JPH04319248A - Deuterium discharge tube - Google Patents

Abstract

PURPOSE:To stabilize the light output by making a slit formed in a cathode diaphragm of an electrode shielding box like a strip or a circular shape. CONSTITUTION:A small hole aperture 5 to narrow the electric discharge is formed between a cathode 3 and an anode 4 of a deuterium or hydrogen discharging tube. The cathode 3 and the anode 4 are so surrounded with metal plates such as nickel as to be shield by a shielding box 2. A slit 7 to limit the discharging route is formed in a diaphragm of a cathode chamber in the anode 3 side. The shape of the slit 7 is made either circular or like a strip and the slit 7 is made to cross rectangularly with a filament. Consequently, the fluctuation due to the movement of a cathode bright point is suppressed and the fluctuation of radiation brightness is lessened and thus the light output is stabilized.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a deuterium discharge tube used as an ultraviolet light source for spectrophotometers, liquid chromatography, etc. Regarding improvements.

0002

[Prior Art] Deuterium discharge tubes are described in "Characteristics and Usage of Light Sources, edited by the Spectroscopical Society of Japan (March 1985, Society Publishing Center), pages 20 to 30."

[0003] A deuterium discharge tube has hydrogen or deuterium gas sealed in an airtight container consisting of a bulb and stem made of quartz or the like, and uses a coiled cathode and a flat anode as electrodes. A small hole is provided in the middle of the cathode and anode to constrict the discharge, and the cathode chamber also has a vertically elongated slit. This discharge tube has a structure in which the electrodes are surrounded by a complex-shaped metal shielding box made up of several parts.

FIG. 4 shows a partial sketch of the electrode section of a conventional deuterium discharge tube. Inside the shielding box 2, a cathode 3 and an anode 4 made of a filament are arranged as shown in the figure.

[0005] A rectangular slit 6 is provided in the partition plate covering the cathode chamber, and this hole controls the discharge path. Conventionally, the slit hole was a rectangular shape with a width of 3 mm and a length of 5 mm.
Since it was installed parallel to the filament, almost the entire cathode coil of the filament could be seen. Therefore, when the cathode bright spot moves during lighting, the discharge path changes vertically, causing fluctuations in the discharge. For this reason, fluctuations in discharge appear as fluctuations in radiance, causing optical output to become unstable.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a deuterium discharge tube in which fluctuations in radiance are reduced by eliminating the fluctuations in the discharge path caused by the movement of the cathode bright spot as described above. It is in.

[0007]

[Means for Solving the Problems] The above object can be achieved by making the cathode chamber slit hole circular or by providing a rectangular slit orthogonal to the filament.

[0008]

[Operation] The cathode of the deuterium discharge tube is a filament made of tungsten wire coated with an electron emitting substance, and the anode is a flat electrode made of molybdenum or the like. shadow,
A small aperture is provided between the anodes to constrict the discharge. Each electrode is surrounded and shielded by a metal plate made of nickel or the like. Further, the discharge tube has a structure in which a rectangular slit hole is provided in the anode side partition plate of the cathode chamber to limit the discharge path.

The purpose of the above configuration is to obtain a discharge path in which discharge passes through the cathode, the cathode chamber slit, and the discharge constriction aperture to reach the anode.

[0010] Due to the discharge, deuterium gas emits strong light at the aperture portion where the discharge is constricted, and ultraviolet rays are emitted.

[0011] The cathode bright spot may move to a location on the filament where thermionic emission is more likely.

When the cathode bright spot moves in this way, in the conventional structure in which the slit and the filament are provided in parallel, the discharge path changes in the vertical direction, causing fluctuations in the discharge. When such discharge fluctuations occur, the radiance also slightly fluctuates, which becomes a factor that worsens stability. If the slit is provided at right angles to the filament, or if it is circular, the discharge path will not move up or down even if the cathode bright spot moves along the filament, so fluctuations in the discharge can be minimized. Therefore, the radiance is also stable.

If the diameter of the circular slit or the length of the short side of the strip-shaped slit perpendicular to the filament is between 2 and 3 times the diameter of the aperture for discharge constriction, the brightness will decrease. It had the characteristics of good stability and good discharge starting characteristics.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view showing the center of an electrode of a deuterium discharge tube according to an embodiment of the present invention. Reference numeral 1 designates the container of the discharge tube, which is made of quartz or hard glass and whose end is welded to the stem to form a closed container. Deuterium gas or hydrogen gas is sealed in the container at several Torr. 2 shows the shielding box of the electrode part, and the filament of the triple coil made of tungsten is coated with thermionic emitters BaO and Sr.
A cathode 3 coated with an oxide such as O or CaO and a flat anode 4 are arranged. Further, between the cathode and the anode, there is a partition plate provided with an aperture 5 having a diameter of φ1 for narrowing the discharge. The cathode and anode are surrounded by metal such as nickel to control the discharge path. The anode chamber in which the anode is placed is sealed vertically with metal such as nickel to limit the discharge path. 7 is a slit for controlling the cathode chamber discharge path provided in the partition plate on the anode side of the cathode chamber.

8 is a window for extracting ultraviolet rays;
Quartz with few impurities is used. 9 indicates the light extraction direction.

The movement of the cathode bright spot that occurs during lighting of the discharge tube is due to the movement of the cathode bright spot to a location on the filament where it is easy to emit thermionic electrons, and is mostly in the vertical direction of the filament installed vertically. Therefore, fluctuations in the discharge path also appear as fluctuations in the vertical direction.

FIG. 2 is a sketch of the electrode portion of the deuterium discharge tube of the present invention. A cathode 3 made of a triple-coiled filament is covered with an insulator 10 to electrically insulate it from the shielding box 2, and is connected to an external lead wire via an introduction wire. The slit 7 provided in the anode-side partition plate of the shielding box where the cathode is placed must be made φ2, which is twice the diameter of the aperture for discharge constriction, in order to prevent the discharge starting voltage and lamp voltage from increasing. It was placed so that it was in the center of the

FIG. 3 shows a sketch of the electrode section of the second embodiment. The slit 11 provided in the anode-side bulkhead plate of the shielding box where the cathode is placed was shaped horizontally so as to be perpendicular to the filament, and was a rectangle with a length of 2 mm and a width of 5 mm, and was placed in the center of the filament as described above. .

By making the slit provided on the anode side of the shielding box in which the cathode is arranged into a round slit or a horizontally elongated slit that is slightly larger than the aperture diameter, the cathode bright spot moves during lighting. Since the discharge path is always located at the center of the filament, fluctuations in discharge can be reduced, resulting in a deuterium discharge tube with extremely small fluctuations in radiance.

[0020]

Effects of the Invention In the deuterium discharge tube of the present invention, the cathode bright spot can be reduced by making the slit in the anode side partition plate of the shielding box in which the cathode filament is arranged circular or horizontally elongated. Since it is possible to suppress the fluctuation of the discharge path due to the movement of the deuterium discharge tube, the fluctuation of the radiance can be reduced, and a highly stable deuterium discharge tube can be obtained.

[Brief explanation of drawings]

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

FIG. 2 is a sketch of an electrode portion showing an example.

FIG. 3 is a sketch of an electrode portion showing a second embodiment.

FIG. 4 is a sketch of an electrode portion showing a prior art.

[Explanation of symbols]

1... Container, 2... Shielding box, 3... Cathode, 4... Anode, 5... Aperture, 7... Slit, 8... Light extraction window.

Claims (1)

[Claims] Claim 1: In the electrode shielding box of a discharge tube filled with deuterium or hydrogen gas, the slit hole for controlling the discharge path provided in the cathode chamber partition plate between the cathode and the anode has a circular structure or a strip-shaped slit. A deuterium discharge tube characterized by having a cathode filament and a cathode filament perpendicular to each other.