High speed axial flow gas laser generator

A high-speed axial-flow gas laser generator has a plurality of anodes radially provided at the inlet section of the laser tube, and a ring-shaped cathode is provided on the gas discharge section side of the laser tube. On the upstream side from the anodes, viewed from the laser gas flow in the laser tube, a nozzle is provided which imparts a spiral rotary motion to the gas flow in the laser tube.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The percent invention relates to a high-speed axial-flow gas laser 
generator, and, specifically, to a high-speed axial-flow gas laser 
generator provided with a nozzle which imparts a spiral rotary motion to 
the gas flow in the laser tube. 
2. Description of the Related Art 
As high-speed axial-flow gas laser generators, there are the transverse 
inflow type which employs a system wherein the laser gas flows into the 
laser tube in a transverse direction relative to the laser tube, and the 
inclined inflow type wherein the laser gas flows into the laser tube at a 
predetermined angle relative to the laser tube. 
Generally, in the transverse inflow type a ceramic nozzle is mounted at 
right angles to the laser tube in the laser gas inflow section of the 
laser tube, and an anode pin is provided in the interior of this ceramic 
nozzle. A ring-shaped cathode is mounted in the laser gas discharge 
section of the laser tube. A high voltage power source is connected 
between the cathode and the anode pin. 
In the inclined inflow type of high-speed axial-flow laser gas generator, a 
ring shaped anode and a ceramic nozzle are generally mounted on the laser 
gas inflow side of the laser tube at a predetermined distance with an 
inclined slot therebetween. A ring-shaped cathode is mounted on the laser 
gas discharge side of the laser tube. A high voltage power source is 
connected between the cathode and the anode. 
In the transverse inflow type of high-speed axial-flow laser gas generator, 
because the laser gas is bent at a right angle when it flows into the 
laser tube an undulation phenomenon is produced close to the laser gas 
inflow section of the laser tube. This causes the upstream gas flow to 
become unstable so that the plasma generated by the electric discharge is 
also unstable. In addition, in the area close to the downstream cathode 
the laser gas is expanding and is flowing at a high speed, so that the 
Reynolds number of the laser gas is in the turbulent flow area and 
turbulent flow occurs. This turbulent flow acts to break up a turbulent 
flow of larger scale which appears locally uniform within the laser tube. 
Accordingly, because the laser gas flow fluctuates from the lack of 
turbulent flow of larger scale in the laser gas, the generation of plasma 
is unstable. This fact becomes strikingly obvious when the discharge 
current increases. 
In addition, in the inclined inflow type of high-speed axial-flow laser gas 
generator, because the anode is ring-shaped, the discharge spot moves on a 
ring, or grows, and a uniform electric discharge is difficult to obtain. 
In addition, in the same way as in the previous example, because the gas 
flow close to the downstream cathode fluctuates, the plasma generation is 
unstable. This becomes strikingly obvious when the electric discharge 
current increases. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide, with due consideration to 
the drawbacks of such conventional devices, a high-speed axial-flow gas 
laser generator wherein stable plasma is produced over the entire area 
within the laser tube. 
In order to accomplish these objects, in the high-speed axial-flow gas 
laser generator of the present invention a plurality of anodes are 
radially provided at the inlet section side of the laser tube, and a 
ring-shaped cathode is provided on the gas discharge section side of the 
laser tube. On the upstream side from the anodes, viewed from the laser 
gas flow in the laser tube, a nozzle is provided which imparts a spiral 
rotary motion to the gas flow in the laser tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Now referring to FIG. 1, a high-speed axial-flow gas laser generator 1 
comprises a pair of laser tubes 3, 5 which are provided in series next to 
the cathode side through a common gas discharge section 7. On the anode 
sides of the laser tubes 3, 5, a pair of gas inflow sections 9, 11 are 
provided. A gas circulating blower 13, a gas cooler 15, and a gas supply 
tube 17 are provided between the gas discharge section 7 and the gas 
inflow sections 9, 11. A laser beam output mirror 19 is provided at the 
left end of the gas inflow section 9, and a rear mirror 21 is provided at 
the right end of the gas inflow section 11. The laser beam is discharged 
in the direction of the arrow L. A high voltage power source 31 is 
provided between the anode 23 and the cathode 25. A high voltage power 
source 33 is provided between the anode 27 and the cathode 29. 
There is provided a nozzle section in the present invention whereby the 
flow of the laser gas which inflows from the upstream anode receives a 
spiral rotary motion from the nozzle, and the flow of the laser gas has a 
uniform distribution over the entire area within the laser tube. 
Accordingly, stable plasma is produced throughout the entire area within 
the laser tube. 
The details of the nozzle section of the gas inflow section 9 are shown in 
FIG. 2 and FIG. 3. (This also applies equally to the gas inflow section 
11). As shown in FIG. 2, an inner nozzle 37 formed from insulating 
material and an outer nozzle 39 constructed from insulating material are 
combined and secured at one end surface of a gas supply tube 35 at the gas 
inflow section 9 by means of four bolts 41 with set pin holes in one face. 
An end section of a tube 43 which extends in the direction of the output 
mirror 19 is mounted on the inner nozzle 37 through an O-ring 45. One end 
section of the laser tube 3 is mounted on the outer nozzle 39 by means of 
a fixed member 49 and a bolt 51, through an O-ring 47. 
A plurality of straightening orifices 53 are provided in the inner nozzle 
37 as a straightening section to temporarily straighten the flow of the 
laser gas. A tip section 55 of the nozzle 37 is constructed of an 
insulating, heat resistant material such as a ceramic. On the cone shaped 
surface of the outer periphery of the inner nozzle 37, as shown in FIG. 4, 
a plurality of fins 57 which impart a rotary motion to the laser gas flow 
are provided with a uniform interval therebetween and inclined at a 
suitable angle (in this embodiment .alpha. degrees) with reference to the 
axial direction of the laser tube. Also, the angle between the cone shaped 
surface of the nozzle and the direction of the axis of the laser tube 
(hereinafter referred to as the nozzle angle) is .beta. degrees. 
Once again, referring to FIG. 2 and FIG. 3, a plurality of anodes 23 and a 
plurality of ballast resistances 59 are connected in series and are 
radially provided at regular intervals on the outer nozzle 39. An outer 
nozzle tip section 61, which is penetrated by the anode 23, is constructed 
from a insulating and heat resistant material, for example a ceramic, so 
that the discharge is concentrated at the anode 23 and so that it resists 
the high temperature. This nozzle angle is .theta. degrees. A grounded 
earth band 63 is provided on the outer perimeter of the outer nozzle 39. 
As shown in FIG. 5, one end of each ballast resistance 59 is connected 
radially. At the other end of each ballast resistance 59, as previously 
stated, there is connected one of the anodes 23 positioned radially. 
Describing the shape of the anodes 23 more clearly than shown in FIG. 2, 
each anode 23 is provided with a T-shaped head section, and a mounting 
screw 67 connected to one end of the respective ballast resistance 59 
contacts this head section through a conducting coil spring 65. 
As a result of this configuration, the laser gas supplied in the direction 
of the arrow G in the gas inflow section 9 as shown in FIG. 2 is 
straightened through the straightening orifices 53 of the inner nozzle 37, 
and flows parallel to the axis in the axial direction. By means of a fin 
57 between the inner nozzle 37 and the outer nozzle 39, a rotary motion 
flow having an angle of .alpha. degrees relative to the direction of the 
axis is imparted. This rotary motion flow contacts the anodes 23 which are 
positioned radially, and inflows to the laser tube 3 from the nozzle tip 
section 61 of the outer nozzle 39. The laser gas flowing into the laser 
tube 3, flows with a rotary motion inside the tube and, at the same time, 
flows uniformly so that the laser gas is distributed uniformly. The 
discharge is therefore uniformly produced and a uniform plasma is formed 
throughout the entire tube. 
Specifically, as shown in FIG. 6, the cylindrical space of the discharge 
section between the anodes and the cathodes is partitioned into, for 
exammple, 8 parts, and the impedances are respectively designated as R1 to 
R8. Then, in the case where the laser gas flow (indicated by the arrow) 
does not have a rotary motion, if the impedance of one of the spaces, for 
example, R1, drops for some reason below that of the other spaces, the 
discharge, when produced, becomes concentrated in that one space and the 
generation of a uniform plasma is impossible. However, when a 
spiral-shaped rotary flow is imparted to the laser gas flow, as shown in 
FIG. 7, the impedance of each space becomes uniform and a uniform plasma 
distribution is obtained. 
As can be understood from the foregoing explanation, because of the 
configuration herein described, a spiral-shaped rotary motion is imparted 
to the laser gas in the laser tube so that the entire region inside the 
tube becomes uniform, and it is possible to obtain a stable plasma over 
the entire region of the laser tube. 
This embodiment of the present invention is given as an example only, but 
the present invention can appear in embodiments with other modes, and 
various modifications and changes can be made without departing from the 
scope of the present invention.