JPS61160985A - Gas laser - Google Patents

Abstract

PURPOSE:To enable stable discharge under high gas pressure by efficiently cooling pin electrodes, by a method wherein a gas laser is provided with a nozzle in the tubular path equipped with pin electrodes, and the pin electrodes are vibrated with gas flows by eccentricity to the center hole of this nozzle. CONSTITUTION:This device is provided with a means of vibrating pin electrodes 11, 12 in the direction almost rectangular to gas flows 8. For example, when a gas flow 8 passes through a nozzle 19, a force Fa acts on the tip of the pin electrode 11 in the direction rectangular to the gas flow 8 because of the eccentricity of this pin electrode 11 to the center hole 19a of the nozzle 19. Thereby, on the deflection of the pin electrode 11, it will be restored to the original position by the action of a force Fb reverse to the Fa under the elasticity belonging to this electrode 11. On account of rapid expansion after passage through the nozzle 19, the gas flow 8 is disturbant and so leads to vibration of the pin electrode 11 without the coincidence of Fa with Fb. This device is also effective in cooling the pin electrode 11 at the same time because of the adiabatic expansion of the gas flows 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a gas laser that oscillates a laser, and particularly to a high-speed axial flow gas laser that uses a capacitive blower to flow high-speed gas inside a discharge tube.

[Background of the invention]

A pin-shaped anode and a cylindrical cathode are provided in the discharge tube, and while high-speed gas is flowing inside the discharge tube, a discharge is generated between the electrodes to generate laser light, which can be used for processing such as cutting and welding of metals, cutting of cloth, etc. High-speed axial flow gas lasers are currently widely used. However, the pin-shaped electrode that forms the anode has a diameter of about 1 square inch, and has a smaller heat capacity than the cylindrical electrode that forms the cathode, so the temperature of the discharge area rises significantly, so much so that it remains red even after the discharge has stopped. . The reason for this is that although gas flows around the pin-shaped electrode, there is a part on the surface of the pin-shaped electrode where the gas flows slowly, and this part acts as a temperature boundary layer, making it impossible to cool the electrode sufficiently. It is estimated that there is.

As a result, a sputter phenomenon occurs, causing spatter to adhere to the inside of the discharge tube and reducing the discharge output.

Furthermore, since the discharge point moves around irregularly, causing fluctuations in output, there is a problem in that it is not possible to increase the gas pressure or input power, and the device must be operated at low output.

To solve this problem, Y, Knait and
O.

Bib1arz: J, Appl, Phys.
50 (7), P4692. July 1979 and Japanese Unexamined Patent Publication No. 58-178579 have proposed stirring the gas flow around a pin-shaped electrode, but in all of these proposals the pin-shaped electrode is fixed and the pin-shaped electrode itself is cooled. However, it had the disadvantage of poor cooling efficiency.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its object is to provide a gas laser that can efficiently cool a pin-shaped electrode and that can perform stable discharge under high gas pressure.

[Summary of the Invention] The present invention provides a pin-shaped anode electrode and a cylindrical cathode that are provided in a closed pipeline of a gas laser substantially parallel to the gas flow flowing at high speed in the pipeline, and generate a laser beam by discharging between them. Among the electrodes, a pin-shaped electrode is vibrated in a direction substantially perpendicular to the gas flow.

According to the above configuration, the influence of the temperature boundary layer near the surface of the pin electrode is reduced, and the pin electrode can be efficiently cooled, so that stable discharge can be obtained.

[Embodiments of the invention]

An embodiment of the gas laser according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

In FIG. 1, at one end of a tubular discharge tube 1 on the left side in the figure, a reflecting mirror 2 for total reflection made of, for example, a copper plate coated with gold is fixed, and at one end on the right side, a reflector mirror 2 formed of a semiconductor Zn5a, etc., is fixed. A semi-transmissive mirror 3 that outputs is fixedly installed. Near both ends and in the center of the discharge tube 1, conduits 4, 5.6 are connected to the discharge tube 1 at approximately right angles, and these three
The lower ends of the main pipes 4 and 5° 6 are connected via an upper heat exchanger 7.

It is sealed together with the discharge tube 1 from the outside air. A high-pressure gas 8 consisting of CO* + N z + Ha is confined within these tubes. Further, a capacitive blower 9 and an upper heat exchanger 10 are provided in the central pipe line 6. Near the upper ends of the pipes 4 and 5 are pin-shaped electrodes 11 and 12 made of tungsten or the like so that their tips do not protrude into the discharge tube 1 and are approximately parallel to the pipes 4 and 5. Cylindrical electrodes 13.14 made of copper or the like are provided near the conduit 6 inside the discharge tube 1 and are opposed to these pin-shaped electrodes 11.12, and serve as an anode and a cathode, respectively. is formed. A DC power supply 15°16 and a stabilizing resistor 17.18 are respectively provided in series between these two poles, and a glow discharge is generated between the two poles to emit a laser beam. The flow direction and the laser beam direction have a coincident axial flow.

Nozzles 19 and 20 are provided on the inner diameter surfaces of the conduits 4 and 5 at positions facing the pin-shaped electrodes 11 and 12, respectively. The structure of the nozzle 19, 20 is shown in FIG. 2. In the figure, the nozzle 19 has a ring shape with a central axis that almost coincides with the tube axis, and is made of Teflon or the like and has a middle part. A center hole 19a with a reduced inner diameter is formed. The pin-shaped electrode 11 is provided eccentrically with respect to the central axis of the center hole 19a.

The operation of this embodiment configured as described above will be described below. N3 in the composition of gas 8 sealed in the pipe
helps excite the discharge, He has the effect of stabilizing the discharge, and CO is the main gas that is excited. The high-pressure gas 8 having such a composition enters the upper heat exchanger 7 through the blower 9 as shown by the arrow, and is heated to about 20 ml to improve the efficiency of laser oscillation.
℃, branched into pipes 4 and 5, and blown out.

This high-pressure gas 8 enters the electrical tube 1 through pipes 4 and 5, respectively, and is connected to a ballast resistor 17 by a DC power source 15, 16, respectively.
．． Pin-shaped electrode 11゜12 and cylindrical electrode 13 via 18
．． After being exposed to the glow discharge generated during 14, it joins the insulating conduit 6, is cooled in the upper heat exchanger (0), is sucked into the blower 9 again, and circulates. 0
This cooling has the effect of suppressing the thermal expansion of the blower 9. The flow velocity of this high pressure gas 8 is 100 to 300 m/see.

The blower 9 is preferably a capacitive type that discharges a constant flow rate even if there is a pressure drop.The laser light generated by the glow discharge is reflected by the reflector 2 and travels around the center of the cylindrical electrode 13,14. It passes through as a columnar light beam and is output from the semi-transmissive mirror 3.

At this time, when the gas flow 8 passes through the nozzle 19, the pin-shaped electrode 11 is eccentric with respect to the center hole 19a of the nozzle 19. The force of is applied. Therefore, the pin-shaped electrode 1
1 is deflected, a force Fls in the direction opposite to Fa acts due to the elastic force of this pin-down type Fii 11, and it attempts to return to its original position.

Since the gas flow 8 rapidly expands after passing through the nozzle 19, the gas flow 8 is turbulent, and Fa and Fb do not match, causing the pin-shaped electrode 11 to vibrate. At this time, there is also the effect of cooling the pin-shaped electrode 11 due to the adiabatic expansion of the gas flow 8. The same thing can be said about the nozzle 20 as well.

According to this embodiment configured as described above, the pin-shaped electrode 1
Since the vibration of 1 does not slow down the gas flow on the surface and the pin-shaped electrode can be sufficiently cooled, stable glow discharge is possible, and laser light can be generated efficiently and stably.

In the embodiment described above, the pin-shaped electrode 1 is
The explanation has been made regarding the case where 1 is vibrated.

The pin-shaped electrode 11 may be made of a magnetic material, or may be partially coated with a magnetic material and vibrated by applying a magnetic field from the outside of the conduit 4. Alternatively, a piezoelectric element may be provided on the pin-shaped electrode to make it vibrate from the outside. Vibration may be caused by applying an electric field or by known mechanical vibration means. In these cases, the same effects as in the first embodiment described above can be obtained. In this embodiment, the case where the pipe line is perpendicular to three axes with respect to the discharge tube 1 has been described, but it is of course applicable to the case where the pipe line is perpendicular to two axes. Further, when the nozzle 19 is provided, the shape of the nozzle is not limited to the serpentine shape.

〔Effect of the invention〕

As described above, according to the present invention, a nozzle is provided in a conduit provided with a pin-shaped electrode of a gas laser.

The pin-shaped electrode is eccentric to the center hole of the nozzle so that it is vibrated by the gas flow.
The pin-shaped electrode can be efficiently cooled, allowing stable discharge under high gas pressure.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the gas laser according to the present invention, and FIG. 2 is a configuration diagram showing details of the anode portion of FIG. 1. 1...Discharge tube, 4,5.6...Pipe line, 8...High pressure gas. 11.12... Pin-shaped electrode, 13.14... Cylindrical electrode, 19.20... Nozzle, 19a... Center hole.

Claims (1)

[Claims] 1. A pin-shaped electrode forming an anode and a cylindrical electrode forming a cathode are provided in a sealed conduit through which high-pressure gas flows, substantially parallel to the gas flow direction, and a cylindrical electrode forming a cathode is provided on the anode side. In a gas laser that forms the gas flow from the electrode toward the cathode and generates laser light by discharging between these electrodes,
A gas laser comprising means for vibrating the pin-shaped electrode in a direction substantially perpendicular to the gas flow. 2. The means for vibrating the pin-shaped electrode includes providing a nozzle on the inner diameter surface of the conduit at a position where the pin-shaped electrode is disposed, and eccentrically centering the pin-shaped electrode with respect to the center hole of the nozzle. A gas laser according to claim 1, characterized in that: