JPS5824025B2 - Stable eddy convection laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the field of laser devices, and in particular to the design of gas flow lasers.

Currently, the majority of carbon dioxide (CO2) lasers on the market are of the tubular structure type.

This is because it is the easiest to assemble and has proven to be the most reliable.

Generally, assembly as a tubular structure follows three basic measures.

The simplest and lowest power method uses electrical discharge in a water-cooled tube, and this means is currently used in commercially available CO2 lasers.

This output limit is approximately 70 W per meter of discharge length.

Another basic means for constructing high-power lasers consists of so-called "convection lasers".

The gas is circulated through the discharge region where the molecules are excited by the discharge and heated to produce the laser action. The laser gas is fed through a cooling section and the waste heat is removed from the gas, after which the process is repeated. is recirculated within the discharge area where it is generated.

Convection lasers have no special limitations on power per unit length.

This is because it depends on variables such as gas flow rate and gas pressure.

The third basic approach, commonly referred to as a dynamic gas laser, utilizes rocket engine technology.

Since this measure does not apply to the present invention, it will not be mentioned further.

The basic tubular type laser tube design has the advantage that its long and narrow discharge shape provides good laser beam characteristics (TEMOO mode) and allows gas to flow through the laser discharge region at low flow rates. have.

However, a major drawback of this type of laser is its limited power output.

In this way, the improvement of the basic tubular type laser output is
Has great commercial value.

This is because it does not involve any conversion of existing designs to convection laser designs.

Referring to the drawings, FIG. 1 shows a stable vortex convection laser 100 in which the cooling tube 10 is a glass tube extending the length of the laser.

The concentric glass tubes 11 act as water jackets for the cooling tubes 10.

During operation, water enters the area between tubes 10 and 11 through port 12 and exits through port 13.

Gas discharge electrodes 14 and 15 are arranged at both ends of the laser tube 10.

These electrodes are hollow metal cylinders connected by wires 14a, 15a through vacuum-tight seals to an external power source (not shown).

The laser reflector 16 is a total reflection mirror, and the laser reflector 17 is a semitransparent reflector.

The reflectors 16, 17 are aligned with one another to the axis of the tube 10 within tolerances known to those skilled in the art.

The reflective surfaces of reflectors 16,17 can be either spherical or flat.

Those skilled in the art are familiar with the criteria for determining both the curvature and reflectance of these deflectors.

Gas inlet 19 passes laser gas, preferably a mixture of carbon dioxide, nitrogen and helium, into tube 10.

Gas outlet 18 serves as an exit passageway for the laser gas mixture from tube 10 .

The coiled metal ring 20 (as will be shown in more detail next time) is a spring-like metal ring in closed contact with the inner wall of the tube 10.

A finned portion 29 (FIG. 3) projects from the fin ring 20 into the center of the tube.

In this example, five fin rings 20 are illustrated.

However, the actual number of rings is a function of the desired characteristics of each laser.

FIG. 2 is a cross-sectional view of the embodiment shown in FIG. 1 taken along line 2--2.

In FIG. 2, a water jacket tube 11 and an inner glass tube 10 are shown.
The concentric relationship of is shown.

Typically, water (or other suitable coolant) is supplied to tubes 10 and 11.
flowing between.

An end view of the spring-like metal ring 20 illustrates the closed, intimate contact between the ring and the inner surface of the tube 10.

The gas vortices generated in the laser gas flow are indicated by dotted lines 21, 22,
23 and 24.

These works will be reprinted and explained in detail.

FIG. 3 is a perspective view of a typical fin ring 20.

The fins 29 are part of the basic metal strip used to make the coil 20, portions of which have been cut and bent at approximately 90° relative to the metal strips I-IJ.

FIG. 4 shows the fin ring 20 when it is unfolded flat.

It can be seen that there are four groups 25, 26, 27, 28 of fins 29 oriented at different angles with respect to the length of the strip.

These fins are formed by making a series of L11-shaped cuts in the metal strip 20, as shown in FIG. 4, and then bending each tab.

The thin metal strip 20 is easily bent into the ring shape shown in FIG.

This ring tends to revert to a flat configuration.

Thereby the ring is connected to the coil 2 as shown in FIG.
0 is held tightly against the glass when inserted into tube 10.

The operation of the laser according to the invention can best be seen by describing an experimental laser that was carried out to test this principle.

This laser has electrodes 14 and 15 as shown in FIG.
with a spacing of 1.8 m (6 ft) between them.

Tube 10 has an inner diameter of about 2.8 crrL (1.1 inches) and tube 11 has an inner diameter of about 3.6 crrL (1.4 inches).

The total length of the strike IJ tube 20 shown in Figure 4 is approximately 8.76C.
1rL (3.45 inches), width approximately 0.953C/rL (
0.0127 (11771 (0,
0.005 inch) thick hard brass.

The fins 25, 26, 27, and 28 are made by chemically etching thin "P" shaped wires into the brass strip 20 to form flap or tab areas.

The remaining flap area is 2.0 as shown in Figure 4.
bent perpendicular to the surface of

Each fin is 0.203 cfrL (0.08 inches) high, 0.305 CrrL (0.12 inches) wide and makes a 450 angle with the brass end.

The fins in group 25, 27 are all parallel to each other and form an angle of 45° with the long piece of brass strip 20.

The fins in groups 26, 2B are also parallel to each other and in groups 25, 2B.
It forms an angle of 90° with respect to the direction of the fins in 7.

The brass strip 20 is wound into a ring as shown in FIG. 3 and inserted into the laser tube as shown in FIG.

All fin rings are precisely oriented such that each of the fin segments has the same direction.

That is, all groups 25, 26° 27, 28 are aligned in a straight line parallel to the tube axis.

The fin rings are spaced approximately 2 inches apart.

Therefore, in a real laser there are more rings than shown in FIG.

The mixed gas of carbon dioxide, nitrogen, and helium is approximately 0.02 per minute.
7 m' (120 f t3) at a total pressure of 20 Torr through port 19 and exit through port 18.

A power supply (not shown) is connected to the electrodes 14-15 and a current of approximately 250 mA is passed through the laser gas mixture.

Cooling water also enters through port 12 and exits through port 13 at a rate of approximately 1891 (5 gallons) per minute.

Under these conditions, a laser beam of approximately 420 W is obtained from the output coupler 17.

This power exceeds the average power expected from a typical tube-type laser without fin ring segments by approximately 3.
This results in an improvement of more than 5 times.

The rationale behind this improvement in power is based on the fact that the performance of carbon dioxide lasers is limited by the ability to remove heat from the laser gas.

In conventional tubular type lasers, this heat removal is limited by the thermal conductivity of the laser gas mixture.

Since the laser gas is at low pressure and has a small average atomic weight, reaching conditions that would cause turbulence is impractical due to permissible pressure drops.

Turbulent flow is a condition in which irregular turbidity causes rapid mixing of gases, thereby increasing the heat transfer rate above that normally expected for laminar flow.

The fin ring 20 is configured such that the gas flowing through the laser tube is directed by the fins as shown in FIG.
It is oriented to resolve into four stable counter-rotating vortices.

These thin tubes are stable, unlike turbulent flow, and are ideal for moving gas from the center of the tube, where it is heated, to the tube wall, where it is cooled.

The four conditions shown in FIG. 2 are also the optimum conditions for stabilizing ionization.

It is generally the case that ionization is deflected by the transverse gas flow.

The four swirls, as shown in FIG. 2, also slightly deflect the gas discharge while preventing it from becoming unstable or off center of the tube.

An even further increase in power per unit length can be achieved by increasing the fin dimensions,
It is also anticipated that this is possible by optimally arranging the fin angles and ring spacing within the laser tube.

The arrangement of the fins to generate 4 pores creates optimal heat transfer conditions, while the use of fins that are oriented to generate 2 or 6 pores
It is also understood that the tube may provide improvements over tubes without fins.

It will be apparent to those skilled in the art that the angle and arrangement of the fins can be varied to produce two or six fins according to the teachings of this application.

[Brief explanation of drawings]

1 is a perspective view of a stabilized eddy convection laser according to the present invention; FIG. 2 is a cross-sectional view along line 2-2 of the embodiment shown in FIG. 1 including a gas flow pattern; FIG. FIG. 4 is a perspective view of the blank of the swirl generating fin before it is bent into an annular shape. 10... Inner tube, 11... Outer tube, 12.
...Cooling water inlet, 13...Cooling water outlet, 14,15...Electrode, 16,17...
...Reflector, 18...Gas inlet, 19.
...Gas exhaust port, 20...Fin ring, 21, 22, 23, 24...Zuzu, 25゜26
．． 27.28.29...Fin group.

Claims (1)

[Scope of Claims] 1. A convection gas laser including a means for supplying a laser generating gas and a means for generating an electric discharge in the gas, wherein the convection gas laser includes a means for supplying a laser-generating gas, and a means for generating an electric discharge in the gas, wherein the convection gas laser includes a means for supplying a laser-generating gas, and a means for generating an electric discharge in the gas. at least one fin ring arranged, said fin ring consisting of at least two adjacent groups of upright fins projecting inside said tube, for producing a stable rotating eddy in said laser gas flowing through said tube; characterized in that it comprises an improvement consisting of adjacent groups of said group of upright fins oriented substantially at about 90° to each other and at about 45° to the length of said fin ring with opposing angular directions of deflection. convection laser. 2. The convection laser according to claim 1, wherein the flanges are disposed in close contact with the inner surface of the tube. 3. The convection laser according to claim 1, wherein the fin ring is formed from an elastic metal. 4 a plurality of fin rings, the groups of upright fins of each fin ring being aligned with each other along the length of the tube;
A convection laser according to claim 1, disposed within the tube. 5. Adjacent groups of upright fins extend said fin rings substantially at about 90° from each other with opposing angular deflection directions to create a stable counter-rotating vortex in the laser gas as it flows through said tube. 2. A convection laser as claimed in claim 1, wherein the convection laser is oriented at approximately 45° relative to the length of the convection laser. 6. A convection laser as claimed in claim 1, wherein every other group of upright fins has substantially the same or parallel orientation. 7. said fin ring comprising an even number of substantially identically sized fin groups, each said fin group producing a circumferential deflection angle of between 25° and 55° for gas flowing parallel to the axis of said tube; oriented such that adjacent ones of said fins are oriented at substantially 90° to each other and have opposing deflection angles, and every other one of said fins is oriented parallel to each other. A convection laser according to claim 1.