JPS636887A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To improve the discharge resistance, heat resistance and adhesion to a discharge electrode of a discharge electrode covering dielectric by using a glass material having the main components of SiO2, N2O and K2O with an additive of TiO2 as the dielectric. CONSTITUTION:In a discharge excitation type gas laser apparatus, a glass material having the main components of SiO2, NO2 and K2O with an additive of 10%-30% TiO2 is used as a dielectric 10 to cover discharge electrodes 2 and 3. Since the dielectric 10 thus constituted has a large permittivity, injection electric power to a discharge can be increased by applying a higher voltage. Further, since TiO2 reduces a coefficient of thermal expansion, an adhesion to the discharge electrodes 2 and 3 can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a discharge-excited gas laser device, and specifically relates to an improvement in a dielectric material coated on a discharge electrode.

Conventional technology The general configuration of the above gas laser device is shown in Figure 1).
, (vBJ). In both figures, one or both of the -pair of discharge t When applied between the electrodes 2 and 3, an alternating current discharge is generated in the discharge space 4 through the dielectric layer, and this discharge flows into the space 4.
The laser medium gas 5 in which the part is enclosed is excited. As a result, laser oscillation is generated between the optical resonator made up of the total reflection mirror 6 and the partially transmitting mirror 7, and a part of the oscillated light is extracted from the partially transmitting mirror 7 as a laser beam. At this time,
The laser medium gas passes through the discharge space 4 by the proar 8 at a speed of several 1° to several room m/z, is cooled by the heat exchanger 9, and is sent into the discharge space 4 again.

An example of the discharge electrode described above is shown in FIGS. 2 and 3.

The discharge electrode 2.3 is made of a steel tube, and the circumference of the discharge electrode 2.3 is covered with a dielectric material 10. Note that cooling water is circulated within each electrode 2.3.

The dielectric material covering the discharge electrode 2.3 is required to have insulation properties, voltage resistance (insulating strength), denseness, heat resistance, and the like. Conventionally, the discharge electrodes 2 and 3 are made of pyre as a dielectric material.
Materials such as borosilicate glass and enamel were used.

Problems to be Solved by the Invention Borosilicate glass and enamel conventionally used as dielectric materials have the following problems.

Borosilicate glass has advantages such as low expansion (average coefficient of linear expansion at 25° C. to 32° C. 32 to 36 XIO), heat resistance, and chemical resistance. However, coating is difficult due to the large difference in expansion coefficient between metal and borosilicate glass. In addition, borosilicate glass has a high forming temperature (16°C for melting).
There is also the problem that the cooling rate is fast and processing is difficult.

On the other hand, enamel can be used up to 400-500℃,
At temperatures below this temperature, the material is not damaged, but it is an electrical insulator up to about 200°C. Radiation t′kL pole 2
．． The dielectric temperature during discharge in No. 3 is estimated to be approximately 300°C.

Therefore, the insulation properties of the enamel during discharge are considered to be poor. Under high-density energy discharge such as laser-excited discharge, there is essentially a problem in discharge resistance. In addition, the air bubbles that remain on the surface of the medicine are called bubbles, and the pore-like formations that are punctured by a needle when the air bubbles collapse are called pinholes. However, during the manufacturing process, wrinkles are likely to occur on the surface of the above-mentioned wires, pinholes, skipped nails, or enamel. Therefore, there are problems in that arc discharge is likely to occur and a dielectric electrode with unstable discharge is likely to be formed.

Means for Solving the Problems The present invention seeks to provide a dielectric that eliminates the problems of dielectrics (borosilicate glass, enamel) conventionally used as coatings for dielectric electrodes. In the present invention, in order to increase the expansion coefficient without reducing heat resistance and discharge resistance, and to achieve a suitable value for good adhesion with iron and a working temperature of 700°C to 800°C, Sin, -Na, o -A, 7'i0. (Titania) 1
It was added in an amount of 0 to 30%. TiO, some Altos
*P, 0. , B, o.

may be included.

The range of components of the basic glass is as follows.

Sin: 60% to 90%, Na, O: 1 to 15%
, and O:Q~5chi. i-th order, AI, 0.
, P* 05, when Bt Os is added, the following component range is obtained. Al2O,: 0-35%, p, o
, : o~10%, BvOm: O~20%.

The characteristics of common glasses of the Sin, -Na, O-, and O systems are that they have a large coefficient of expansion and a low working temperature. T i O, has the following characteristics.

cL) Since it is a heavy metal oxide, it has a large dielectric constant. That is,
The power injected into the discharge can be increased by increasing the applied voltage.

b) A component that lowers the coefficient of thermal expansion. It has good adhesion to iron and adheres to the iron-glass interface through the growth of dendrites (iron titanate).

From the above characteristics, T10. By adding , discharge resistance and heat resistance (
The combination of low and high expansion coefficients results in an appropriate value), producing glass that has good adhesion to iron. Therefore, according to the present invention, it has become possible to improve the electrical characteristics of conventional dielectric electrodes and to easily manufacture highly reliable electrodes.

Embodiments Currently, the technology of coating borosilicate glass on a discharge electrode for an ozonizer using alternating current discharge has been established. However, when AC discharge is used as an excitation discharge for a laser, the discharge power is larger than when used for an ozonizer, etc., and it is difficult to cover the electrode with a borosilicate glass coating that can withstand that much discharge power, so it cannot be used as an electrode for a long time. No one has been found that can withstand this discharge.

Therefore, the electrode life will be compared between the case where enamel is used as the covering dielectric material and the case where fC is used as the dielectric material to which the Tie of the present invention is added.

The experimental results were as follows. A failure condition is a condition in which the coating material is damaged.

From the results in the margin below, the average failure time of enamel is 1 & 2j!
/ The average failure time can also be calculated as follows. The mean time to failure is expressed as MTTF.

T: Electrode life at reliability level (1-α) α: If the electrode fails by a certain time (from the formula), T
Find the MTTF t- of a dielectric material containing ie.

Assume that α=α9, that is, the worst case value is 384B, which is the value when the reliability level is 10%. At this time a(rrp = 166.
8jt seven. Therefore, Tie, Sin added,
It can be seen that the life of the dielectric electrode of the -Na, 0-KtO MTTF is about 9.1 times longer than that of the current one.

When T i O, contained 10% M, 384B, 20% M contained 406B, and 30% M contained no damage up to 398H, and the electrode is still in operation, with no signs of damage. T
At present, the electrode is operating without problems in a component range in which the i O content is 10% to 30%, and the experimental data shows that an electrode with a longer life than the conventional technology has been created.

When the TL Ot content was 5% and 35%, both were damaged in about 200H.When the TL Ot content was 5% and 35%, however, the T10.
This is probably because it does not contribute. Moreover, when the content rate is 35%, 1' i 0. Because the content is large, the dielectric thermal expansion coefficient is larger than that of iron, and 5 L 0
It is thought that the content of 1 decreased, resulting in loss of heat resistance to high temperatures, leading to electrode dielectric damage. Therefore Tie,
Practically speaking, it is desirable that the content is in the range of 10% to 30%.

Effects of the Invention S i Oo-Na, O- and O-based general glasses have a large expansion coefficient and a low working temperature. T i O, has the following characteristics.

(α) Since it is a heavy metal oxide, it has a large dielectric constant. That is,
The injection force can be increased without increasing the applied voltage.

Cb) A component that lowers the coefficient of thermal expansion. @ with iron
Layering is good, and dendrites (
Punto 2ite iron titanate) grows closely.

From the above characteristics, by adding Ti and the like to SiO, -Na, OK, O-based glass, a glass with discharge resistance, heat resistance, and adhesion to iron can be produced. Therefore, according to the present invention, it has become possible to realize a highly reliable dielectric electrode with improved electrical characteristics and without deterioration of mechanical characteristics.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing the general configuration of an AC discharge excitation type gas laser device. 3 is a sectional view showing the connected structure, and FIG. 3 is a sectional view taken along the line ■-m in FIG. 2. 1 is an AC power source, 2.3 is a discharge electrode, 5 is a laser medium glass, and 10 is a dielectric material

Claims (4)

[Claims] (1) In a discharge-excited gas laser device comprising a pair of discharge electrodes, at least one of which is covered with a dielectric, and a power source that applies an alternating current electric field between the electrodes to induce discharge, the dielectric as SiO_2, N_
2O, K_2O as main components, 10% to 30% Ti
A gas laser device characterized by using a glass material added with O_2. (2) The gas laser device according to claim 1, wherein the frequency of the alternating current electric field is a high frequency of 1 KHz or more. (3) In addition to the above glass material, Al_2O_3 and P_2O
The gas laser device according to claim 1, characterized in that the gas laser device contains at least one component among _5 and B_2O_3. (4) The gas laser device according to claim 1, wherein a metal other than iron (having a coefficient of linear thermal expansion of 1 x 10^-^7 to 1 x 10^-^4) is used as the metal base material of the electrode. .