JP2714286B2 - Metal vapor laser equipment - Google Patents

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 apparatus, and more particularly to a metal vapor laser apparatus using a metal vapor as a laser medium to improve a laser discharge output and efficiency by improving a discharge state.

[0002]

2. Description of the Related Art As a typical metal vapor laser apparatus currently used in industry, there is a copper vapor laser apparatus used for uranium enrichment technology by laser.

The configuration and operation 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 made of a ceramic material or the like is accommodated as a discharge tube in the center of the oscillation tube indicated by reference numeral 1. A positive electrode 3 and a negative electrode 4 are provided at both ends of the furnace core tube 2 so as to face each other. The electrodes 3 and 4 are supported by electrode support flanges 5 and 6, respectively, and are formed between the electrodes 3 and 4. In the discharge space 7, a pulse bipolar discharge is performed. For example, copper for generating metal vapor is provided at the bottom of the furnace core tube 2.
A metal vapor source 8 in the form of particles such as gold is disposed.

Further, 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 around the outer periphery of the heat insulating material 9. A long external vacuum vessel 11 having a vacuum heat insulating layer 12 is provided around the outer periphery of the protective tube 10. Vacuum insulation layer 12 is exhaust device 13
Connected to External vacuum vessel 11 and electrode support flange 4
A break pipe 14 is provided between the two.

[0005] The break tube 14 is provided at the end of the external vacuum vessel 11, that is, usually on the cathode 4 side, for insulating the positive electrode and the negative electrode 4. Brewster tubes 24, 25 are connected to the electrode support flanges 5, 6, respectively. 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.

[0006] The operation for performing the laser oscillation is, first, an 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 into the discharge space 7 from the buffer gas supply source 15 through the Brewster tube 25. The inside is kept at a constant pressure.

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

[0008]

[SUMMARY OF THE INVENTION FIGS. 2 and 3 Ru der what voltage applied to break pipe ends of oscillating tube common metal vapor laser apparatus and showing a waveform of the discharge current.
The voltage peak reaches at about 20 to 25 kv with a rise time of about 100 nsec, and the current peak reaches about 1500 to 2000 A at about 150 nse.
It reaches at the rise time of c. FIG. 4 shows a position where the electric field intensity applied to the oscillation tube of the conventional metal vapor laser device is highest when such a discharge is performed .
Between the break pipe 14 and the furnace core pipe 2, approximately 20
It is estimated that ~ 25kv was added. FIG.
3A and 3B are views showing a discharge path (flow path) in the oscillation tube 1. FIG . Due to the strong electric field applied in the radial direction of the oscillation tube,
In addition to the original discharge current path shown in FIG.
The discharge flowing in the gap between the heat insulating material 9 and the protection tube 10 or the gap between the heat insulating material 9 and the furnace core tube 2 shown in FIG. Thus, 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 extremely high, there is a problem that the life of these components is shortened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to prevent the occurrence of an abnormal discharge due to a local electric field in a laser oscillation tube to shorten the life thereof, thereby achieving a long life and stable laser output performance. An object of the present invention is to provide an obtained metal vapor laser device.

[0010]

SUMMARY OF THE INVENTION The present invention provides a furnace core tube in which a metal vapor source for generating metal vapor is disposed, a heat insulating material provided around the furnace core tube, and both ends of the furnace core tube. A pair of electrodes installed on the outside, an external vacuum vessel and a break pipe provided around the outer periphery of the heat insulating material via a protective tube, and electrodes supporting the electrodes and connected to both ends of the external vacuum vessel. A supporting flange, a Brewster tube attached to the electrode supporting flange, and a laser light extraction window attached to the Brewster tube, wherein the outer vacuum vessel has substantially the same left and right sides as the outer vacuum vessel. length
The first short vacuum vessel divided into two from the central part
The external vacuum vessel,
Characterized in that the break pipe is arranged at the center of the.

[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 potential of the discharge plasma. When the discharge as shown in FIGS. 2 and 3 is generated, assuming that the position of the break tube is changed from the end of the external vacuum vessel of the oscillation tube to the center, the expression (1) is obtained. In addition, the voltage Vp applied between the break tube and the furnace core tube, which has been a problem, decreases from the voltage V applied to both ends of the break tube due to the voltage drop due to the inductance L of the oscillation tube and the voltage drop due to the plasma resistance R. Value. Vp = V− (L · dI / dt−RI) · α (1) α: constant determined by the break position I: discharge current As an example, when the break tube is installed at the center of the external vacuum vessel of the oscillation tube, In equation (1), α is the maximum value (0.5). At this time, the inductance L of the oscillation tube is 700 nH, the resistance of the discharge plasma is 10 Ω, the peak value of the voltage V applied to both ends of the break tube is 25 kv, and the peak value of the discharge current I is Value 2000A,
Assuming that the rise time is 150 nsec, the magnitude of the voltage drop due to the oscillation tube inductance L 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, the effect can be expected sufficiently when considering that the Vp value approaches the V value (25 kv).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a 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 denoted 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 disposed as a discharge tube in the center of the oscillation tube indicated by reference numeral 1. A positive electrode 3 and a negative electrode 4 are installed at both ends of the furnace core tube 2 to face each other. The electrodes 3 and 4 are supported by electrode support flanges 5 and 6, respectively, and are formed between the electrodes 3 and 4. In the discharge space 7, a pulse bipolar discharge is performed. A metal vapor source 8 in the form of particles, such as copper or gold, for generating metal vapor is disposed at the bottom of the furnace core tube 2.

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 to fix and protect the heat insulating material 9 at a predetermined position. 10 is provided around the outer periphery of the heat insulating material 9. A break pipe 14 is disposed at the center of the outer circumference of the protection pipe 10, and the left and right sides of the break pipe 14 are substantially the same on both sides.
First and second short vacuum vessels 11a and 11b, each of which is divided into two parts from the center in length , are provided. The external vacuum vessel 11 shown by these short vacuum devices 11a and 11b is constituted. Break tube 14 and first and second short vacuum vessels
A vacuum heat insulating layer 12 is formed on the lower surfaces of 11a and 11b, and the vacuum heat insulating layer 12 is connected to an exhaust device 13 to maintain a reduced pressure. Brewster tubes 24 and 25 are connected to the outer ends of the first and second shortened vacuum vessels 11a and 11b via electrode supporting flanges 5 and 6, respectively. These Brewster tubes 24 and 25 are connected to windows 19 and 20 respectively. Is attached. An output mirror and a total reflection mirror 23 are arranged in front of the windows 19 and 20. Also, the first and second short vacuum vessels 11a, 11b
A pulse circuit 17 is connected to the inner end of the, and a high-voltage power supply 16 and a pulse drive power supply 18 are connected to the pulse circuit 17.

In order to perform laser oscillation with the steam metal laser apparatus having the above structure, first, the exhaust device 13 is operated to exhaust the inside of the discharge space 7 through the Brewster tube 24. A gas such as Ne (neon) is introduced from the source 15 into the discharge space 7 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 started in this state, the positive electrode 3 and the negative electrode 4 are activated.
During this time, a pulsed high voltage is applied to form a discharge plasma 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 electrons in the plasma and are excited to a higher energy level, a laser beam of a predetermined wavelength is generated when the atoms transition to a lower level. The laser light generated in the discharge space 7 passes through windows 19 and 20 attached to the Brewster tubes 24 and 25, and further forms an output mirror 2 forming a laser light resonator 21.
2, and is amplified while being repeatedly reflected by the total reflection mirror 23, and is emitted from the output mirror 22. The subsequent operation is as described in the above-mentioned operation section.

The metal vapor laser apparatus of the above embodiment is a modification of the break line installed in the vicinity of the negative electrode of the external vacuum vessel end of a conventional oscillating tube to the central portion, the first short external vacuum vessel oscillating tube the vacuum vessel and a second short vacuum vessel was binary <br/> split conductive by changing the installation position of the break line
The field distribution becomes uniform. This flows outside the core tube
Suppress leakage (reactive) current and dielectric breakdown of internal structures
it can.

[0017]

According to the present invention, since the oscillation tube structure is effective for reducing the electric field strength applied to the end of the break tube and the end of the furnace core tube, the amount of ineffective discharge components flowing on the surface of the heat insulating material is reduced. And a high laser output can be efficiently obtained. In addition, the above-described 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 the 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 at the time of discharge in a general metal vapor laser device.

FIG. 3 is a current waveform diagram at the time of discharge in a general metal vapor laser device.

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

FIG. 5A is a schematic diagram showing a normal discharge path generated in an oscillation tube of a general metal vapor laser device. (B) is a schematic diagram showing a discharge path in the case of an abnormality.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Oscillation tube, 2 ... Furnace tube, 3 ... Positive electrode, 4 ... Negative electrode,
5, 6: electrode support flange, 7: discharge space, 8: metal vapor source, 9: heat insulating material, 10: protective tube, 11: external vacuum vessel, 11
a, 11b: first and second short vacuum vessels, 12: vacuum 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)

(57) [Claims] A core tube in which a metal vapor source for generating metal vapor is arranged; a heat insulating material provided around the core tube; a pair of electrodes provided at both ends of the core tube; An external vacuum vessel and a break pipe provided around the heat insulating material through a protective tube, an electrode supporting flange supporting the electrodes and connected to both ends of the external vacuum vessel, and an electrode supporting flange. comprising a Brewster tube is wearing, and a window for the laser beam extraction attached to the Brewster tube, the outer vacuum vessel the external
The left and right sides of the vacuum vessel are divided into two parts from the center to almost the same length.
The first short vacuum vessel and the second short vacuum vessel
And the break at the center of the external vacuum vessel
A metal vapor laser device comprising a tube arranged.