JPH0635487Y2 - Metal vapor laser discharge tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a laser discharge tube of a metal vapor laser that uses plasma of metal vapor such as copper as a laser medium, and is used for uranium enrichment, medical treatment, and various materials. It is preferably used as an external mirror type laser tube for the above laser, which has a wide range of applications such as processing.

(Prior Art) As a laser discharge tube of this kind, a ceramic plasma tube is loaded inside a laser tube via a heat insulating material layer, and a tubular portion is provided at both ends thereof and a mounting flange portion continuously provided at one end thereof. A positive electrode and a negative electrode side of the ring electrodes are arranged with the tubular portion inserted into the plasma tube, and a Brewster window located on the axis of the plasma tube is provided at both ends of the laser tube. There is.

That is, such a laser discharge tube is a so-called coaxial discharge type in which the discharge direction for excitation and the laser oscillation axis coincide with each other, and a metal piece such as copper is preliminarily loaded in an appropriate position in the plasma tube to fill the inside of the laser tube with helium gas. It is sealed in a low-pressure atmosphere such as, and a pulse discharge is generated between both electrodes to evaporate the metal piece into plasma by the heat, and reveal the excited state of population inversion necessary for laser oscillation. An external reflecting mirror arranged coaxially with the plasma tube on both sides outside the laser tube performs optical amplification to cause laser oscillation.

(Problems to be solved by the invention) However, in the above conventional metal vapor laser discharge tube,
There is a problem that the stability of the discharge in the pulse discharge is poor, the excitation efficiency is inferior, and local overheating easily occurs in the electrode mounting portion or the like to cause damage, so that the durability is insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a metal vapor laser discharge tube having excellent discharge stability, high excitation efficiency, and long life.

(Means for Solving the Problem) As a means for achieving the above object, the metal vapor laser discharge tube according to the present invention is such that a ceramic plasma tube is provided inside a laser tube body with an insulating layer surrounding the plasma tube. At the same time as loading, the positive and negative ring electrodes, each of which has a tubular portion and a mounting flange portion continuously provided at one end of the tubular portion, are inserted into the plasma tube at both ends thereof. In a separately arranged metal vapor laser discharge tube, at least one flat doughnut-shaped sub-electrode plate is coaxial with the ring electrode and an adjacent sub-electrode plate at least outside the ring electrode on the negative electrode side. It adopts a configuration characterized by being attached in a shape.

Further, in the present invention, as the vapor laser discharge tube, the sub-electrode plates are attached to both the positive electrode side and the negative electrode side, and the plasma tube is divided into a plurality of portions which are axially divided at required intervals and slidably fitted to each other at their ends. A preferred embodiment is configured by a plurality of short cylinders, and a ceramic push rod that presses these short cylinders toward the negative electrode side by a spring force on the positive electrode side is provided with the auxiliary electrode plate on the positive electrode side as a moving guide. I am trying.

(Operation) In the metal vapor laser discharge tube of the present invention, since the flat donut-shaped auxiliary electrode plates are spaced apart and coaxially attached to the outside of the ring electrode on the negative electrode side, discharge stability during pulse discharge Is extremely good. That is, when pulse discharge is performed only by the ring electrode as in the conventional case, the discharge area of the ring electrode on the negative electrode side becomes insufficient, and the part other than the tubular part which is the original discharge part, for example, the metal of the electrode mounting part Electrons are emitted from positions far away from the plasma tube axis, such as the substrate and electrode mounting screws, resulting in a partial bias in the discharge area and local overheating, resulting in unstable discharge. To be However, when the above-mentioned sub-electrode plate is provided, in order to compensate for the discharge area shortage of the ring electrode due to uniform electron emission from the inner peripheral portion of the sub-electrode plate during pulse discharge, Electrons are not emitted from the electrode mounting screws,
Therefore, it is presumed that uneven discharge area and local overheating are prevented and uniform and stable discharge can be obtained.

The number of such sub-electrode plates is not limited to one, and if necessary to stabilize the discharge, two or more, preferably about 3 to 5, can be attached in a parallel arrangement state in which a gap is maintained between them. Further, since this sub-electrode plate also functions as a heat reflection plate, by attaching it to the positive electrode side as well, it becomes possible to protect the periphery of the electrode attachment portions of both electrodes from high heat due to discharge.

On the other hand, the plasma tube is composed of a plurality of short cylinders which are axially divided at a predetermined interval and whose ends are slidably fitted to each other. By providing the push rod for pressing, it is possible to absorb the thermal expansion and contraction of the plasma tube and avoid damage due to the thermal expansion and contraction. In this case, however, it is possible to provide the auxiliary electrode plate on the positive electrode side and use it as a guide for moving the push rod.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 to 3, reference numeral 1 denotes a laser discharge tube, and a similar quartz glass tube is provided at both ends of an elongated cylinder 2a made of a quartz glass tube through annular electrode flanges 3 and 4 made of aluminum or the like. The short cylinders 2a and 2b are connected to each other, and the ends of the short cylinders 2b and 2b are closed by an end plate 6 having a Brewster window 5 attached to the center thereof to form a laser tube body 7. Then, inside the laser tube body 7, a plasma tube 8 composed of a large number of alumina short tube bodies 8a, 8a ...
Are concentrically loaded through a heat insulating material layer 9 disposed between both electrode flanges 3 and 4, and the electrode flanges 3 and 4 and the end plate are provided on both inner ends of the laser tube body 7. Electrode chambers 7a and 7b are formed between the electrode chambers 6 and 6. The Brewster windows 5, 5 on both sides are set to be arranged on the axis of the plasma tube 8.

On the side surfaces of the two electrode flanges 3 and 4 facing the electrode chambers 7a and 7b, respectively,
As shown in FIGS. 2 and 3, a flat donut-shaped electrode mounting plate 10 abutting against the side surface and four flat donut-shaped sub-electrode plates 11, 11 ... To
Conductive spacer rings fitted to and attached to the mounting screws 12 at a plurality of locations evenly arranged in the circumferential direction.
They are mounted coaxially with the plasma tube 8 while maintaining a gap between them via 12a, 12a .... Then, on the inner peripheral side of each electrode mounting plate 10, a molybdenum ring electrode 13 composed of a tubular portion 13a and a mounting flange portion 13b continuously provided at one end thereof is provided. The mounting flange part is installed in a state where it is inserted into the inside while being separated from the inner circumference.
It is fixed at 13b.

On the positive electrode side (left side in FIG. 1), an annular space 9a is formed between the inner circumference of the heat insulating material layer 9 and the tubular portion 13a of the ring electrode 13, and the plasma tube 8 is provided in this space 9a. The plurality of ceramic push rods 14 that press the
They are evenly arranged in the circumferential direction of 13a. This each push rod 1
Reference numeral 4 denotes an integrally formed push plate portion 14b at the tip of the shaft portion 14a, which is in contact with the end surface of the tubular body 8a located on the most positive electrode side of the plasma tube 8, and the shaft portion 14a is formed of the ring electrode 13. While slidably penetrating the flange portion 13b and the sub-electrode plates 11, 11 ...
A compression coil spring 15 fitted between the flange portion 13b and the push plate portion 14b is elastically biased toward the negative electrode side.

On the other hand, the inner and outer double glass tubes 16a and 16b are fitted between the electrode flanges 3 and 4 on the outer periphery of the laser tube body 1, and the gap between the electrode flanges 3 and 4 and the end plates 6 and 6 is Also, the glass tube 16c is fitted in each of them. Then, long cylinder 2a
Between the inner glass tube 16a and the inner glass tube 16a constitutes an annular vacuum chamber 17 maintained at a high vacuum by vacuum suction from the gas vent 17a, and between the inner and outer glass tubes 16a and 16b a water inlet 18a and a water outlet. Water cooling chamber 18 that continuously circulates cooling water via 18b
And the short cylinders 2b, 2b on both sides and the glass tube 16
A similar water cooling chamber 19 having a water inlet 19a and a water outlet 19b is formed between c and 16c.

Further, the gas inlet 20a is provided in the negative electrode chamber 7a of the laser tube body 7.
However, a gas outlet 20b is provided in the positive electrode side electrode chamber 7b, respectively, and these gas inlet 20a and gas outlet 20b are communicated with each other through a gas recirculation path (not shown). In order to prevent the charged particles from moving and causing a pressure difference in the discharge tube.

Reference numeral 21 is a metal piece such as copper that evaporates with high heat due to discharge to generate plasma that becomes a laser medium, and is loaded in an appropriate position in the plasma tube 8 beforehand. Then, each tubular body 8a of the plasma tube 8 is provided with an annular groove 8b on the inner peripheral surface for holding the metal piece 21 at a fixed position.

As the heat insulating material layer 9, short cylindrical ceramic molded bodies having excellent heat insulating properties are preferably used alone or arranged in the axial direction with ceramic fibers interposed therebetween.
Further, as the material of the sub-electrode plate 11, molybdenum similar to that of the ring electrode 13 can be used, but aluminum is used in view of economical efficiency,
Copper or alloys thereof are preferred. Therefore, the inner diameter of the sub electrode plate 11 is preferably set to be the same as or slightly larger than the inner diameter of the ring electrode 13. The shape of the short tubular body 8a of the plasma tube 8 can be changed in various ways other than the example.

According to the metal vapor laser discharge tube 1 having the above-described structure, as in the conventional one, the reflecting mirrors are arranged outside the both sides so as to be positioned on the axis of the plasma tube 8, and the ring electrodes 13, 13 on both sides are arranged.
By performing pulse discharge between them, the metal piece 21 evaporates to generate plasma and is further excited to the inverted distribution state, and the light accompanying the change in the energy level is amplified through both reflecting mirrors and required. Pulse laser oscillation is performed to emit laser light when the intensity is reached. At the time of the above-mentioned discharge, the electrons are emitted from the negative electrode side mainly by the tip portion of the cylindrical upper portion 13a of the ring electrode 13 and the inner peripheral portions of the sub-electrode plates 11, 11 ... 3 does not generate electron emission from the inner surface portion, local overheating of these portions is avoided, and the heat reflecting action of the sub-electrode plates 11, 11 ... A uniform and extremely stable discharge is performed. Further, the thermal expansion of the plasma tube 8 due to the high heat generated by the discharge causes the coil spring 15
Absorbed by the compression of.

(Effects peculiar to the device) According to the present invention, the coaxial discharge type laser discharge tube for an external mirror type metal vapor laser has extremely excellent discharge stability, high excitation efficiency, and local area other than the electrode part. It is possible to provide a laser discharge tube having a long life and a structurally simple structure in which damage around the electrode mounting portion is prevented without causing excessive overheating.

Further, according to the configuration of claim (2) of the present invention, there is no fear that the thermal expansion and contraction of the plasma tube will be naturally absorbed, and the destruction due to the thermal expansion and contraction will not occur, and the heat other than the electrode parts on the positive and negative electrode sides will be generated. It is possible to provide the laser discharge tube in which the impact is alleviated and the durability is further improved, and the functions of absorbing the thermal expansion and contraction and relaxing the thermal shock are functionally exhibited based on an extremely simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a metal vapor laser discharge tube according to an embodiment of the present invention, FIG. 2 is an enlarged vertical cross-sectional view showing a main part on the positive electrode side of the same, and FIG. 3 is a main part on the negative electrode side. It is an expanded longitudinal cross-sectional view shown. 1 ... Laser discharge tube, 7 ... Laser tube body, 8 ... Plasma tube, 8a ... Short cylinder, 9 ... Heat insulation layer, 11 ... Sub-electrode plate, 13 ... Ring electrode, 13a .... Upper part of cylinder, 13b …… Flange for mounting, 14 …… Push bar, 15 …… Compression coil spring.

Claims (2)

[Scope of utility model registration request] 1. A laser tube body is loaded with a ceramic plasma tube via a heat insulating material layer surrounding the laser tube body, and a tubular portion and an end thereof are continuously attached to both end portions of the plasma tube. In the metal vapor laser discharge tube in which the positive electrode and the negative electrode on the negative electrode side, which are composed of the flange portion, are arranged separately by inserting the tubular portion into the plasma tube, at least outside the ring electrode on the negative electrode side, A metal vapor laser discharge tube, characterized in that one or more flat donut-shaped sub-electrode plates are mounted coaxially apart from the ring electrode and adjacent sub-electrode plates. 2. A sub-electrode plate is attached to both the positive electrode side and the negative electrode side, and the plasma tube is divided into a plurality of short tube bodies which are axially divided at required intervals and slidably fitted to each other at their ends. The metal vapor laser discharge according to claim 1, wherein a ceramic push rod configured to press these short cylinders toward the negative electrode side by a spring force is provided on the positive electrode side, and the auxiliary electrode plate on the positive electrode side is provided as a moving guide. tube.