JPS5851486A - Gas discharge tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ready-made gas discharge tube for protecting communication equipment and the like from high pressure surges.

This type of ready-made gas AT pipe is as shown in Figure 1.
The end surface of the insulating tube a is sealed with opposing electrodes S and C with silver solder G and H' interposed between them, and an inert gas such as argon is sealed inside the tube, and the tube inner wall DLC is used as a discharge trigger. In this case, a linear conductive strip e is provided. For example, the conductive strip e is extended from the − force electrode to the front of the other force electrode C, and a minute gap is formed between the strip tip f and the electrode C, so that it is difficult to apply surges or the like. First, a trigger discharge is performed in a small gap. As such a conductive strip e, a carbon strip has conventionally been put into practical use.

The carbon strips are formed by marking the inner wall d of the insulating tube a with graphite or the like. When ceramic is used as the insulating tube a, the inner wall d of the tube is roughened due to its particle size, so that it adheres to the inner wall d of the tube in powder form by scribing and rubbing it.

Such adhesion merely maintains a state of physical contact and lacks adhesive properties. Furthermore, since carbon has a high melting point of about 3500°C, it is not affected by the heat during heating manufacturing of gas discharge tubes, and even after heating manufacturing, it remains attached in a powder state. It's something that doesn't exist. Therefore, when a high pressure surge is applied, for example, the carbon strip e becomes an arc path, causing the carbon powder to scatter at an early stage, resulting in a lack of repeatability. The repeatability of the carbon strip e is significantly lower than that of the gas discharge tube, and only the strip life runs out early.
This had an adverse effect on the discharge characteristics. Moreover, the powder state tends to cause spatter, which, together with powder scattering, promotes tube wall contamination.

As an alternative to the above-mentioned carbon strip, a conductive strip is known which is formed into a band shape by performing a blinding process such as vapor deposition on the inner wall of the tube in advance. However, requiring a metallization process such as vapor deposition in addition to the discharge tube fM fabrication process imposes a heavy workload and is expensive. Also, mainly Ag
When metalizing alloys, Ag and Zn are not the same, but
The metal plate was relatively easy to sputter, and the contamination of the tube wall was highly advanced.

In view of the above circumstances, we conducted research on conductive strips. First, it is desired that the conductive strip suppresses variations in discharge starting voltage and improves trigger characteristics so as to prevent delays. Although it is known that the discharge surface of an electrode is provided with a low work function metal having a large electron emission ability, there is no explanation of the work function of a conductive strip. However, when the size is limited, such as in the case of a conductive strip, the larger the amount of electron emission, the more effective it should be, and it is thought that the effectiveness of the trigger will increase.

Next, it is desired that the conductive strips are resistant to sputtering and do not cause contamination of the tube wall. It has been found that spatter can be suppressed by increasing the sealing gas pressure, but the boiling point of the metal also has a significant effect. Experiments have shown that the lower the boiling point, the easier it is to sputter, and the degree of contamination of the tube wall is greater. From this point of view, those with low work functions and low boiling points such as %, Mg, K, Zn, Ba, etc. should be excluded.

It has also been confirmed that spatter depends not only on the boiling point but also on the immersion state of the conductive strip. That is, if the carbon strips are attached in powder form, the strips become arc paths when a high pressure surge is applied, which also affects sputtering. Therefore, it is required to firmly bake the n-strips onto the inner wall of the pipe. Seizure is determined by melting point. A separate baking process is undesirable from the viewpoint of workability, similar to the above-mentioned blinding process such as vapor deposition.
The heating temperature of the discharge tube manufacturing process must be available. Here, the melting point is the heating temperature of 800°C to 10°C.
A temperature approximately equal to or lower than 00° C. is selected.

Furthermore, the provision of the conductive strips requires a light workload. From this point of view, it is most desirable to be able to draw lines like the carbon strip. Furthermore, radioactive isotopes are excluded because they are undesirable from a safety perspective.

As a result of the above experiments, it was concluded that the best conductive strip would be a metal material with a low work function, a high boiling point, a melting point of about 1000° C. or less, and the ability to write on ceramics.

An object of the present invention is to provide a conductive strip in which In, Aj, or a material mainly composed of these is adhered and baked onto a tube wall surface. Hereinafter, the present invention will be explained using In as a practical example.

Indium has a work function of approximately 3, a melting point of approximately 156°C,
The boiling point is about 2100°C. When insulating tube a was marked on alumina ceramic, it was possible to adhere it well. In particular, since it is soft, it can be applied evenly to the uneven surface of the inner pipe wall d. As shown in FIG. 2A, indium is in a powder state.

In addition, since 100 yen is relatively stable in the atmosphere,
It can be prepared by attaching it to the insulating tube a in advance. Silver solder g is applied to both end faces of this insulating tube a.

When we examined a gas discharge tube that was heat-sealed for about 30 minutes at a heating temperature of 800°C ~]OOOO°C for about 30 minutes after exhaust gas was introduced with electrodes A and C facing each other through h, we found that Fig. 2 B As shown in the figure, 1 ndium was baked onto the uneven surface of the tube wall surface d.

Table 1 above provides experimental data for a gas discharge tube with a conductive strip e' formed by baking 1 ndium. A comparison is shown between the conventional carbon strip and the non-conductive strip. As is clear from Table 1, the AC discharge starting voltage of the conductive strip e' of 1 N is lower than that of the carbon strip, and the width of the variation is half that of the carbon strip. Therefore, the range of variation is reduced, indicating remarkable stability. Shock wave is 10x200μs
.

When 1000V is applied, the conductive strip e' is
It is the same as the carbon strip at low values of the shock wave discharge starting voltage, but the width of the variation is half that. conductive strip e
' can be said to narrow the range of variation in the starting voltage. Furthermore, the delay time with respect to the shock wave shows a value of 3 μs to 3.5 μs, and although a difference from the carbon strip is recognized, it is clearly not significant in this respect.

Further, when repeated discharges were performed, the conductive strip e' did not have powder scattered like the carbon strip. The carbon strips in the powder state were scattered faster than expected, and their resistance to shock waves was remarkable. conductive strip e'
It was confirmed that the strip life span was several times longer than that of carbon strips. Concerning tube wall contamination, the progress of contamination was slow due to the high boiling point and lack of powder scattering such as carbon strips.

Furthermore, they tried manufacturing conductive strips by adding antimony and tin to indium to raise its melting point. In this case, if a small amount of antimony or tin was added, the work function of the strip as a whole would deteriorate, but since the discharge was performed by the work function of indium, the same experimental values as above were obtained. Indium, antimony, etc. are baked in an alloy state or in a mixed state that retains their respective characteristics.

Aluminum is an example of a metal similar to the above-mentioned indium. Aluminum has a work function of approximately 3, a melting point of approximately 660°C, and a boiling point of approximately 2270°C. When the ink was scribed on alumina ceramic, it was able to adhere well. This aluminum is the second indicative of indium.
As shown in Figure A, it was deposited in a powder state, and was baked as shown in Figure B during production heating. This aluminum conductive strip showed almost the same experimental values as in Table 1 above,
The repeated durability was also approximately the same. A conductive strip made of aluminum containing indium, antimony, tin, etc. can also have similar effects.

In the above-mentioned practical example, the conductive strip is shown extending from the -force electrode to the non-force electrode, but the present invention is not limited to the position in which the conductive strip can be attached. Also,
One bait for one bait; one bait for one bait.

Furthermore, although alumina-based ceramics have been described as an insulating tube, other ceramics can also be used; in the case of glass, there is no need to roughen the inner wall of the tube.

In particular, since In has a low melting point, it can be effectively combined with glass tubes.

As explained above, in the present invention, since the conductive strip of the gas discharge tube is formed of In, Aj, or a material mainly composed of these, the conductive strip is formed on the wall surface of the insulated tube using the heating temperature during manufacturing. was able to be strongly baked, improving the life and repeatability of the trigger. Also,
The variation in discharge starting voltage was reduced to half that of conventional carbon strips, and stable discharge characteristics were obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view explaining a conventional gas discharge tube;
Figures A and B are partially enlarged sectional views showing the conductive strip of the gas discharge tube according to the present invention. a... Insulating tube, b, c... Electrode, d... Tube inner wall,
e. e′...conductive strip. Patent applicant: Hakusan Seisakusho Co., Ltd.

Claims (1)

[Claims] The tube ends of the insulated tube are sealed with a pair of opposing electrodes, and an inert gas is sealed inside the tube.A conductive strip is provided on the tube wall surface as a trigger means, and a discharge is generated in the gap between the opposing electrodes. A gas discharge tube characterized in that the conductive strip is made mainly of In, Al, or these materials and is baked onto the tube wall surface.