JPH05102553A - Metal steam laser device - Google Patents

Abstract

PURPOSE:To obtain a long lifetime and stable laser output performance by preventing the generation of abnormal discharge by a local field in an oscillation tube which reduces service life. CONSTITUTION:An insulation material 9 and a protection pipe 10 are installed to the outer periphery of a furnace core pipe where a metal steam source 8 is laid out. In the central part of the protection pipe is installed a break pipe 14. On both sides of the break pipe 14 there are installed a first short vacuum vessel 11a and a short second vacuum vessel 11b formed by dividing a long vacuum vessel into two portions. A vacuum adiabatic layer 12 on the break pipe 14 and the bottom of the first and second short vacuum pipes 11a and 11b is depressurized by means of an exhaust device 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor laser device, and more particularly to a metal vapor laser device configured to use metal vapor as a laser medium to improve a discharge state and improve laser oscillation output and efficiency.

[0002]

2. Description of the Related Art At present, as a typical metal vapor laser device used in industry, there is a copper vapor laser device used for uranium enrichment technology by laser.

The structure and operating principle of a conventional metal vapor laser device will be described with reference to FIG. In FIG. 6, a heat-resistant and electric-resistant furnace core tube 2 such as a ceramic material is housed as a discharge tube in the central portion of the oscillation tube indicated by reference numeral 1. A positive electrode 3 and a negative electrode 4 are installed opposite to each other at both ends of the furnace core tube 2. These electrodes 3 and 4 are supported by electrode supporting flanges 5 and 6, respectively, and are formed between the electrodes 3 and 4. Pulsed bipolar discharge is performed in the discharge space 7 which is formed. At the bottom of the furnace core tube 2, for example, copper for generating metal vapor,
A particulate metal vapor source 8 such as gold is placed.

A heat insulating material 9 made of a material such as alumina fiber is provided around the outer periphery of the furnace core tube 2, and a protective tube made of quartz or the like is used to fix and protect the heat insulating material 9 at a predetermined position. 10 is provided on the outer periphery of the heat insulating material 9. A long external vacuum container 11 having a vacuum heat insulating layer 12 is provided around the outer periphery of the protective tube 10. The vacuum heat insulating layer 12 is an exhaust device 13
Connected to. External vacuum vessel 11 and electrode support flange 4
A break pipe 14 is provided between and.

The break tube 14 is installed at the end of the external vacuum container 11, that is, usually on the side of the cathode 4 in order to insulate the positive electrode and the negative electrode 4. Brewster tubes 24, 25 are connected to the electrode support flanges 5, 6. Brewster tube 24,
Windows 19 and 20 are attached to the end of 25,
An output mirror 22 and a total reflection mirror 23 are arranged in front of the windows 19 and 20.

The operation for lasing is first to the exhaust device.
13 is operated to evacuate the discharge space 7 through the Brewster tube 24, and then a gas such as Ne (neon) is introduced from the buffer gas supply source 15 into the discharge space 7 through the Brewster tube 25. , Keep constant pressure inside.

When the high-voltage power supply 16, the pulse circuit 17, and the pulse drive power supply 18 are activated in this state, the positive electrode 3 and the negative electrode 4
A pulsed high voltage is applied during this period to form discharge plasma in the discharge space. This discharge causes the vapor source 8 placed in the furnace core tube 2 to evaporate, and the vaporized atoms are excited to a high energy level by the collision of electrons in the plasma,
When transitioning to a low level, laser light with a predetermined wavelength is generated. Laser light generated in the discharge space 7 is Brewster tube
The light passes through the windows 19 and 20 attached to 24 and 25, is amplified while being repeatedly reflected by the output mirror 22 and the total reflection mirror 23 that form the laser optical resonator 21, and is emitted from the output mirror 22.

[0008]

FIGS. 2 and 3 show waveforms of voltage and discharge current applied to both ends of a break tube of an oscillation tube of a general metal vapor laser device.
The peak voltage reaches about 20-25kv with a rise time of about 100nsec, and the peak current reaches about 150nse at about 1500-2000A.
Reached at the rise time of c. FIG. 4 shows the position where the electric field strength applied to the oscillation tube of the conventional metal vapor laser device is the highest when such discharge is performed. About 20-25 close to the voltage
It is estimated that kv was added. Also, FIG.
5A and 5B are diagrams showing a discharge path (flow path) in the oscillation tube 1, which is caused by a strong electric field applied in the radial direction of the oscillation tube.
In addition to the original discharge current path shown in FIG.
A discharge flowing through the gap between the heat insulating material 9 and the protective tube 10 or the gap between the heat insulating material 9 and the furnace core tube 2 is added. In this way, there is a problem that the discharge energy component injected into the effective discharge path for exciting the metal vapor is reduced and the laser oscillation output is reduced. At the same time, since the electric field strength applied to the furnace core tube 2 and the heat insulating material 9 is remarkably high, there is a problem that the life of these components is shortened.

The present invention has been made in order to solve the above problems, and prevents abnormal discharge from being generated in a laser oscillation tube due to a local electric field and shortens the life of the laser oscillation tube. An object is to provide an obtained metal vapor laser device.

[0010]

According to the present invention, there is provided a furnace core tube in which a metal vapor source for generating metal vapor is arranged, a heat insulating material provided on the outer periphery of the furnace core tube, and both ends of the furnace core tube. A pair of electrodes, an external vacuum vessel and a break tube provided on the outer periphery of the heat insulating material via a protective tube, and an electrode supporting the electrodes and connected to both ends of the external vacuum vessel. A support flange, a Brewster tube attached to the electrode support flange, and a laser light extraction window attached to the Brewster tube are provided, and the break tube is arranged near the center of the external vacuum container. It is characterized by

[0011]

In order to reduce the electric field near the break tube, it is effective to install the break tube at a position close to the electric potential of the discharge plasma. If the position of the break tube is changed from the end to the center of the oscillation tube when the discharge as shown in FIGS. 2 and 3 is generated, (1)
As expressed by the equation, the voltage Vp applied between the break tube and the furnace core tube, which has been a problem, is the voltage V applied across the break tube from the voltage V due to the inductance L of the oscillation tube and the voltage due to the plasma resistance R. The value is reduced by the action of. Vp = V- (L · dI / dt-RI) · α (1) α: Constant determined by break position I: Discharge current As an example, when the break tube is installed at the center of the oscillation tube, the above formula (1) is used. Α in it is the maximum value (0.5). At this time, the inductance L of the oscillation tube is 700nH, the resistance of the discharge plasma is 10Ω, the peak value of the voltage V applied across the break tube is 25kv, the peak value of the discharge current I is 2000A, Assuming a rise time of 150 nsec, the inductance L of the oscillation tube
The magnitude of the voltage drop due to the plasma resistance R and the voltage drop due to the plasma resistance R can be calculated as 14.6 kv, and the voltage Vp applied between the break tube and the furnace core tube is 10.4 kv. On the other hand, in the case of the conventional break position, since the constant α in the equation (1) is almost 0, considering that the Vp value is close to the V value (25kv),
The effect can be expected sufficiently.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the metal vapor laser device according to the present invention will be described with reference to FIG. The same parts as those in FIG. 6 are designated by the same reference numerals. In FIG. 1, a heat-resistant and electric-resistant furnace core tube 2 made of a ceramic material or the like is arranged as a discharge tube in the central portion of the oscillation tube indicated by reference numeral 1. A positive electrode 3 and a negative electrode 4 are installed opposite to each other at both ends of the furnace core tube 2. The electrodes 3 and 4 are supported by electrode supporting flanges 5 and 6, respectively, and are formed between the electrodes 3 and 4. Pulsed bipolar discharge is performed in the discharge space 7 in which At the bottom of the furnace core tube 2, a particulate metal vapor source 8 such as copper or gold for generating metal vapor is arranged.

Further, a heat insulating material 9 made of a material such as alumina fiber is provided on the outer peripheral surface of the furnace core tube 2, and a protective tube made of quartz or the like is used for fixing and protecting the heat insulating material 9 at a predetermined position. 10 is provided on the outer periphery of the heat insulating material 9. A break pipe 14 is arranged in the central portion around the outer periphery of the protection pipe 10, and the first and second break pipes 14 are arranged on both sides of the break pipe 14.
The short vacuum containers 11a and 11b are provided. The external vacuum container 11 shown by these short vacuum devices 11a and 11b is configured. A vacuum heat insulating layer 12 is formed on the lower surfaces of the break pipe 14 and the first and second short vacuum containers 11a and 11b.
The vacuum heat insulating layer 12 is connected to the exhaust device 13 to maintain the reduced pressure.
Brewster tubes 24, 25 are provided at the outer ends of the first and second shortened vacuum vessels 11a, 11b via electrode supporting flanges 5, 6.
Are connected, and windows 19 and 20 are attached to these Brewster tubes 24 and 25, respectively. Window 1
An output mirror and a total reflection mirror 23 are arranged in front of 9, 20. In addition, the first and second short vacuum containers 11
A pulse circuit 17 is connected to the inner ends of a and 11b, and a high voltage power supply 16 and a pulse drive power supply 18 are connected to the pulse circuit 17.

However, in the operation of lasing with the vapor metal laser device having the above-described structure, first, the exhaust device 13 is operated to exhaust the discharge space 7 through the Brewster tube 24, and then the buffer gas is supplied. A gas such as Ne (neon) is introduced into the discharge space 7 from the source 15 through the Brewster tube 25 to maintain the inside of the oscillation tube 19 at a constant pressure.

When the high-voltage power supply 16, the pulse circuit 17, and the pulse drive power supply 18 are activated in this state, the positive electrode 3 and the negative electrode 4
A pulsed high voltage is applied during this period and discharge plasma is formed in the discharge space 7. This discharge causes the vapor source 8 arranged in the furnace core tube 2 to evaporate. After the electrons in the plasma collide with the vaporized atoms to be excited to a high energy level, a laser beam having a predetermined wavelength is generated when the vaporized atoms transit to a low level. The laser light generated in the discharge space 7 passes through the windows 19 and 20 attached to the Brewster tubes 24 and 25, and further, the output mirror 2 constituting the laser light resonator 21.
2 and amplified while repeatedly reflected by the total reflection mirror 23, and emitted from the output mirror 22. The subsequent action is as described in the above-mentioned action section.

In the metal vapor laser device of the above embodiment, the break tube installed in the vicinity of the cathode at the end of the conventional oscillation tube is changed to the center side, and the external vacuum container of the oscillation tube is changed to two.
It can be easily implemented by dividing and changing the position. Regarding the installation position of this break tube, the central part of the oscillation tube is the most suitable from the theoretical consideration, but if it is difficult due to the reasons of arrangement etc., even if it is arranged in a position biased to either the positive or the cathode, Demonstrate a certain effect.

[0017]

According to the present invention, since the oscillation tube structure is effective for reducing the electric field strength applied to the break tube end and the furnace core tube end, the amount of the reactive discharge component flowing on the surface of the heat insulating material is reduced. It is possible to efficiently obtain a high laser output. In addition, the reduction of the electric field strength makes it possible to extend the life of the heat insulating material and the furnace core tube.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a metal vapor laser device according to the present invention.

FIG. 2 is a voltage waveform diagram during discharge in a general metal vapor laser device.

FIG. 3 is a current waveform diagram during discharge in a general metal vapor laser device.

FIG. 4 is a cross-sectional view schematically showing the point where the electric field strength is highest in the oscillation tube of the conventional metal vapor laser device.

FIG. 5A is a schematic diagram showing a discharge path in a normal state that occurs in an oscillation tube of a general metal vapor laser device. FIG. 6B is a schematic diagram showing a discharge path at the time of abnormality.

FIG. 6 is a cross-sectional view showing a conventional metal laser device.

[Explanation of reference numerals] 1 ... Oscillation tube, 2 ... Furnace core tube, 3 ... Positive electrode, 4 ... Cathode electrode,
5, 6 ... Electrode support flange, 7 ... Discharge space, 8 ... Metal vapor source, 9 ... Insulating material, 10 ... Protective tube, 11 ... External vacuum container, 11
a, 11b ... First and second short vacuum containers, 12 ... Vacuum heat insulating layer, 13 ... Exhaust device, 14 ... Break tube, 15 ... Buffer gas supply source, 16 ... High-voltage power supply, 17 ... Pulse circuit, 18 ... Pulse Drive power supply, 19, 20 ... Window, 21 ... Laser optical resonator, 22 ... Output mirror, 23 ... Total reflection mirror, 24, 25 ... Brewster tube.

Claims (1)

[Claims] 1. A furnace core tube in which a metal vapor source for generating metal vapor is disposed, a heat insulating material provided on the outer periphery of the furnace core tube, and a pair of electrodes installed at both ends of the furnace core tube. An external vacuum vessel and a break tube provided on the outer periphery of the heat insulating material via a protective tube, an electrode support flange that supports the electrode and is connected to both ends of the external vacuum vessel, and the electrode support. A Brewster tube attached to the flange; and a laser light extraction window attached to the Brewster tube, wherein the break tube is arranged near the center of the external vacuum container. Metal vapor laser equipment.