JPS6197882A - Metallic vapor laser oscillation tube - Google Patents

Abstract

PURPOSE:To hermetically seal the end of a ceramic inner tube and to facilitate replacement of the inner tube by a method wherein a metallic ceramic-inner- tube-connecting tube installed at the end surface part of the ceramic inner tube is welded at the tip to a bellows-welding flange welded to one end of the bellows. CONSTITUTION:The metallic ceramic-inner-tube-connecting tubes 21 of almost the same outer diameter are permanently installed to the end surfaces at both ends of the ceramic inner tube 1. On the other hand, one end of the bellows 13 is welded to the outer tube 14, and the other end to a bellows-connecting flange 22. The flange 22 with an inner diameter slightly larger than that of said tube 21 is fitted to the outer periphery of the tube 21 and to the outer periphery of the end outer periphery of the ceramic inner tube 1. Then, both tips are welded, thus completely isolating the atmosphere of the discharge part 2 in the inner tube 1 from that of a vacuum heat-insulating chamber 16 by the weld part 23. The permanent seal of the inner tube is carried out in such a manner. In the case of replacing the inner tube 1, the weld part 23 is cut off after the anode side container 25 and the cathode side container 26 are removed via laser emitter flange 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal vapor laser oscillation tube, and more particularly to a structure for hermetically sealing a ceramic inner tube in a replaceable manner.

[Technical background of the invention and its problems]

A metal vapor laser oscillation tube used for isotope separation technology using a laser for metallic uranium generally has a structure as shown in FIG. In FIG. 1, reference numeral 1 denotes a ceramic inner tube with excellent heat resistance, into which a discharge section 2 is supplied with a discharge buffer gas such as He or Ne from a gas supply system 3, and is exhausted by a rotary pump 4. , the voltage applied from the pulse high voltage power supply 7 between the anode 5 and the cathode 6 is several kV to 10-odd kV, and the repetition frequency is several kHz to 10-odd kilovolts.
A pulsed bipolar discharge is performed using a pulsed high voltage of Hz to generate plasma. Gold mud particles 8 are inside the ceramic inner tube 1.
are arranged, and the metal particles 8 come into contact with the discharge plasma and the ceramic inner tube 1 is heated to an extremely high temperature, whereby the metal particles 8 evaporate, thereby generating metal vapor that becomes the laser medium. This metal vapor is transferred to the ceramic inner tube 1.
The Brewster window 9
The laser beam is amplified by an optical resonator made up of an output mirror 10 and a total reflection mirror 11 placed at both ends of the ceramic inner tube 1, and is output as a laser beam from the output mirror 10 side.

The ceramic inner tube 1 is supported at both ends by an outer tube 14 via an O-ring 12 and a bellows 13, and the space between the outer tube 14 and the inner tube 1 is evacuated by a rotary pump 15 to form a vacuum insulation chamber 16. ing. This vacuum insulation chamber 16
A heat shield plate 17 is provided inside. In addition, the outer tube 14
A cooling pipe 18 is provided around the . moreover,
An insulating tube 19 is inserted in the middle of the outer tube 14 to electrically isolate the anode 5 side and the cathode 6 side.

In order to stably maintain the interior of the ceramic inner tube 1 at a high temperature in this manner, a vacuum insulation structure is adopted.

The temperature of the ceramic inner tube 1 rises to about 1500° C., so that linear expansion occurs due to the heat. The bellows 13 is used to absorb this linear expansion by allowing freedom in the movement of the ceramic inner tube 1 in the tube axis direction. Conventionally, an O-ring 1 is used for airtight sealing between the bellows 13 and the ceramic inner tube 1.
I was using 2. However, since the ceramic inner tube 1 reaches a fairly high temperature of about 300° C. even near the end, there is a high risk of burning out the O-ring 12, and the ceramic inner tube 1
The performance of the O-ring 12 is also likely to deteriorate due to thermal expansion.

For these reasons, in the past, there was a problem in that the vacuum retaining performance of the vacuum insulation chamber 16 was insufficient, which adversely affected the laser oscillation performance.

In order to solve this problem, it is conceivable to employ a permanent airtight sealing method such as welding or brazing to improve vacuum retention performance, but in that case, the following new problems will occur. That is, the metal particles 8 evaporate inside the ceramic inner tube 1.

Due to the repeated precipitation, the insulation performance deteriorates and abnormal discharge occurs over long periods of use, so it has a shorter lifespan than other ditch forest materials and must be replaced midway through use. However, when a permanent airtight seal as described above is provided, there is a problem in that it becomes extremely difficult to replace the ceramic inner tube 1.

[Purpose of the invention]

The present invention has been made in view of these points, and an object of the present invention is to provide a metal vapor laser oscillation tube in which the end of the ceramic inner tube is permanently hermetically sealed and the ceramic inner tube can be easily replaced. do.

[Summary of the invention]

In order to achieve the above object, the present invention supplies a discharge gas into a ceramic inner tube in which metal particles are arranged, and applies a high voltage between an anode and a cathode provided at both ends of the ceramic inner tube. This is a laser oscillation tube in which a discharge plasma is formed to vaporize metal particles, and the vaporized metal particles are excited by free electrons in the discharge plasma to perform laser oscillation. In the laser oscillation tube supported by the outer tube through the ceramic inner tube, a connecting tube for the ceramic inner tube made of metal is permanently attached to the end face of the ceramic inner tube and has approximately the same outer diameter as the ceramic inner tube; a bellows connecting flange having a slightly larger inner diameter than the inner pipe connecting pipe and welded to one end of the bellows so that the tip thereof is located at approximately the same position as the distal end of the ceramic inner pipe connecting pipe; It is characterized by a ceramic inner tube connection tube and a bellows connection flange welded together at the tip.

[Embodiments of the invention]

The structure of the metal scrap laser oscillation tube according to an embodiment of the present invention is shown in FIG. 1, and the main part 2 is surrounded by broken lines.
The detailed structure of 0 is shown in FIG.

Components corresponding to those of the conventional metal vapor laser oscillation tube shown in FIG. 3 are given the same reference numerals, and differences from FIG. 3 will be mainly explained.

In FIGS. 2 and 3, ceramic inner tube connecting tubes 21 having approximately the same outer diameter as the ceramic inner tube 1 are permanently attached to the end faces of both ends of the ceramic inner tube 1. As shown in FIG.

The connecting tube 21 is made of metal such as Kovar, and is attached by, for example, metallizing the end face of the ceramic inner tube 1 and brazing it thereto.

On the other hand, one end of the bellows 13 is welded to the outer tube 14, and the other end is welded to the seven flange 22 for connecting the bellows. The 7 flange 22 for bellows connection is the connection pipe 21 for the ceramic inner pipe.
It has a slightly smaller inner diameter and is fitted onto the outer circumference of the ceramic inner tube connecting tube 21 and the outer circumference of the end of the ceramic inner tube 1.

Here, the ceramic inner pipe connecting tube 21 and the bellows connecting flange 22 are formed to have sufficient length, and the wall thickness is thinned from the middle to the tip, so that the tip of the image is at almost the same position. It is set up so that and,
The tips of the ceramic inner pipe connecting pipe 21 and the bellows connecting flange 22 are welded as shown at 23. This welded part 23 completely separates the discharge part 2 inside the ceramic inner tube 1 from the atmosphere of the vacuum insulation hole 16. That is, the ceramic inner tube 1 is permanently hermetically sealed.

In addition, in this embodiment, in consideration of replacing the ceramic inner tube 1, an anode side container 25 and a cathode side container 26 are connected to the outer tube 14 through laser emitting flanges 24 which are removably provided at both ends of the outer tube 14. It has a structure that can be separated from the

In the Kinba steam laser oscillation tube with such a configuration, when replacing the ceramic inner tube 1, after removing the anode side container 25 and the cathode side container 26 via the laser emitting part flange 24, replace the ceramic inner tube connecting tube. 21 and the welded part 23 at the tip of the bellows connecting flange 22 is cut off. This cutting method can be done using a mechanical method such as a pipe cutter, for example.
Alternatively, there is a method such as thermal cutting with a laser beam, but in any case, the length of the ceramic inner tube connecting tube 21 and the bellows connecting flange 22 must be sufficiently long, and the wall thickness near the tip must be sufficiently thick. If it is made thin, it is easy to cut off the welded part 23.

When installing a new ceramic inner tube, the length of the bellows connecting flange 22 whose tip has been cut off is slightly shorter than the original length, but it is necessary to install a connecting tube for the ceramic inner tube made to match this length in advance. Prepare the ceramic inner tube attached by brazing, insert it into the outer tube 14, and complete the replacement by welding the tip of the ceramic inner tube connection tube and the bellows connection flange 22 in the same way as the initial assembly. can do. Such a ceramic inner tube 1
Each time the ceramic inner tube connecting tube 21 and the bellows connecting flange 22 are replaced, the lengths of the ceramic inner tube 21 and the bellows connecting flange 22 become shorter, and eventually it becomes impossible to achieve an airtight seal by welding. Since the number of replacements can be approximately calculated, these connecting pipes 21 and flanges 22 should be designed to a length that can withstand the number of replacements.
All you have to do is make it.

(Effects of the Invention) As described above, according to the present invention, by creating a permanent airtight seal between the ceramic inner tube and the outer tube, not only is the vacuum holding performance excellent, but the ceramic inner tube can be easily replaced. A metal vapor laser oscillation tube can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a metal vapor laser oscillation tube according to an embodiment of the present invention, FIG. 2 is a sectional view showing the main parts of the same embodiment in detail, and FIG. FIG. 3 is a diagram showing the configuration of a laser oscillation tube. DESCRIPTION OF SYMBOLS 1... Ceramic inner tube, 2... Discharge part, 3... Gas supply system, 4... Rotary pump, 5... Anode, 6
... Yin and Yang, 7... Pulse high voltage power supply, 8... Metal particles, 9... Brewster window, 1o... Output mirror, 11... Total reflection mirror, 13... Bellows, 14
...Outer tube, 15...Rotary pump, 16...Vacuum insulation chamber, 17...Heat shielding plate, 18...Cooling pipe, 19...Insulating tube, 21...Inside ceramic Connecting tube for pipe, 22... Bellows connection flange, 23... Welding part, 24... Laser emission part flange, 25... Anode side container, 26... Cathode side container.

Claims (3)

[Claims] (1) A discharge buffer gas is supplied into a ceramic inner tube in which metal particles are placed, and a discharge plasma is formed by applying a high voltage between an anode and a cathode provided at both ends of the ceramic inner tube. A laser oscillation tube that vaporizes metal particles and excites the vaporized metal particles with free electrons in discharge plasma to perform laser oscillation, the inner ceramic tube being supported by the outer tube via a bellows. In the laser oscillation tube, a connecting tube for the ceramic inner tube made of metal is permanently attached to the end face of the ceramic inner tube and has an outer diameter approximately the same as that of the ceramic inner tube, and an inner diameter slightly larger than the connecting tube for the ceramic inner tube. and a bellows connection flange welded to one end of the bellows so that the tip end is at approximately the same position as the tip of the ceramic inner pipe connection pipe, and a bellows connection flange welded to one end of the bellows, and a bellows connection flange with a top end of the ceramic inner pipe connection pipe. A metal vapor laser oscillation tube characterized by having a flange and a tip welded together. (2) Metal vapor laser oscillation according to claim 1, characterized in that the ceramic inner tube connecting tube and the bellows connecting flange are formed so that the wall thickness near the tip is thinner than other parts. tube. (3) The metal vapor laser oscillation tube according to claim 1, wherein the end face portion of the ceramic inner tube is metallized and connected to the ceramic inner tube connecting tube by brazing.