RU2800225C1 - Sensor for measuring cosmic particle parameters - Google Patents

Abstract

FIELD: space technology.

SUBSTANCE: sensor for studying the parameters of cosmic particles comprises a body made in the form of a hollow cube, all faces of which are composite detectors, consisting of external and internal sensitive elements. Each sensitive element comprises a set of adjacent strips of a volumetrically polarized PVDF film placed in parallel in the same plane. The bands of the outer and inner sensitive elements of the composite detector are oriented mutually perpendicular. The sensor body is made in the form of a frame, on one side of which there is a mount for communication with the spacecraft with flexible information loops passing through it. The sensitive elements of the detectors are connected by means of connectors to the mentioned flexible information loops, which are configured for transmitting information to the spacecraft electronics unit.

EFFECT: increased sensitivity of the sensor.

1 cl, 1 dwg

Description

The invention relates to space technology. The sensor for studying the parameters of cosmic particles can be used to solve scientific and applied problems. It can be used to obtain information about the spatial density of micrometeoroids, technogenic particles and cosmic dust particles, their distribution in speed and direction of movement, size and mass. The practical significance of the sensor for solving specific problems can be implemented in: the study of pollution of near-Earth space; collecting information to make adjustments to the National Standard “Space Environment…” [1]; development of protection of space vehicles (SC) from the dangerous effects of particles; ensuring safety during spacecraft tracking in orbit.

A known sensor for recording and measuring the parameters of meteoroid and technogenic particles, interstellar and interplanetary dust affecting the spacecraft [2]. The sensor consists of two hemispherical multilayer PVDF airgel detectors, each of which contains thin flexible plates made of polarized material with flexible electrodes, a calibrated airgel spacer located between the plates, an external heat-insulating airgel screen-damper, an internal airgel substrate in contact with one of its surfaces with a thin flexible plate, and the other with a hemispherical sensor shell. The sensor housing is made of nanocomposite material. Embedded L-shaped flanges with sockets for fixing flat brackets with clamps are installed in hemispherical shells. A hollow adapter is fixed in the lower hemispherical shell, designed to lead wires from the detector electrodes to the electronic unit and install the sensor on the spacecraft.

The operation of the sensor is as follows: When approaching, the particle overcomes the external heat-insulating airgel screen and collides with the first piezoactive plate - a PVDF film, which generates the first electrical signal in the form of a pulse, the amplitude and time of which is recorded in the corresponding channel of the electronics unit. Next, the particle passes through a calibrated airgel pad, which plays the role of a measuring base, pierces the second piezoactive plate - a PVDF film, which generates a second electrical signal in the form of a pulse, the amplitude and time of which are also recorded in the corresponding channel of the electronics unit. Knowing the measured base and the time to overcome it, it is easy to determine the average speed of the registered particle. The information obtained by deciphering electrical impulses helps to estimate the mass of the particle, its volume and drag coefficient.

Sensor Disadvantages

1. The sensor is not able to determine the velocity vector of the registered particles.

2. The thickness of the calibrated airgel spacer was taken as the measuring base, and its value is considered to be a constant value. In reality, however, the vast majority of registered particles do not cross the calibrated airgel spacer along the normal to the surface; therefore, the measured base does not always coincide with the actual particle ranges.

3. As a result, the determined value of the average particle velocity can differ significantly (and sometimes by several times) from the true value. A similar situation appears when determining other parameters of the particle with the participation of the average velocity in the calculated dependences.

4. The thickness of the airgel spacer is relatively small, the time it takes for a particle to pass through it is also small, so it is difficult to obtain a reliable value of the velocity of registered particles on such a dimensional basis.

The closest analogue to the claimed sensor for the study of the parameters of cosmic particles, selected as a prototype is a sensor for the study of flows of meteoroid and technogenic particles in outer space [3].

The prototype sensor is made in the form of a cube, all faces of which are composite detectors, consisting of external and internal sensitive elements (SE). External SEs are made of a thin film, on which many cells with conductive tracks are deposited, and internal SEs are made of a volumetrically polarized PVDF film, which provide high information content of the recorded parameters and ensure their comprehensive assessment. The measured span base is determined individually for each particle by the distance between the reacted cells on different faces of the sensor, which makes it possible to determine with high accuracy the direction of motion of the detected particle (velocity vector) and its average speed.

The operation of the prototype sensor is as follows. When the spacecraft enters the flow of meteoroid and/or technogenic particles, their high-speed collision with the detectors of the sensor occurs. The particle sequentially pierces the outer and inner SE of one face of the sensor, then the inner and outer SE of the other face. In this case, the equipment registers four signals tied to the spacecraft onboard time system. Based on the signals from the external SE, the signal processing unit using the controller detects the coordinates of the triggered cells, determines the velocity vector and the flying distance of the particle L, and having information on the time difference of the registered signals _Δ t, calculates the average particle velocity (w _s ) _cp =L/ _Δ t.

The signals from the internal SE come in the form of pulses I _s proportional to the momentum of the particle P _s , i.e. I _s ~P _s . Then (I _s ) _cp ~(P _s ) _cp =m _s *(w _s ) _cp. Thus, the signal processing unit determines the particle mass m _s =(P _s ) _cp /(w _s ) _cp .

With the help of a prototype sensor, it is possible to determine and/or evaluate the following parameters of meteoroid and technogenic particles experimentally and experimentally-calculatively:

1. The countable number of particles that collided with the sensor, with reference to the parameters of the spacecraft's orbit and its onboard time.

2. Particle flux density.

3. Direction of motion of particles registered in the flow (velocity vector).

4. The average speed of the particle (w _s ) _cp =L/ _Δ t.

5. Momentum (momentum) of a particle P _s .

6. Particle mass m _s =(P _s ) _cp /(w _s ) _cp .

7. Particle volume V _s =m _s /ρ, where ρ is the average particle density, it can be judged from [1], where for small (up to 5 mm) cataloged space objects the value ρ=2.5…2.7 g/cm ³ is given.

8. Particle midsection area - estimated based on the defined particle volume V _s and engineering considerations. In addition, the size of a particle can be estimated from the fact that it was registered by both SE detectors or only by the internal one. In this case, it should be taken into account that the external SE is capable of registering particles with a size of 0.05 ... 0.15 mm and more.

Sensor Disadvantages:

1. Relatively low sensitivity due to the characteristics of the external SE. In this case, the thickness and material of the SE have the greatest influence, which impede the passage of particles with low kinetic energy. In addition, the external SE is not capable of detecting particles smaller than 0.05…0.15 mm with the existing technology for applying conductive tracks.

2. Termination of the functioning of the cell of the external SE in case of violation of the integrity of its conductive path by the registered particle (ie, the cells are disposable).

The technical problems solved by the proposed invention are:

- increasing the sensitivity of the sensor (expanding the range under study in terms of the size and energy of the detected particles);

- improving the reliability of the sensor.

The solution of technical problems is achieved by the fact that in the proposed sensor for studying the parameters of cosmic particles, made in the form of a hollow cube, all faces of which are composite detectors, consisting of external and internal sensitive elements, the new feature is that each sensitive element contains a set of adjacent parallel strips of a volumetrically polarized PVDF film placed in the same plane, while the stripes of the external and internal sensitive elements of the composite detector are oriented mutually perpendicular.

The use of a more sensitive than the prototype material for the manufacture of external SE made it possible to solve the first of the technical problems. The solution of the second technical problem is ensured by the fact that after the detected particle passes through the bands of the volume-polarized PVDF film, they do not cease to function.

The essence of the invention is illustrated by the figure (Fig.). The sensor housing 1 is made in the form of a frame, on one side of which there is a mount for communication with the spacecraft with flexible information loops passing through it (not shown in the figure). A unified frame with a composite detector 2 is installed on each side of the frame. The inner 3 and outer 4 sensitive elements of the detector are connected by connectors to flexible information cables that transmit information to the electronics unit (not shown in the figure). The outer side of the detector is covered with a layer of porous-fibrous material - airgel 5 (thickness, for example, 1 mm), which is a heat-insulating airgel screen-damper. Between SE there is a thin layer of insulator 6. The implementation of the sensor in the form of a cube, all faces of which are detectors, allows you to explore a wide range of recorded directions of the meeting of cosmic particle flows 7. The proposed arrangement in the form of a frame with detector frames installed on it ensures the manufacturability of the process of assembling the sensor and its debugging in laboratory conditions.

The outer and inner SE of the detector are identical, they are made of a set of adjacent strips of thin (for example, 30 μm thick) and elastic volumetrically polarized PVDF film, placed in parallel in the same plane, and equipped with flexible electrodes. Since the bands in these SEs are mutually perpendicular, the places where the bands of the outer and inner SEs intersect are peculiar cells - cells. Depending on which of the bands of the outer and, accordingly, the inner SE, electrical signals appeared, the coordinates of the flight of the registered particle are determined. The accuracy of determining the coordinates, to a greater extent, depends on the width of the strips used. The production of porous-fibrous material - airgel and polarized PVDF film is currently mastered in the Russian Federation, these promising materials have been repeatedly used in research on the MIR orbital station and other spacecraft.

The operation of the proposed sensor is as follows. When the spacecraft enters the flow of meteoroid and/or technogenic and/or dust particles, their high-speed collision with the detectors 2 of the sensor occurs. Particle 7 sequentially pierces the outer 4 and inner 3 SE of one face of the sensor, then the inner and outer SE of the other face. In this case, the equipment registers four signals tied to the spacecraft onboard time system. The first two signals determine which of the detectors has worked and the coordinates of the entry of the particle. The next two signals give the exit coordinates of the particle and, accordingly, the spent detector (face) of the sensor. Using the coordinates of the triggered cells, using the electronics unit (not shown in the figure), the velocity vector and the flying distance of the particle L are determined, and having information on the time difference of the registered signals _Δ t, the average particle velocity (w _s ) _cp =L/ _Δ t is calculated.

The SE signals arrive in the form of pulses I _s proportional to the momentum of the particle P _s , i.e. I _s ~P _s . Then (I _s ) _cp ~(P _s ) _cp =m _s *(w _s ) _cp. Thus determine (estimate) the mass of the particle m _s =(P _s ) _cp /(w _s ) _cp. The received information enters the group telemetry signal generation device and is transmitted to the Earth.

The range of cosmic particle parameters determined and estimated using the proposed sensor is similar to the prototype sensor, however, the range under study has been significantly expanded in terms of the possibility of detecting fine particles, as well as particles with low kinetic energy.

The increase in the reliability of the sensor is due to the use of strips of a volumetrically polarized PVDF film as SE, which, unlike disposable cells with conductive tracks of the prototype sensor, retain the ability to re-detect cosmic particles.

It is necessary to indicate that the sensor must undergo preliminary experimental testing on a ballistic stand for the impact of high-speed particles with the construction of calibration dependencies. To cover the full range of spatial registration of particles, it is advisable to place two sensors on different sides of the spacecraft. In the inventive sensor, the tightness of its internal volume in relation to the external environment - space is not required. On the contrary, the passage of a measured base by a particle in its natural conditions contributes to an increase in the accuracy of measurements.

Bibliographic list

1. National standard of the Russian Federation. Space environment (natural and artificial). GOST R 25645.167-2005 // M. Standartinform, 2005, p. 41.

2. Pat. 2457986 RF, IPC B64G 1/68. Sensor for recording and measuring the parameters of meteoroid and technogenic particles, interstellar and interplanetary dust affecting the spacecraft / N.N. Ivanov, A.N. Ivanov. - No. 2011114041/11; declared 04/12/2011; publ. 08/10/2012, Bull. No. 22.

3. Pat. 2618962 RF, IPC G01R 19/00. Sensor for studying the flows of meteoroid and technogenic particles in outer space / P.S. Goncharov [i dr.]. - No. 2016108570; declared 09.03.2016; publ. 05/11/2017, Bull. No. 14.

Claims (1)

A sensor for studying the parameters of cosmic particles, containing a housing made in the form of a hollow cube, all faces of which are composite detectors, consisting of external and internal sensitive elements, characterized in that each sensitive element contains a set of adjacent strips of a volumetrically polarized PVDF film placed in parallel in the same plane, while the strips of the external and internal sensitive elements of the composite detector are oriented mutually perpendicularly, while the sensor housing is made in the form of a frame, on one side of which there is a mount for communication with the spacecraft with bends passing through it by means of connectors, and the external and internal sensitive elements of the detectors are connected with the mentioned flexible information loops, which are made with the possibility of transmitting information to the spacecraft electronics unit.