JPH08167360A - Laser trigger type gap switch - Google Patents

Abstract

PURPOSE: To reliably control switching even if the laser beam has low energy by generating plasma by means of converging and applying the laser beam which passes through one electrode back side and a through hole to the other electrode front side. CONSTITUTION: When laser beam 32 is outputted from a laser beam generating apparatus 31, the laser beam is reflected by a reflection mirror 33 and made incident on a condenser lens 34 and converged. Then, after the laser beam passes a window 37 of a gap switch 35 and a through hole 43 of an electrode 38a, the laser beam irradiates the surface of the electrode 38b. Air above the electrode 38b is ionized due to the energy of the beam 32 and plasma is generated from the surface of the electrode 38b. The plasma grows in the direction almost as same as the direction to which the beam 32 is applied, extends toward the other electrode 38a, and when the plasma grows to some extent, a current path is formed in the plasma through the electrodes 38a, 18b and the electrodes 38a, 38b are electrically continued. Consequently, even if the laser beam has small energy, switching control can be done reliably with the laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a laser trigger type gap switch for switching high voltage and large current.

[0002]

2. Description of the Related Art Generally, when switching a high voltage and a large current, a pair of electrodes are arranged so as to face each other, a high voltage and a large current are supplied to the pair of electrodes, and the pair of electrodes is connected. A laser-triggered gap switch is used which performs switching control by generating plasma between electrodes by irradiating a strong laser beam in between.

FIG. 12 is a diagram showing the structure of a conventional laser trigger type gap switch. In this gap switch, a holding material 1 is arranged at a required position, and a pair of substantially hemispherical electrodes 2 and 3 having a void in the center are provided at predetermined intervals on the same surface portion on both end sides of the holding material 1. Then, they are attached so as to face each other. A high-voltage power supply (not shown) is supplied to the pair of electrodes 2 and 3 via power supply terminals 4 and 5, respectively.
Is applied.

On the other hand, the optical system for guiding the laser light is composed of a reflection mirror 7 for reflecting the strong pulsed laser light 6 generated from a laser light generator (not shown) and a laser light reflected by the reflection mirror 7. A condenser lens 8 that collects light and irradiates the gap between the pair of electrodes 2 and 3 through the gap of the electrode 2 is arranged.

Therefore, in the gap switch as described above, the intense pulsed laser light 6 from the laser light generator is condensed by the condenser lens 8 and a condensing point is formed in the atmosphere between the pair of electrodes 2 and 3. Since it is formed, the atmosphere is generated at the converging point of the pulsed laser light 6. As a result, the plasma triggers the conduction between the electrodes 2 and 3, and the switching operation of the gap switch is performed.

[0006]

However, since the laser trigger type gap switch as described above has to generate a plasma by condensing the laser light in the atmosphere between the pair of electrodes, it has a very high peak energy. A high laser light generator must be used.

There is a certain limit to the dielectric strength that can be maintained by one gap switch, for example, 1000
When trying to drive a [kv] withstand voltage capacitor bank with a gap switch, it is necessary to install a large number of gap switches 11a to 11i as shown in FIG. As a result, the laser light generator 12 is, for example, 2
The size of the laser beam 13 is about 1.5 × 1 [m] and the laser beam 13 generated from the laser beam generator 12 is generated.
Also, the optical system 15 for distributing light by the mirror 14 becomes very complicated and large.

Further, since switching is performed in the normal atmosphere using the gap switch, disturbance from the outside,
For example, there is a problem that the switching operation of the gap switch becomes unstable due to the influence of humidity, dust, etc., which makes it impossible to perform switching control under stable conditions.

Further, since pulsed laser light is focused in the atmosphere to generate plasma, and a large current is broken down by this plasma to perform switching control, there is a drawback that the operation noise becomes large during the switching operation. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser trigger type gap switch that reliably performs switching control even with laser light having a small energy.

Another object of the present invention is stable and
It is to provide a laser-triggered gap switch that performs switching control with high accuracy. Another object of the present invention is to provide a laser-triggered gap switch that reduces operating noise during switching operation.

[0012]

In order to achieve the above object, the invention corresponding to claim 1 is a laser trigger type gap switch for switching a high voltage / a large current by using a laser beam. An airtight container having a window attached to a portion for taking in light, and a substantially spherical shape or a hemispherical shape which is arranged in the airtight container so as to face each other at a predetermined interval and which is supplied with the high voltage and large current. A pair of electrodes and a laser through which a through hole that communicates from the electrode back surface to the electrode surface is formed on one electrode side of the pair of electrodes, and a laser that passes through the one electrode back surface and the through hole from the window A laser-triggered gap gap provided with switching control means for performing switching control by generating plasma by condensing and irradiating light on the surface of the other electrode. It is a pitch.

According to a second aspect of the invention, in a laser trigger type gap switch for switching a high voltage and a large current by using laser light, an airtight container having an opening formed in a portion for taking in the laser light is provided. , The airtight container is attached so as to close the opening, and the condensing means for condensing the laser light to enter the airtight container is faced to the airtight container at a predetermined interval. A pair of substantially spherical or hemispherical electrodes that are arranged to supply the high voltage and large current, and a through hole that communicates from the electrode back surface to the electrode surface is formed on one electrode side of the pair of electrodes. At the same time, the laser light focused by the focusing means and passing through the back surface of the one electrode and the through-hole is focused and irradiated on the surface of the other electrode to generate plasma and to switch. A laser-triggered gap switch having a switching control means for performing ring control.

Further, the invention according to claim 3 is a laser trigger type gap switch for performing switching control by condensing and irradiating a laser beam on an electrode surface provided in an airtight container, or a condensed laser beam. A laser-triggered gap switch for performing switching control by using an insulating gas supply unit for supplying an insulating gas into an airtight container, and an insulating gas pressure supplied to the airtight container by the insulating gas supply unit. It is a laser trigger type gap switch provided with pressure detecting means for detecting and dielectric strength adjusting means for adjusting dielectric strength between the electrodes based on gas pressure detected by the pressure detecting means.

Further, the invention according to claim 4 is a laser-triggered gap switch for performing switching control by condensing and irradiating a laser beam on an electrode surface provided in an airtight container, or condensing a laser beam. A laser-triggered gap switch for performing switching control by means of an electrode support body projecting from the back surface of each electrode to the outside of the airtight container and the pair of electrodes by driving these electrode support bodies back and forth. The laser trigger type gap switch is provided with the dielectric strength adjusting means for adjusting the electrode spacing and adjusting the dielectric strength between the pair of electrodes.

Further, the invention according to claim 5 is, in a laser trigger type gap switch for switching a high voltage and a large current by using laser light, an airtight container having an opening formed in a portion for taking in the laser light. A light condensing unit which is attached to the opening of the airtight container so as to be closed, and condenses the laser light to enter the airtight container.
A pair of substantially spherical or hemispherical electrodes, which are arranged so as to face each other in the airtight container at a predetermined interval and which are supplied with the high voltage / large current, and one of the pair of electrodes A through hole communicating from the back surface to the front surface of the electrode is formed on the side, and the laser light collected by the light collecting means and passing through the back surface of the one electrode and the through hole is collected on the surface of the other electrode. Switching means for performing switching control by generating plasma by irradiation and the other electrode are fixed positions, and the one electrode is provided so as to be capable of advancing and retreating, and the position of the one electrode is changed. It is a laser trigger type gap switch provided with a focusing position adjusting means for adjusting the focusing position of the laser beam on the other electrode surface.

When switching between the high voltage and the large current, a laterally excited atmospheric pressure carbon dioxide laser is used as a laser light generator to selectively output laser light having a wavelength of 9 μm band, and the airtight container. An insulating gas of SF6 is used inside. Further, graphite is used for the pair of electrodes.

[0018]

First, in the invention according to claim 1, when the laser light enters the airtight container through the window, the switching control means causes the laser light to pass through the through hole formed in one of the electrodes. Is focused and irradiated on the surface of the other electrode, so that plasma grows from the surface of the other electrode toward the one electrode. When this plasma grows to some extent, a high voltage applied to the electrodes forms a current path in the plasma. As a result, the electrodes are brought into conduction, and the switching operation of the gap switch is performed.

According to the second aspect of the present invention, when the laser light is condensed by the condensing means and is incident on the airtight container, the laser light incident on the switching control means is formed in one electrode through the through hole. Since the other electrode surface is focused and irradiated through the laser beam, the laser beam can be accurately focused on the other electrode surface, and the switching operation can be reliably performed.

The invention according to claim 3 uses a laser trigger type gap switch for performing switching control by condensing and irradiating a laser beam on an electrode surface provided in an airtight container, or a condensed laser beam. In the laser trigger type gap switch, switching control is performed by supplying insulating gas into the airtight container by the insulating gas supply means, and detecting the pressure of the insulating gas in the airtight container by the pressure detection means. The dielectric strength adjusting means can adjust the dielectric strength between the electrodes based on the gas pressure detected by the pressure detecting means.

The invention according to claim 4 uses a laser trigger type gap switch for performing switching control by condensing and irradiating a laser beam on an electrode surface provided in an airtight container, or a condensed laser beam. It is a laser trigger type gap switch that performs switching control by means of the dielectric strength adjusting means, and the dielectric strength can be adjusted by driving the electrode support body forward and backward to adjust the distance between the electrodes.

According to the invention corresponding to claim 5, the condensing position adjusting means adjusts the condensing position of the laser beam condensed by the condensing means, and the laser beam whose condensing position is adjusted is adjusted. Since the switching control means performs switching control, it is possible to provide a gap switch that can perform a highly accurate switching operation.

As a laser light generator, a laterally excited atmospheric pressure carbon dioxide laser is used to selectively output laser light having a wavelength in the 9 μm band, and the laser light is made incident on an airtight container filled with SF 6 gas. So under optimal conditions,
The switching operation can be performed accurately. Also, by using graphite for the material of the electrodes, it is possible to perform stable switching operation for a long period of time without hindering the conductivity of the electrodes.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a block diagram of a laser trigger type gap switch device according to a first embodiment of the present invention.

The laser light incident optical system of this gap switch has a laser light 32 generated from a laser light generator 31.
A reflecting mirror 33 is arranged on the laser optical path of the above, and a condenser lens 34 for collecting the reflected laser light 32 is provided on the output side of the laser light 32 reflected by the reflecting mirror 33. A gap switch 35 is provided on the output optical path of the laser light 32 condensed by the condenser lens 34.

The gap switch 35 includes an airtight container 36 in which dry air at atmospheric pressure is enclosed, a window 37 for taking the laser light 32 condensed by the condenser lens 34 into the airtight container 36, and the airtight container 36. It is constituted by a pair of electrodes 38a, 38b arranged so as to face each other on the optical path of the laser light 32 taken in.

The window 37 is attached and fixed by a window support member 40 so as to close an opening 39 formed in the outer wall of the airtight container 36 on the laser light incident side.

The pair of electrodes 38a and 38b are
It is attached to the airtight container 36 via holding members 41a and 41b and power supply terminals 42a and 42b so as to face each other at a predetermined interval. A high voltage is applied to the power supply terminals 42a and 42b.

Further, the gap switch 35 is provided with switching control means for performing switching control by generating plasma between the pair of electrodes 38a and 38b using laser light. In this switching control means, a through hole 43 is formed so as to communicate from the back surface of the electrode 38a located on the window 37 side to the electrode surface side,
The laser light captured by the window 37 is irradiated through the through hole 43 so as to be focused on the surface of the other electrode 38b directly facing the electrode 38a.

Next, the operation of the laser trigger type gap switch according to this embodiment will be described. Now, when the laser light 32 is output from the laser light generator 31, the laser light 32 is reflected by the reflection mirror 33 and is condensed by the condenser lens 34.
Gap switch 3
After passing through the window 37 of No. 5 and the through hole 42 of the electrode 38a, the surface of the electrode 38b is irradiated.

Then, the energy of the laser beam 32 ionizes the air on the electrode 38b to generate plasma from the surface of the electrode. This plasma grows almost in the direction irradiated with the laser beam 32 and extends to the other electrode 38a.

When the plasma grows to some extent, a high voltage applied to the electrodes 38a and 38b forms a current path in the plasma. As a result, the electrodes 38a,
38b becomes conductive, and the switching operation of the gap switch 35 is performed.

Therefore, according to the laser trigger type gap switch of the present embodiment, the laser beam 32 is directly applied to the electrode 38b of the gap switch 35 to generate plasma to perform the switching operation. It is sufficient to generate laser light having a certain amount of energy from 31, and it is not necessary to use a special laser light generator that generates high peak energy. For example, the laser light generator 31 may use a normal TEACO2 laser (transversely excited atmospheric pressure carbon dioxide laser) or a pulse YAG laser.

Since the surface of the electrode 38b forming the gap switch 35 is directly irradiated with the laser beam 32 to generate plasma, the switching operation is performed.
A compact laser trigger gap switch can be realized.

Further, since the switching operation is performed between the electrodes 38a and 38b contained in the airtight container 36, there is no influence of external disturbance such as humidity and dust, and the operation is stable and accurate. Good switching control can be realized.

Furthermore, since the switching operation is performed in the airtight container 36, the operation noise during the switching operation can be reduced and the laser light can be blocked from the outside. <Second Embodiment> FIG. 2 is a block diagram of a laser trigger type gap switch according to a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Here, only different parts will be described.

That is, in the laser trigger type gap switch of this embodiment, instead of the window 37 described in the first embodiment, a lens 51 for condensing the laser light 32 is provided in the opening 39 of the airtight container 36. It is attached so as to be closed. Thereby, the condenser lens 3 of the laser trigger type gap switch according to the first embodiment described above.
4 can be dispensed with. Further, the mirror 33 is arranged at a position where the reflected light of the laser light 32 is directly incident on the lens 51.

Further, in order to respond to changes in the voltage applied to the electrodes 38a and 38b, the electrode 38b is fixed to the airtight container 35, while the electrode 38a is attached so as to be able to move forward and backward along the optical path of the laser beam 32. An adjusting mechanism 52 for adjusting the distance between the electrodes 38a and 38b is provided. Specifically, the adjusting mechanism 52 includes a holding material 41a that holds the electrode 38a, and the airtight container 35 from the back surface of the holding material 41a.
And a driving means (not shown) provided outside the airtight container 35 and having a feed screw mechanism for driving the power feeding terminal 42a according to the voltage applied to the electrode. Has been done.

Next, the adjustment of the electrode spacing by the adjusting mechanism 52 will be described. Using the adjusting mechanism 52, the electrodes 38a,
It is desirable to increase the electrode spacing of 38b to increase the dielectric strength of the gap switch, but if the applied voltage is too low compared to the dielectric strength, it will not be possible to trigger even if laser light is irradiated, or when the trigger voltage is applied. Discharge delay time and jitter may increase. Therefore, it is necessary to set the electrode interval to an appropriate interval according to the applied voltage.

FIG. 3 shows a case where the applied voltage of the electrodes 38a and 38b is 30 [KV], atmospheric pressure air is used instead of the insulating gas, and a TEACO2 laser 3.5J is used as the laser light generator. It is a figure which shows the electrode gap dependence characteristic of a discharge delay time and a jitter.

As shown in the figure, when the voltage applied to the electrodes is 30 [KV], the electrode interval must be about 12 [mm]. Moreover, since the dielectric strength when the electrode interval is 35 [mm] is estimated to be around 97 [KV], the practical withstand voltage ratio of the gap switch (applied voltage / applied voltage /
The dielectric strength) is estimated to be about 30%.

With reference to such data, the adjusting mechanism 52 moves the position of the electrode 38a to adjust the electrode interval. Therefore, according to the laser trigger type gap switch according to the present embodiment, the electrode spacing is adjusted by the adjusting mechanism 52 according to the voltage applied to the electrodes 38a and 38b, so that the focus position of the laser light 32 is adjusted. Without doing so, the switching operation can be performed with appropriate discharge delay time and jitter.

Further, the adjusting mechanism 5 is provided from the outside of the airtight container 36.
Since the electrode interval can be adjusted by 2, it is possible to realize a laser-triggered gap switch having a very good drivability and a wide operating range.

Furthermore, in the second embodiment, since the condenser lens 51 is attached to the airtight container 35 instead of the window 37, the lens arranged as the laser beam incident optical system is not necessary, and a cheaper laser is provided. A trigger type gap switch can be realized.

In the above embodiment, the distance between the pair of electrodes 38a and 38b is adjusted by moving the position of the electrode 38a using the adjusting mechanism 52. However, for example, the relative position of the pair of electrodes 38a and 38b is adjusted. The dielectric strength can be changed by changing the value and adjusting the distance between the pair of electrodes. <Third Embodiment> FIG. 4 is a structural diagram of a laser trigger type gap switch according to a third embodiment of the present invention. In the figure, the same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. Here, only different parts will be described.

That is, in the gap switch according to the present embodiment, the insulating gas supply device for supplying the insulating gas into the airtight container 36, the vacuum exhaust device for evacuating the airtight container 36 to a vacuum, and the inside of the airtight container 36. A pressure gauge 66 for detecting atmospheric pressure is provided.

More specifically, the insulating gas supply device includes a cylinder 61 for supplying an insulating gas, a regulator 62 for adjusting the flow rate of the insulating gas output from the cylinder 61, and an output from the regulator 62 for storing in the airtight container 36. And a valve 63 that adjusts the flow rate of the supplied insulating gas. The vacuum evacuation device is composed of a vacuum pump 64 that evacuates the airtight container 36 to a vacuum, and a vacuum valve 65 that adjusts the flow rate of the insulating gas that is evacuated by the vacuum pump 64.

The regulator 62 has a pressure gauge 66.
There is provided a dielectric strength adjusting means 67 for adjusting the flow rate of the insulating gas based on the atmospheric pressure in the airtight container 36 detected in the step 3 to adjust the dielectric strength between the electrodes 38a and 38b.

FIG. 5 shows the types and characteristics of general insulating gases {High-voltage high-current engineering (The Institute of Electrical Engineers of Japan) Ohmsha
Issuing 1988, 9, 30}. As shown in the figure, it is understood that SF6 gas widely used in the field of electric power equipment has about three times as high dielectric strength as ordinary air and nitrogen at 1 atm. It is also found that some CFCs have good dielectric strength. The dielectric strength of carbon tetrachloride is attractive, but the boiling point is 1 ° C and 78 ° C.
Therefore, it is a liquid in a normal state and cannot be used as an insulating gas.

Therefore, in consideration of the above characteristics, the cylinder 61
It is effective in terms of dielectric strength if SF6 is filled with an insulating gas. Fig. 6 shows the flashover voltage (dielectric strength) between electrodes when air and SF6 gas are used as the insulating gas {High Voltage High Current Engineering (The Institute of Electrical Engineers of Japan) Ohmsha
Issuing 1988, 9, 30}.

As shown in the figure, it can be seen that when the distance d between the electrodes is fixed and the pressure p is increased 10 times, the dielectric strength is also increased 10 times. Also, it can be seen that if the pressure p is halved, the dielectric strength is also halved.

Therefore, it is desirable to increase the dielectric strength of the gap switch 36 by adjusting the pressure p of the insulating gas. However, if the applied voltage is too low with respect to the dielectric strength, a trigger can be generated by laser light irradiation. If not, the discharge delay time and the jitter at the time of triggering become large.

FIG. 7 is a diagram showing the atmospheric gas pressure dependence characteristics of the discharge delay time and the jitter. The measurement conditions in this case are as follows: electrode spacing 30 [mm], electrode applied voltage 30 [kv], atmosphere gas is air, laser light generator 3
1 uses a TEACO2 3.5J laser.

As shown in the figure, the electrode interval is 3 at atmospheric pressure.
The dielectric strength at 0 [mm] is 85 [kv]. Further, the discharge delay time at atmospheric pressure is 200 [μs] or more, which is very large, and therefore is not shown in the figure. In addition, the gas pressure of the atmospheric gas is shown as minus with the atmospheric pressure set to zero for the sake of simplicity.

According to this, it is understood that the discharge delay time and the jitter are improved by reducing the pressure between the electrodes 38a and 38b. Therefore, in this embodiment, similarly to the case where the electrode interval is adjusted in the above-described second embodiment, in this embodiment, the pressure in the airtight container 36 is set to a required value while referring to the pressure characteristics. . Specifically, while referring to the pressure in the airtight container 36 detected by the pressure gauge 66, the insulating gas is supplied by the cylinder 61, and the dielectric strength adjusting means 6 is supplied.
If the pressure in the airtight container 36 is set to a predetermined value by 7, the dielectric strength can be similarly increased.

Therefore, according to the laser trigger type gap switch according to the present embodiment, by changing the insulating gas filled in the cylinder 61, an arbitrary insulating gas is supplied into the airtight container 36, and the dielectric strength is adjusted. Since the pressure in the airtight container 36 can be set to an arbitrary value by the means 67, the switching operation can be performed under an appropriate discharge delay time and jitter without adjusting the focal position of the laser light 32. You can

The insulating gas supply device, the vacuum exhaust device, and the pressure gauge described in this embodiment can be applied to the laser-triggered gap switch of the first and second embodiments described above. Needless to say. <Fourth Embodiment> Next, a laser trigger type gap switch according to a fourth embodiment of the present invention will be described.

Here, the influence of the transmittance of laser light in the insulating gas will be considered. In the case of an insulating gas that is transparent to the naked eye, it can be considered that the transmittance of laser light near the normal visible light (eg, YAG laser, ruby laser) is considerably good. In many cases, ultraviolet lasers (for example, ArF excimer lasers) do not pass through due to some having an absorption band in the wavelength region or direct reaction between gas and laser light.

FIG. 8 is a diagram showing a light absorption spectrum of SF6 gas (Osaka University Laser Fusion Center data). This FIG. 8 shows the light wavelength of 9.0 to 11.0 [μm].
Shows the absorption spectrum of SF6 gas in the range of
It is shown that the transmittance around 10.5 [μm] is extremely poor.

FIG. 9 shows the laser output obtained when the TEACO 2 laser has a wavelength selection function as an oscillation spectrum in the same light wavelength range of 9.0 to 11.0 [μm]. (Refer to Optical Engineering CO2 Laser Spectrometer Catalog).

The oscillation output at this time is shown by relative intensity. When the TEACO2 laser is oscillated in the normal free line state without selecting the wavelength, it is usually 1
0P20 line is generated and its wavelength is 10.6 [μm]
Then, it exactly coincides with the absorption band of SF6 gas.

However, when the TEACO 2 laser is provided with a wavelength selection function and is oscillated in the 9 μm band, it is understood that the laser beam is transmitted because there is no absorption in this wavelength band.

Here, when 9P20 is selected as the oscillation wavelength of the TEACO2 laser, a wavelength of about 9.5 [μm] is obtained, and its output is 9P20 for the line of 10P20.
About 70% of the output on the line can be obtained. Other than that, several kinds of gases were also investigated by using a TEACO2 laser, but as shown in FIGS. 10 (a) to 10 (e), none of them has an insulating property and an absorptance suitable for laser light.

Therefore, the laser trigger type gap switch device is constructed by using SF6 gas as the insulating gas and using the TEACO2 laser having the wavelength selection function. FIG. 11 is a diagram showing the configuration of a laser trigger type gap switch device according to the fourth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Here, only different parts will be described.

That is, in the gap switch according to the present embodiment, a TEACO2 laser having a wavelength selection function is used as the laser light generator 31, and the airtight container 36 is filled with SF6 gas as an insulating gas.

The gap between the electrodes of the gap switch is 100
The pressure of SF6 gas sealed in the airtight container 36 can be adjusted to 0.1 to 10 atm. As a result, the operating voltage can be increased from 30 [kv] to a maximum of 1000 [kv] with the focus position fixed without mechanically changing the gap switch.

By the way, when SF6 gas is used as the insulating gas, there is a problem that the SF6 gas is decomposed by the strong laser beam 32 and the large current flowing between the electrodes.
Since the decomposition of SF6 gas is on the order of PPM,
Although it does not significantly affect the insulating property of the gas, the HF gas generated as a by-product due to the mixing of the F2 gas and the water generated by the decomposition of the SF6 gas is corrosive.

Therefore, when a metal such as copper or brass is used for the electrodes 38a and 38b, a metal fluoride is formed on the surface due to corrosion. The fluoride is an insulator, and therefore the electrodes 38a, 38b The conductivity of 38b is significantly hindered. When the material of the electrodes 38a, 38b is SUS, nickel or the like, there is some corrosion resistance, but the surface condition deteriorates when used for a long time.

Therefore, graphite (carbon graphite) is used as the material of the pair of electrodes 38a, 38b constituting the gap switch according to the present embodiment. Graphite is made of carbon and has a high corrosion resistance to fluorine, and even if it reacts with fluorine, it becomes CF4 and vaporizes in the gas, so it does not affect the conductivity of the electrodes 38a, 38b. Because.

Next, the operation of the gap switch of this embodiment will be described. Now, when the laser beam 32 of 30J outputted from the TEACO2 laser 31 whose wavelength is selected is outputted to the line 9P20, this laser beam 32 is reflected by the mirrors 33a and 33b and is incident on the lens 34.

The laser light 32 incident on the lens 34 is
While passing through the window 37 of the gap switch and the electrode 38a while being focused by the lens 34, the focused laser beam 32 is emitted toward the surface of the electrode 38b.

Then, the energy of the laser beam 32 ionizes the SF6 gas sealed in the airtight container 36 to generate plasma from the surface of the electrode 38b. This plasma grows almost in the direction irradiated with the laser beam 32 and extends to the other electrode 38a.

When this plasma grows to some extent, the high voltage applied to the electrodes 38a and 38b forms a current path in the plasma. Thereby, the electrode 38
Conduction is established between a and 38b, and the gap switch 35
Switching operation is performed.

Therefore, according to the gap switch of this embodiment, the laser light generator 31 having a wavelength selecting function,
Since the airtight container 36 is filled with SF6 gas, the switching operation can be performed accurately.

Further, since the electrodes 38a and 38b are made of graphite, the conductivity of the electrodes is not hindered.
The switching operation can be stably performed over a long period of time. In addition, in the above-described first to fourth embodiments, the shape of the electrode is described as a hemispherical shape, but it may be a spherical shape.

[0076]

As described above in detail, according to the present invention, switching control can be reliably performed even with laser light having low energy, and stable and accurate switching control can be performed. You can further,
It is possible to reduce the operating noise during the switching operation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a laser trigger type gap switch according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a laser trigger type gap switch according to a second embodiment of the present invention.

FIG. 3 is a diagram showing the characteristics of the electrode delay dependence of discharge delay time and jitter in the example.

FIG. 4 is a diagram showing a configuration of a laser trigger type gap switch according to a third embodiment of the present invention.

FIG. 5 is a diagram showing types of general insulating gas and their characteristics.

FIG. 6 is a diagram showing a flashover voltage (dielectric strength) between electrodes when air and SF6 gas are used as an insulating gas.

FIG. 7 is a diagram showing the atmospheric gas pressure dependence characteristics of discharge delay time and jitter.

FIG. 8 is a diagram showing a light absorption spectrum of SF6.

FIG. 9 is a diagram showing an oscillation spectrum of a TEACO2 laser.

FIG. 10 is a diagram showing the relationship between the insulating gas and the transmittance of laser light.

FIG. 11 is a diagram showing a configuration of a laser trigger type gap switch device according to a fourth example of the present invention.

FIG. 12 is a diagram showing a configuration of a conventional laser trigger type gap switch.

FIG. 13 is a diagram showing a configuration of a conventional laser trigger type gap switch.

[Explanation of symbols]

31 ... Laser light generator, 32 ... Laser light, 33 ... Mirror, 34 ... Lens, 35 ... Gap switch, 36 ... Airtight container, 37 ... Window, 38a, 38b ... Electrode, 3
9 ... Window support member, 40a, 40b ... Holding material, 4
2a, 42b ... Power supply terminal, 43 ... Through hole, 51 ... Lens, 52 ... Adjustment mechanism, 61 ... Cylinder, 62 ... Regulator, 63 ... Valve, 64 ... Vacuum pump, 65 ... Vacuum valve, 66 ... Pressure gauge, 67 ... Dielectric strength adjustment means.

Claims (7)

[Claims] 1. A laser-triggered gap switch for switching a high voltage and a large current by using a laser beam, wherein an airtight container having a window attached to a portion for taking in the laser beam, and a predetermined interval in the airtight container. And a pair of substantially spherical or hemispherical electrodes which are arranged so as to face each other and which is supplied with the high voltage and large current, and one of the pair of electrodes, one electrode side of which is the electrode back surface to the electrode surface. And a laser beam coming from the window through the back surface of the one electrode and the through hole is focused and irradiated onto the surface of the other electrode to generate plasma, thereby performing switching control. A laser-triggered gap switch, comprising: switching control means for performing the switching. 2. A laser-triggered gap switch for switching a high voltage and a large current by using laser light, wherein an airtight container having an opening formed in a portion for taking in the laser light, and the opening of the airtight container is closed. Attached to
A light collecting unit that collects the laser light and makes it enter the airtight container, and a substantially spherical body that is arranged so as to face the airtight container at a predetermined interval and that is supplied with the high voltage and large current. A pair of electrodes having a shape or a hemisphere, and a through hole communicating from the back surface of the electrode to the surface of the electrode is formed on one electrode side of the pair of electrodes, and the one of the electrodes is focused by the focusing means. A laser trigger type characterized by comprising switching control means for performing switching control by generating plasma by converging and irradiating the laser light coming through the back surface of the electrode and the through hole on the other electrode surface. Gap switch. 3. The laser-triggered gap switch according to claim 1, wherein the insulating gas supply means supplies an insulating gas into the airtight container, and the insulating gas supply means supplies the insulating gas into the airtight container. A laser trigger characterized by adding pressure detecting means for detecting the pressure of the insulating gas, and dielectric strength adjusting means for adjusting the dielectric strength between the electrodes based on the gas pressure detected by the pressure detecting means. Type gap switch. 4. The laser-triggered gap switch according to claim 1 or 2, wherein an electrode support body projecting from the back surface of each electrode to the outside of the airtight container so as to be able to move forward and backward, and these electrode support bodies. And a dielectric strength adjusting means for adjusting the dielectric strength between the pair of electrodes by adjusting the distance between the pair of electrodes by advancing and retreating. 5. A laser-triggered gap switch for switching a high voltage and a large current by using laser light, wherein an airtight container having an opening formed in a portion for taking in the laser light and the opening of the airtight container are closed. Attached to
A light collecting unit that collects the laser light and makes it enter the airtight container, and a substantially spherical body that is arranged so as to face the airtight container at a predetermined interval and that is supplied with the high voltage and large current. A pair of electrodes having a shape or a hemisphere, and a through hole communicating from the back surface of the electrode to the surface of the electrode is formed on one electrode side of the pair of electrodes, and the one of the electrodes is focused by the focusing means. Switching means for performing switching control by generating plasma by condensing and irradiating the laser light passing through the back surface of the electrode and the through-hole on the surface of the other electrode, and the other electrode at a fixed position, and One of the electrodes is provided so as to be able to move forward and backward, and the focusing position adjusting means for adjusting the position of the one electrode to adjust the focusing position of the laser beam on the surface of the other electrode is provided. Riga gap switch. 6. A laterally pumped atmospheric pressure carbon dioxide laser is used as a means for switching a high voltage and a large current to 9 μm.
6. The laser-triggered gap switch according to any one of claims 1 to 5, wherein a laser beam having a band wavelength is selectively output and an SF6 insulating gas is supplied into the airtight container. 7. The laser trigger type gap switch according to claim 1, wherein the material of the pair of electrodes is graphite.