JPH0660852A - Heavy-hydrogen discharge tube - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a deuterium discharge tube that can be miniaturized while avoiding a reduction of the enclosed gas and avoiding a short life. [Structure] In order to recombine deuterium gas ions or deuterium atoms generated by electric discharge, an enclosure 10 made of metal or the like is provided to further cover the metal partition wall 6 except for a part in the light extraction direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deuterium discharge tube used as a UV light source such as a spectrophotometer or a photodetector for liquid chromatography, which has a particularly improved life.

[0002]

2. Description of the Related Art A deuterium discharge tube is described on pages 20 to 30 of "Characteristics and Usage of Light Source" edited by The Spectroscopical Society of Japan (March 1985, Academic Society Publishing Center).

As shown in FIG. 5 (a), the deuterium discharge tube has a bulb 1 made of quartz or hard glass welded to a stem 2 made of the same kind of glass to form a closed vessel. The tube of the valve 1 is filled with an electrode portion covered with a metal partition wall 6 forming a shielding box and deuterium gas or hydrogen gas of several Torr. Further, 19 indicates a light extraction window, and 12 indicates a light extraction direction. Reference numeral 28 is a lead wire for supplying electric power to the electrodes.

FIG. 5 (b) shows a cross-sectional view of the center of the electrode of a conventional deuterium discharge tube. A cathode 3 made of a coil-shaped filament and a plate-shaped anode 4 are arranged as electrodes, and a partition plate 7 having a small hole 5 for narrowing discharge is provided in the middle of the cathode 3 and the anode 4. It is a discharge tube. Further, in order to control the discharge path, a metal partition wall 6 in which a shielding box sealed with a metal such as nickel is formed covers the electrode. When a DC voltage is applied to the discharge tube having the above structure to discharge, plasma 29 is generated between the cathode 3 and the anode 4,
Since the enclosed gas emits light in the portion of the discharge constriction small hole 5, it emits a strong continuous spectrum in the ultraviolet region.

[0005]

In the deuterium discharge tube according to the above-mentioned prior art, when the lamp is turned on, the enclosed gas is gradually reduced, and the life is shortened based on this.
It is necessary to set the volume of the bulb to about 30 to 50 cm ^3. If the volume is less than the above volume, reduction of the enclosed gas is significantly promoted and the life is shortened. Therefore, it is difficult to downsize the discharge tube.

It is an object of the present invention to obtain a deuterium discharge tube which can prevent a reduction of the enclosed gas and can have a long life even if it is downsized.

[0007]

The above object is to provide a metal partition wall which surrounds a cathode and an anode coated with an electron emitting material in a tube containing deuterium or hydrogen and forms a discharge path from the cathode to the anode. In a deuterium discharge tube in which a small hole for narrowing the discharge path is provided in a part of the metal partition wall, the metal partition wall is further covered with a metal such as nickel except for a part in the light extraction direction. This is achieved by providing a closed enclosure.

The inventors made a deuterium discharge tube having a double tube structure as shown in FIG. 6, and the decrease of the enclosed gas was reduced by diffusion and permeation into glass or was trapped on a metal surface or the like. It was confirmed by experiments whether the decrease was caused by the above. In the experiment, a quartz bulb 1 and a stem 2 each having an outer diameter of a discharge tube of 20 mm and a length of 50 mm were welded to form a closed vessel, and the closed vessel contained a cathode 3 and an anode 4 and a small hole for narrowing the discharge. An electrode portion such as a partition wall plate 7 having a metal plate 5 is arranged, and a metal partition wall 6 covered with a metal plate is provided around the electrode portion. The surface of the valve 1 was covered with a quartz tube having an outer diameter of 30 mm to form a double tube 24, and the inside of the valve was filled with deuterium gas of several Torr as in the conventional case. The light extraction window 8 of the bulb 1 is also the flat window 2
The space 25 made of quartz having No. 7 was welded to form a double structure. Quartz double wall covering valve 1 and valve 1
A deuterium discharge tube having a double-tube structure in which the space between and was maintained at a high vacuum was prototyped, and changes in the enclosed gas were measured while lighting with a constant current power supply of 300 mA. From the results of the above experiment, deuterium gas leaks to the outer high vacuum space side surrounding the bulb 1 by lighting, and the amount of deuterium gas on the outer high vacuum space side increases in proportion to the lighting time. It was found that the deuterium gas in the valve 1 was decreasing.

In the above phenomenon, the plasma generated by the discharge does not occur only between the cathode 3 and the anode 4, but also extends from the opening of the metal partition wall 6 to the outside. In particular, deuterium ions or deuterium atoms generated outside the metal partition wall 6 progress toward the tube wall of the valve 1 and diffuse into glass such as quartz and permeate therethrough, so that the deuterium gas in the valve 1 decreases. It can be presumed to do. Therefore, in order to prevent deuterium gas ions or deuterium atoms from reaching or penetrating the valve wall, a second enclosure is provided by further covering the outside of the metal partition wall 6 with a metal or the like to provide the deuterium gas ions or deuterium. If the atoms are recombined, the deuterium gas in the discharge tube can be prevented from decreasing, and the above object can be achieved.

[0010]

The deuterium discharge tube is, as described in the section of the prior art, enclosed in a closed container in which a valve and a stem are welded, a metal partition wall covering the cathode and the anode, and a space between the cathode and the anode. Deuterium gas or hydrogen gas is enclosed together with a partition plate that has small holes for narrowing the discharge path to be formed, but it is generated by discharge when a voltage is supplied to the discharge tube with the above configuration to cause discharge. The deuterium ions or deuterium atoms that are generated travel toward the tube wall of the valve by diffusion, but most of the ions and atoms recombine at the metal partition that surrounds the electrode. However, as described above, the plasma generated by the discharge leaks out from the opening of the metal partition wall, so that deuterium ions or atoms are generated outside the metal partition wall, and these ions or atoms enter the inner wall of the valve. Head over.

In the deuterium discharge tube of the present invention, a metal coating or a conductive coating is formed on the inner wall or outer wall of the bulb by vapor deposition or the like. Therefore, the deuterium gas ions generated by the discharge proceed toward the tube wall, and when they reach the metal coating or the conductive coating provided on the tube wall, the deuterium gas ions and the deuterium atoms are recombined. Original deuterium gas (D
Return to the state of ₂ ). It has been confirmed that the above-mentioned phenomenon can be obtained even with a coating of an insulating material formed by sputtering quartz. Further, in the case where a metal enclosure further covering the metal partition wall is provided, even if the deuterium gas ions or deuterium atoms are generated outside the metal partition wall, they are recombined by the metal enclosure further covering them. It

Therefore, in the structure according to the present invention, deuterium gas ions and deuterium atoms that reach, diffuse and permeate the quartz glass bulb are eliminated, and deuterium gas in the bulb is prevented from decreasing due to discharge. It is possible to extend the life of the discharge tube and downsize it.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a sectional view of an electrode portion showing a first embodiment of a deuterium discharge tube according to the present invention, FIG. 2 is a sectional view of an electrode portion showing a second embodiment of the deuterium discharge tube, and FIG. FIG. 4 is a horizontal sectional view of an electrode portion showing a third embodiment of the discharge tube, and FIG. 4 is a vertical sectional view of the electrode portion of the above embodiment.

In FIG. 1, which is the first embodiment of the present invention,
Reference numeral 1 denotes a bulb, which is a discharge tube container, made of quartz glass, and an end portion thereof is welded to a quartz stem 2 to form a closed container. Several torr of deuterium gas is stored in the valve 1.
It is enclosed. A metal partition wall 6 that shields the electrode portion separates the cathode chamber and the anode chamber, and a partition plate 7 is provided inside the metal partition wall 6.
To the filament of the triple coil made of tungsten, and BaO, SrO, CaO which are thermionic emission materials.
A cathode 3 coated with an oxide such as the above, and a flat plate-shaped anode 4 made of molybdenum are formed into a small hole 5 for discharge narrowing of the partition plate 7.
They are placed opposite each other. A small hole having a diameter of 2 mm is provided in the center of the anode 4. In addition, the cathode 3 and the anode 4
The diameter of the small hole 5 for narrowing the discharge between and is 1 mm. The discharge paths of the cathode 3 and the anode 4 are restricted by metal partition walls 6 surrounded by a metal such as nickel. Further, a small hole having a diameter of 3 mm is also provided in the front of the metal partition wall 6 surrounding the anode 4 in the light extraction direction so as not to block light.
Further, in the cathode chamber in which the cathode 3 made of a filament is placed, the filament is heated at the time of lighting, and the discharge path when a high voltage is applied between the cathode and the anode has the small hole 5 for discharge constriction having a diameter of 1 mm. A metallic lid was attached to the back side to prevent discharge between the filament and the anode without passing through. Valve 1
8 at the tip of the is a window for taking out ultraviolet rays, and quartz containing few impurities was used. In the present invention, nickel is vacuum-deposited on the discharge tube having the above structure to form a nickel coating 10 on the inner wall of the bulb 1, and the light extraction window 8 for extracting the ultraviolet rays is also provided with a small hole 11 having a diameter of 5 mm that does not block light. A nickel coating was provided on the remaining part.

When the filament of the cathode 3 is heated in the discharge tube having the above structure and a DC voltage is applied between the cathode and the anode to turn on the light, a small hole 5 having a diameter of 1 mm provided in the partition plate 7 for discharge constriction. The deuterium gas emits intense light at and emits a continuous spectrum in the ultraviolet region. In the present embodiment, the radiated light passes through a small hole having a diameter of 2 mm provided in the anode 4 and a small hole having a diameter of 3 mm provided in the metal partition wall 6, and the light extraction window 8 has a diameter of 5 m.
It can be obtained from the small hole 11 of m. The plasma generated by the discharge is generated not only between the cathode and the anode but also outside the metal partition wall 6 as described above. However, deuterium ions and deuterium atoms generated in the plasma outside the metal partition wall 6 are generated. Is the nickel coating 10 provided on the inner wall of the valve 1.
Is neutralized by and returns to deuterium molecules without diffusion / permeation through the valve 1.

The metal film vacuum-deposited on the inner wall of the valve 1 like the above nickel film is not limited to nickel and may be another metal such as copper or aluminum, or a conductive film is formed instead of the metal film. However, the same effect can be obtained as long as the film has a melting point of 350 ° or more, which is higher than the temperature of the discharge tube, but it is confirmed that the same effect can be obtained even with a film made of an insulating material obtained by sputtering quartz. ing.

In the second embodiment of the present invention shown in FIG. 2, the metal coating 10 made of nickel or the like is vapor-deposited on the outer wall of the bulb 1 which is a container for a deuterium discharge tube over almost the entire surface. The structure is the same as that of the first embodiment shown in FIG. 1 except for the metal coating 10. Even if the deuterium gas diffuses into the quartz of the bulb due to the discharge, it cannot pass through the metal coating 10 provided on the outer wall, so that the deuterium gas in the bulb 1 decreases even after the discharge time has elapsed. Without shortening the life of the discharge tube.

FIG. 3 showing a third embodiment of the present invention is a cross-sectional view of an electrode portion of a deuterium discharge tube. Reference numeral 1 is a bulb made of quartz glass or hard glass. It is formed, and several torr of deuterium gas is enclosed inside. The metal partition wall covering the electrode portion shown in the bulb 1 is divided into an anode shielding box 14 and a cathode shielding box 15, and a flat plate-shaped anode 4 made of molybdenum is arranged in the anode shielding box 14 to form the cathode shielding box. 15 made of tungsten 3
The filament of the heavy coil is made of Ba
A cathode 3 coated with an oxide such as O, SrO or CaO is installed. Between the cathode 3 and the anode 4, there is a partition plate 7 having a small hole 5 with a diameter of 1 mm for confining the discharge between the electrodes. The cathode 3 and the anode 4 have a structure in which they are surrounded by a metal such as nickel to limit the discharge path between the two electrodes. However, a light passage window 24 is provided in the metal partition wall, and the light passage window 24 is provided. In this embodiment, an enclosure 17 is further provided so as to cover the metal partition wall in the vertical direction, and the surrounding of the light passage window 24 is covered. The enclosure 17 is provided with a through hole 18 coaxially with the discharge constricting small hole 5, the light passage window 24 and the light extraction window 19 of the discharge tube so as not to prevent passage of light.

FIG. 4 is a vertical cross-sectional view of the above electrode portion, but the anode shielding box 14 is covered by the upper lid 20 and the lower lid 21 both in the vertical direction. Further, the cathode shielding box 15 is further provided with the enclosure 17 for covering the cathode shielding box 15 as described above, and the upper lid 22 of the enclosure 17 is provided.
And the lower lid 23 are respectively extended to provide the cathode shielding box 1
The vertical direction of 5 is covered.

When the discharge tube having the above structure is discharged, the deuterium gas emitted through the small hole 5 of 1 mm in diameter for narrowing the discharge provided in the partition plate 7 emits a continuous spectrum in the ultraviolet region,
The synchrotron radiation is through-hole 1 of the enclosure 17 that further covers the metal partition wall.
It can be obtained from the light extraction window 19 via 8. The plasma generated by the discharge spreads to the outside of the metal partition in addition to the discharge path between the electrodes as described above. for that reason,
The deuterium gas ions or deuterium atoms in the plasma that have spread out of the metal partition wall diffuse and reach the enclosure 17 that further covers the metal partition wall to be recombined and returned to the deuterium molecule. Depletion of deuterium gas inside is prevented.

[0021]

As described above, the deuterium discharge tube according to the present invention encloses a cathode and an anode coated with an electron-emitting substance in a tube filled with deuterium or hydrogen, and a discharge path from the cathode to the anode. In a deuterium discharge tube in which a metal partition wall is formed, and a small hole for narrowing the discharge path is provided in a part of the metal partition wall, except for a part in the light extraction direction, a further covered enclosure is provided. As a result, deuterium gas ions or deuterium atoms in the plasma that spread outside the metal partition during discharge are recombined by the enclosure that further covers the metal partition, so that the deuterium gas in the discharge tube decreases. Less, you can get a long life deuterium discharge tube,
There is an effect that the discharge tube can be downsized while avoiding a short life.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrode portion showing a first embodiment of a deuterium discharge tube according to the present invention.

FIG. 2 is a sectional view of an electrode portion showing a second embodiment of the deuterium discharge tube.

FIG. 3 is a cross-sectional view of an electrode portion showing a third embodiment of the deuterium discharge tube.

FIG. 4 is a vertical cross-sectional view of an electrode portion of the above embodiment.

5A and 5B are views showing a conventional deuterium discharge tube, in which FIG. 5A is an external view and FIG. 5B is a cross section of an electrode portion.

FIG. 6 is a view showing a cross section of a deuterium discharge tube used in an experiment.

[Explanation of symbols]

1 valve 3 cathode 4 anode 5 small hole for discharge confinement 6 metal partition 10 and 17 metal enclosure

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Go Fukuda 888 Fujibashi, Ome-shi, Tokyo Hitachi Ltd. Ome factory

Claims (4)

[Claims] 1. A metal partition for enclosing a cathode and an anode coated with an electron emitting substance in a tube filled with deuterium or hydrogen and for forming a discharge path from the cathode to the anode. In a deuterium discharge tube having a small hole for narrowing the discharge path in its part, except for a part in the light extraction direction, the metal partition wall is provided with an enclosure further covered with a metal such as nickel. Characteristic deuterium discharge tube. 2. The enclosure further covering the metal partition wall is a metal coating such as nickel, a conductive coating or a coating of an insulating material, which is provided on the inner surface or the outer surface of the tube while avoiding the electrode introduction line. The deuterium discharge tube according to claim 1. 3. The deuterium discharge tube according to claim 2, wherein the metal coating, the conductive coating or the insulating material coating has a melting point of 350 ° or more. 4. The deuterium discharge tube according to claim 1, wherein the enclosure that further covers the metal partition wall is an enclosure that covers the periphery of the metal partition wall except a part in the light extraction direction.