JPS63227068A - Highly repetitive pulse laser electrode - Google Patents

Abstract

PURPOSE:To obtain laser beams having a stable output by specifying the sectional shape of the cross direction of a main electrode at xy coordinates using an end section on one side of the main electrode as an origin. CONSTITUTION:The sectional shape of the cross direction of a main electrode 1b is formed to the so-called voltaic electrode shape satisfying x= sinpsi-lntan{(psi/2)+(pi/4)}, y=1-cospsi, psi=0-pi when gap length is brought to pi, using the point A of an electrode end section as an origin. The electrode shape of a main electrode 1a is also formed to the same voltaic electrode shape, employing the point A' of an electrode end section as an origin. Unstable glow discharge at the electrode end section and the generation of breakdown and the turbulence of a gas current are removed by improving the sectional shape of the main electrodes, thus allowing an output from stable laser beams having high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a high repetition pulse laser electrode used in a discharge section of a high repetition pulse laser device.

(Conventional technology) In recent years, with the remarkable progress in technological development of various high repetition pulse laser devices such as CO2 laser, excimer laser, copper vapor laser, etc., from the viewpoint of expanding practicality and versatility,
There is a demand for further compactness and higher performance for high-repetition pulse laser devices in general. Among such high repetition pulse laser devices, a discharge excitation type high repetition pulse laser device is a device that generates a glow discharge between main electrodes, thereby exciting a laser gas to perform laser oscillation.

FIG. 2 is a sectional view mainly showing the discharge section of such a high repetition pulse laser device. In the same figure, 1a,
1b is a main electrode placed oppositely in the laser gas of the laser body, 2 is a glow discharge generated between main electrodes 1a and 1b, 3 is a high-speed gas flow flowing between main electrodes 1a and 1b, and 4 is an electrode end. Section 5 is a pulse power supply device.

During operation of the high repetition pulse laser device shown in FIG. 2 having such a configuration, the main electrodes 1a, 1
A high-speed pulse current is input to b, and after pre-ionization is performed with this current, a high-speed pulse glow discharge 2 is generated between the main electrodes 'la and lb. This glow discharge 2 excites the laser gas in the laser body, causing laser oscillation. By installing a resonator therein, laser light can be extracted in a direction perpendicular to the plane of the drawing.

On the other hand, after the glow discharge 2 is generated by a high-speed pulse and disappears, it is necessary to remove the residual gas between the main electrodes 1a and 1b as soon as possible and to cool it, so generally the main electrode "l"
A method is adopted in which a high-speed gas flow 3 is caused to flow in a direction perpendicular to a and 1b.

However, in the high repetition pulse laser electrode as described above, there is a problem in that the glow discharge becomes unstable and stable laser light output cannot be obtained, as will be explained below.

That is, in a high repetition pulse laser device as shown in FIG. 2, in order to obtain stable laser light, the main electrodes 1a and 1b must be
It is necessary to stably generate the glow discharge 2 in the central flat part in the width direction of the electrode, but generally, in a flat electrode as shown in Fig. 4, the electric field tends to be higher, and even if a pre-ionization method is used, glow discharge may occur at the electrode end 4, causing dielectric breakdown or arcing. When the glow discharge 2 becomes unstable in this way, stable laser oscillation is hindered, and as a result, stable laser output cannot be obtained.

As a countermeasure to this problem, methods are taken to increase the radius of curvature at the end of the electrode, or more generally, the shape of the electrode is changed to a Rogowski shape to reduce the electric field at the end of the electrode. Both of these methods have the disadvantage that the shape of the end portion becomes significantly large, resulting in an uneconomical device.

On the other hand, in high-voltage, high-repetition pulse lasers, the importance of high-speed gas flow for residual gas removal and cooling is increasing, but when using a flat plate electrode as shown in Figure 2, The gas flow that has healed on the electrode surface causes contraction and the flow becomes turbulent, which may not only increase the flow resistance but also reduce the flow velocity. This, in turn, has an undesirable effect on the stabilization of the discharge of the next pulse, and deteriorates the laser characteristics. In this case, as described above, methods such as increasing the radius of curvature at the end or using Rogowski type methods are useful for improving the electric field, but do not have the same effect on gas flow.

(Problems to be solved by the invention) As mentioned above, since the conventional high repetition pulse laser electrode has a flat plate shape, the electric field at the end of the electrode becomes high, making it difficult to obtain a stable glow discharge. As it disappears,
The problem has been that the laser output becomes unstable because the flow of high-speed gas for removing residual gas between the electrodes and cooling the electrodes is obstructed.

The present invention was proposed to solve these problems, and its purpose is to provide a laser with stable output by making it possible to obtain stable glow discharge and reduce gas flow resistance. The purpose is to provide an excellent high repetition pulse laser electrode that can obtain light.

[Groove bottom of the invention] (Means for solving the problem) The high repetition pulse laser electrode of the invention has a cross-sectional shape in the width direction of the main electrode in xy coordinates with one end of the main electrode as the origin. , x=−[sinψ−吏ntan ((ψ/2)+(π/
4))] The structure is characterized by a so-called boulder electrode shape such that y=1-cos ψ=0 to π.

(Function) In the present invention having the above configuration, the electric field at the electrode end is reduced, so no glow discharge occurs at the electrode end, and therefore a stable glow discharge can be obtained at the center of the electrode. As a result, stable laser output can be obtained.

In addition, since the electrode surface has a shape that provides a uniform flow velocity distribution, there is no disturbance in the gas flow, and therefore, residual gas removal and cooling can be performed efficiently, which also reduces the laser output. It can contribute to stabilization.

(Embodiment) An embodiment of the present invention as described above will be described with reference to FIG.

In FIG. 1, the cross-sectional shape of the main electrode 1b in the width direction is x=s i nψ−1njan((ψ/2)×(π/ 4
)) It has a so-called boulder electrode shape such that y=1-cos ψ=0 to π.

Further, the electrode shape of the main electrode 1a is also a similar boulder electrode shape with the point A' at the end of the electrode as the origin. In addition,
When setting the gap length arbitrarily, this shape may be used in proportion to π.

Main electrodes 1a and 1b of this embodiment having such electrode shapes
, the electrode surface A-B-C from point A at one end of the main electrode 1b to point C at the opposite end corresponding to this point.
A uniform electric field value of 1q is obtained on the electrode surface A--B=-C- of the main electrode 1a. Therefore, compared to conventional high-repetition pulse laser electrodes that cause unstable glow discharge at the electrode end, as well as dielectric breakdown and arcing, this electrode does not cause insulation problems even at the electrically damaged end. Uniform and stable glow discharge can be obtained.

On the other hand, regarding the resistance of the gas flow 3, compared to the conventional technology in which the flow was turbulent in a flat plate-shaped electrode, the electrode surface A-B-C, A--8-- of the boulder electrode shape of this example
In C-, a uniform flow velocity distribution is given to the gas flow 3, so that turbulence of the gas flow does not occur. As a result,
Compared to the conventional technology, the gas flow loss is small and residual gas removal and electrode cooling can be performed with much higher efficiency. Therefore, from this point of view as well, it can contribute to the generation of uniform and stable glow discharge.

Roughly speaking, in the conventional Rogowski electrode shape, the width of the end of the electrode is about twice as large as the gap length, whereas in the boulder electrode shape of this embodiment, it is about 0.75 times larger than the gap length. There is also the advantage that the efficiency is greatly improved by about 2.7 times.

[Effects of the Invention] As explained above, in the present invention, by improving the cross-sectional shape of the main electrode, which is a simple structure improvement, unstable glow discharge and dielectric breakdown at the end of the electrode, which occurred in the conventional technology, can be avoided. This solves the problems of generation of gas and turbulence of gas flow, making it possible to obtain an even and stable glow discharge, as well as reducing gas flow resistance and performing efficient residual gas removal and electrode cooling, resulting in stable and high efficiency. It is possible to provide an excellent high repetition pulse laser electrode capable of outputting laser light of .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a high repetition pulse laser electrode according to the present invention, and FIG. 2 is a sectional view showing a conventional high repetition pulse laser electrode. 1a, 1b...Main electrode, 2...Glow discharge, 3...
- Gas flow, 4... Electrode end, 5... Pulse power supply device. ′;“゛) −・, Figure 1

Claims (1)

[Scope of Claims] A high repetition pulse laser electrode that is disposed in a laser gas and has a pair of main electrodes facing each other with the laser optical axis direction as the longitudinal direction, wherein the cross-sectional shape in the width direction of the main electrodes is the same as that of the main electrodes. On the xy coordinates with the origin at one end of
)}] A high repetition pulse laser electrode characterized by having a shape such that y=1-cos ψ=0 to π.