JPH0636447B2 - Metal vapor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a metal vapor laser device, in particular, to prevent discharge outside the furnace core tube, to effectively utilize discharge energy, and to achieve high efficiency. The present invention relates to a metal vapor laser device capable of oscillating high-power laser light.

(Prior Art) Laser devices are used in a wide range of fields such as material cutting, optical communication, medical technology, and the nuclear industry. Especially in the nuclear industry, it is the core of the uranium isotope enrichment technology by the laser method for selectively exciting and separating a specific isotope from a plurality of uranium isotope mixtures.

As a metal vapor laser device used in the enrichment of uranium isotopes, a copper vapor laser device that is highly efficient and can obtain a laser with the highest output is generally adopted. This device applies discharge energy to copper metal and heats it to a high temperature to form metal vapor, and at the same time, to generate plasma that becomes a laser medium,
It is configured to oscillate laser light having a predetermined wavelength.

FIG. 5 is a sectional view showing the structure of a conventional metal vapor laser device of this type. A furnace core tube 2 as a heat-resistant discharge tube is housed in the center of the oscillation tube body 1. At both ends of the furnace core tube 2, a positive electrode 3 and a negative electrode 4 are disposed so as to face each other, and these electrodes 3 and 4 are supported by electrode supporting flanges 5 and 6, respectively, and are formed between these electrodes. The pulsed bipolar discharge is performed in the discharge space 7 that is formed. At the inner bottom of the furnace core tube 2, a metal vapor source 8 for generating metal vapor, such as copper particles, is arranged.

A heat insulating layer 9 made of a material such as alumina fiber is formed on the outer periphery of the furnace core tube 2, and a protective tube 10 made of quartz or the like is used as a heat insulating layer to fix the heat insulating layer 9 at a predetermined position and protect it. It is provided on the outer circumference of 9. A vacuum heat insulating chamber 12 is formed between the protection tube 10 and an external vacuum container 11 arranged outside the protection tube 10. The vacuum insulation chamber 12 and the discharge space 7 in the furnace core tube 2 are connected to an exhaust device 13 so that the inside is maintained in a vacuum state.

Further, in order to insulate the positive electrode 3 and the negative electrode 4 and obtain a good discharge, a break tube 14 made of an insulating material such as ceramic or glass is provided between the external vacuum container 11 and the electrode supporting flange 6. It is installed.

In the operation of oscillating the laser light, first, the exhaust device 13 is operated to exhaust the inside of the vacuum heat insulating chamber 12 and the discharge space 7, and then the buffer gas supply source 15 into the discharge space 7 Ne.
A buffer gas such as is introduced to keep the inside pressure constant.

When the high voltage power supply 16, the pulse circuit 17, and the pulse drive power supply 18 are activated in this state, a pulsed high voltage is applied between the positive electrode 3 and the negative electrode 4, and discharge plasma is generated in the discharge space 7. Floating metal vapor collides with free electrons in this discharge plasma to excite the metal vapor,
Laser light having a predetermined wavelength is generated when the excited metal vapor makes a transition to a low energy level. The laser light generated in the discharge space 7 passes through the Brewster windows 19 and 20, and further increases in amplitude while being reflected by the output mirror 22 and the total reflection mirror 23 forming the laser light resonator 21, so that the output mirror It oscillates from 22.

(Problems to be Solved by the Invention) In the metal vapor laser device having the conventional structure as described above, discharge plasma is generated in the discharge space by applying a pulsed high voltage between both electrodes. This discharge phenomenon does not occur only between the tips of both electrodes as illustrated in FIG. 6 (A), but actually also outside the furnace core tube as illustrated in FIG. 6 (B). It has occurred.
In particular, since the outermost peripheral portion of the electrode support flange is close to the end surface of the heat insulating layer and faces the discharge surface, discharge between them easily occurs,
In some cases, a discharge current i may flow in the gap between the heat insulating layer 9 and the protective tube 10 as indicated by an arrow, or the discharge current i may directly pass through the inside of the heat insulating layer 9 to discharge. If this furnace core tube discharge occurs frequently, the discharge energy is not applied to the inside of the furnace core tube and diffuses to the outside of the apparatus, and the temperature raising efficiency of the furnace core tube and the operating efficiency of the apparatus are reduced. In addition, the discharge energy for exciting the metal vapor in the furnace core tube may be insufficient, which may make laser oscillation difficult.

In addition, since the discharge current i flows through the heat insulating layer 9, deterioration of the heat insulating material is promoted, which causes problems in maintenance management such as the need for early replacement.

The present invention has been made to solve the above problems, and is configured so that discharge energy is prevented from escaping to the outside of the furnace core tube and is effectively used to raise the temperature of the furnace core tube. It is an object of the present invention to provide a metal vapor laser device capable of improving efficiency, increasing the excitation rate of metal vapor filling the furnace core tube, and oscillating laser light with high efficiency and high output.

[Structure of Invention]

(Means for Solving the Problems) A metal vapor laser device according to the present invention includes a furnace core tube that generates discharge plasma serving as a laser medium by applying discharge energy to a metal, and both end portions of the furnace core tube. A cylindrical electrode which is provided so as to face the core core for pulse discharge in the furnace core tube, an electrode supporting flange for supporting the electrode, and an outer periphery of the furnace core tube for holding the discharge heat in the furnace core tube. A heat insulating layer is provided, and a large number of protrusions are formed on the tip or inner surface of the upper electrode facing the opposing surface.

(Operation) According to the metal vapor laser device having the above-described configuration, the electrodes provided at both ends of the furnace core tube are formed with a large number of protrusions, and therefore discharge between the positive electrode and the negative electrode is likely to occur. That is, since the tips of the protrusions provided on the positive electrode and the tips of the protrusions provided on the negative electrode face each other via the discharge space, discharge is likely to occur between the tips. Therefore, the formation of a discharge path from the electrode support flange through the inside of the heat insulating layer or through the gap between the heat insulating layer and the protective tube is relatively suppressed, and the discharge outside the core tube is significantly reduced. To do.

Therefore, since the discharge energy is effectively concentrated in the furnace core tube, the temperature rising efficiency of the furnace core tube and the laser oscillation efficiency are improved, and the laser output can be increased. Further, since the heat insulating material is less deteriorated due to the discharge outside the core tube, the maintenance management work required for replacing the heat insulating material is greatly simplified.

(Example) Hereinafter, the Example of this invention is described with reference to an accompanying drawing.

FIG. 1 is a sectional view showing an embodiment of the metal vapor laser device according to the present invention. The metal vapor laser device according to the present invention is characterized by the structure of the electrode and the electrode supporting flange, and other parts are the same as the constituent elements of the conventional example shown in FIG. The same reference numerals are given and detailed description thereof is omitted.

In the metal vapor laser device according to the present embodiment shown in FIG. 1, a furnace core tube 2 for generating plasma serving as a laser medium is arranged at the center of an oscillation tube body 1, and both ends of the furnace core tube 2 are arranged. The positive electrode 3 and the negative electrode 4 are provided so as to face each other. The positive electrode 3 and the negative electrode 4 are supported and fixed by electrode supporting flanges 5a and 6a, respectively. A large number of protrusions 24 are formed on the inner peripheral surfaces of the positive electrode 3 and the negative electrode 4 formed in a cylindrical shape.

For example, as shown in FIG. 2 (A), the projections 24 are formed by implanting a large number of projection elements 24a having sharp tips on the inner peripheral surfaces of the electrodes 3 and 4, or on the side surfaces of the electrodes 3 and 4. It is formed by cutting in a triangular shape, bending the cut piece toward the center of the electrode, and projecting the pointed end. Further, as illustrated in FIG. 2 (B), it is also possible to cut the tip end peripheral portions of the electrodes 3 and 4 into a saw-tooth shape to form a continuous protrusion 24. Alternatively, a so-called etching treatment may be used to partially corrode and dissolve the electrode surface by electrolysis to form irregularities to form protrusions.

The electrodes 3 and 4 having the projections 24 are integrally joined to the electrode support flanges 5a and 6a, respectively, and are supported and fixed at predetermined positions in the oscillation tube body 1. Here, the electrode support flanges 5a and 6a are formed in a tapered shape so as to have an inclined surface 25 that faces the end surface 9a of the heat insulating layer 9 and that expands outward of the furnace core tube.

In addition, the electrode support flanges 5a and 6a and the end surface 9 of the heat insulating layer 9 are
Insulator 26 is interposed between a and a. Insulator 26
Is made of an insulating material such as ceramic, quartz, or glass.

According to the metal vapor laser device of this embodiment, the discharge space 7 is sandwiched and a large number of projections 2 are provided on the electrodes 3 and 4 which are arranged facing each other.
4 is formed, discharge easily occurs between the tips of the protrusions 24. Therefore, the electrode support flange 5a,
The ratio of the discharge outside the furnace core tube discharged from 6a through the heat insulating layer 9 is reduced, and the discharge energy is effectively utilized.

Further, the electrode supporting flanges 5a and 6a, which serve as paths for flowing a discharge current to the electrodes 3 and 4, are formed in a tapered shape so as to face the end surface 9a of the heat insulating layer 9 and have an inclined surface 25 that expands outward. Therefore, as the distance from the outer periphery of the connection portion with the electrodes 3 and 4 increases in the radial direction, the heat insulating layer end surface 9a and the electrode support flange 5a,
6a is widened, the discharge resistance between them is increased, and the discharge outside the furnace core tube is reduced.

Furthermore, the electrode support flanges 5a and 6a and the heat insulating layer end surface 9a
By interposing the insulator 26 between and, it is possible to more effectively prevent discharge between the two. Therefore,
Since the discharge energy applied between the electrodes 3 and 4 is effectively concentrated in the furnace core tube 2, the temperature raising efficiency of the furnace core tube 2 and the laser oscillation efficiency are improved, and the laser output can be enhanced. .

Further, since there is no discharge outside the furnace core tube in the heat insulating layer 9 and the deterioration of the heat insulating material is small, maintenance management work such as adjustment and replacement of the heat insulating material is significantly simplified.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4. In the embodiment shown in FIG. 3, the electrode supporting flange 6b for supporting the electrode 4 is integrally formed with the electrode 4, the end portion thereof is curved outward, and the curved portion 27 is fitted on the inner surface of the head 28. The electrode 4 is supported and fixed by.

In this case, since the curved portion 27 and the heat insulating layer end surface 9a are separated from each other, the discharge between them is small. Further, as compared with the conventional disc-shaped electrode support flange 6, the electrode support flange 6b of the present embodiment is formed integrally with the electrode 4 and can be fixed in the head 28 simply by drying. Easy to attach and remove parts.

Further, in the embodiment shown in FIG. 4, the electrode supporting flange 6c for supporting the electrode 4 is formed integrally with the electrode 4, and the end portion thereof is expanded outward to form the expanded portion 29. An inner surface of the head 28 is fitted with an insulator 26a between the inner surface of the head 28 and the electrode support flange 6c.

Also in this case, since the expanded portion 29 and the heat insulating layer end portion 9a are separated from each other, the amount of discharge between them is small. Further, since the insulator 26a is interposed between the two, discharge can be prevented more effectively. Further, the conventional disk-shaped electrode supporting flange is not used, and the expanding portion 29 formed integrally with the electrode 4 is used.
Since the electrode 4 can be fixed simply by fitting it into the head 28, the maintenance of the electrode portion becomes easy.

〔The invention's effect〕

As described above, according to the metal vapor laser device of the present invention, in the cylindrical electrode installed facing both ends of the furnace core tube, a large number of protrusions are formed on the tip or inner surface of the facing surface side. Therefore, even if the furnace core tube or heat insulating layer exists in the discharge area where it is easy to discharge, it is possible to select and discharge only the discharge space in the furnace core tube, and prevent discharge to other areas. can do. That is, the discharge is guided so as to be directed to the discharge space in the furnace core tube between the protrusion of the positive electrode and the protrusion of the negative electrode. Therefore, it is relatively suppressed that a discharge path is formed from the electrode support flange through the inside of the heat insulating layer or through the gap between the heat insulating layer and the protective tube, and the discharge outside the core tube is significantly reduced. To do.

Therefore, since the discharge energy is effectively supplied into the furnace core tube, the temperature raising efficiency of the furnace core tube and the laser oscillation efficiency are improved,
The output of the laser device can be increased. In addition, since there is little power in the heat insulation layer, maintenance management work such as replacement of heat insulation materials is greatly simplified.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a metal vapor laser device according to the present invention, FIGS. 2 (A) and 2 (B) are perspective views showing the shape of the electrode tip portion, and FIG. 2 is a partial sectional view showing a second embodiment, FIG. 4 is a partial sectional view showing a third embodiment of the present invention, FIG. 5 is a sectional view showing the configuration of a conventional metal vapor laser device, and FIG. ) And (B) are cross-sectional views showing a discharge state between electrodes. 1 ... Oscillation tube body, 2 ... Furnace core tube, 3 ... Positive electrode, 4 ...
... Cathode electrode, 5, 5a, 6, 6a, 6b, 6c ... Electrode support flange, 7 ... Discharge space, 8 ... Metal vapor source, 9 ...
… Insulating layer, 9a …… End surface of insulating layer, 10 …… Protective tube, 1
1 ... External vacuum container, 12 ... Vacuum insulation chamber, 13 ... Exhaust device, 14 ... Break tube, 15 ... Buffer gas supply source, 16 ... High voltage power supply, 17 ... Pulse circuit, 18
...... Pulse drive power supply, 19, 20 …… Brewster window, 21 …… Laser light oscillator, 22 …… Output mirror, 2
3 ... Total reflection mirror, 24 ... Projection, 24a ... Projection element, 25 ... Inclined surface, 26, 26a ... Insulator, 27 ...
... curved part, 28 ... head, 29 ... expanded part, i ... discharge current.

Claims (3)

[Claims] 1. A furnace core tube for generating discharge plasma as a laser medium by applying discharge energy to a metal,
Cylindrical electrodes provided at opposite ends of the furnace core tube for performing pulse discharge in the furnace core tube, an electrode supporting flange for supporting the electrode, and a furnace core for holding discharge heat in the furnace core tube. A metal vapor laser device comprising: a heat insulating layer formed on the outer circumference of the tube; and a large number of protrusions formed on the tip or inner surface of the electrode facing the facing surface. 2. The metal vapor laser device according to claim 1, wherein the electrode supporting flange is formed in a taper shape facing the end surface of the heat insulating layer and expanding toward the outside of the furnace core tube. 3. The metal vapor laser device according to claim 1, wherein the electrode supporting flange includes an insulator interposed between the electrode supporting flange and the end surface of the heat insulating layer.