JPS62126683A - Gas laser device - Google Patents

Abstract

PURPOSE:To make it possible to adopt a cooling apparatus having less cooling capability and to obtain stable and uniform laser oscillation, by providing dielectrics between electrodes, exciting laser medium gas with soundless discharge generated by applying an AC power source across the electrodes, thereby making the temperature increase of the laser medium gas less. CONSTITUTION:Laser medium gas, in which one or more kinds of N2, He, O2 and Xe are mixed in CO gas, is sealed in an airtight chamber 1. Electrodes 2 and 3 are provided in a discharge space so as to face each other. Dielectrics 2b and 3b are provided between the electrodes 2 and 3. Then an AC power source 4 is applied across the electrodes 2 and 3, and soundless discharge is generated in the discharge space 5. The laser medium gas is excited in the discharge space 5 by said soundless discharge. Solid dielectrics 2b and 3b are provided on the facing surfaces of, e.g., metal electrodes 2a and 3a, in the electrodes 2 and 3 (a). Or the solid dielectric 2b is provided only on 2a of the metal electrodes 2a and 3a (b). Or the solid dielectrics 2b and 3b are provided between the metal electrodes 2a and 3a. For example, a blower 7 and a heat exchanger 8 are provided so as to face each other at the inner bottom part of the airtight container 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a gas laser device that amplifies light generated during energy relaxation of co and extracts it as laser light in a silent discharge pumped laser using alternating current discharge as an excitation source.

BACKGROUND OF THE INVENTION Conventional discharge excitation systems for CO lasers using CO as the laser medium dregs include a self-sustaining DC glow discharge excitation system and an electron beam controlled discharge excitation system.

Problems to be Solved by the Invention The self-sustaining DC glow discharge excitation method described above applies a DC high-voltage power source between the anode electrode and the cathode electrode to generate a glow discharge between the two electrodes, and the two electrodes face each other with a discharge space in between. It is designed to excite the laser medium gas within the nine resonators and extract the laser light, and in order to obtain continuous and stable laser oscillation, a stable and steady glow discharge is required.

Conventionally, in order to obtain a stable glow discharge, the discharge state is maintained by a secondary mechanism on the cathode using an ion flow, but in this method, the temperature of the gas increases.

However, in the case of a CO laser, the temperature of the gas has a large influence on the excitation, so the laser medium gas needs to be at a low temperature. This increases the cost of equipment because it has to be cooled, and there are many restrictions on obtaining stable glow emission.

Furthermore, compared to the self-sustaining DC glow discharge excitation method described above, the structure of the excitation part of the electron beam controlled discharge excitation method is more complex, and the lifespan of the electron beam transmission film is several hundred hours. It has some disadvantages, such as being inferior to the DC glow discharge excitation method.

The object of the present invention is to provide a gas laser generator that improves both of the above-mentioned problems.

Means for Solving Problems and Working Electrodes are disposed opposite each other through a discharge space in an airtight chamber filled with a laser medium gas in which at least one type of N2 m H'# 01 * X- is mixed with CO gas, A dielectric material is provided between these electrodes, and an AC power source is applied between each of the electrodes to generate a silent discharge in the discharge space, and the laser medium gas in the discharge space is excited by this silent discharge. A gas laser device designed to provide stable and uniform laser oscillation.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. In the figure, in summer, it is an airtight container filled with CO laser medium gas.
A pair of electrodes 2.3 are installed at the upper part of the airtight container 1, spaced apart from each other in the vertical direction. These electrodes 2.3 may have a structure in which solid dielectrics 2b and 3b are provided on mutually opposing surfaces of metal electrodes 2α and 3α as shown in FIG.
As shown in b), a solid dielectric 2bt is provided only on one 21Z of the metal electrodes 2cL and 3α, or a solid dielectric 2b is provided between each metal electrode 2α and 3a.

3b, and an AC power source 4 of frequency f is applied between these electrodes 2.3. As a result, a silent discharge is generated in the discharge space 5 between each electrode 2.3, and the CO laser medium gas present in the discharge space is excited, and total reflection mirrors 6cL are installed to face each other across the discharge space. The laser medium gas is excited between the optical co-imager 6 and the partial reflecting mirror 6b. A part of this oscillation light is transmitted as a laser beam 10 to the airtight container 1 through the partially reflecting mirror 6b.
It is designed to be taken outside.

On the other hand, a blower 7 and a heat exchanger g are disposed opposite to each other at the inner bottom of the airtight container 1, and the CO laser medium gas in the discharge space 5 is circulated to the heat exchanger ε by the blower 7.
After being cooled down, it is configured to be circulated again to the discharge space 5.

Next, to explain the effect, the CO sealed in the airtight container 1
In the above embodiment, a laser medium gas having the following composition range was used.

C02~10%, N, 8~20%, Hg'lO~90%
.

However, it is not always necessary to mix the three types of assist gases mentioned above with CO; HC"!, N!, Xe, 01, etc. may be mixed alone.

As mentioned above, a silent discharge occurs between the electrodes 2.3 to which the AC power supply 4 is applied, and the CO laser medium gas in the discharge space 5 between these electrodes 2.3 is excited to generate laser oscillation. When the AC power source 4 is applied between the electrodes 2 and 3, only the electron temperature increases and the gas molecule temperature does not increase further, so a stable non-equilibrium discharge can be realized. This is the case when the frequency of the AC power source 4 is relatively high.It depends on the spacing between the electrodes 2.3, but usually the frequency f
is about 1oOKHz.

At frequencies below that, the situation is exactly the same as when the peak value is considered to be equal to the DC voltage.

Next, in order to understand this phenomenon, consider the movement of electrons and ions between the electrodes 2.3. If the gap length between the electrodes 2.3 is d, μt: ion mobility, μe: Electron mobility: E■ωVelocity of ions and electrons in a large alternating electric field 1) 1. tle is IJ
i-μi E cos ω large...-(1) C e-μgBcos
ω large...warm...(2) Too much.

Letting the positions of positive ions and electrons be xi and xe, and integrating both sides, we get xi-fvid large-',''' 5ina+ large...
...(31 Therefore, the moving distance tLi, t of ions and electrons
ie is d,,2piB...(5]d,-2
st E, 6 degrees.

When 2μCE 2μiE , >61 > , the number of positive ions reaching the electrode is extremely small, and most of the positive ions stay within the electrodes 2 and 3. In this state, almost no positive ions move, and only electrons move. Therefore, the rise in gas temperature is small and the amount of heat generated at the cathode is also small.

Further, since arc discharge is dominated by a secondary mechanism at the cathode caused by positive ions, AC discharge is difficult to transition to arc discharge in this frequency range.

Furthermore, the discharge sustaining voltage also decreases due to the space charge action caused by positive ions within the gap.

Therefore, by setting a frequency such as cl d that satisfies the condition 2ttaB > ω > 2siB, stable silent discharge can be maintained.

For example, when glow discharge is performed in He gas IOTOrr, the mobility μi of Ha+ ions is μt' oa
m”/V, S, the electric field E is 20, l K
'V1511, when the gap length of the electrode 2.3 is ct 2, and the charged particle is an electron field μg-4x I O"m"
/V, 8, so the frequency f is 6.4MHz >
It is sufficient to set f>16KHz.

Silent discharge in which a dielectric is provided between the electrodes 2 and 3 on one side and an alternating current voltage is applied between each electrode 2 and 3 has the above-mentioned alternating current discharge characteristics, and by providing the dielectric, the electron In addition to suppressing the flow of water, a situation is created in which chemical reactions are more likely to occur. From an electrical point of view, this is not much different from an instantaneous discharge on the face of a needle, and is equivalent to partial discharge, which is treated as a cause of discharge deterioration of insulators in electrical engineering.

Also, the frequency of the alternating current applied between each electrode 2.3 is usually 5
0 H! ~ several tens of KEz. In this range, the discharge form does not change depending on the frequency, and due to the action of the dielectric provided between the electrodes 2 and 3, the discharge is localized or uniform without concentration. In addition to obtaining a uniform discharge distribution, the dielectric is not destroyed and the discharge does not shift to a developed discharge such as a glow or an arc, and a uniform discharge with little temperature rise is possible due to stable silent discharge.

In the above embodiments, a three-axis orthogonal type laser generator has been described, but the present invention is not limited to this, and can also be applied to a coaxial type or two-axis orthogonal type laser generator.

Effects of the Invention As described in detail above, this invention generates a silent discharge between each electrode to excite the CO laser medium gas, and causes laser oscillation in a resonator that faces each other with a discharge space in between. Since high-frequency discharge is used, the temperature rise of the laser medium gas can be reduced. This makes it possible to employ a cooling device with a small cooling capacity for the laser medium gas, which is economical, and also allows the device itself to be made smaller. In addition, stable and uniform discharge can stabilize the output of the generated CO gas laser, further improving efficiency and reliability, and the dielectric provided between the electrodes allows transition to arc discharge. ,
Equipment life is also dramatically improved.

[Brief explanation of drawings]

The blade surface shows one embodiment of the present invention; FIG. 1 is a front view of the inside of the airtight chamber, FIG. 2 is a side view of the same, and FIG.
C) is an explanatory diagram showing different embodiments of electrodes. 1 is an airtight chamber, 2.3 is an electrode, 2b and 3b are dielectrics, 4 is an AC power source, and 5 is a discharge space.

Claims (1)

[Claims] At least one of N_2, He, O_2, and Xe in CO gas
Electrodes 2 and 3 are arranged opposite to each other with a discharge space interposed in an airtight chamber 1 filled with a mixed type of laser medium gas, and dielectrics 2b and 3b are provided between these electrodes 2 and 3. A gas laser device characterized in that an AC power source 4 is applied between electrodes 2 and 3 to generate a silent discharge in a discharge space 5, and a laser medium gas in the discharge space 5 is excited by the silent discharge.