by perovskite oxide, and the laser output and operating life can be kept in the best condition. It is something.

Means for solving the problems The technical means of the present invention for solving the above problems are as follows:
A laser tube, a negative electrode and a positive electrode for discharge provided in the laser tube, and a laser gas sealed in the laser tube, at least the negative electrode of the discharge electrodes is formed of perovskite oxide, and the discharge The temperature of self-heating caused by the reaction is lower than the redox reaction temperature.

According to the above structure, the present invention can prevent O2 in the laser gas from decreasing during operation, and can maintain a good catalytic effect on Co for a long period of time.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, reflecting mirrors 2 and 3 constituting a laser resonator are fixed by adhesive at both ends of a laser tube 1 in an optically adjusted state. The reflecting mirrors 2 and 3 may not be fixed to the laser tube 1, but may be connected flexibly through a bellows,
Alternatively, a transparent window such as a Brewster window may be installed in place of the reflecting mirror 2.3 and combined with an external mirror camera. Branch portions 4.5 are provided on both sides of the laser tube 10, and a negative electrode 6 and a positive electrode 7 are provided inside each branch portion 4,5. The negative electrode 6 is formed from perovskite oxide, and the positive electrode 7 is formed from a platinum rod. A cooling jacket 8 is provided around the outer periphery of the laser tube 1, and this cooling jacket 8 is provided with an inlet 9 and an outlet 10 for a cooling fluid such as water or oil. After pretreatment exhaustion, laser gas is sealed in the laser tube 1 from the enclosure 11, and the enclosure 11 is closed. What is the composition of the laser gas?

For example, CO2: 2.4 Torr, N2: 5.
8 Torr.

He: 13.8 Torr, Xs: 0.5
Torr. In this embodiment, only the negative electrode 6 is formed of perovskite oxide, so the negative electrode 6
and the positive electrode 7 are connected to a DC excitation power source 12. When the lower side of the positive electrode is also formed of perovskite oxide, an alternating current or high frequency excitation power source can be used.

By applying a direct current to the negative electrode 6 and the positive electrode 7, a laser beam can be output from the resonator formed by the reflecting mirror 2.3. The relationship between the amount of O2 gas absorbed and the surface temperature of the negative electrode 6 was tested.

La o , y S r o , s Co on the negative electrode 6
Using O3 oxide, the volume is 1.6 CI! , surface area 1a,
It was formed into a cylindrical shape of eca.

The laser gas is Co2: 2.2 Torr, 02:
2.0 Torr.

N2: 5. OTorr, Xs: 0.5 Torr
r, the remainder consists of He, and the total pressure is 22. s Tor
It was set as r. And the cathode e o 02 waste emission amount (Δ
PD(O2)〉(1) and absorption amount of 02 gas (Δ, PD(
The relationship between the surface temperature TD of the negative electrode 6 and the surface temperature TD of the negative electrode 6 is as shown in FIG. 2, and there is a very clear tendency despite the short discharge time of 1 to 20 minutes. In Figure 2,
The point where ΔPD (O2) on the vertical axis of the six surfaces of the negative electrode and ΔPD is zero, that is, the temperature TB at which the redox reaction occurs in a state where the reaction in equation (1) above is exactly balanced, is 2 3 in terms of discharge current. mA, the electrode surface temperature is in an operating state higher than 300'C. The discharge occurs above the cathode θ, and when the size of the cathode 6 becomes relatively small, the discharge current that causes TB becomes a value lower than 23 mA.

The conditions for causing the N dox reaction are determined not only by the surface temperature of the cathode 6 but also by the composition of the cathode 6.

As an example of perovskite oxide, Fig. 3 shows the composition by I value and δ value of La1-ESrxCoO3-δ, and the electrode surface temperature TB(1) and redox during operation correspond to each composition. A curve producing the reaction was obtained. In the composition of region A above this value σ), as long as it is operated at the TB(I) temperature, the cathode 6 has a reducing action that releases 02 gas.
On the other hand, the region B below TB(I) has an oxidizing effect by sucking the 02 gas. In the figure, the redox reaction curve when the surface temperature of the cathode 6 is higher is shown as TB(I+α), and the redox reaction curve when the surface temperature is lower is shown as TB(I−
α). In this way, depending on the surface temperature of the cathode 6, that is, the size of the cathode 6 and the magnitude of the discharge current, an electrode of the same composition can operate on either the gas release side or the gas suction side.

As another test example, the negative electrode 6 was made of perovskite oxide “0”.
．． 78rO. 3”03 -0.01 The X value of 5 is 0.3
, kneaded with a composition with a δ value of 0.015, and pre-fired at a temperature of 900.
After pre-firing at ℃, press pressure 0,5 ton/c
The pellets molded using RD were fired at a main firing temperature of 1150°C for several hours. 1 idle period during press molding: o. 5cIll,
Surface area: 3.6 crtt small cylindrical electrode, volume 1.6
i. Two types of large cylindrical electrodes with a surface area of 14 and ecrA were manufactured.

The test laser tube 1 has a structure as shown in FIG.
CO2 in the CC space: 2, 6 Torr,
O2: 1, 0 Torr, N2: 5. O Torr
%Xs: 1.0 Torr.

He: 20 Torr total pressure 29.6 To
Laser gas was filled with rr.

As a result of conducting a continuous operation life test at a discharge current of 20 mA, as shown in Figure 4, the large cylindrical electrode had an operation life of more than 100 hours as shown by a, whereas the small cylindrical electrode had an operation life of more than 100 hours. As shown by b, the operating life is just over 100 hours, and there is a difference in performance of about one order of magnitude.

As a result of mass spectrometry analysis of the gas composition during discharge in both cases, it was found that the amount of 02 gas released and sucked in at the electrode ΔPD(O2) was +1. The emission characteristics are measured at O Torr and 10.0 Torr for a small cylindrical electrode. The suction characteristics are shown at 2 Torr.

As is clear from the above test results, the electrode of the perovskite oxide part is operated in its own reduction region where the oxidation ability of Co is exerted, so that the electrode surface temperature due to self-heating due to discharge is lower than the redox reaction temperature. Because
During operation, the O2 gas in the laser gas can be prevented from decreasing, the catalytic effect of the electrode on CO can be maintained well for a long time, and a constant amount of Co2 gas can be maintained to ensure a long operating life. And this kind of effect is
The size of the electrode formed of perovskite oxide is 0.8 cIjt or more in volume, e in area, 7H or more, and La
1-x Sr, CoO3-, X value of y is 0.2<x<
This can be achieved by appropriately selecting the δ value in the range o, oos < δ < 0.055, and by continuously operating this electrode at a discharge current of 25 mA or less.

Effects of the Invention As is clear from the above explanation, according to the present invention, at least the negative electrode of the negative electrode and positive electrode provided in the laser tube is formed of perovskite oxide, and the temperature of self-heating due to discharge is reduced by the redox reaction. I try to keep it lower than the temperature. Therefore, this perovskite oxide electrode is 0□
The gas can be released, the catalytic effect on Co can be maintained for a long time, and the CO2 gas can be maintained in a certain amount, improving the laser output and the operating life.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main part of the sealed CO□ laser of the present invention, Fig. 2 is a diagram showing the dependence of O2 gas release and suction characteristics on the electrode surface temperature in a perovskite oxide electrode, and Fig. 3
The figure shows the relationship between the composition of the perovskite oxide electrode and the redox reaction, and FIG. 4 shows the operating life of the perovskite oxide electrode depending on its size. 1...Laser tube, 2,3...Reflector,
6... River/negative electrode, 7... Positive electrode, 8...-
...Cooling jacket, 12...Power supply. Name of agent: Patent attorney Toshio Nakao and one other name
1111 t -1, -ft 2-R axis 3-Oimura Mosquito C-Reiqe 7--γQin Supplement 8-One small condolence jacket tube 2 Figure 1113 Figure' lW, -8δrlCo03-tr 'tfI Fourth
Figure 1

Claims (4)

[Claims] (1) A laser tube, a cathode and an anode for discharge provided in the laser tube, and a laser gas sealed in the laser tube, wherein at least the cathode among the discharge electrodes is made of perovskite oxide. 1. A sealed CO_2 laser characterized in that the temperature of self-heating due to discharge is lower than the redox reaction temperature. (2) The sealed CO_2 laser according to claim 1, wherein the electrode formed of perovskite oxide has a volume of 0.8 cm^3 or more and an area of 6 cm^2 or more. (3) The electrode formed from perovskite oxide is 25
The sealed CO_2 laser according to claim 1, which operates continuously with a discharge current of mA or less. (4) Perovskite oxide is La_1_-_xSr_
The x value of xCoO_3_−_δ is 0.2≦x≦0.5, δ
The sealed CO_2 laser according to claim 1, wherein the value is 0.005≦δ≦0.055.