JPS6032244A - Deuterium discharge tube - Google Patents

Abstract

PURPOSE:To obtain a deuterium discharge tube which requires only a low firing potential to start discharging by forming a conductive film having a surface resistance within specified range between the anode and the shielding case. CONSTITUTION:An anode 2 is fused (by electric welding) to the exposed portion of a lead-in wire 22 covered by glass 21; the lead-in wire 22 penetrates the bottom plate 3' of a shielding case 3 with an insulator 23 interposed. A part of the surface of the insulator 23 located above the bottom plate 3' is coated with a conductive film 24 consisting of one of tin oxide, Cr-SiO and Cr-N, so that the anode 2 is electrically connected to the bottom plate 3' through the conductive film 24. The thickness of the conductive film 24 is adjusted so that its surface resistance is in the range of 5kOMEGA-5MOMEGA. Owing to the above constitution, precedent discharge develops between the anode 2 and a pin hole 5. During this precedent discharge, a cathode 1 is heated to produce suspended thermions. Following that, discharge develops between the anode 2 and the cathode 1. Accordingly, discharge can stably be initiated with a low firing potential.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a deuterium discharge tube used in a spectrophotometer.

[Background of the invention]

A deuterium discharge tube is usually used as a radiation source for the ultraviolet continuous spectrum used in a spectrophotometer, and a radiation source that emits strong triplet wavelengths that are emitted in conditions close to a point light source is particularly required. . In the continuous spectrum emission of deuterium, when the concentration of deuterium molecules is high and the electron energy is high, the spectrum due to the transition from an excited state to an excited state appears strongly, and in particular, the triplet spectrum from 2Sσ3Σg to 2P♂ΣU appears strongly. . The shape of a positive column in a deuterium gas discharge is different from that in a general discharge, and a standing positive column is formed in a region where the discharge current and deuterium density are high. The formation of this ray-stationary positive column appears more prominently as the deuterium recombination rate increases, so it has the same tendency as continuous spectrum radiation.

Therefore, a deuterium discharge tube for continuous ultraviolet spectrum uses a partition wall of a metal plate with a recess with pinholes as a cathode to focus the above-mentioned standing positive column of light and increase the recombination rate of deuterium. It is installed between the anode and the anode. Therefore, a particularly bright area is generated in the pinhole and the vicinity of the pinhole, and a discharge between the anode and the cathode occurs with a focused positive column in this bright area and a standing positive column with light stripes in front of it. A column of focused sunlight in the bright area shows a continuous spectrum.

A conventional deuterium discharge tube has a directly heated electron emitting cathode 1 and an anode 2 made of a molybdenum plate, as shown in the partial cross-sectional view of FIG. 1 and the A-A cross-sectional view of FIG. In order to block light emission due to the arc spot on the surface of the cathode 1 generated during discharge and the anode glow generated on the surface of the anode 2, the cathode 1 and the anode 2 are surrounded and isolated except for a part with a metal shielding case 3. There is. A slit 4 is provided on the side surface of the shielding portion surrounding the cathode 1, and a shielding plate 6' having a recess 6 with a pinhole 5 in the center is arranged on the front surface of the anode 2.
A discharge path between the cathode 1 and the anode 2 is curved through the pinhole 5. A central slit 7 is provided in the shielding case 3 located in front of the pinhole 5, and the whole is hermetically sealed with a quartz bulb 9 having a window 8 for transmitting ultraviolet rays on the front thereof. Filled with deuterium gas of several Torr, the cathode heating lead wire 10
．． 11, Anode lead wire 12, Lead wire for shielding case 13
are led out of the quartz pulp 9 via stems] 4, respectively. If the lead wire 13 for the shielding case of the deuterium discharge tube having the above structure is connected to the lead wire 10 or 11 for cathode heating and discharge is caused, the pinhole 5 in the center of the slit 4 and recess 6 on the side surface of the cathode 1 Of the positive light pillars formed between the two, the light from the focused positive light pillar near the pinhole 5 passes through the central slit 7 and the ultraviolet transmission window 8 and is emitted to the front as a continuous spectrum of ultraviolet rays.

The discharge starting voltage is determined by Paschen's law, and as can be seen from FIG. 3, which shows the relationship between the discharge tube diameter and the discharge starting voltage, as the discharge tube diameter becomes smaller, the discharge starting voltage increases accordingly. :Curve in Figure 53] 5.16, I7
, ]8.19.20 are discharge tube diameters of 5 and 2, respectively.
crn, 2.1-cm% 1.3 cmz O,
95 cps 0.5 ffi.

The figure shows the discharge starting voltage of discharge in air when the distance between the electrodes is 2.7 cm in the case of 0.3 on. In the deuterium discharge tube described in 2 above, the discharge between the cathode 1 and the anode 2 is carried out through the pinhole 5, so the discharge path is partially constricted, and as in the case shown in FIG. The discharge starting voltage becomes higher than that of a discharge tube having a general structure. This has disadvantages in that the cathode 1 in the hot cathode discharge tube 46 is consumed to a large extent, and it also has a disadvantageous effect on lighting circuits using semiconductor elements and pulse lighting circuits, such as requiring high withstand voltage.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a deuterium discharge tube for use in the continuous ultraviolet spectrum, which has a low firing voltage.

[Summary of the invention]

In order to achieve the above object, the deuterium discharge tube according to the present invention has a cathode and an anode each partially shielded by a shielding case, and a recess located between the cathode and the anode and having a pinhole in the center. In a deuterium discharge tube, a shielding plate electrically connected to the shielding case is provided, and these are sealed together with deuterium gas in a quartz bulb having an ultraviolet-transmitting window. By providing a conductive thin film with a resistance of 51Ω or more and 5MΩ or less, a preliminary discharge is generated between the anode and the above pinhole, and then the discharge is transferred between the anode and the cathode. The discharge tube is designed to discharge at a low discharge starting voltage.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 is a partial sectional view showing an embodiment of the deuterium discharge tube according to the present invention, FIG. 5 is a sectional view taken along line AA in FIG. 4, and FIG. 6 is a sectional view of the anode portion in the above embodiment. FIG. 7 is a diagram showing the relationship between the cathode heating voltage and the discharge starting voltage in the above embodiment, FIG. 8 is a diagram showing the change in the discharge starting voltage with respect to the resistance value of the conductive thin film in the above embodiment, and FIG. The figure is a partial sectional view showing another embodiment of the deuterium discharge tube according to the present invention. As shown in FIGS. 4 and 5, the basic structure of the deuterium discharge tube according to the present invention is the same as the conventional deuterium discharge tube shown in FIGS. 1 and 2. That is, it has a directly heated electron emitting cathode 1 and an anode 2 made of a long and thin molybdenum plate bent as shown in FIG. I'm doing○
A molybdenum shielding plate 6' having a slit 4 on the side surface of the shielding part surrounding the cathode 1 and a recess 6 with a pinhole 5 in the center on the front surface of the anode 2 is arranged and electrically connected to the shielding case 3. The shielding case 3 located in front of the pinhole 5 is provided with a central slit 7) The whole is hermetically sealed with quartz pulp 9 having an ultraviolet transmitting window 8, and heavy/hydrogen gas of several Torr is filled. There is. The difference from the conventional deuterium discharge tube is the structure of the anode portion shown in FIG. 6, and the shielding case lead wire J3 is not led out to the outside of the flare of the stem 14 connected to the quartz bulb 9. The anode 2 has a lead-in wire 22 covered with a glass 21 connected to the bottom plate 3' of the shielding case 3.
In this embodiment, the surface of the insulator 23 located on the bottom plate 3' is coated with tin oxide, Or-Sin, or Or-N. A conductive thin film 24 is formed, and the anode 2 is electrically connected to the bottom plate 3' of the shielding case 3 through this conductive thin film, and the surface resistance of the conductive thin film 240 is 5Ω to 5MΩ.
The film thickness was adjusted to fall within the range of . FIG. 7 is a diagram showing the discharge starting voltage with respect to the cathode heating voltage of the above example,
In the figure, curve A shows the discharge starting voltage when the resistance of the conductive thin film 24 of this embodiment is 50 kΩ, and curve B shows the discharge starting voltage when the shielding case 3 is connected to the cathode 1 and the pinhole 5 is connected to the cathode 1.
Curve C shows the discharge starting voltage when the shielding case 3 is electrically floated. It was confirmed that when the cathode heating voltage was 5 V or more, the deuterium discharge tube of this example discharged at a very low firing voltage. In this case, a preliminary discharge occurs between the anode 2 and the pinhole 5, but during that time the cathode 1 is heated, creating a floating state of thermionic electrons, and then the discharge shifts to between the anode 2 and the cathode. it is conceivable that. FIG. 8 shows an example of the relationship between the surface resistance value of the conductive thin film 240 and the discharge starting voltage. is also small, so no discharge occurs. Furthermore, if the resistance value exceeds 5MΩ, the discharge starting voltage will rise rapidly;
As shown in FIG. 8, within the range of Ω to 5 MΩ, the deuterium discharge tube of this embodiment can stably discharge at a low firing voltage.

Another embodiment of the deuterium discharge tube according to the present invention is as shown in FIG. Conductive thin film 24 between case lead wire 13
, and the surface resistance value of the conductive thin film 240 is in the range of 5Ω to 5MΩ, and the same functions and effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, the deuterium discharge tube according to the present invention includes a cathode and an anode each partially shielded by a shielding case, and a shielding plate located between the cathode and the anode and having a recess with a pinhole in the center. A deuterium discharge tube is provided electrically connected to the shielding case, and these are sealed together with deuterium gas in a quartz bulb having an ultraviolet transmission window.The surface resistance between the anode and the shielding case is 55. By providing a conductive thin film of Ω or more and 5 MΩ or less, a preliminary discharge is generated between the anode and the pinhole, and the discharge is subsequently transferred to the heated cathode.
It is possible to obtain a deuterium discharge tube that discharges at a lower firing voltage than conventional deuterium discharge tubes, and it is possible to make the spectrophotometer compact.

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional view of a conventional deuterium discharge tube, Figure 2 is a cross-sectional view taken along line A-A in Figure 1, Figure 3 is a diagram showing the relationship between discharge tube diameter and firing voltage, and Figure 4 is a diagram showing the relationship between discharge tube diameter and firing voltage. The figure is a partially cutaway Ini diagram showing one embodiment of the deuterium discharge tube according to the present invention, and Figure 5 is A of Figure 4.
- A sectional view, FIG. 6 is a sectional view of the anode part in the above embodiment, FIG. 7 is a diagram showing the relationship between the cathode heating voltage and the discharge start type L]-' in the above embodiment, and FIG. FIG. 9 is a partial cross-sectional view showing another embodiment of the deuterium discharge tube according to the present invention. 1... Cathode, 2... Anode, 3... Shielding case, 5
...pinhole, 6...dent, 6'...shielding plate,
8... Ultraviolet transmitting window, 9... Quartz pulp, 24...
・Conductive thin film. Representative Patent Attorney Junnosuke Nakamura Figure 1 Figure 2 Figure 3 Figure Off Figure L2 Years and Power 0 Power QfX (v) Buddha's Value (1) Figure 9

Claims (1)

[Claims] A cathode and an anode each of which is partially shielded by a shielding case, and a shielding plate located between the cathode and the anode and having a recess with a pinhole in the center are provided and electrically connected to the shielding case. In a deuterium discharge tube in which deuterium gas is sealed in quartz pulp with an ultraviolet-transmitting window, there is a surface resistance of 5 between the anode and the shielding case.
A deuterium discharge tube characterized in that a conductive thin film of Ω or more and 5 MΩ or less is provided on the tube.