JPH0515720Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pinch seal stem of a deuterium discharge tube used in a spectrophotometer.

[Conventional technology]

The ultraviolet continuous spectrum radiation source used in a spectrophotometer usually uses a deuterium discharge tube, and in particular a radiation source that generates a strong triplet spectrum that is emitted under conditions close to a point light source is desired. . The form of a positive column in a deuterium gas discharge is different from that in a general discharge, and a positive column with light stripes is formed in a region with a certain discharge current and deuterium density. The formation of this light striped standing positive column appears more prominently as the recombination rate of deuterium increases, so it has a tendency similar to that of continuous spectrum radiation. Therefore, the deuterium discharge tube used for ultraviolet continuous spectrum is a metal tube with a concave pinhole in order to focus the above-mentioned light striped standing solar column and increase the recombination rate of deuterium. A partition wall is provided between the cathode and the anode. Therefore, a particularly bright part is generated in the pinhole and the vicinity of the pinhole, and a discharge occurs between the focused positive light column in this part and the light striped standing positive light column in front of it, but the focused positive light column is generated in the above bright part. It exhibits a continuous spectrum. The radiation output is shown in FIG. 3, and the radiation output decreases as the wavelength increases from around 170 nm to 360 nm. Even with such a continuous spectrum, the light that our naked eyes perceive is 486 nm, which is much weaker than the intensity of the continuous ultraviolet spectrum.
The only spectral lines are the Hβ line and the Hα line at 656 nm. As shown in FIG. 4, the continuous spectrum intensity distribution of the deuterium discharge tube varies depending on the wavelength, and the peak of the maximum value is closer to the cathode side than the center of the pinhole of the deuterium discharge tube, and the shape of the change is steep. In FIG. 4, a shows the wavelength dependence, and b shows the discharge current dependence. In the above-mentioned mountain shape, a second mountain appears on the wavelength side longer than 260 nm. As mentioned above, the intensity distribution of the spectrum is steep, and adjusting the position of a spectrophotometer using this to obtain the maximum value at each wavelength is a technique that requires great skill.

The mechanism of the electrode section of the deuterium discharge tube will be explained using FIG. FIG. 1a is a partial cross-sectional view of a deuterium discharge tube, and FIG. 1b is a cross-sectional view taken along line A-A. As shown in a and b, it has a directly heated thermionic emission cathode 1 and an anode 2 made of a molybdenum plate. In order to block light emission, the cathode 1 and anode 2 are placed in a metal shielding case 3.
All but a few areas are surrounded and isolated.
Further, a front shielding case 4 surrounding the cathode 1 is provided, and a recess 6 with a pinhole 5 in the center is provided on the front surface of the anode 2.
is provided, and the discharge path between the cathode 1 and the anode 2 is
It is formed in a curved manner so as to pass through the pinhole 5 mentioned above. A central slit 7 of the front shielding case 4 is provided in front of the pinhole 5 (in the direction of the arrow), and the whole is hermetically sealed with a quartz bulb 8 in the case shown in FIG. , several Torr of high-purity deuterium gas is sealed in the quartz bulb 8, and each lead wire 9, 10, 1
1 and 12 are led out of the quartz bulb 8. If the lead wires of the deuterium discharge tube of the above structure are connected through the necessary auxiliary resistors and discharged, the pinhole 5 in the center of the cathode 1 and the recess 6
Among the positive light pillars formed between the central slit 7 and
A continuous spectrum of ultraviolet rays is emitted to the front through a quartz glass bulb that also serves as a window for transmitting ultraviolet rays. To obtain the maximum value of this emitted UV continuum spectral intensity distribution, the deuterium discharge tube is lit,
Set the wavelength of the spectrophotometer to a wavelength below 250 nm,
The mounting position of the deuterium discharge tube must be adjusted and set so that the spectrophotometer meter shows the maximum value. This operation is very difficult to adjust the mounting position for the above setting because the shape of the peak indicating the maximum value in the continuous spectral distribution characteristic curve is steep.

By the way, typical examples of the stem and bulb of a conventional deuterium discharge tube are shown in FIGS. 5a and 5b. That is, in FIG. 5a, the bulb 16 is a quartz glass tube, and the stem 14 contained in the bulb 16 is as follows:
Each lead wire 9, 10, 11, 12 is melt-sealed using an ordinary glass tube (molybdenum glass), and a quartz bulb 1 is attached to the tubular end of the stem 14.
A Gradual Seal 19 is provided for welding to 6. Also, the fifth
In FIG. b, ordinary glass (molybdenum glass) is used for the bulb 17, and a gradual seal 20 is used to weld the synthetic quartz glass window 18 to this. For this reason, the stem 15 enclosed in the bulb 17 has lead wires 9, 10, 11, and 12 melt-sealed to common glass such as molybdenum glass. Therefore, in the conventional mounting adjustment of the deuterium discharge tube, mounting metal fittings were provided on the outer circumferential surfaces of the bulbs 16 and 17 to support the discharge tube and adjust the optical axis.

[The problem that the idea aims to solve]

However, the installation location of the deuterium discharge tube in a spectrophotometer is generally small, and the wall temperature of the bulb glass during lighting adjustment is approximately 120°C.
The operation was extremely difficult.

Some commercially available deuterium discharge tubes have a flanged metal fitting with a fitting hole made in advance that aligns with the set position on the spectrophotometer and is glued to the outer circumference of the bulb with cement. shows the position of the fitting hole at this time by aligning the center of the spherical image of the light striped standing positive column appearing in the recess 6 of the deuterium discharge tube and the pinhole 5 as the optical axis of the spectrophotometer. ing. The light from the hydrogen discharge tube that allows the image of the above-mentioned light striped standing positive column to be seen with the naked eye is Hβ with a wavelength of 486 nm and
This is light in the Hα spectral line of 656 nm, which is quite different from the ultraviolet continuous spectral distribution. Compared to when the meter is adjusted at a wavelength of 250 nm or less, the former is only about 36% of the latter's light intensity.

The object of the present invention is to obtain a deuterium discharge tube that can be reliably, easily and securely mounted in addition to optical axis adjustment and support.

[Means to solve the problem]

The above objective is achieved by making the stem of the deuterium discharge tube an outer pinch seal stem made of quartz glass, and by attaching and operating a metal fitting that also serves as optical axis adjustment at the position of the pinch seal stem. Ru.

[Effect]

A bulb of a deuterium discharge tube is formed using quartz glass, each lead wire is led out from the base of the bulb, and a stem is formed by pinch-sealing from the outside. The stem thus formed has the lowest glass wall temperature in the deuterium discharge tube.
Therefore, by attaching a metal fitting for optical axis adjustment and installation to the stem portion, and supporting and installing the discharge tube using this metal fitting, the adjustment operation can be made easily and reliably with a small size. Furthermore, since the support portion is the lowest temperature portion of the bulb, there is no risk of cracking the glass due to thermal shock.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. Fig. 1 shows a deuterium discharge tube showing an embodiment of the pinch seal stem according to the present invention, in which a is a partial sectional view, b is a sectional view taken along line A-A, and Fig. 2 is an enlarged sectional view of the above embodiment. It is a diagram. In the pinch seal stem of the above embodiment, a welded encapsulation lead-in line is prepared prior to pinch sealing. The edges of a rectangular molybdenum foil with a thickness of 30 μm are sharply edged, and four molybdenum foil conductors 25,
26, 27, and 28 are formed. The cathode heating lead wire 9 and the conductor 21 connected to the cathode 1 are fixed to both ends of the first molybdenum foil conductor 25 by electric welding, for example. Similarly, each of the other lead wires 10, 1
1 and 12 are respective molybdenum foil conductors 26,
Through 27 and 28, the other end conductor 22 of the cathode 1,
The conductor 23 connected to the anode 2 and the conductor 24 connected to the shielding case 3 are welded, respectively. Note that a quartz glass tube 29 is inserted into the conductor 23 connected to the anode 2 so as to surround its outer periphery, as shown in FIG. The molybdenum foil conductors 25, 26, 27, 28, each of which has been welded to each lead wire and each conductor as described above, are correctly installed at predetermined dimensional positions of the quartz bulb 8 forming the deuterium discharge tube. Pinch-seal the valve 8 from the outside with a pinch-seal machine while heating it to 1200°C or higher relative to the installation position, and pinch-seal the welded part 1.
form 3. At this time, the quartz glass tube 29 placed over the conductor 23 connected to the anode 2 is simultaneously welded, and discharge to the anode conductor 23 can be completely prevented. Pinch formed as above
The seal stem part has a thick welded glass part and strong mechanical strength, and is also the part of the deuterium discharge tube bulb 8 where the temperature rise is the lowest, so it is necessary to safely attach the support fitting for positioning adjustment. I can do it.

[Effect of idea]

As described above, the pinch seal stem of the deuterium discharge tube according to the present invention is a pinch seal stem of the deuterium discharge tube that emits continuous ultraviolet spectral lines, and the pinch seal is placed on the outside of the discharge tube bulb. By installing the optical axis adjustment and mounting bracket on the pinch seal section, the pinch seal stem part has a thick wall and strong mechanical strength, so the mounting bracket can be used for optical axis adjustment and support. Since it is firmly and reliably installed, and the temperature distribution of the glass wall as a deuterium discharge tube is the lowest, cracks due to thermal shock that tend to occur when installing the metal fittings mentioned above are less likely to occur, which was conventionally done. It is safer and less dangerous than installation at the valve part. Furthermore, since the deuterium discharge tube according to the present invention does not use a gradient seal, there is no fear of cracks or slow leaks in the above-mentioned gradient seal portion, and a highly reliable deuterium discharge tube can be obtained. .

[Brief explanation of the drawing]

Fig. 1 shows a deuterium discharge tube showing an embodiment of the pinch seal stem according to the present invention, in which a is a partial cross section, b is a sectional view taken along line A-A, and Fig. 2 is an enlarged sectional view of the above embodiment. , FIG. 3 is a diagram showing a continuous spectrum radiation output curve with respect to wavelength of deuterium discharge tube characteristics,
Fig. 4 is a continuous spectrum intensity spatial distribution curve diagram of the discharge tube, where a shows the wavelength dependence, b shows the discharge current dependence, and Fig. 5 shows a conventional deuterium discharge tube. , a is a diagram showing a stem using a gradual seal, and b is a diagram showing an example using an ordinary flared stem. 8... Valve, 13... Pinch seal.

Claims (1)

[Scope of utility model registration request] In the pinch seal stem of a deuterium discharge tube that emits ultraviolet continuous spectral lines, the pinch seal is performed outside the discharge tube bulb, and the optical axis adjustment and mounting fittings are provided in the pinch seal part. Pinch of deuterium discharge tube characterized by
seal stem.