RU2799385C1 - Device for measuring the height profile of the quasi-static electric field of the atmosphere - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: invention can be used to measure the altitude profile of a quasi-static electric field and the ionospheric potential of the atmosphere. In the moving part of the device rotating at a frequency of at least 6000 rpm, the sensing element is a hemisphere with two metallized sectors connected to an instrumental amplifier that acts as amplification and filtering units. The movable part also houses a unit for determining the position of the sensing element and a power supply. The fixed part includes a motor connected to the sensing element and a microcontroller. The fixed part and the moving part are connected via an optical channel.

EFFECT: possibility to measure the electric field without a priori known body potential ("grounding"), small size and low weight.

2 cl, 3 dwg

Description

The invention relates to the field of measurement technology and can be used to measure the altitude profile of a quasi-static electric field and the ionospheric potential of the atmosphere.

A device is known, described in the article (R.G. Harrison, G.J. Marlton "Fair weather electric field meter for atmospheric science platform", Journal of Electrostatics, 107, 2020, 103489), which is essentially a classic electrostatic fluxmeter (Imyanitov I.M. " Devices and methods for studying the electricity of the atmosphere "- M: GTTI, 1957, 483 p.). The device consists of an external horizontal fixed plate, a calibration plate, a rotor with sector cuts, a measuring electrode, a rotating support disk, a reference electrode and a screen. The main disadvantage is the small area of the measuring electrode, which in turn is a requirement for miniaturization of the device. This leads to very small useful signal currents, on the order of 5 nA, which is comparable to thermal noise currents. Amplification and synchronous detection of such a signal requires the use of special circuitry, highly sensitive and expensive electronic components. Other disadvantages of this device include a rather complex design, which hinders mass inexpensive production.

Many other devices, in particular, devices described in patent documents: RU 2199761 "Device for measuring the intensity of a static and quasi-static electric field" (IPK G01R 29/12, publ. 27.02.2003), RU 104729 "Electrostatic fluxmeter" ( IPC G01R 1/00, pub. 05/20/2011), RU 2501029 "Compensating electrostatic fluxmeter" (IPK G01R 29/12, publ. 12/10/2013), RU 2722477 "Electrostatic fluxmeter" (IPK G01R 29/00 , publ. 06/01/2020), US 5315232 "Electric field measuring system" (IPC G01R 29/12, G01R 31/02, publ. 05/24/1994), allow to improve the design of a classic electrostatic fluxmeter and do not consider the possibility of using them for measuring height profiles.

The closest is the device described in US patent 8536879 "Rotating electric-field sensor" (IPC G01R 29/12, G01R 27/26, publ. 09/17/2013), selected as a prototype. This device contains a metalized cylinder, divided into 4 sectors, which is a rotating sensing element. Structurally, amplifiers, filters, analog-to-digital converters for 4 channels of 4 sectors and a transmitter for the fixed part are placed inside the cylinder. Together they form the moving part of the device, rotating at a speed of 600 rpm. The fixed part contains a data receiver, a computer processor, a controlled motor that drives the movable part, a position sensor, a power supply unit and a data transmission unit. The disadvantage of the device is its large size and weight, which makes it difficult to use it on a standard weather balloon suspension.

The problem to which this invention is directed is the development of a small-sized, lightweight and technically simple device that can be used by placing it on standard weather balloons to measure the altitude profile of the electric field.

The technical result in the developed device is achieved due to the fact that it, like the prototype, contains a movable part, including a sensitive element rotating around a fixed axis, consisting of sections, electrically connected to amplification, filtering and analog-to-digital conversion units, and a fixed part, including a motor connected to the sensing element, and a microcontroller, as well as a power supply, a block for determining the position of the sensing element. What is new in the developed device is that in the moving part rotating at a frequency of at least 6000 rpm, the sensing element is a hemisphere with two metallized sectors connected to an instrumental amplifier that performs the functions of amplification and filtering units, while the block for determining the position of the sensitive The element and the power supply are placed in the moving part, and the fixed part and the moving part are connected by means of an optical channel.

In a particular case of the implementation of the device, a latch to the weather balloon is located on the fixed part.

The invention is illustrated by the following figures.

In FIG. 1 shows the appearance of the device.

In FIG. 2 shows the electrical block diagram of the device.

In FIG. 3 shows a photo of the developed device.

At the moment, there is no small-sized lightweight device that can completely solve the problem of measuring the ionospheric potential using standard weather balloons.

The developed device makes it possible to measure the electric field without a priori known case potential (“grounding”). At the same time, it is small-sized (maximum linear dimension does not exceed 100 mm), lightweight (weight less than 250 g) and technically simple device with low power consumption, suitable for use as a suspension to a standard weather balloon. The altitude profile of the electric field makes it possible to obtain the value of the ionospheric potential - the difference in electric potentials between the ionosphere and the Earth's surface - a unique geophysical index that has the same value when measured at any point on the Earth.

In FIG. 1 shows the appearance of the device in different projections and in isometry. The device consists of movable 1 and fixed 2 parts. The movable part 1 includes a sensitive element in the form of a hemisphere formed by two metallized sectors 3 with a dielectric separator 4 between them. Inside the movable part 1 there is an instrumental amplifier 5, which performs the functions of amplification and filtering, a position determination unit 6 of the sensitive element, a power supply 7 and the first microcontroller 8, including the ADC unit (Fig. 2). The fixed part 2 includes a motor 9 connected to a rotating sensing element and a second microcontroller 10. The fixed part 1 and the movable part 2 of the device are connected via an optical channel.

The sensitive element in the form of a sectoral metallized hemisphere is a capacitor of capacitance C, both plates of which are closed to the "zero" point through load resistors 11 with resistance R. When this capacitor rotates in an external uniform electric field, the charge that ensures the fulfillment of the boundary conditions for the normal component of the field flows from one capacitor plate to another. Thus, a current i appears in the circuit, proportional to the external field:

i=4⋅π⋅γ⋅ΔU⋅R⋅С,

where γ is the rotation frequency in hertz,

ΔU - potential created by an external uniform field E _o on a capacitor without rotation:

ΔU=E _o ⋅d,

where d is the effective distance between the capacitor plates.

At a frequency γ of the order of 100 Hz, load resistance R=100 kOhm, capacitance C=1 pF, ΔU=0.1 V with an external field of 100 V/m (fair weather field), the current i is estimated in the order of magnitude at 10 μA, which is a significant improvement in the design of small-sized electric field meters and allows the use of standard circuitry.

The instrumental amplifier 5 is used to suppress the total and isolate the useful difference signal and amplify it for further digitization, the gain is set by the resistor 12. The signal is input to the analog-to-digital converter built into the first microcontroller 8. The position determination unit 6 of the sensitive element includes the first phototransistor 13, and the first LED 14 acts as a reference for determining the location of the moving part 1 of the device. When the hemisphere rotates, the first phototransistor 13 receives pulses of the location of the rotating element. When the dielectric separator 4 passes a strictly horizontal position, a pulse arrives, which triggers the analog-to-digital converter once and performs synchronous detection of the useful signal by the location signal of the first phototransistor 13. The measurements are carried out for 1 second, the useful signal and the number of revolutions of the hemisphere are simultaneously measured. After measurements are taken, the results are averaged and transmitted in a serial code of the minimum possible size of 4 bytes to the second microcontroller 10 using the second LED 15 and the second phototransistor 16, which form an optical data transmission channel. That is, the second microcontroller 10 receives information about the amplitude of the useful signal and the rotational speed. Then the data is converted into the XDATA format, which are transmitted to the inputs 17 of the weather balloon. Then the measurements are repeated. The main signal processing occurs in digital form using a specialized code for the first and second microcontrollers 8 and 10.

The advantages of this device are the formation of a useful signal much higher than the noise level due to the high frequency of rotation of the hemisphere (~6000 rpm) and digital signal processing directly in the rotating element.

In a particular case of the implementation of the developed device, the authors used a Sunon KDE0504PFB3 5V 40 × 40 × 10 mm 6500 rpm fan as an electric motor, the plastic case of the device was printed on a 3D printer. Inside the rotating metallized hemisphere, two batteries of the LR42 type were located, as well as an instrumental amplifier 5, the first microcontroller 8, a position detection unit 6 of the sensitive element, including the first phototransistor 13, and the second LED 15, placed on a printed circuit board. On the body of the device there is a latch 18 to the weather balloon with a guide 19. In Fig. 3 shows the location of the developed device directly on the weather balloon.

Thus, the developed device for measuring the altitude profile of the quasi-static electric field of the atmosphere is small, lightweight and technically simple due to the use of a light metallized hemisphere divided into two sectors as a sensitive element. To increase the useful signal, a high rotational speed of this hemisphere is used - at least 6000 rpm. A useful signal from a sensitive rotating element is amplified, filtered, synchronously detected and digitized inside the rotating element based on modern electronic analog and digital components with reduced power consumption. And to transmit a useful signal from a moving part to a fixed part, an optical channel is used, since the sliding contacts used in analog devices operate only at frequencies not exceeding 1000 rpm.

Claims (2)

1. A device for measuring a quasi-static electric field, containing a movable part, including a sensing element rotating around a fixed axis, consisting of sections, electrically connected to amplification, filtering and analog-to-digital conversion units, a fixed part, including a motor connected to the sensing element, and a microcontroller, as well as a power supply unit, a unit for determining the position of the sensing element, characterized in that in the moving part rotating at a frequency of at least 6000 rpm, the sensing element is a hemisphere with two metallized sectors connected to an instrumental amplifier that performs the functions of amplification and filtering units , while the block for determining the position of the sensing element and the power supply are placed in the movable part, and the fixed part and the movable part are connected via an optical channel. 2. A device for measuring a quasi-static electric field according to claim 1, characterized in that a latch to the weather balloon is located on the fixed part.

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