JPH0630345B2 - Plasma thin tube for gas laser tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plasma capillary used by being incorporated in a gas laser tube.

[Conventional technology]

Gas lasers generate plasma of gas such as He-Ne and Ar, and amplify and extract the light of a certain wavelength of the discharge light generated at this time, and it is characterized by continuous oscillation. It is used for material processing and measurement.

As shown in FIG. 2, a gas laser tube for oscillating a gas laser includes a plasma thin tube 1 formed by penetrating an elongated discharge path 2 in a longitudinal direction, and a reflecting mirror 8 and a cathode 5 at both ends of the plasma thin tube 1. Alternatively, it is a vacuum container in which the envelopes 7 on which the anodes 6 are installed are fixed. A gas such as Ar of 0.01 to 0.1 torr is enclosed in this gas laser tube, a voltage is applied between the cathode 5 and the anode 6 to generate plasma of the enclosed gas, and the specific wavelength light of the discharge light generated at that time is generated. Is reciprocated between the reflecting mirrors 8 to be amplified and taken out.

The most important component of such a gas laser tube is a plasma capillary tube having a discharge path capable of withstanding a large discharge current and large power consumption. That is, the plasma thin tube 1 has an important role of narrowing the generated plasma diameter in the discharge path 2 in order to increase the current density of plasma and improve the output of laser. Therefore, since the discharge passage 2 is exposed to high-temperature plasma when the plasma is narrowed from both ends 2 ′ of the discharge passage 2 which are gradually expanded in diameter toward the narrow central portion, the plasma thin tube 1
Needs to be formed of an electrically insulating material having high thermal conductivity and excellent heat dissipation.

Conventionally used plasma thin tubes are beryllia porcelain, which has good thermal conductivity, and high-heat-resistant materials such as graphite and tungsten discs, which are arranged at regular intervals in a high-heat-resistant container such as quartz. However, beryllia porcelain is toxic and difficult to handle, and the one in which graphite and tungsten discs are housed in a quartz container has a complicated structure and is weak against shock during transportation.

[Problems to be solved by the invention]

In view of the above-mentioned conventional circumstances, it is an object of the present invention to provide a plasma thin tube for a gas laser tube, which has a simple structure, is easy to handle, can withstand a large discharge current and a large power consumption, and is excellent in output stability.

[Means for solving problems]

As shown in FIG. 1, a plasma thin tube 1 for a gas laser tube of the present invention penetrates in the lengthwise direction an elongated discharge path 2 in which the central portion has the same inner diameter and the inner diameters gradually increase toward both ends at both ends. Aluminum nitride cylinder 3 made of a sintered body containing aluminum nitride as a main component, and the spatter resistance provided on the inner surfaces of both ends of the discharge path including at least a portion of the aluminum nitride cylinder 3 having an enlarged inner diameter. It has a peripheral wall 4 which is made of an excellent material and is resistant to spatter.

The aluminum nitride cylinder 3 is a sintered body containing AlN as a main component, and is added in order to improve sinterability.
It may also contain oxides, nitrides or carbides of Group a elements.

The spatter-resistant peripheral wall 4 is preferably at least one selected from the group consisting of tungsten, molybdenum, boron carbide, silicon carbide, and carbides of Group IVa, Va, and VIa elements. As a method of forming the spatter-resistant peripheral wall 4 at both ends of the discharge path 2, a peripheral wall made of a sintered body of the above-mentioned substance is embedded, or a known ion plating method or a CVD method is applied. The method of can be adopted.

[Action]

The inventors of the present invention have a simple structure and are easy to handle, and as a material of a plasma thin tube that can withstand a large discharge current and a large power consumption,
We examined the use of aluminum nitride, which is an electrical insulator with high thermal conductivity.

However, both ends of the discharge path 2, particularly both ends 2'having an expanded inner diameter, are subjected to intense sputtering due to plasma such as Ar ⁺ , and the N ₂ gas generated at that time makes the plasma discharge unstable, As a result, it was discovered that the oscillation output of laser light fluctuates.

Therefore, in the plasma thin tube 1 of the present invention, the peripheral wall 4 made of a substance having excellent spattering resistance is formed on the inner surface of both ends of the discharge path 2 including at least the portions where the inner diameters of the both ends 2'where the spattering by plasma is particularly severe are enlarged. By forming the above, the spattering is reduced. Although this spatter-resistant peripheral wall 4 is not completely sputtered by the plasma, even if it is sputtered, no gas component that makes the discharge of the plasma unstable is generated, so that a stable laser oscillation can always be obtained. Be done.

〔Example〕

Example 1 95% by weight of AlN powder having an average particle size of 1.0 μm and an average particle size of 0.8 μ
5% by weight of Y ₂ O ₃ powder of m was inserted into a nylon pot using a nylon ball together with ethanol, and pulverized and mixed by wet for 24 hours. After drying the obtained slurry, an organic binder is added to form a thin plasma tube by an extrusion method, and after degreasing, the temperature is set to 1 at 1800 ° C. in an N ₂ atmosphere.
Sintered for hours.

As shown in FIG. 1 of the obtained AlN cylinder, tungsten spattering-resistant peripheral walls were buried in both ends of the portion where the inner diameter of the discharge path was enlarged and the portion where the inner diameter was the same, to manufacture a plasma thin tube. A laser tube was assembled by attaching electrodes, reflecting mirrors and the like to both ends of this plasma thin tube as usual.
After evacuating the inside of this laser tube to 10 ^-6 torr, 0.1 to
Ar gas of rr was filled.

This laser tube is oscillated under a discharge condition of 300 V and 20 A,
It was possible to extract the laser light with a stable output at 1000 hours continuous oscillation.

However, under the same discharge conditions as above, a laser tube assembled using a plasma thin tube consisting of only an AlN cylinder manufactured in the same manner as above except that it does not have a tungsten spatter-resistant peripheral wall at both ends of the discharge path. When oscillated, the discharge voltage fluctuated and stable oscillation could not be obtained.

Example 2 A TiC layer having a thickness of 20 μm was deposited by a CVD method on both ends of the discharge path of the AlN cylinder manufactured in the same manner as in Example 1 so as to form a spatter-resistant peripheral wall, and a plasma thin tube was formed. Manufactured. Using this plasma thin tube, Ar was carried out in the same manner as in Example 1.
When a laser tube filled with gas was assembled and oscillated under the same conditions as in Example 1, a laser beam with a stable output could always be taken out in continuous oscillation for 1000 hours.

〔The invention's effect〕

According to the present invention, it is possible to provide a plasma thin tube for a gas laser tube, which has a simple structure and is easy to handle, can withstand a large discharge current and a large power consumption, and is excellent in output stability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of the plasma capillary tube of the present invention.
The figure is a cross-sectional view of a laser tube incorporating a plasma capillary. 1 ... Plasma thin tube, 2 ... Discharge path 3 ... Aluminum nitride cylinder 4 ... Spatula-resistant peripheral wall, 5 ... Cathode 6 ... Anode, 7 ... Envelope, 8 ... Reflector

Claims (2)

[Claims] 1. A sintered body containing aluminum nitride as a main component, which is formed by penetrating in the lengthwise direction an elongated discharge path whose central portion has the same inner diameter and whose inner diameters gradually increase toward both ends at both ends. A plasma thin tube for a gas laser tube, comprising: an aluminum nitride cylinder; and a spatula-resistant peripheral wall made of a material having excellent spatter resistance, which is provided on inner surfaces of both ends of a discharge path including at least an expanded diameter portion of the aluminum nitride cylinder. 2. A material having excellent spatter resistance constituting the spatter resistant peripheral wall is at least one selected from the group consisting of tungsten, molybdenum, boron carbide, silicon carbide and carbides of Group IVa, Va and VIa elements. The plasma thin tube for a gas laser tube according to claim 1, characterized in that it is a seed.