JPS6114782A - Gas laser generator - Google Patents

Abstract

PURPOSE:To stably increase a laser output by providing a cylindrical cathode provided coaxially with a discharge tube, and a porous cylindrical conductor provided coaxially with the cathode in an insulating state, thereby preventing an electric field for concentrating. CONSTITUTION:Since a porous cylindrical conductor 16 is coaxial with a cylindrical cathode 13, an electric field E perpendicular to the surface of a conductor is generated between the cathode 13 and the conductor 16. The conductor 16 has no charge concentration due to its conductivity, but the field E becomes uniform. Electrons (e) emitted from the cathode 13 are accelerated by the uniform field E, through the hole 18 of the conductor 16 to a laser amplifying region A. Since the electrons (e) supplied to the region A are based on the uniform field E, the charge distribution inside the conductor 16 is equalized. Thus, the local concentration of the field is prevented, the transfer to an arc discharge is prevented, thereby stably maintaining a glow discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to gas laser oscillation η-23, particularly to gas lasers in which electricity is used as a laser oscillation excitation source.

It is something.

Conventional structure and its problems Laser generation using a gaseous material as a laser medium 2: In order to generate a negative temperature distribution in the medium, it is generally practiced to use a discharge as an excitation source. There is.

In this case, in order to increase the laser output, it is important to increase the electrical input injected as a glow discharge.

On the other hand, as the electrical input increases during glow discharge, the medium temperature increases, which hinders the generation of negative temperature distribution.

However, in order to increase the laser output, it is necessary to prevent the increase in medium temperature.
It is essential to increase the glow discharge input. Glow discharge area (inside the discharge tube) to prevent temperature rise of the medium
It is well known that cooling is forcibly performed by the medium itself by creating a flow of medium gas.

However, if the medium gas flow is small, it is possible to fill the discharge tube with glow discharge almost uniformly, but as the flow rate increases, the discharge path becomes narrower and the discharge occurs only in a portion of the discharge tube. It ends up like there isn't one. As a result, the effective discharge volume that contributes to laser oscillation within the discharge tube decreases, leading to a decrease in laser output. This tendency tends to become stronger as the glow discharge electrical input increases, and an increase in the electrical input does not necessarily increase the laser output.

Moreover, due to the increase in electrical input, a local rapid increase in the current density of glow discharge is observed, and in this case, the discharge becomes unstable and eventually transitions to arc discharge.
Laser generation is inhibited.

In order to eliminate the above drawbacks, methods for controlling the flow of medium gas have been proposed (for example,
8-24025 Publication 1 "Stable Eddy Convection Laser").

However, the above method of simply controlling the gas flow cannot directly control the discharge itself, and there are limits to the effects that can be obtained.

That is, the conventional method aims at stabilizing the positive column in glow discharge with a gas flow, but it is the form of discharge at the cathode that mainly controls the glow discharge, not the gas flow.

Generally, in normal glow discharge, there is a current density specific to the electrode material and gas, and an increase in discharge current is achieved by increasing the surface area of the cathode where discharge occurs. On the other hand, if there is a gas flow or the gas pressure is high, it becomes impossible to increase the effective surface area where the discharge occurs as much as necessary, and the only way to increase the laser output is to increase the current by increasing the current density, that is, by locally concentrating the discharge. Unavoidably, in this case, the discharge becomes unstable and shifts to arc discharge, which impedes laser generation.

OBJECTS OF THE INVENTION An object of the present invention is to provide a gas laser generator capable of solving the above conventional problems and sustaining stable glow discharge.

Structure of the Invention The gas laser generator of the present invention includes a cylindrical cathode provided substantially coaxially with the discharge tube outside one end of the discharge tube, and a cylindrical cathode provided inside the cathode in an insulated state from the cathode. and a perforated cylindrical conductor provided substantially coaxially.

The structure of the present invention focuses on the fact that in glow discharge, a large potential difference that occurs just before the cathode, the so-called cathode fall state, has a great effect on the stability of the discharge, and the electric field concentration at the cathode fall part is diffused over the entire cathode area. It is designed to achieve the above purpose by taking the form.

The effect of this configuration is as follows. That is, since the perforated cylindrical conductor is coaxial with the cylindrical cathode, an electric field perpendicular to the plane of the conductor is generated between the cathode and the conductor. That is, it is an electric field in the centripetal direction.

Because of its conductivity, there is no concentration of charge in the conductor, and the electric field becomes uniform.

Electrons emitted from the cathode are accelerated by such a uniform electric field, pass through the holes in the conductor, and reach the laser amplification region. Since the electrons supplied to this laser amplification region are based on a uniform electric field, the charge distribution inside the conductor is also made uniform.

Therefore, local concentration of the electric field is prevented, transition to arc discharge is prevented, and glow discharge is stably maintained.

By preventing this electric field concentration (reducing current density), it becomes possible to sustain glow discharge even with a large electric input, thereby stably achieving an increase in laser output.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration diagram of a carbon dioxide laser generator as an example.

Two discharge tubes 1 made of an insulating material such as glass for generating a glow discharge for laser amplification are shown in this figure. The anode part 2 is common to both electric tubes 1.1, and a cathode part 3.3 is arranged opposite to the anode part 2.

A gas inlet 4.4 is connected to the cathode section 3.3, and a gas outlet 5 is provided at the anode section 2.

Discharge tube 1. Reflecting mirrors 6 and 7 are arranged to sandwich l,
It constitutes an optical resonator. The reflecting mirror 6 that takes out the laser output is called an output mirror, and the other reflecting mirrors 7 are generally concave reflecting mirrors.

The laser medium gas is circulated by a blower 9 or the like through a circulation path 8.8 to form a flow in the discharge tubes 1,1. The positive output terminal of the DC power supply 10 is connected to the anode section 3, and the negative output terminal is connected to the cathode section 3.3 via a stabilizing resistor 11.11 or the like. It goes without saying that configuring a constant current circuit using a vacuum tube or the like instead of the stabilizing resistor 11 to maintain the discharge current constant is effective in improving the stability of glow discharge. .

The above configuration is a three-axis coaxial laser generator in which the gas flow, discharge direction, and tip shaker center axis are the same, and the fundamental mode T
It is well known that there are characteristics that make it easy to obtain EMo o mode.

FIG. 2 is an enlarged sectional view of the cathode section 3. A cylindrical cathode 13 is provided outside one end of the discharge tube 1 and is substantially coaxial with the discharge tube 1 with an insulator 12 interposed between the discharge tube 1 and the one end. The inner diameter of this cathode 13 is the discharge tube 1
larger than the inner diameter of

The other end side of the cathode 13 is also supported by an insulator 14, and a laser tube 15 is supported by this insulator 14.

Inside the cathode 13, a perforated cylindrical conductor 16 substantially coaxial with the cathode 13 is connected to insulators 12.14 on both sides.
It is supported by. This conductor 16 has a cylindrical body 17 with a large number of holes 18 formed therein.

The cylindrical body 17 is usually made of metal, but may also be made of conductive semiconductors, carbon, perovskite metal oxides, and the like. Further, the conductor 16 may be a cylindrical body with holes or a net wound into a cylindrical shape. Cathode 13 is copper.

It is made of metal material such as stainless steel.

The outer diameter of the conductor 16 is smaller than the inner diameter of the cathode 13, and a cylindrical gap 19 is formed between the two.

Further, the inner diameter of the conductor 16 is substantially equal to the inner diameter of the discharge tube 1.

Since the perforated cylindrical conductor 16 is coaxial with the cylindrical cathode 13, an electric field E perpendicular to the plane of the conductor is generated between the cathode 13 and the conductor 16. Due to its conductivity, there is no concentration of charges in the conductor 16, and the electric field E becomes uniform.

Electrons e emitted from the cathode 13 are accelerated by such a uniform electric field E, pass through the hole 18 of the conductor 16, and reach the laser amplification region A. Since the electrons e supplied to the laser amplification region A are based on the uniform electric field E,
The charge distribution inside the conductor 16 is also made uniform.

Therefore, local concentration of the electric field is prevented, transition to arc discharge is prevented, and glow discharge is stably maintained.

Effects of the Invention According to this invention, since charge is supplied under a uniform electric field, it is possible to prevent electric field concentration (reduce current density) even in the laser amplification region, thereby reducing glow discharge to a large electric input. This has the effect of stably achieving an increase in laser output.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part thereof, and FIG. 3 is an explanatory diagram of the operation. 1...Discharge tube, 12.14...Insulator, 13...
Cathode, 16... Conductor, 17... Cylindrical body, 18...
Hole Figure 1 e 13 Figure 3

Claims (6)

[Claims] (1) A cylindrical cathode provided outside one end of the discharge tube substantially coaxially with the discharge tube, and a cylindrical cathode provided inside the cathode insulated from and substantially coaxial with the cathode. A gas laser generator comprising a perforated cylindrical conductor. (2) The gas laser generator according to claim (1), wherein the conductor is a cylindrical body with a plurality of holes. (3) The gas laser generator according to claim (1), wherein the conductor is a mesh wound into a cylindrical shape. (4) The gas laser generator according to claim (1), wherein the conductor is made of any one of metal, semiconductor, carbon, and perovskite metal oxide. (5) The gas laser generator according to claim (1), wherein the inner diameter of the conductor is substantially equal to the inner diameter of the discharge tube. (6) Claim No. 1 (1) configured as a triaxial coaxial type
) The gas laser generator described in section 2.