Atmospheric electric field observation device

Abstract

An atmospheric electric field observation device 1 comprises: a lightning arrester 10 that is connected to a metal body in the atmosphere and that discharges to the metal body after having been charged to a certain level; a detecting circuit 20 that detects the discharge; and an estimating unit 30 that estimates an electric field strength in the atmosphere on the basis of a detection time interval of the discharge.

Description

Atmospheric Electric Field Observation Device

[0001] The present disclosure relates to an atmospheric electric field observation device.

[0002] There are technologies to prevent damage from lightning strikes by controlling lightning. For example, there is a technology that induces lightning (lightning attraction) by flying a drone equipped with a lightning rod and a grounded induction wire, and then safely guides it to the ground (Non-Patent Document 1). There is also a technology that surrounds a drone with a Faraday cage to protect it from lightning strikes (Non-Patent Document 2).

[0003] To trigger lightning, a drone must be flown over a location where a large amount of electric charge has accumulated. When electric charges accumulate within a thundercloud, the atmospheric electric field between the cloud and the ground becomes stronger, so a field mill is used to observe the electric field strength in the atmosphere (Non-Patent Document 3).

[0004] "E03, Lightning Control and Charging Technology, Protecting People and Equipment from Electrical Strikes and Utilizing Lightning Energy," NTT R&D Forum 2020 Connect, 2020. Masuda and three others, "Basic Study on Improving Drone Lightning Resistance," 2021 IEICE University, B-4-6, 2021, p. 179, "Technical Information, Technical Series No. 15 Lightning," [Retrieved June 8, 2023], Internet<URL : https: / / www.jstage.jst.go.jp / article / jwea1977 / 32 / 4 / 32_4_79 / _pdf / -char / ja>

[0005] However, because field mills observe electric field strength by rotating a metal plate, the motors used to rotate the metal plate are prone to failure and are vulnerable to external shocks.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide an atmospheric electric field observation device that can reduce the risk of failure.

[0007] An atmospheric electric field observation device according to one aspect of the present disclosure includes a lightning arrester connected to a metal body in the atmosphere and discharging after the metal body is charged to a certain level or more, a detection circuit for detecting the discharge, and an estimation unit for estimating the electric field strength in the atmosphere based on the detection time interval of the discharge.

[0008] According to the present disclosure, an atmospheric electric field observation device capable of reducing the risk of failure can be provided.

[0009] Fig. 1 is a diagram showing the overall configuration of an atmospheric electric field observation system according to a first embodiment. Fig. 2 is a diagram showing a flow of an atmospheric electric field observation method. Fig. 3 is a diagram showing the relationship between the voltage across both ends in a first lightning arrester and the current detected in a detection circuit. Fig. 4 is a diagram showing the overall configuration of an atmospheric electric field observation system according to a second embodiment. Fig. 5 is a diagram showing the configuration of a switch unit according to a third embodiment. Fig. 6 is a diagram showing the overall configuration of an atmospheric electric field observation system according to a fourth embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0011] [Summary of the Disclosure] The disclosure provides an atmospheric electric field observation device comprising a lightning arrester, a detection circuit, and an estimation unit, which estimates the electric field strength in the atmosphere by utilizing the discharge phenomenon of the lightning arrester due to charging current from a metal body and the detection of the discharge phenomenon. In other words, the magnitude of the charge amount in a thundercloud is estimated based on the presence or absence of a discharge and the time interval between detections of the discharge. This eliminates the need for mechanical components such as motors, thereby reducing the risk of failure of the atmospheric electric field observation device.

[0012] 1 is a diagram showing the overall configuration of an atmospheric electric field observation system according to Embodiment 1. The atmospheric electric field observation system includes an atmospheric electric field observation device 1 that observes electric fields in the atmosphere, and a drone 2 enclosed in a metal Faraday cage 3.

[0013] The atmospheric electric field observation device 1 includes a first surge arrester 10 , a detection circuit 20 , and an estimation unit 30 .

[0014] The first lightning arrester 10 has one terminal connected to the Faraday cage 3 of the drone 2 and the other terminal connected to the earth 4, and a charging current I due to charging is discharged from the Faraday cage 3. Ａ When the Faraday cage 3 is charged to a certain level or more, a discharge occurs between both ends of the interior of the lightning arrester.

[0015] The first surge arrester 10 can be realized by using, for example, a GDT (Gas Discharge Tube). A surge arrester is an element that, when a voltage or current exceeding a certain level is applied to both ends of the surge arrester, instantly starts discharging and emits light, causing both ends to become in the same state as when a switch is turned on.

[0016] The detection circuit 20 is disposed close to the first surge arrester 10 and is a circuit that detects discharge of the first surge arrester 10. For example, the detection circuit 20 detects discharge light emission of the first surge arrester 10 and detects a current I that flows through the detection circuit 20 due to the discharge light emission of the first surge arrester 10. For example, the detection circuit 20 is a circuit in which a photodiode 21 that detects discharge light emission, a resistor 22, and an ammeter (not shown) that measures the current value photoelectrically converted by the photodiode 21 are connected in series.

[0017] The estimation unit 30 has a function of estimating and calculating the electric field strength in the atmosphere based on whether or not a discharge is detected by the detection circuit 20 and the time interval between detections of the discharge. For example, the estimation unit 30 calculates the electric field strength based on whether or not a discharge light emission is detected by the detection circuit 20 and the time interval between detections of the discharge light emission. The estimation unit 30 calculates the electric field strength based on whether or not a current is detected by the detection circuit 20 and the time interval between detections of the current. For example, the estimation unit 30 can be realized using a circuit, a computer, or a software program.

[0018] FIG. 2 is a diagram showing the flow of the atmospheric electric field observation method.

[0019] Step S1: When a thundercloud occurs, the user flies the drone 2 around or within the thundercloud. Electrostatic induction caused by the flight of the drone 2 causes electric charge to accumulate in the Faraday cage 3 surrounding the drone 2.

[0020] Step S2: When the amount of charge in the thundercloud is large or when the distance between the charge in the thundercloud and the drone 2 is short, the amount of charge in the Faraday cage 3 increases. Step S1 is repeated until the amount of charge in the Faraday cage 3 reaches a certain level, and once the Faraday cage 3 is charged to a certain level or more, the process proceeds to step S3.

[0021] Step S3: After the Faraday cage 3 is charged to a certain level, the charge accumulated in the Faraday cage 3 is discharged between both ends of the first surge arrester 10, causing light to be emitted.

[0022] Step S4: The detection circuit 20 detects the discharge light emission of the first surge arrester 10, and detects the current flowing through the detection circuit 20 due to the discharge light emission.

[0023] Step S5: The estimation unit 30 calculates the electric field strength in the atmosphere while the drone is flying, based on whether or not the detection circuit 20 detects a current and the time interval between current detections.

[0024] 3 , when the voltage V across the first surge arrester 10 reaches a certain value, the detection circuit 20 detects the current I due to the discharge light emission within the first surge arrester 10. The estimation unit 30 acquires the detection time interval of the current I, and if the detection time interval of the current I is short, the Faraday cage 3 accumulates charge quickly and a large amount of charge accumulates around the drone 2, so that the electric field strength in the atmosphere is high. Conversely, if the detection time interval of the current I is long, the estimation unit 30 calculates that the electric field strength in the atmosphere is low.

[0025] Step S6: If it is considered that there is still charge around the thundercloud, such as when the thundercloud remains or a new thundercloud has appeared, the process returns to step S1. If it is considered that there is no charge around the thundercloud, such as when the thundercloud has disappeared, the process ends.

[0026] According to this embodiment, the atmospheric electric field observation device 1 is configured using the first surge arrester 10 that discharges after the Faraday cage 3 is charged to a certain level or more, the detection circuit 20 that detects the discharge of the first surge arrester 10, and the estimation unit 30 that estimates the electric field strength in the atmosphere based on the detection time interval of the discharge in the detection circuit 20. This eliminates the need for mechanical parts such as motors, and reduces the risk of failure of the atmospheric electric field observation device 1.

[0027] In addition, the charge status around the current location of the drone 2 can be grasped in real time, enabling efficient lightning triggering activities and improving lightning trigger accuracy. Furthermore, the drone 2 can be efficiently flown toward the charge location, saving battery life for the drone 2 and extending its flight time.

[0028] [Second embodiment] Figure 4 is a diagram showing the overall configuration of an atmospheric electric field observation system according to a second embodiment. In order to protect the atmospheric electric field observation device 1 from lightning surges, a switch unit 40 is connected between the Faraday cage 3 and the first lightning arrester 10 in the atmospheric electric field observation device 1 of the first embodiment. The configuration other than the switch unit 40 is the same as that of the first embodiment.

[0029] The switch unit 40 switches the connection destination of the Faraday cage 3 between the first surge arrester 10 and the earth 5 depending on the discharge situation. Specifically, when electrostatic induction is occurring, the switch unit 40 connects the Faraday cage 3 to the first surge arrester 10 and prevents the charging current I from the Faraday cage 3. Ａ When lightning is occurring, the Faraday cage 3 is connected to the earth 5, and the lightning surge current I Ｂ is passed to the earth 5. The switching operation of the switch unit 40 may be performed manually by the user or may be performed remotely via wireless communication.

[0030] The second embodiment also does not use mechanical parts such as a motor, thereby reducing the risk of failure of the atmospheric electric field observation device 1. Furthermore, the second embodiment further includes a switch unit 40 that can switch the connection destination of the Faraday cage 3 from the first lightning arrester 10 to the earth 5, thereby protecting the atmospheric electric field observation device 1 from lightning surges. As a result, the risk of failure of the atmospheric electric field observation device 1 can be further reduced.

[0031] 5 is a diagram showing the configuration of a switch unit 40 according to a third embodiment. While the switch unit 40 of the second embodiment exclusively switches the current path, in the third embodiment, the Faraday cage 3 is connected to both the first surge arrester 10 and the earth 5.

[0032] The switch section 40 is configured by combining a filter 41 and a second surge arrester 42. The filter 41 is connected between the first surge arrester 10 and a conductor branch section 43 leading from the Faraday cage 3 to the first surge arrester 10 and earth 5. The second surge arrester 42 is connected between the conductor branch section 43 and earth 5.

[0033] Charging current I Ａ The frequency of the lightning surge current IＢ Therefore, the filter 41 is configured to filter the lightning surge current I Ｂ This prevents the lightning surge current I Ｂ Since the current does not flow to the first surge arrester 10, the atmospheric electric field observation device 1 can be protected from lightning surges.

[0034] The second surge arrester 42 is designed so that the discharge start voltage V2 of the second surge arrester 42 is equal to or higher than the discharge start voltage V1 of the first surge arrester 10.

[0035] The third embodiment also does not use mechanical parts such as motors, thereby reducing the risk of failure of the atmospheric electric field observation device 1. Furthermore, according to the third embodiment, a filter 41 that prevents lightning surge current is provided between the Faraday cage 3 and the first lightning arrester 10, and a second lightning arrester 42 whose discharge start voltage is equal to or higher than the discharge start voltage of the first lightning arrester 10 is provided between the Faraday cage 3 and the earth 5, so that the atmospheric electric field observation device 1 can be protected from lightning surges. As a result, the risk of failure of the atmospheric electric field observation device 1 can be further reduced.

[0036] 6 is a diagram showing the overall configuration of an atmospheric electric field observation system according to a fourth embodiment. In the fourth embodiment, an atmospheric electric field observation device 1 is mounted on a drone 2. The atmospheric electric field observation device 1 is preferably the atmospheric electric field observation device 1 according to the second or third embodiment, which is equipped with a protection function against lightning surges.

[0037] For example, as shown in FIG. 6, a lightning surge current I flows between the Faraday cage 3 of the drone 2 and the first lightning arrester 10. Ｂ The other terminal of the first surge arrester 10 is connected to the circuit board ground 6 of the drone 2. The filter 41 prevents the charging current I from the Faraday cage 3. Ａ is passed through the first surge arrester 10, and the lightning surge current I Ｂ does not flow to the first surge arrester 10. Ｂ will flow to the ground via the induction wire 7 which is grounded to the Faraday cage 3.

[0038] Even in the third embodiment, since no mechanical parts such as a motor are used, the risk of failure of the atmospheric electric field observation device 1 can be reduced.

[0039] [Modifications of Each Embodiment] (Modification 1) The Faraday cage 3 is an example of a means for accumulating electric charge in the atmosphere. Any metal body may be used other than a Faraday cage. For example, a metal plate or sphere may be used.

[0040] (Variation 2) The photodiode 21 of the detection circuit 20 is an example of a means for detecting the discharge of the first surge arrester 10. Any means may be used as long as it can detect the discharge of the first surge arrester 10. For example, a camera or the like may be used. In this case, the estimation unit 30 detects the presence or absence of discharge in the first surge arrester 10 from the captured image, and estimates the electric field strength in the atmosphere based on the time interval between detections of the discharge.

[0041] REFERENCE SIGNS LIST 1 atmospheric electric field observation device 2 drone 3 Faraday cage 4 earth 5 earth 6 substrate earth 7 induction wire 10 first lightning arrester 20 detection circuit 21 photodiode 22 resistor 30 estimation unit 40 switch unit 41 filter 42 second lightning arrester 43 conductor branch unit

Claims

1. An atmospheric electric field observation device comprising: a lightning arrester that is connected to a metal body in the atmosphere and discharges when the metal body is charged to a certain level or more; a detection circuit that detects the discharge; and an estimation unit that estimates the electric field strength in the atmosphere based on the detection time interval of the discharge.

2. The atmospheric electric field observation device according to claim 1, further comprising a switch section for switching the connection destination of the metal body to the lightning arrester or earth.

3. An atmospheric electric field observation device as described in claim 2, wherein the switch section is connected between the metal body and the lightning arrester and is provided with a filter for preventing a lightning surge current.

4. An atmospheric electric field observation device as described in claim 3, wherein the switch unit further comprises a lightning arrester connected between the metal body and the earth and having a discharge start voltage equal to or higher than the discharge start voltage of the lightning arrester.

5. The atmospheric electric field observation device according to claim 1, which is provided on an unmanned aerial vehicle.

6. The atmospheric electric field observation device according to claim 1, wherein the metal body is a Faraday cage that surrounds an unmanned aerial vehicle.

7. The atmospheric electric field observation device of claim 1, wherein the estimation unit estimates that the electric field strength in the atmosphere is high when the detection time interval of the discharge is short, and estimates that the electric field strength in the atmosphere is low when the detection time interval of the discharge is long.