JPS6240875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silent discharge type gas laser device, and particularly to an electrode structure in a silent discharge type carbon dioxide laser oscillator.

2. Description of the Related Art Conventionally, as this type of silent discharge type carbon dioxide laser oscillator, the one shown in FIG. 1 is known. 1st
In the figure, 1 is a pair of dielectric electrodes whose surfaces are coated with a dielectric material such as glass, and 2 is this dielectric electrode 1.
3 is a discharge space, 4 is carbon dioxide gas (CO ₂ )
This is a blower that supplies a mixed gas to effectively oscillate a laser beam containing 5 and 6 constitute resonator mirrors for oscillating and amplifying laser beams, 5 is a total reflection mirror, and 6 is a partial reflection mirror, and a part of the laser beam amplified from this partial reflection mirror 6 is It is taken out to the outside in the direction shown by the arrow in Figure 1. Reference numeral 7 denotes a housing that houses each of the above components.

2a and 2b are a front view and a partially cutaway side view showing the structure of a dielectric electrode used in the silent discharge type carbon dioxide laser oscillator of FIG. 1. FIG. Figure 2a,
In b, 8 is an electrode tube made of a metal tube, 9 is a dielectric material such as glass coated on the surface of the electrode tube 8, and the dielectric electrode 1 is constituted by the electrode tube 8 and the dielectric material 9 such as glass. The dielectric electrode 1 consists of a pair facing each other. Reference numeral 10 denotes an insulator made of a dielectric material that forms an electrically insulating boundary of the discharge space 3 and also constitutes a support for the dielectric electrode 1, and this insulator 10 covers approximately the upper half of the dielectric electrode 1. It is formed in close contact so as to embed the above. 1
1 is cooling water that cools the dielectric electrode 1 from inside;
2 and 13 are the inlet and outlet of the cooling water 11, respectively;
Reference numeral 4 denotes a high-voltage power supply terminal, and a discharge 15 in the discharge space 3 occurs on the surfaces of a pair of dielectric electrodes 1 bounded by an insulator 10. In laser oscillation, it is necessary that the discharge 15 in the discharge space 3 be uniform, and therefore it is essential that the discharge 15 in the discharge space 3 be performed only on the opposing surfaces of the dielectric electrodes 1 that form a pair. This point is a condition,
The discharge limiting effect of the insulator 10 plays a large role.

Since the dielectric electrode 1 used in the conventional silent discharge type carbon dioxide laser oscillator is constructed as described above, the dielectric material 9, such as glass, coated on the surface of the electrode tube 8 covers the entire circumference. Therefore, the entire surface has the same dielectric constant, and therefore, the insulator 10 serving as the discharge limiting material must reliably cover all surfaces of the dielectric electrode 1 other than the area where the discharge 15 occurs. However, this has resulted in drawbacks such as a complicated structure and a large size. In addition, conventionally this type of insulator 1
The dielectric constant ε _s of 0 was relatively small at about ε _s ≦8, but recently, in order to increase the discharge density per unit area, materials with a high dielectric constant of about ε _s ≧10 have been developed. Since it has come into use, it has had drawbacks such as the difficulty in selecting the structure and selection of the insulator 10 as a discharge limiting material.

The present invention has been made to eliminate the drawbacks of the conventional ones as described above, and includes a ground side electrode and a high voltage side electrode, at least one of which is coated with a dielectric material such as glass, and a high voltage is applied between these two electrodes. a power source that generates a discharge in the discharge space between both electrodes, a total reflection mirror located at both ends of the discharge space that generates laser oscillation when the discharge occurs, and a partial reflection mirror on the laser output side. It has a structure in which a fluorine-based polymer is coated only on the area on the dielectric material such as glass where no discharge occurs, and has a simple electrode structure to further enhance the discharge limiting effect in the discharge area of the electrode. It is an object of the present invention to provide a silent discharge type gas laser device that can be improved.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figures 3a and 3b are a front view and a partially cutaway side view showing the structure of a dielectric electrode used in a silent discharge gas laser device, which is an embodiment of the present invention, and are the same parts as in Figures 2a and b. are indicated using the same reference numerals, and detailed explanation thereof will be omitted. Figure 3 a, b
As shown, 16 is a high dielectric constant dielectric material such as glass coated on the surface of the metal tube 8;
Reference numeral 7 denotes a low-permittivity dielectric that coats only the area on the high-permittivity dielectric 16 where no discharge is caused. This low permittivity dielectric material is used in the discharge space 3.
The smaller the dielectric constant value is, the more preferable it is for the purpose of preventing discharge in areas other than the discharge area. In addition, as the dielectric material 17 with a low dielectric constant, the main component is CO ₂ , which is necessary for discharge resistance against silent discharge and laser oscillation.
It is necessary to have resistance to oxidation and deterioration when exposed to gases such as O and O ₃ generated when a mixed gas containing CO, Ne, He, etc. is excited. In the present invention, a fluorine-based polymer is used as a material for the dielectric material 17 having a low dielectric constant that satisfies the above matters. This fluorine-based polymer can be produced by, for example, coating the powder dispersion with a dielectric material 16 having a high dielectric constant and heat-treating it at a temperature higher than its melting point.
It is formed into a uniform film that adheres to the surface of 6. In particular, the fluorine-based polymer is hexafluoropropylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, polychlorotrifluoroethylene, or chlorotrifluoroethylene-tetrafluoroethylene copolymer, or When it is polyvinylidene fluoride, or chlorotrifluoroethylene-vinylidene fluoride copolymer, or polyvinylidene fluoride, or ethylene-tetrafluoroethylene copolymer, or perfluoroalkoxy resin,
It has been experimentally confirmed that it is most suitable for the above conditions. The table shown in FIG. 4 shows an example of the physical property values of the fluorine-based polymer used in the present invention. On the other hand, the same effect can be obtained even if the circular cylindrical shape of the electrode tube 8 constituting the dielectric electrode 1 shown in FIG. 3b is changed to a square cylindrical shape or an elliptical cylindrical shape.

Now, as in the example shown in the table in FIG. Assuming that the dielectric constant of allopropylene-tetrafluoroethylene copolymer (FEP) is approximately 2.1, the thickness of the glass dielectric coated on the electrode surface is 0.6 ^t , and the thickness of FEP is 0.5 ^t .
Let's look at the case of coating. As a result,
When a voltage is applied between the ground side electrode and the high voltage side electrode, the potential difference shared by each of the above dielectrics is between the area of only the glass dielectric and the area of the glass dielectric with FEP.
Unlike the area coated with FEP, in the latter case, the presence of the FEP layer created a large potential difference and no longer caused a discharge. In other words, it has been revealed that this phenomenon effectively acts on the control of the discharge region that provides the discharge limiting effect between the two electrodes.

In addition, as a modification of the embodiment of the present invention described above, only the region where discharge is caused is coated with a dielectric material having a large relative dielectric constant, and the region where discharge is not caused is coated directly with the above fluorine-based polymer on the metal electrode. It is also possible to use a different configuration, and in this case as well, the same effects as in the above embodiment can be achieved.

As described above, according to the silent discharge type gas laser device according to the present invention, the fluorine-based polymer is coated only on the region where no discharge is caused on the dielectric material such as glass coated on at least one of the ground side electrode and the high voltage side electrode. Because of this structure, it has an extremely simple electrode structure and has the excellent effect of significantly improving the discharge limiting effect in the discharge region of the electrode.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional silent discharge type carbon dioxide laser oscillator, and FIGS. A partially cutaway side view, FIGS. 3a and 3b are a front view and a partially cutaway side view, FIG. 1 is a table showing an example of physical property values of a fluorine-based polymer used in the present invention. DESCRIPTION OF SYMBOLS 1... Dielectric electrode, 2... Support, 3... Discharge space, 4... Blower, 5... Totally reflecting mirror, 6... Partially reflecting mirror, 7... Housing, 8... Electrode tube, 9... Dielectric such as glass, 10... Insulator, 11... Cooling water, 12... Inlet, 13... Outlet, 14... Power supply terminal, 15... Discharge, 16... High dielectric constant dielectric , 17... Dielectric material with low dielectric constant. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A ground side electrode and a high voltage side electrode, each of which is coated with a dielectric material such as glass on at least one side, and a power source that applies a high voltage between the two electrodes to generate a discharge in the discharge space between the two electrodes. and located at both ends of the discharge space,
It is equipped with a resonator consisting of a total reflection mirror that generates laser oscillation when the discharge occurs and a partial reflection mirror on the laser output side, and a fluorine-based polymer is coated only on the area on the dielectric material such as glass that does not cause discharge. A silent discharge gas laser device characterized by having a configuration consisting of. 2 The fluorine-based polymer is hexafluoropropylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, polychlorotrifluoroethylene, or chlorotrifluoroethylene-tetrafluoroethylene copolymer, or Claims characterized in that the polyvinylidene fluoride, chlorotrifluoroethylene-vinylidene fluoride copolymer, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, or perfluoroalkoxy resin The silent discharge gas laser device according to item 1.