JPS629977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen discharge tube, and more particularly to improvements in a hydrogen discharge tube used as a light source for spectroscopic analysis.

In recent years, spectroscopic analyzers have been required to have higher performance, and increasing the brightness of their light sources has become an important issue. Among these, hydrogen discharge tubes used as correction light sources during atomic absorption spectrometry are desired to have a longer lifespan and be easier to handle. Generally, increasing the discharge current of a hydrogen discharge tube increases the emission intensity. However, simply increasing the current density causes the temperature of the hydrogen discharge tube to rise, making the heat resistance of each electrode problematic and requiring cooling of the tube. If the so-called lifespan is shortened, there is no practical value.

An object of the present invention is to provide a hydrogen discharge tube that has a long life and can provide high analytical accuracy.

The present invention includes, in a tube, an anode chamber having a radiation density enhancement hole, a cathode chamber having a cathode chamber discharge path hole, and a partition wall having a light extraction window for restricting the direction of light extraction, and a cathode inside the cathode chamber. an anode is placed in the anode chamber, a discharge is caused between the cathode and the anode through the radiation density enhancement hole and the cathode discharge path hole, and as a result of this discharge, the area near the radiation density enhancement hole is In the hydrogen discharge tube, a third electrode is provided at a position that does not obstruct the discharge path during discharge between the cathode and the anode and the path of light restricted by the light extraction window. , the cathode chamber is arranged in a position that does not obstruct the passage of light restricted by the light extraction window, the size of the radiation density enhancement hole is formed smaller than the size of the cathode discharge path hole, and the cathode A main discharge is caused intermittently between the cathode and the anode, and at least during the stop period of the intermittent main discharge, a power that is lower than the main discharge power is applied between the cathode, one of the anodes, and the third electrode. The present invention is characterized in that auxiliary discharge is performed with a small discharge sustaining power.

In the present invention, by causing an auxiliary discharge between the cathode or the anode and the third electrode using a small discharge sustaining power, floating electrons are generated in the space inside the tube, and a high discharge starting voltage is generated during the main discharge. care has been taken to ensure that this is not required. Light emission occurs not only during the main discharge but also during the auxiliary discharge, but since the supplied power is low in the auxiliary discharge, the luminescence intensity is much lower than that during the main discharge (usually several tenths or less). In the present invention, both the third electrode and the cathode chamber are arranged at positions that do not interfere with the passage of light restricted by the light extraction window.

Generally, when a discharge occurs without any physical constraints on the discharge path, a light emission phenomenon occurs in a region far from the anode and close to the cathode. In other words, light is emitted near the cathode. However, if something that narrows the discharge path, such as a radiation density enhancement hole, exists in the discharge path, the current density of the discharge is rapidly increased by the hole, and a light emission phenomenon occurs near the hole. In this manner, strong light emission occurs near the radiation density enhancement hole during the main discharge in the present invention.

On the other hand, in preferred embodiments of the present invention, a case is shown in which a cathode chamber wall is used as the third electrode, a case in which an electrode 30 is used in place of an anode, and a case in which an electrode 32 is used in place of a cathode. These third electrodes are used for auxiliary discharge with low power between the original cathode or anode, but the location where the weak light generated during the discharge is emitted is similar to the path of the light that should be taken out during the main discharge. The weak light is prevented from leaking to the outside by a partition wall having a light extraction window or by the anode itself.

FIG. 1 is a sectional view showing the structure of a hydrogen discharge tube according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A' in FIG. The anode 2 is placed in the anode chamber 9. The cathode chamber 10 and the discharge light emitting chamber 11 have a cylindrical shape that is open in the vertical direction, and the anode chamber 9 is integrally formed in a box shape that is closed in the vertical direction and is supported by the stem 8 by a conductor 12. . Further, the cathode 1 and the anode 2 are similarly supported by the stem 8 by conductors, and these conductors protrude from the lower part of the tube body 7. .

As shown in FIG. 2, the tube body 7 is a cylindrical glass tube with a part thereof protruding, and a glass plate that transmits ultraviolet rays well is attached to the tip of the tube so as to be perpendicular to the light beam 23, and deuterium is sealed therein. ing. The above cathode chamber 10
A cathode discharge path hole 6 is provided in the partition wall between the discharge light emitting chamber 11 and the discharge light emitting chamber 11, a radiation density enhancement hole 4 is provided in the partition wall between the discharge light emitting chamber 11 and the anode chamber 9, and a light outlet of the discharge light emitting chamber 11 is provided with a radiation density enhancement hole 4. It has a light extraction window 5.

In the hydrogen discharge tube configured as above, when the cathode 1 is appropriately heated and DC power is continuously applied between the cathode 1 and the anode 2 to cause continuous light emission,
The electric circuit for receiving and processing the light becomes complicated, and the amount of heat generated is limited, making it impossible to obtain strong light emission. On the other hand, if DC power is intermittently applied between cathode 1 and anode 2 to generate a rectangular wave pulse, a large discharge starting voltage will be required each time power is applied, and this high voltage will accelerate the discharge. The ions collide with the cathode and consume it, accelerating the deterioration of the hydrogen discharge tube.

In the hydrogen discharge tube of this embodiment, the common metal plate partition 3 forming the electrode chambers 9, 10 and the discharge luminous chamber 11 is connected to a power source, and an auxiliary discharge is generated between the cathode 1 and the cathode chamber wall. This is what I did.

FIG. 3 shows a power supply circuit for causing the hydrogen discharge tube of this embodiment to emit light. A cathode 1 and an anode 2 are arranged in the tube body 7 of this embodiment, and the anode 2 is connected to the DC power source 13.
The cathode 1 conducts a cathode heating input 19 to the contacts 17 of the relay 15 through the conductor of the relay 15.
It is connected to the contact 16 of. On the other hand, the third electrode (metal partition plate) 3 is connected to the relay 15 via the DC power supply 14.
It is connected to the contact 18 of. First, as shown in FIG. 3, the third electrode 3 and the cathode 1 are connected and a low direct current is applied to generate a discharge to start the discharge. Next, switch the contact piece of contact 16 to contact 17, and
A strong current is passed between the anode 2 and the anode 2 to cause a discharge, and this is done alternately. That is, a low current is passed between the cathode 1 and the third electrode 3, and a strong current is passed between the cathode 1 and the anode 2 to cause discharge.

FIG. 4 is a diagram showing the relationship between the light extracted from the hydrogen discharge tube of this embodiment and the power supply status, and the horizontal axis represents time. Top pulse-shaped curve 2
0 indicates the electric power supplied between the cathode 1 and the anode 2, and the middle curve 21 indicates the intensity of the light emitted and extracted to the outside accordingly. The lowest curve shows the power supplied between the cathode 1 and the third electrode 3.

Returning to FIG. 2, the relationship between FIGS. 3 and 4 will be explained. By applying power as shown in curve 22 intermittently between the cathode 1 and the third electrode, an auxiliary discharge occurs between the cathode 1 and the wall of the cathode chamber. Due to this discharge, light is emitted near the cathode 1, but since the current density is increased near the cathode discharge path hole 6, light is also emitted near the cathode discharge path hole 6. Although this light emission is relatively weak, if it leaks into the photometry system of the analyzer, it causes an increase in noise. In this example, the partition wall around the light extraction window 5 functions as a shielding plate, so that the light from the vicinity of the cathode discharge path hole 6 passes through the light extraction window 5 into the light beam 23.
It cannot be taken out in the direction of On the other hand, since the discharge between the cathode 1 and the anode 2 is carried out through the radiation density enhancement hole 4, which is smaller in size than the cathode discharge path hole 6,
With the intermittent application of high power, strong light emission as shown by the curve 21 in FIG. 4 occurs near the radiation density enhancement hole 4. The light accompanying this main discharge is transmitted through the light extraction window 5.
It can be taken out through. In this case, the discharge power applied between the cathode 1 and the third electrode 3 may be set to the lowest resistance power at which this hydrogen discharge tube can maintain discharge, so when the hydrogen discharge tube of this embodiment is in operation. It is possible to reduce the temperature rise of the cathode 1.
The advantages are reduced ion bombardment and reduced cathode wear, resulting in longer life, reduced power consumption, and simpler power supply circuitry.

The cathode chamber wall, which functions as the third electrode, is located away from the light extraction line so as not to obstruct the path of the light being used, and the discharge light that is continuously emitted near the cathode discharge path hole 6 is Light beam 2 from light extraction window 5
Since it is not taken out in the direction 3, it has the advantage that the accuracy of background correction during atomic absorption analysis is improved.

Since such a sealed hydrogen discharge tube is often used as a light source for a photoelectric spectrophotometer in the near-ultraviolet region, it is required that the amount of light emitted does not change significantly depending on the wavelength. In addition, as mentioned above, it is important to emit pulsed light at as low a power as possible in order to extend the life of the hydrogen discharge tube, and for this purpose, the discharge voltage is lowered while the pulsed emitted light is paused to allow continuous discharge. I am making them do this.

Therefore, since continuous spectrum light due to hydrogen is obtained from the light extraction window 5, background correction in the atomic absorption photometer is suitably performed, and analysis accuracy is improved.

FIG. 5 is a sectional view of a hydrogen discharge tube according to another embodiment of the present invention, FIG. 6 is a side view of FIG. 5, and FIG. 7 is a sectional view taken along line BB' of FIG. The same members as in the previous embodiment shown in FIGS. 1 to 3 are given the same reference numerals, but the difference in this embodiment is that the third electrode is provided separately from the partition plate. . In Figure 7,
A third electrode 30 is provided in the discharge light emitting chamber 11, and discharge sustaining power is continuously applied between the cathode 1 and the third electrode 30. The third electrode 30, which serves as an anode, is located at a position where it does not obstruct the path of the light that is restricted by the light extraction window during main discharge. In the auxiliary discharge at this time, no light is generated in the discharge light emitting chamber 11, and the cathode discharge path hole 6
Although weak light emission occurs in the vicinity, this weak light emission is not extracted in the direction of the light beam 23 as in the previous example. At the same time, by applying strong power in the form of a rectangular wave between the cathode 1 and the anode 2, a strong pulsed light beam can be extracted.

FIG. 8 is a diagram showing the relationship between the light extracted from the hydrogen discharge tube of FIG. 7 and the power supply situation. The trapezoidal curve 31 at the bottom shows the discharge sustaining power flowing between the cathode 1 and the third electrode 30 of this embodiment, and the curve 20 at the top shows the rectangular waveform power between the cathode 1 and the cathode 2. The middle curve 21 is the light intensity taken out of the tube.

This example has the same effect as the hydrogen discharge tube of the previous example, does not require intermittent discharge sustaining power, and because the cathode and the third electrode directly face each other, it is easier to discharge and the discharge sustaining force is less. There is an advantage.

FIG. 7 also shows an example in which a third electrode 32 is provided in the anode chamber 9 to serve as a cathode, and an auxiliary discharge is caused between the third electrode 32 and the anode 2.
A low discharge sustaining power is applied between the anode 2 and the third electrode 32 to generate floating electrons within the tube body 7.
An auxiliary discharge between the third electrode 32 and the anode 2 causes the electrode 32 to
Although weak light is generated nearby, it is blocked by the anode 2 and is not extracted in the direction of the light beam 32. Luminous discharge with high power is caused to occur between the cathode 1 and the anode 2. At this time, the relationship between the light extracted from the hydrogen discharge tube and the power supply status is similar to that shown in FIG. 8.

The reason why the lifespan is extended by each of the above-mentioned embodiments is that the lifespan of a hydrogen discharge tube largely depends on the consumption of the cathode and the dilution of the gas sealed in the tube body.
This is because each embodiment improves these points. Since these changes are proportional to the power supplied to the electrodes, in the embodiment of the present invention, the discharge sustaining power was lowered and the light emitting power was applied in pulses to reduce the total power. In addition, in an example where the cathode is used for auxiliary discharge, if the cathode side is considered as the main one, it is in a continuous discharge state, so a high discharge starting voltage is not required each time the extraction light is interrupted, and a relatively simple power supply circuit can be used. An additional advantage is that the cathode is less consumed by accelerated ion bombardment. Since the hydrogen discharge tube according to the present invention can produce strong pulsed light emission, the signal-to-noise ratio is large, and since the low-pressure continuous light that is superimposed on the pulsed light emission is not extracted from the light extraction window 5, analysis accuracy is improved. .

As described above, the present invention has the advantage of providing low background during atomic absorption spectrometry and long life.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of a hydrogen discharge tube according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line AA' in Fig. 1, and Fig. 3 is a sectional view showing the structure of a hydrogen discharge tube according to this embodiment. FIG. 4 is a diagram showing the relationship between the light extracted from the hydrogen discharge tube of the embodiment of FIG. 1 and the power supply status, and FIG. 5 is a diagram of another embodiment of the present invention. A cross-sectional view of a certain hydrogen discharge tube, Figure 6 is a side view of Figure 5, Figure 7 is a BB' cross-sectional view of Figure 5, and Figure 8 is the light extracted from the hydrogen discharge tube of Figure 7. FIG. 4 is a diagram showing the relationship between the power supply status and the power supply status. 1... Cathode, 2... Anode, 3, 30, 32... Third electrode, 5... Light extraction window, 7... Tube body, 9... Anode chamber,
10...Cathode chamber, 11...Discharge luminescence chamber.

Claims (1)

[Scope of Claims] 1. An anode chamber having a radiation density enhancement hole, a cathode chamber having a cathode discharge path hole, and a partition wall having a light extraction window for restricting the direction of light extraction are provided in the tube, and the cathode chamber a cathode is disposed in the anode chamber, an anode is disposed in the anode chamber, and a discharge is caused between the cathode and the anode through the radiation density enhancement hole and the cathode discharge path hole;
In a hydrogen discharge tube in which light generated in the vicinity of the radiation density enhancement hole during this discharge is extracted through the light extraction window, the light is limited by the discharge path during discharge between the cathode and the anode and the light extraction window. The third electrode is arranged at a position where it does not obstruct the passage of light, the cathode chamber is arranged at a position where it does not obstruct the passage of light restricted by the light extraction window, and the size of the radiation density enhancement hole is set so that it does not obstruct the passage of light. The discharge path hole is formed smaller than the size of the discharge path hole, and main discharge power is intermittently supplied between the cathode and the anode, and one of the cathode and the anode is formed at least during the period when the intermittent main discharge is stopped. A hydrogen discharge tube characterized in that a power supply source for supplying discharge sustaining power smaller than the main discharge power is provided between the main discharge power and the third electrode. 2. The hydrogen discharge tube according to claim 1, wherein the third electrode also serves as a wall material of the cathode chamber.