RU2644810C2 - Device for vector control of plasma engine strip (options) and method of vector control of plasma engine strip - Google Patents

Abstract

FIELD: motors and pumps.

SUBSTANCE: group of inventions relates to the control of the thrust vector of plasma engines. Device comprises two or four rectangular shaped magnetic coils mounted on the body of the plasma engine in the area behind the outlet channel cutoff, located by the open parts of the frames opposite each other. Coils are mounted symmetrically with respect to the longitudinal axis of the motor, parallel to each other or at a slight angle to each other. Embodiment of the device provides for creating a substantially homogeneous transverse magnetic field behind the cut-off of the engine output channel, incl. – in two orthogonal directions.

EFFECT: technical result is an increase in the control efficiency of the thrust vector of the plasma engine.

3 cl, 10 dwg

Description

The group of inventions relates to plasma technology and is primarily intended for use in space technology as an executive body of an electro-propulsion propulsion system. The invention relates to electric rocket engines (ERE) used on spacecraft, in particular, to stationary plasma engines (SPD) - Morozov engines.

Such engines are designed primarily for use in motion in space. As sources of ions or plasma, they are also used in technology for ionic surface treatment of the material. Due to the high velocity of the expiration of the working fluid or their high specific impulse of traction (from 1500 to 6000 s), they allow more efficiently solve a number of problems of controlling the motion of spacecraft in comparison with chemical jet engines.

SPDs are characterized by a low energy cost of traction due to the creation of conditions favorable for ionization of the working fluid, while the ion flux created by them is quasineutral, which removes the limitations of the ion current density due to the action of the space charge. In this regard, such a plasma engine can operate in a wide range of accelerating voltages. The ion current in modern models of plasma accelerators of this type is close to the discharge current and is determined only by the mass flow rate of the working fluid. Thus, in known SPDs, unlike ionic ones, it is possible to independently change the mass flow rate and accelerating voltage, i.e., thrust and flow rate at high engine efficiency.

Such engines are described in RU 152775 and 2527898, US 4703222.

The control system for the motion of a spacecraft (SC) in near-earth orbit should solve two main dynamic problems: maintaining the calculated parameters of the orbit of the spacecraft (SC) and ensuring its required orientation.

Theoretically, the SPD thrust vector should be necessarily located on the longitudinal axis passing through the center of inertia of the spacecraft. In this case, when the engine is running, there is no force torque deflecting the spacecraft from the straight path and forming its twisting. In reality, when installing the SPD on the spacecraft, it is impossible to fully achieve the passage of the SPD thrust vector through the center of gravity of the spacecraft, since this depends on a large number of design and assembly features. In addition, the center of inertia of the spacecraft can change its position during the development of the working fluid and for other reasons. As a result, in relation to SPD, it is considered, within the limits of tolerances and technological deviations, that the thrust vector practically lies on the longitudinal axis passing through the center of inertia of the spacecraft. Even small deviations lead to the fact that during the operation of the SPD on the spacecraft, the torque is formed on the spacecraft at the latter, which must be corrected, that is, eliminated.

According to practically established requirements, the thrust vector control device must provide a deviation of the thrust vector from the longitudinal axis of the engine by an angle of up to 5-7 ° with a resolution of 1 °. The device should allow you to change and set the thrust vector of the engine in a given azimuthal direction with a discreteness of the angle change in azimuth of not more than 20 °.

In the article "Control of the direction of the thrust vector of an electric rocket propulsion system when placing engines according to the" star "scheme", the authors Obukhov VA, Pokryshkin AI Yashina N.V. // "Cosmonautics and rocket science", 2008, No. 3, pp. 51-58, TsNIImash 2008, describes a method for controlling the motion of the center of mass of a spacecraft using electric propulsion engines arranged in a "star" pattern. This scheme is implemented from six SPDs arranged uniformly around the circumference through 60 ° uniformly along the radius.

This method is protected by RU 2309876, B64G 1/26, publ. 11/10/2007. In this patent, a method for controlling the motion of a spacecraft, which consists in controlling the motion of the center of mass of the spacecraft and in controlling the angular orientation of the spacecraft in space, which includes controlling the spacecraft by turning on at least one small thrust jet engine (SPD-140 engines with two modes work) of a spacecraft propulsion system creating a thrust vector and thrust control moments relative to the three main orthogonal spacecraft inertia axes, control actions are created using small thrust firs located in the common installation plane of the spacecraft body, orthogonal to one of its main axes of inertia, with an angular displacement α between adjacent engines relative to the main axis of inertia of the spacecraft, orthogonal to the installation plane of engines, in sectors of the specified plane in which the equipment preventing the placement of engines, while the value of α is selected from the condition (360 ° -β) / (N + 1) ≤β≤ (360 ° -β) / (N-1), where N is the number of small thrust engines, which is chosen from the condition N≥5; β is the total central angle of the sectors of the installation plane in which equipment is installed that impedes the placement of small thrust engines, and small thrust engines with variable directions of thrust vectors relative to the installation plane of engines and variable directions of thrust vectors in a plane that is parallel or parallel to the installation angle are used to create a control action the plane of the engines, and set so that the lines of the thrust vectors of the engines can be in the same plane and s main axis of inertia of the spacecraft that is orthogonal to the mounting plane engines.

In this case, thrust engines are used, each of which is capable of independently turning the thrust vector relative to the orthogonal rotation axes in mutually opposite directions, and the control action is created by simultaneously turning on two or three thrust engines, whose thrust vector lines are located at the nearest distance from friend, provided that the direction of the control action is between the starting engines. The control action is created when the thrust vectors of the engines are located in a plane intersecting the center of mass of the spacecraft.

From the same source, a spacecraft motion control device is known that includes a navigation block, a block of laws of motion control for the center of mass and the spacecraft’s angular orientation in space, a propulsion system containing small thrust engines that create thrust vectors and thrust control moments relative to the three main orthogonal axes spacecraft inertia, the propulsion system contains at least five small thrust engines located in the common mounting plane of the spacecraft body, orthogonal to one of its main axes of inertia , with an angular displacement between adjacent engines relative to the main axis of inertia of the spacecraft, orthogonal to the installation plane of the engines, in sectors of the specified plane in which equipment preventing the placement of engines is not installed, and small-thrust engines are made with variable directions of the thrust vectors relative to the installation plane of the engines and variable the directions of the thrust vectors in the plane coinciding or parallel to the installation plane of the engines, and are set so that about the line of thrust vectors of the engines can be in the same plane and intersect the main axis of inertia of the spacecraft, orthogonal to the installation plane of the engines.

Each of the thrust engines is located in the installation plane of the spacecraft hull on a cardan suspension providing two degrees of freedom of the engine in order to change the spatial position of the thrust vector relative to two mutually orthogonal rotation axes. Rotation drives of small thrust engines allow, independently of other engines, to change the direction of the vector of each engine relative to two orthogonal rotation axes in mutually opposite directions.

The control action applied to the spacecraft is created by turning on at least one thruster, which is part of the propulsion system. The selected thrust engine creates a thrust vector and / or thrust control moments relative to the three main orthogonal spacecraft inertia axes. This operation by controlling the motion of the spacecraft is possible if the direction of the control action calculated by the block of laws of control of the center of mass and the angular orientation of the spacecraft coincides with one of the discrete directions of the thrust vector of the propulsion system. Otherwise, a preliminary rotation of the spacecraft is necessary to combine the direction of the control action with the nearest discrete direction of the thrust vector of the propulsion system.

The disadvantage of this method and the device that implements it is the complexity of the design, the increased number of small thrust engines, the presence of an algorithmic complex for controlling the angular orientation of the spacecraft in space, including the control action on the spacecraft by turning on at least one small thrust jet engine of the spacecraft propulsion system creating a thrust vector and control thrust moments relative to the three main orthogonal spacecraft inertia axes.

In patents WO 2015082729 (published on November 6, 2015), SU 1839789 (patent status not defined on December 7, 2016) and RU 2445510 (published: March 20, 2012) a thrust vector control device for a plasma engine, characterized in that it contains a plasma engine fixed to the housing in the zone beyond the slice of its output channel, 1-4 magnetic coils (magnetic field generators) for deviating from the motor axis existing behind its slice of the magnetic field created by the magnetic coils of the engine. In WO 2015082729, a thrust vector deflection (OBT) system includes three or more magnetic coils located at the exit of the thruster, coaxially with it, whose axes are angled to the axis of the engine. In patents SU 1839789 and RU 2445510, the axes of the magnetic coils of the OBT system are directed perpendicular to the axis of the engine. These patents describe a method that includes selecting the magnitude of the electric current in each of the coils so as to deviate the axis of the magnetic nozzle from the motor axis by the desired angle.

Solution RU 2445510 is selected as a prototype for the claimed objects.

A disadvantage of the known devices, in particular the device of patent RU 2445510, lies in the fact that the magnetic field of the OBT coils deflects the axis of the magnetic field of the engine. Violation of the configuration (axial symmetry) of the magnetic field of the nozzle (or discharge chamber) of the engine is always accompanied by a decrease in the efficiency of the engine and an increase in the spraying speed of the nozzle (or discharge chamber) by accelerated ions, since in this case the ion-accelerating electric field also deviates from the axis and the ion flux the wall is increasing. An experimental verification of the effectiveness of the OVT system proposed in the indicated patents for SPDs showed that with these devices it is possible to deflect the thrust vector by an angle of up to 3.5 ° (for the device described in WO 2015082729) and by an angle of 1 ° -2 ° for devices described in patents RU 2445510 and SU 1839789). Thus, using known devices, it is not possible to deflect the thrust vector in the SPD by the required angle of 5 °.

The present invention is aimed at achieving a technical result, which consists in changing the design of the magnetic coils of the OVT device, providing a deviation of the plasma flow vector in the SPD by the required angle, and simplifying the method of achieving this deviation.

The specified technical result is achieved by the fact that in the thrust vector control device, the magnetic coils mounted on the plasma engine body in the area beyond the cut of its output channel are made in the form of two rectangular-shaped frame magnetic coils located open parts of the frames opposite each other symmetrically relative to the longitudinal axis of the engine parallel to each other or at a slight angle to each other.

The specified technical result is achieved by the fact that in the thrust vector control device, the magnetic coils mounted on the plasma engine body in the area beyond the cut of its output channel are made in the form of the first two rectangular-shaped frame magnetic coils located open parts of the frames opposite each other, symmetrically relative to the longitudinal the axis of the engine parallel to each other or at a slight angle to each other, and the second two rectangular-shaped frame magnetic coils located open parts p In contrast to each other, symmetrically relative to the longitudinal axis of the engine, and parallel to each other or at a slight angle to each other, the first pair of frame magnetic coils is placed perpendicular to the frame magnetic coils of the second pair and all magnetic coils are located at the same distance from the longitudinal axis of the plasma engine.

The specified technical result is also achieved by the fact that the method of controlling the thrust vector of the plasma engine is that the change in the vector of the plasma flow of the engine in the direction perpendicular to the plasma flow vector is carried out by forming a transverse magnetic field uniform across the volume of the plasma stream, directed across vector plasma flow plasma engine.

These features are significant and are interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

The present invention is illustrated by specific examples of execution, which, however, are not the only possible, but clearly demonstrate the ability to achieve the desired technical result.

In FIG. 1 - SPD (1) with the location of the small pair of magnetic coils (2) relative to the engine, the first example of the location, the axis of the pair of magnetic coils is perpendicular to the direction of plasma flow along the central axis of the SPD, as in patent RU2445510;

FIG. 2 - SPD (1) with the location of the small paired magnetic coils (2) relative to the engine, the second example of the location, the axis of the paired magnetic coils are parallel to the direction of plasma flow along the central axis of the SPD;

FIG. 3 - SPD (1) with one large coil (4), the plane of which is oriented at an angle of 30 ° relative to the central axis of the SPD, as in patent WO2015082729;

FIG. 4 - shows the configuration of the magnetic field lines of the magnetic field of the source α-100M1, corresponding to the outgoing plasma stream in the form of a cone from SPD (without coils);

FIG. 5 shows the configuration of the lines of force of the resulting magnetic field of the source α-100.M1 and a large coil located at a distance of 1.5 cm from the source cut;

FIG. 6 - the configuration of the lines of force of the resulting magnetic field of the source α-100.M1 and a large coil located at a distance of 1.5 cm from the cut of the source, when the direction of the current in it is reversed;

FIG. 7 is a graph showing the experimentally obtained shift of the ion current profiles of an engine jet with different current directions in paired magnetic coils,

FIG. 8 - shows the movement of a positively charged ion in the region of a uniform magnetic field, length l;

FIG. 9 - arrangement of a double parallel rectangular deflecting system relative to the SPD (two parallel coils (5) of the thrust vector deviation along the Y axis), as well as the arrangement of rectangular coils (7) at a small angle 2β to each other;

FIG. 10 is a diagram of the arrangement of four deflecting magnetic coils with respect to the SPD (two parallel coils of the thrust vector deflection along the Y axis (5) and two parallel coils of the thrust vector deflection along the X axis (6).

According to the present invention, the design of a device providing a magnetic deflection of the SPD thrust vector is considered (for the experiments, the SPD model α-100.M1 was used) by creating an additional magnetic field interacting with the SPD's own magnetic field (at its cut).

For this series of experiments, the following method was used to measure the angle of rotation of the thrust vector. The calculation of the angle of rotation of the thrust vector was carried out according to the obtained ion current profiles on a cylindrical probe with a diameter of 1 mm mounted on a coordinate device at a certain distance beyond the cut of the motor. The probe was moved in a plane perpendicular to the central axis of the engine. The coordinate of the displacement of the center of gravity of the ion stream profile of the model jet with and without a magnetic deflecting system was determined. Then, the jet deflection angle was calculated taking into account the distance of the probe from the cut of the model.

A series of experiments to obtain confirmation of the possibility of ensuring magnetic deflection of the SPD 1 thrust vector (in the design described in RU 152775 and 2527898, model SPD α-100.M1) was carried out using two small pair coils 2, mounted on the SPD housing at the engine output channel 3 .

In experiments at the external external magnetic pole of the SPD, additional magnetic coils 2 were located, creating local asymmetry in the output region of the plasma flow (Figs. 1 and 2). Short coils 2 were installed in pairs and were located at an angle of 180 ° relative to each other, in a plane perpendicular to the central axis of the engine. The location and design of the magnetic coils are fully consistent with RU 2445510. In FIG. 1, the longitudinal axes of the small coils are coaxial, and in FIG. 2 longitudinal axis of small coils are parallel to each other and the longitudinal axis of the SPD.

Using a probe placed on a coordinate device, ion current profiles were obtained in cross sections z = 20 and z = 32 cm from the cut of the engine model. The probe was moved in the horizontal plane, in which the coils were located during the experiment. The ion current profile measured in the nominal motor mode (coil current I _k = 0A) was compared with the profile obtained at different currents in additional short coils (I _k = ± 5A, ± 10A). The magnetic induction of one short coil was 1.7 * 10 ^-2 T for a current of 10A and 0.85 * 10 ^-2 T for a current of 5A, measured in the center from the side of the coil (for the case of the arrangement of the coils in Fig. 2). The magnetic induction of the coil, measured along the axis, at its end was 3.2 * 10 ^-2 T for a current of 10A and 1.7 * 10 ^-2 T at a current of 5A (for the case of the location of the coils in Fig. 1). The experiments using small paired coils made it possible to establish the possibility of realizing the magnetic deflection of the SPD thrust vector by creating an additional magnetic field interacting with the SPD's own magnetic field (near its slice). But the calculation of the angle of rotation of the thrust vector showed its insignificant value within 1-2 degrees, independent of the direction of the current in the coils, while the deviation of the plasma flow occurred in only one direction.

To more effectively deflect the plasma jet of the SPD engine, experiments were carried out using a single ring coil 4 (Fig. 3). The location and design of the magnetic coil is fully consistent with the patent WO 2015082729. The geometric dimensions of the coil are calculated from the condition of minimum weight and the creation of a sufficient magnitude of the magnetic field. So with an internal diameter of a single coil of 107 mm, a width of 10 mm and a height of 16 mm, 80 turns were wound in the coil. The plane of the coil was oriented at an angle of 30 relative to the central axis of the SPD.

The magnetic field lines of the engine of the SPD model α-100.M1 without the auxiliary coil turned on are shown in FIG. 4. When such a magnetic coil 4 was turned on near the cut of the engine model along its output channel, a redistribution of the magnetic field of the engine and coil occurred (Figs. 5 and 6). In FIG. 5 shows the configuration of the lines of force of the resulting magnetic field of the α-100.M1 SPD source and coil 4 located 1.5 cm from the source cut (at the output channel of the SPD). In FIG. Figure 6 shows the configuration of the lines of force of the resulting magnetic field of the SPD source α-100.M1 and coil 4, located at a distance of 1.5 cm from the cut of the source, when the direction of the current in coil 4 is reversed.

As a result of the experiments, a deviation of the SPD thrust vector was obtained within 1-3 °. By changing the polarity of the inclusion of the ring coil 4 and, selecting currents in it, we obtained the optimal value of the magnetic field. In this series of experiments, it was possible to change the thrust vector in increments of (1 ± 0.25) ° up to 3.5 ° (Fig. 7).

At the same time, there was a slight effect on the operation mode of the SPD. With the remote location of this coil 4 from the engine - (near edge of the coil z = 5 cm), the mutual influence decreased, but the magnitude of the deviation of the thrust vector also decreased to ~ 2 °. Currents in coils - as input parameters varied in the range from - 6 A to + 6 A. The maximum deviation of the thrust vector corresponds to the maximum current in coil 4. The graphs shown in FIG. 7 curve profiles obtained by the probe at a distance z = 20 cm from the cut of the model (from the output channel of the SPD). Thus, it has been experimentally shown that the efficiency of the OVT devices proposed in the patents WO 2015082729 and RU 2445510 is insufficient to deviate the engine thrust vector by the required angle of 5-7 degrees.

в область однородного магнитного поля, протяженностью l, перпендикулярно вектору магнитной индукции

(фиг. 8). Находясь в магнитном поле, ион движется по окружности радиуса R, так что за время движения в магнитном поле он описывает дугу окружности, опирающуюся на центральный угол α. Поскольку вектор скорости направлен по касательной к траектории движения иона и перпендикулярен к радиусу окружности, то вектор скорости также испытывает поворот на угол α. В силу квазинейтральности плазмы малоинерционные электроны будут «увлекаться» массивными ионами, обеспечивая тем самым поворот на заданный угол всего плазменного потока. Задавая угол отклонения α и исходя из необходимых значений длины области, можно получить оценку для величины магнитного поля. Многочисленные эксперименты и наблюдения показывают, что выходящий из источника плазменный поток является наиболее сформированным на расстоянии одного-двух калибров от источника.The simplest magnetic field deflecting charged particles by a given angle is the region of a uniform magnetic field. For preliminary estimates, we obtain a formula for the deflection angle of a charged particle in this case. Let a positively charged ion carrying a charge q and having mass m fly at an initial velocity

in the region of a uniform magnetic field of length l, perpendicular to the magnetic induction vector

(Fig. 8). Being in a magnetic field, the ion moves along a circle of radius R, so that during the movement in a magnetic field it describes an arc of a circle based on the central angle α. Since the velocity vector is directed tangent to the ion trajectory and is perpendicular to the radius of the circle, the velocity vector also experiences a rotation through the angle α. Due to the quasineutrality of the plasma, low-inertia electrons will be "carried away" by massive ions, thereby ensuring rotation of the entire plasma flow by a given angle. By setting the deflection angle α and proceeding from the necessary values of the length of the region, one can obtain an estimate for the magnitude of the magnetic field. Numerous experiments and observations show that the plasma stream emerging from the source is most formed at a distance of one or two calibers from the source.

An examination of various systems of current coils shows that the simplest configuration that creates a region of a given size in which uniformity of the magnetic field can be ensured within a given deviation and through which a plasma stream exiting the source can freely propagate is a combination of at least two rectangular coils 5 located in parallel planes. Such a device is shown in FIG. 9. By arranging these coils 5 in horizontal planes parallel to the ZY plane, symmetrically with respect to the axis of the plasma source, it is possible to create the necessary vertical (along the X axis) component of the magnetic field, ensuring the rotation of the plasma flow to the right or left (along the Y axis) from the source axis (Z) depending on the direction of current in these coils. The same phenomenon occurs when the coils 5 are arranged in vertical planes symmetrically with respect to the axis of the plasma source, in this case, it is possible to create the necessary horizontal component of the magnetic field, which enables the plasma flow to turn up or down from the source axis depending on the direction of the current in these coils.

Preliminary calculations were performed with coils of various sizes in the approximation when the width of the winding is small compared to their geometric dimensions (i.e., in the approximation of thin coils). The choice of system sizes from such coils corresponded to the plasma flow exiting the α-100.M1 SPD source. The length of the frame was 14 cm, the width of the frame was 11 cm, the distance between the planes of the frames was 11 cm. The magnetic field arising between the frames has a region 5 cm long in the central section, during which the field inhomogeneity lies within 2.5% (reaching a maximum in middle section of the frames). At the border of the frames, the field decreases approximately twice, and decreases by an order of magnitude already 2 cm from the edge of the frames beyond them.

Based on the assessments and calculations, two rectangular-shaped frame coils having 200 turns of wire each (in several layers) were wound for testing. The coils were located at a small angle of 2β to each other and to the horizon, symmetrically with respect to the plasma stream emerging from the source. Such an arrangement of magnetic coils reduces the interception of accelerated ions by the design of the coils, since the plasma flow exiting the engine diverges slightly from the axis. The direction of the thrust vector was determined by the profile of the ion current to the probe. The probe was located on the coordinate device and moved perpendicular to the axis of the fixed engine. The measurements were carried out at different distances from the cut of the engine (Z = 32 cm and Z = 40 cm from the cut of the model). When using an additional magnetic field to rotate the thrust vector, we measured the dependence of the angle of rotation on the magnitude of the current in the magnetic coils creating this field. As a result of creating a thrust vector control device using a magnetic field, a thrust vector deflection angle of ± 5 ° was obtained in increments of 1 °.

When using the method of controlling the thrust vector of a plasma engine by forming a magnetic field with a uniform volume of the plasma stream behind the plasma engine cut-off, created by using a double rectangular coil and directed across the plasma stream vector of the plasma engine,

you can note:

1. The direction of the magnetic field lines in such a system of coils was experimentally determined and it was shown that the deviation of the plasma jet of the engine for a given direction of the magnetic field corresponds to the deviation of positively charged xenon ions. With a change in the polarity of the magnetic field, the deviation of the plasma jet is reversed. The dependence of the angle of rotation of the plasma jet on the magnitude of the magnetic field is close to linear.

2. A slight effect on the mode of operation of the model was found during experiments on rotation of the SPD thrust vector.

Alternatively, it is possible to equip the SPD with both horizontally and vertically placed rectangular pairs of frame coils 5 and 6, as shown in FIG. 10. In this case, the system of coils is formed of coils 5 located in horizontal planes symmetrically with respect to the axis of the plasma source (a vertical component of the magnetic field is created, providing a rotation of the plasma flow to the right or left of the axis of the source, depending on the direction of the current in these coils), and from coils 6 located in vertical planes symmetrically with respect to the axis of the plasma source (in this case, it is possible to create the necessary horizontal component of the magnetic field, ensuring rotation of the plasma flow up or down from the source axis depending on the direction of the current in these coils). The simultaneous inclusion of two pairs of magnetic coils allows you to deflect the thrust vector in any direction in azimuth from the axis of the SPD.

Claims (3)

1. A thrust vector control device, characterized in that the magnetic coils fixed to the plasma engine housing in the area beyond the outlet of its output channel are made in the form of two rectangular-shaped frame magnetic coils located open parts of the frames opposite each other symmetrically relative to the longitudinal axis of the engine, parallel to each other friend or at a slight angle to each other. 2. A thrust vector control device, characterized in that the magnetic coils fixed to the plasma engine housing in the area beyond the slice of its output channel are made in the form of the first two rectangular-shaped frame magnetic coils located open parts of the frames opposite each other symmetrically relative to the longitudinal axis of the engine, in parallel to each other or at a slight angle to each other, and the second two rectangular-shaped frame magnetic coils located by the open parts of the frames opposite each other s It is symmetrical about the longitudinal axis of the engine, parallel to each other or at a slight angle to each other, with the first pair of frame-shaped magnet coils arranged perpendicularly framework magnetic coils of the second pair, and all the magnetic coils are arranged at the same distance from the longitudinal axis of the plasma engine. 3. A method for controlling the thrust vector of a plasma engine, namely, that the deviation of the plasma stream vector of the engine in the direction perpendicular to the plasma stream vector is carried out by forming a magnetic field uniform in volume of the plasma stream behind the plasma engine slice directed across the plasma stream vector of the plasma engine.

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