JPS6139593A - Metallic vapor laser - Google Patents

Abstract

PURPOSE:To obtain high laser output with high efficiency, by radially providing a plurality of plasma guns on each side of cylindrical electrode, and by bombarding a part of incident plasma to a metallic source for vaporizing the metallic atoms. CONSTITUTION:A metallic vapor laser is provided with three plasma guns 20 on each side, with six plasma guns in total. All the high pulse voltages applied form a constant-voltage power supply 42 are synchronized. Plasma entering into a laser radiator tube 10 is deflected along the magnetic lines of force produced by exterior solenoid coils 14, 30a and 30b, and distributed uniformly in the laser radiator tube 10. The plasma thus excited scattered metallic atoms 46, whereby the reverse distribution required for laser radiation is obtained. Thus, the metallic atoms in a certain excited condition are radiated automatically, whereby the metallic atoms in the same excited condition are successively stimulated, and laser beams of the same phase are radiated from Brewster windows 35a and 35b. The radiated laser beams are resonated by a resonator (not shown) and amplified. In this manner, high-output laser beams can be radiated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to metal vapor lasers that utilize the excitation of metal atoms, and in particular to copper vapor lasers that oscillate in the visible range and can provide high efficiency and high laser output. Related to metal vapor lasers.

[Technical background of the invention and its problems]

Conventional metal vapor lasers excite metal atoms,
As shown in Fig. 6(A), there is a bipolar discharge using an arc discharge generated between a cathode and an anode, and as shown in Fig. 6(B), a cylindrical anode ( There is one that utilizes φ hollow cathode discharge by interposing an auxiliary anode 5 between the anode 3 and the small cathode 4.

On the other hand, there are methods to increase the metal vapor pressure required for laser oscillation inside the laser oscillation tube, such as by using the heat generated inside the laser oscillation tube during arc discharge, or by heating it in a separate electric furnace. There is a method of introducing the metal vapor laser into a metal vapor laser oscillation tube.When using the latter electric furnace, it is essential to consume electric power to heat the metal vapor, so the energy efficiency of the metal vapor laser decreases. Regardless of which method is adopted, the inside of the laser oscillation tube is kept at a fairly high temperature, so the heat resistance of the 8! components of the laser oscillation device is a problem.

In general, the conditions for increasing the laser output emitted from a laser oscillation tube include (a) increasing the tube volume of the laser oscillation tube, and (b) increasing the amount of metal vapor necessary and sufficient for laser oscillation. (C) Due to the metal atom density, high-density, high-energy electrons (plasma) are obtained within the laser oscillation tube, and (C) the vaporized gold m atoms are quickly excited.

In addition, since the laser oscillation device performs stable laser oscillation, (d) dielectric breakdown due to contact between plasma and discharge tube (laser oscillation tube) is less likely to occur, and (e) vaporized metal is recovered. (f) It is easy to supply a metal source, and (g) It is desirable to have a long life.

In the bipolar discharge method, which utilizes an arc discharge generated between a cathode and an anode in a conventional metal vapor laser, the arc discharge occurs only in a very narrow local area of both electrodes.

For this reason, even if the area of both electrodes is increased, a uniform plasma (q) is 1lfl, and in this metal vapor laser, the electrode area is small and the gap between the electrodes is large (and the laser oscillation tube is By increasing the length, the above condition (a) is satisfied.

In addition, in vertical discharge metal vapor lasers that employ the two-electrode discharge method, a ceramic tube is housed within the laser oscillation tube.
A metal source is placed in this ceramic duplex. When this metal source is in contact with the plasma, sufficient vaporization occurs, and the required base vaporized metal atoms are (q), but if the plasma in the laser oscillation tube is not uniform, the laser There are problems such as the metal atom density within the tube becoming unstable, resulting in large fluctuations in laser output and unstable laser output, which places severe restrictions on increasing the laser output.

In addition, in metal vapor lasers that use a hollow cathode, the discharge inside the laser oscillation tube is more stable than in the bipolar discharge method, and a plasma with a high free electron temperature can be obtained, but in order to increase the laser output, the electrode area must be expanded. , a uniform plasma cannot be obtained and has the same problem as the bipolar discharge method.

[Purpose of the invention]

The present invention was made in consideration of the above-mentioned circumstances, and
A metal that generates a uniform bladder 7 that is dense and has a high electron temperature, and uses the thermal energy generated by discharge to stably obtain high-density metal vapor, thereby obtaining stable high-output laser oscillation. The purpose is to provide a vapor laser.

[Summary of the invention]

In order to achieve the above-mentioned object, the metal vapor laser according to the present invention houses a cylindrical electrode built in a heat-resistant tube to which a positive potential is applied within the laser oscillation tube, and a solenoid coil for plasma containment is installed opposite to the cylindrical electrode. and a plurality of plasma guns are provided radially on the sides of the cylindrical electrode, and a metal source is disposed opposite to the plasma gun via a plasma diffusion chamber, and the plasma gun enters the plasma diffusion chamber from the plasma gun. A secondary discharge is formed between the plasma and the cylindrical electrode, while a part of the incident plasma is bombarded with a metal source to vaporize metal atoms, and the vaporized metal atoms are transferred to the solenoid coil. This is characterized by the fact that the plasma is excited by the confined plasma and the population inversion necessary for laser oscillation is obtained.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a metal vapor laser according to the present invention will be described below with reference to the drawings.

In FIG. 1, the reference numeral 10 indicates a laser oscillation tube for a metal vapor laser, and this oscillation tube 10 has a tube body 11.
It is constructed integrally so that it can be divided into several parts, and the interior is kept airtight. A cylindrical electrode 12 to which a positive potential is applied is housed in the center of the laser oscillation tube 10, and a ceramic tube 13 as a heat-resistant tube with excellent heat resistance is housed within this cylindrical electrode 12, creating a double-tube structure. be made into Four sets of external solenoid coils 14 are arranged in the tube body 11 in the axial direction so as to surround the cylindrical electrode 12 and the ceramic tube 13 from the outside. An opening 15 formed in the center of the cylindrical electrode 12 and the ceramic tube 13 communicates with an exhaust boat 16,
This exhaust boat 16 is formed in the center of the tube body 11. A mirror magnetic field is formed by energizing the external solenoid fill 14.

On the other hand, a plurality of plasma guns 20 are mounted on both sides of the cylindrical electrode 12 of the laser oscillation tube 10 via ring or plate-shaped insulating members 17 and 18, respectively.

As shown in FIG. 2, this plasma gun 20 includes, for example, three units arranged at equal angles of 120 degrees, and an F3ai mounted on a cylindrical part of a plasma gun body 21 via an insulating material 2.
(cathode) 23 and an anode (anode) 24 equipped with a water-cooled vibe facing this cathode 23.
A rare gas such as helium gas or argon gas is supplied through the gas inlet pipe 25 between .degree. 24 and a pulse discharge as a primary discharge is caused by the helium gas or the like.

The central axis of the anode 24 of the plasma gun 20 is provided with a pore 26 that faces inward in the radial direction, and the plasma generated by the pulse discharge is ejected from this pore 26 and flows into the plasma diffusion chamber 2.
7. This plasma diffusion chamber 27 is defined in the center of the plasma gun body 21, and lesium (Cs), zinc (Zn), selenium (Se ), copper (Cu)
A metal source 28 such as the like is provided. These metals 28 are held at the tip of a cylindrical support 29, and a part of the plasma (thermal energy) incident through the pores 26 directly hits the metal source 28, and the thermal energy generated by the discharge turns the metal into vapor. It has become The metal source 28 may be held so as to be movable from the outside via a bell bell or the like, so that IQ wear of the metal can be dealt with.

Further, on both sides of the laser oscillation tube 10 in which the plasma gun 20 is disposed, cylindrical electrodes 30a and 30b are applied to a positive potential.
are housed in pairs, and ceramic tubes 31a, 31b with excellent heat resistance are housed in the cylindrical electrodes 30a, 30b, forming a double tube structure. These cylindrical electrodes 30
Two sets of solenoid coils 33a, 33b are attached to the tube body 11 of the laser oscillation tube 10 so as to correspond to the solenoid coils 33a, 30b and the ceramic tubes 31a, 31b.
A magnetic field is created by energizing the solenoid coils 33a and 33b.

Furthermore, Brewster windows 35a and 35b are provided at both ends of the laser oscillation tube 10 to output plane-polarized laser light.1. An electron reflecting electrode 36a is provided to suppress the impact on the Brewster windows 35a and a5b.

36b is installed. The electron reflecting electrodes 26a, 36b are provided at both ends of the laser oscillation tube 10 via an insulating member 37, and are opposed to the Brewster windows 35a, 35b.

By the way, the plasma gun 2 attached to the laser oscillation tube 10
The electric circuit 40 that generates a discharge at zero is configured as shown in FIG. A high voltage is applied from the power supply 42. This high voltage is charged by the capacitor 43,
Applied in pulse form. Moreover, the cylindrical electrode ports 30a, 30
b and electron reflecting electrodes 36a, 36b are constant voltage power supply 44a,
A voltage is applied by 44b.

Next, the present invention will be explained in detail.

Activation of the metal vapor laser is performed by discharging the plasma gun 20. This discharge occurs at the cathode 23 of the plasma gun 20.
A pulsed high voltage arc discharge (
Primary discharge; ~10kV.

(several Torr to several tens of Torr), and is pulsed by high voltage switching 41 applied between two poles.

At this time, a rare gas such as 1-IC gas is injected between the two electrodes of the plasma gun 20. The plasma generated between the two electrodes of the plasma gun 20 enters the plasma diffusion chamber 27 in the laser oscillation tube 10 as a high-density jet stream through the pore 26 formed in the anode 24 due to self-pinch action. (See FIG. 4 (A>). At this time, the plasma applies a thermal shock to the metal source 28 placed oppositely, and vaporizes the metal to be excited.

In this case, the plasma gun 20 installed in the metal vapor laser
There are six in total, three on each side, and the high-voltage pulse voltages applied from the constant voltage electricity ai42 are all synchronized. By providing a plurality of plasma guns 20 in this manner and increasing the number of plasma guns 20, it is possible to increase the number of plasma injections and to increase the diameter of the laser oscillation tube 10, thereby increasing the tube volume. Laser output can be increased.

On the other hand, the plasma incident on the plasma diffusion chamber 27 from the plasma gun 20 is transferred to the cylindrical electrode 12.3 which is applied to a positive potential.
No secondary discharge occurs between 0a and 30b, resulting in a trigger.

At this time, the plasma diffusion chamber 27 and the cylindrical electrode 12.30a
, 30b from a constant voltage power supply 43 shown in FIG.

On the other hand, the metal vapor laser has eight sets of external solenoid coils 14.33a for plasma containment.

33b are arranged and these solenoid coils 14.3
3a and 33b, as shown in FIG. Plasma can be spread to the center by placing the magnetic field lines at 4°5.

The diffused plasma is mirrored [! In coordination, it is confined by the mirror magnetic field. This mirror magnetic field configuration also confines the plasma generated by the secondary discharge in this portion, and the uniformity of distribution and increase in plasma density of the confined plasma are achieved.

Thus, the gold i atoms 46 vaporized by the plasma ms to the metal source 28 are scattered around, and as shown in FIG. It will be spread on the internet.

At that time, the plasma that has entered the laser oscillation tube 10 is deflected along the magnetic lines of force 45 created by the external solenoid coil 14, 308.30b, and is uniformly distributed within the laser oscillation tube 10, causing the gold B to fly away. Atom 46 in Figure 4 (C)
Excite as shown in . This excitation occurs when free electrons accelerated in the plasma collide with the metal atoms 46, and the kinetic energy of the electrons is transferred to the internal energy of the metal atoms 46, increasing the excitation unit of the metal atoms 46.

This excitation of metal atoms provides population inversion necessary for laser oscillation. Population inversion refers to the inversion of the atomic number density in each energy unit of metal atoms.

When population inversion is achieved, metal atoms in a certain excited state spontaneously emit radiation, and when the emitted light spreads in all directions, it stimulates metal atoms in the same excited state one after another, causing laser light with the same phase to be blown out. It is radiated from the star windows 35a and 35b.

The emitted laser light is resonated between resonators (not shown), is amplified, and is oscillated as a high-power laser light.

In this metal vapor laser, by enlarging the diameter of the laser oscillation tube 10 and increasing the number of plasma guns 20, the capacity of the generated plasma can be increased, and the solenoid coil can oscillate the laser. Since the plasma can be uniformly confined within the ff10, the oscillated laser output can be increased. Further, by using a part of the plasma discharged from the plasma gun 20 (part of the discharge energy) to vaporize the metal, the metal can be vaporized without using a heating furnace, and the metal vapor can be vaporized without using a heating furnace. It is possible to improve the conversion efficiency.

〔Effect of the invention〕

As described above, the metal vapor laser according to the present invention has a circle I! Since a plurality of plasma guns are arranged radially on the side of the electrode, it is possible to increase the tube volume by increasing the tube diameter of the 7 oscillation tube, and the plasma capacity can also be increased. Even if the plasma capacity increases, this plasma can be uniformly contained within the laser oscillation tube by the solenoid coil, so the plasma density increases and high laser output can be obtained.

In addition, a part of the plasma ejected from the plasma gun impacts the metal source, vaporizes the metal, and scatters it.
An independent heating furnace such as an electric furnace is not required to vaporize the fA source, the energy efficiency of vaporizing metal atoms is increased, and stable, high-density vaporized metal atoms can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a laser oscillation tube showing an embodiment of the metal vapor laser according to the present invention, and FIG. 2 is an IF-IF diagram of FIG.
3 is a wiring diagram of the power supply system that applies voltage to each electrode of the metal vapor laser of the present invention, and FIGS. 4 (A) to (C) are sectional views taken along the line, and FIG. Explanatory diagrams explained step by step, Figure 5 does not show the magnetic field configuration formed by the external solenoid coil, Figure 6 (A) and (
B) is a diagram showing a conventional dipole type laser oscillation tube and a conventional borocathode type laser oscillation tube, respectively. 10... Laser oscillation tube, 12.30a, 30b...
・Cylindrical electrode, 13.31a, 31b- Ceramic tube (heat-resistant tube), 14.33a, 33b... External solenoid coil, 16... Discharge 1" boat, 20...
・Plasma gun, 23...Anode, 24...Anode, 26
... Pore, 27... Plasma diffusion chamber, 28... Metal source, 35a. 35b... Brewster window, 36a, 36b... electron reflecting electrode, 41... switching, 42, 44a. 44b... Constant voltage power supply, 45... Lines of magnetic force, 46...
・Metal atoms.

Claims (1)

[Claims] 1. A cylindrical electrode built into a heat-resistant tube that is applied with a positive potential is housed in the laser oscillation tube, and a solenoid coil for plasma containment is provided opposite to this cylindrical electrode, and a solenoid coil for plasma containment is provided on the side of the cylindrical electrode. a plurality of plasma guns are arranged radially in the plasma gun, and a metal source is arranged opposite to the plasma gun via a plasma diffusion chamber, and between the plasma entering the plasma diffusion chamber from the plasma gun and the cylindrical electrode. While forming a secondary discharge, a part of the incident plasma is bombarded with a metal source to vaporize metal atoms, and the vaporized metal atoms are excited by the plasma confined by the solenoid coil, causing laser oscillation. A metal vapor laser characterized in that the population inversion required for this purpose is obtained. 2. The metal vapor according to claim 1, wherein a plurality of plasma guns are provided radially on both sides of the cylindrical electrode, and a metal source is provided in each plasma gun so as to face each other in the diameter direction of the laser oscillation tube. laser. 3. The metal vapor laser according to claim 1, wherein the heat-resistant tube built into the cylindrical electrode is a ceramic tube.