JP2516516Y2 - Discharge tube - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube, and more particularly to a discharge tube filled with an inert gas at a pressure higher than atmospheric pressure.

[0002]

2. Description of the Related Art Conventionally, as a gap switch for starting oscillation of a laser device, a discharge tube filled with an inert gas has been used in various devices. As shown in FIG. 3, such a discharge tube 1 includes a pair of metal electrode plates 4 each having a discharge electrode portion 3 in which both open ends of a cylindrical body 2 made of an electrically insulating material such as ceramics face each other. The cylinder 2 is filled with an inert gas such as argon at a high pressure of, for example, several atmospheric pressures to several tens of atmospheres.

The discharge tube 1 filled with such a high-pressure inert gas is incorporated as, for example, an oscillation start gap switch of a laser device, and a predetermined potential difference is applied between the electrode plates 4, so that the discharge tube 1 is provided. In the ideal state, the equipotential lines 5 are as shown in FIG. 4, and the discharge is generated between the discharge electrode portions 3 facing each other having the steepest potential gradient, and the discharge start voltage is sufficiently increased. , A sufficient discharge starting voltage required for the device can be obtained.

However, the discharge tube 1 is rarely used in the above-mentioned ideal state, and in reality, as shown in FIG.
Around the discharge tube 1, for example, a ground body 6 or the like having the same potential as the one electrode plate 4a to which a predetermined voltage is not applied may be located. In such a case, as shown in the figure, the line of electric force is The equipotential lines 5 formed in a direction orthogonal to the electric field line wrap around to the side of the other electrode plate 4b to which a voltage is applied. Therefore, as shown by the portion A in the figure, the above-mentioned discharge In addition to between the electrode portions 3, a portion having a steep potential gradient is formed. As shown in FIG. 3 from the portion A, the so-called creeping corona 7 is formed prior to the discharge between the discharge electrode portions 3. In some cases, the creeping corona 7 is connected to the creeping flashover 8 that occurs along the entire inner surface of the cylindrical body 2, and the necessary discharge starting voltage between the discharge electrode portions 3 cannot be obtained. was there.

Therefore, the discharge tube 1 of the above-mentioned conventional shape has a limited place of use, and in order not to limit the place of use, the above-mentioned inconvenience is avoided. I had to take steps.

Therefore, as shown in FIG. 6, a collar portion 9 is formed on the inner peripheral surface of the cylindrical body 2 where the above-mentioned creeping flashover 8 may occur, and a gap between the electrode plates 4 is formed along the inner surface of the cylindrical body 2. It has been considered that the creepage flashover 8 is less likely to occur by increasing the distance of.

[0007]

However, even if the collar portion 9 is formed as described above, the distance between the electrode plates 4 does not dramatically increase, and it is not very effective in preventing the creeping flashover 8. The effect cannot be expected, and on the contrary, the formation of the collar portion 9 disturbs the electric field inside the discharge tube 1 and changes the discharge characteristics.

The present invention has been made in view of the above points, and a discharge tube capable of preventing creeping flashover without disturbing the electric field inside the discharge tube and sufficiently increasing the discharge starting voltage. It is intended to be provided.

[0009]

In order to achieve the above-mentioned object, a discharge tube according to the present invention comprises a pair of electrode plates having discharge electrode portions opposed to each other and having open end portions of an electrically insulating cylinder sealed with each other.
In a discharge tube in which an inert gas is sealed in the cylinder, at least one electrode plate side inner end of the cylinder is located around the discharge electrode portion, and its surface shape is the pair of electrode plates. It is characterized in that insulating projections having a shape substantially along the equipotential lines formed between the electrode plates when a predetermined potential difference is applied therebetween are formed.

[0010]

According to the present invention, the inner surface of at least one electrode plate side of the tubular body forming the discharge tube is located around the discharge electrode portion, and its surface shape is between the pair of electrode plates. Since an insulating protrusion having a shape that is substantially along the equipotential line formed between the electrode plates when a potential difference is applied is formed, a ground with the same potential as the electrode plate to which a predetermined voltage is not applied is formed around the discharge tube. When the body etc. is located and the equipotential line in such a discharge tube goes around the electrode plate side to which a voltage is applied, the discharge tube is connected to If it is used as the electrode plate on the applied side, it is possible to suppress the occurrence of creeping corona without disturbing the electric field inside the discharge tube, and to suppress the growth of creeping corona even if it occurs. Prevents creeping flashovers Rukoto can, is capable of a sufficiently high discharge start voltage.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 show an embodiment of a discharge tube according to the present invention. In this discharge tube 1, both open ends of a cylindrical body 2 made of an electrically insulating material such as ceramics face each other. It is sealed with a pair of metal electrode plates 4 having a discharge electrode part 3 for discharging, and an inert gas such as argon is contained in the cylindrical body 2 at a high pressure of, for example, atmospheric pressure or higher to several atmospheric pressure to several tens of atmospheric pressure. It is designed to be sealed by pressure.

Of the pair of electrode plates 4 for sealing the cylindrical body 2, the cylindrical body 2 on the side of the electrode plate 4b to which a predetermined voltage is applied in the usage state of the discharge tube 1 will be described later. The inner end portion is provided with an insulating protrusion 10 formed integrally with the inner peripheral surface 2a of the cylindrical body 2 so as to be located around the discharge electrode portion 3b of the electrode plate 4b. Numeral 10 extends from the end face 2b of the tubular body 2 toward the discharge electrode portion 3b so as to contact the electrode plate 4b, and the inner end thereof is the discharge electrode portion 3b.
A base end face 10a left with a slight gap x, an inner peripheral face 10b extending from the inner end of the base end face 10a along the discharge electrode part 3b to the tip side of the electrode part so as to surround the electrode part, and It comprises a tapered surface 10c extending from the tip of the peripheral surface 10b toward the base end surface 10a. In addition, the insulating protrusion 1
The taper surface 10c of 0 has a shape substantially along the equipotential line 5 of the discharge tube 1 when the discharge tube 1 is in use as shown in FIG.

Then, the discharge tube 1 in which such a high-pressure inert gas is sealed and in which the insulating projections 10 are formed is incorporated as, for example, an oscillation starting gap switch of a laser device, and a predetermined potential difference is established between the electrode plates 4. By applying the voltage, discharge is generated between the discharge electrode portions 3 in a state where the discharge starting voltage is sufficiently increased, and a sufficient discharge starting voltage required for the device can be obtained.

Here, as described above, the discharge tube 1 is rarely used in an ideal state, and in practice, for example, a predetermined voltage is applied around the discharge tube 1 as shown in FIG. There is a case where the grounding body 6 or the like having the same potential as the one electrode plate 4a which is not formed is located. In such a case, as shown in the figure,
Equipotential lines 5 formed in a direction orthogonal to the lines of electric force
However, since it goes around to the other electrode plate 4b side to which the voltage is applied, as shown in the portion A in the figure,
A portion having a steep potential gradient is formed in addition to between the discharge electrode portions 3, and so-called creeping corona may occur prior to the discharge from the portion A to the discharge electrode portion 3.

In such a case, as shown in FIG. 2, if the discharge tube 1 is used so that the electrode plate 4b on the insulating projection 10 side becomes the electrode plate to which the above voltage is applied, The creeping corona 7 may be generated from a contact portion B between the electrode plate 4b and the cylindrical body 2 having the insulating projection 10, and the generated creeping corona 7 is formed along the inner peripheral surface 10b of the insulating projection 10 and has a tip C thereof. However, even in such a case, since the tapered surface 10c of the insulating projection 10 has a shape substantially along the equipotential line 5 as described above,
There is no possibility that the creeping corona 7 that has grown to the tip C of the inner peripheral surface 10b will further grow on the tapered surface 10c that has no potential difference, which may cause such creeping corona 7 to lead to creeping flashover as in the conventional case. Absent.

Further, the contact portion B between the electrode plate 4b and the cylindrical body 2 having the insulating protrusion 10 where the creeping corona 7 may occur as described above is located at the inner base end portion of the insulating protrusion 10. Therefore, the electrostatic shielding effect of such a portion is improved and the electric field concentration can be avoided, whereby the generation of the creeping corona 7 itself can be sufficiently suppressed.

Further, the insulating projection 10 described above hardly disturbs the electric field inside the discharge tube as compared with the collar portion formed on the inner peripheral surface of the conventional cylindrical body 2, whereby the electric field is disturbed. It is also possible to prevent a situation in which the discharge characteristic is changed due to.

Therefore, in this embodiment, the inner surface of at least one electrode plate 4b of the tubular body 2 constituting the discharge tube 1 is located around the discharge electrode portion 3b and has a surface shape 10 thereof.
Since c forms the insulating protrusion 10 having a shape substantially along the equipotential line 5 formed between the electrode plates 4 when a predetermined potential difference is applied between the pair of electrode plates 4, the c is formed around the discharge tube 1. ,
In the case where the earth body 6 or the like having the same potential as the electrode plate 4a to which the predetermined voltage is not applied is located, the equipotential line 5 in such a discharge tube 1 goes around to the electrode plate 4b side to which the voltage is applied. Under such a circumstance, when such a discharge tube 1 is used so that the electrode plate 4b on the side of the insulating protrusion 10 serves as the electrode plate on the side to which a voltage is applied, the creeping surface can be obtained without disturbing the electric field inside the discharge tube 1. The generation of corona can be suppressed, and even if the creeping corona occurs, its growth can be suppressed to prevent the creeping flashover, and the discharge starting voltage can be sufficiently increased.

The present invention is not limited to the above embodiment, and for example, the insulating protrusion 10 may be fitted inside the cylinder 2 as a separate structure from the cylinder 2. Various changes can be made as necessary.

[0020]

As described above, the discharge tube according to the present invention is located at the inner end portion of at least one electrode plate side of the cylindrical body constituting the discharge tube, around the discharge electrode portion, and has a surface shape of , The insulating corrugations having a shape substantially along the equipotential lines formed between the electrode plates when a predetermined potential difference is applied between the pair of electrode plates are formed, so that the creeping corona does not disturb the electric field inside the discharge tube. Can be suppressed, and even if a creeping corona occurs, its growth can be suppressed to prevent the creeping flashover, and the discharge starting voltage can be made sufficiently high. In addition, such a creeping flashover prevention structure does not limit the place of use of the discharge tube, and has the effect of increasing its versatility.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a discharge tube according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a cross-sectional view showing a conventional discharge tube.

FIG. 4 is equipotential lines in a discharge tube used in an ideal state.

FIG. 5 is an equipotential line in a discharge tube in an actual use state.

FIG. 6 is a cross-sectional view showing another conventional discharge tube.

[Explanation of symbols]

 1 Discharge tube 2 Cylindrical body 3 Discharge electrode part 4 Electrode plate 5 Equipotential line 6 Earth body 7 Creeping corona 8 Creeping flashover 9 Collar part 10 Insulation protrusion

Claims (1)

(57) [Scope of utility model registration request] 1. A discharge tube in which an open end portion of an electrically insulating cylinder is sealed with a pair of electrode plates having discharge electrode portions facing each other, and an inert gas is sealed in the cylinder. At least one electrode plate inner end of the body is located around the discharge electrode portion, and its surface shape is an equipotential formed between the electrode plates when a predetermined potential difference is applied between the pair of electrode plates. A discharge tube having an insulating protrusion having a shape substantially along a line.