RU2726152C1 - Electric rocket engine (versions) - Google Patents

Abstract

FIELD: engines.SUBSTANCE: invention relates to electric rocket engine used to control spacecraft movement in space, including orbital maneuvers. Electric rocket engine has, as a variant, photoemission cathodes – electron sources for neutralization of the ionised working medium, light detector photodetector for control of engine operation modes, energy recuperation device.EFFECT: technical result is higher efficiency of using electric energy and power efficiency of engine by using energy of light flux from ion torch and neutral atoms (molecules) to ensure engine operation.4 cl, 2 dwg

Description

The invention relates to an electric rocket engine (ERE) used to control the movement of a spacecraft (SC) in outer space.

Various types of electric propulsion are known for providing spacecraft motion. Unlike the known evaporative and chemical rocket engines with a maximum torch speed of up to 4000 m / s, the electric propulsion engines provide an order of magnitude greater speed. When using compressed gases, thrust density is achieved up to 1 N / m ² , jet stream outflow speed from 2 km / s to more than 50 km / s with electric power up to 5 kW and more. [Franklin R. Chang-Diaz, "Plasma Propulsion for Interplanetary Flight," Thin Solid Films, Vol. 506-507 (May 26, 2006.): - P. 449-453; Electrostatic rocket engines. / Ed. Yu.A. Ryzhova. - M: Mir, 1964 .-- 408 p .; Goebel DM, Katz I. Fundamentals of Electric Propulsion: Ion and Hall Thrusters. Wiley, 2008. 508 p.].

Each known analogue is an ion-plasma electric propulsion jet device as part of a spacecraft having a storage ring with a working fluid (RT) in it, a reactor chamber, in particular, a gas discharge chamber connected to the indicated storage ring, equipped with electrodes for structure transformation, ionization, acceleration and neutralizing the particles of the specified working fluid by means of an electromagnetic field (EMF), a system for creating a magnetic field. The main working gas of the possible ones (N ₂ , Ar, Xe, etc.) is Xe, which is effective, but has great limitations, which include the high cost and low volumes of gas production, the high cost of ground tests in vacuum chambers at low temperatures, lack of natural resources for the further development of space engines. In addition to inert gases, cesium, mercury, bismuth, zinc, tin, magnesium, gallium, iodine, teflon, ionic liquids, colloidal solutions, and ammonia are tested as consumable RTs. Teflon (other names fluoroplastic, PTFE) as a solid RT is used in an ablation pulsed electric-discharge motor. A special design with a strong electric field has been created for the RT in the form of molten metal. For RTs in the form of colloidal or ionic solutions, the design of an electro-spray source with a charge of small drops of liquid is used.

In analog devices of the present invention, a volume plasma is created from particles of RT from which ions are extracted, including using partitions with holes. In order to eliminate the negative phenomena associated with a significant spatial divergence of ions in the accelerating channel, magnetic devices are used - ion beam concentrators. Patent RU 2163309 (IPC: F03H 1/00, H05H 1/54, published February 20, 2001) describes the design of an expanded magnetic pole tip in the form of a truncated cone, which provides the formation of a narrowly directed stream of accelerated ions in a given direction. In the patent US 5581155 (publ. 03.12.1996) describes a rocket engine of low thrust, built on the Hall effect. This thruster also uses an electromagnetic field to accelerate positively charged particles. The outflow speed in this type of thruster is about 15 km / s with a thrust density of less than 5 N / m ² and a power of 1.3 kW.

The invention 2525442 C2 (published on 08/10/2014) relates to a plasma generator and to a method for controlling it by controlling the plasma formed in the generator using a high-frequency alternating electric or electromagnetic field.

An analogue, in particular, is a device for accelerating the flow of charged particles (patent for the invention of the Russian Federation No. 2104411, publ. 02.10.1998), containing a plasma source (gas discharge chamber) and a multi-beam ion-optical system having at least three electrodes sequentially located at a distance from each other, and the first electrode (screen) is the end wall of the gas discharge chamber and is positively charged. The second accelerating electrode is negatively charged. To improve the structure of the ion flux, after the accelerating electrode, a third slowing electrode is installed, which slows down the fastest ions. The formation of a multipath flux is due to the fact that the electrodes of the ion-optical system have a set of separate coaxial holes for the passage of individual ion beams.

A device for creating an adjustable traction force in an electric rocket engine (patent for invention US 4838021, IPC: F03H 1/00, publ. 06/13/1989), containing an ionization chamber and an ion-optical system with two electrodes (screen and accelerating) between which a constant accelerating potential difference is applied. The modulation of the current of the multipath ion flow is carried out by pulse modulation of the discharge current in the ionization chamber.

For charge neutralization of extracted ions after their acceleration and, accordingly, obtaining a recoil momentum, thermionic or field (field-by-electron) electron sources are used.

Analogs in the form of electric propulsion with volumetric ionization of a gas and closed Hall electron drift are the main systems of operating spacecraft. The analogue of RU 2527267 C2 (publ. 08.27.2014) is an ion-plasma jet engine with a neutralizing electron plasma based on the Hall effect, containing a main ring channel of ionization and acceleration, having an open output end, at least one cathode, a ring anode concentric to the main annular channel, a pipeline and a distributor for supplying ionizable gas to the channel and the magnetic circuit to create a magnetic field in the main annular channel. In the patent EP 0900196 A1 (publ. 10.03.1999 g.) Describes the ERE with a closed electron drift in a magnetic field. It includes an outer pole piece that is magnetized by a ring coil. French patent document 2693770 A1 (publ. 10/14/1994) describes an electric propulsion electric propulsion system with a closed electron drift in a magnetic field with three coils, including an outer ring coil. The invention RU 2509918 C2 (publ. March 20, 2014) relates to an electric rocket engine with a closed electron drift. Plasma EREs with a closed electron drift in a magnetic field have a thermal disadvantage, since the outer ring coil encloses a long wire, which leads to a high level of heat dissipation, and with respect to the mass of the coil, which is also large. The operation of such electric propulsion is associated with high energy consumption and significant heat loss.

The invention is a prototype [Pat. 2474984 Russian Federation, IPC Н05Н 1/54, F03H 1/00. Closed electron drift plasma accelerator / Kozlov V.I. [and etc.]; Applicant and patent holder Fed. state the budget. arr. institution of higher prof. education "Moscow Aviation Institute", - stated. 10.24.11; publ. 02/10/13] refers to the plasma technique and can be used in the development of plasma accelerators with a closed electron drift and an extended acceleration zone. A cathode-compensator (electron emitter) is installed at the edge of the accelerator channel. High demands are placed on the cathode, it must provide a stable high emission, and additional devices that increase mass and dimensions are required. In addition, the disadvantages are associated with a high cathode heating power, a decrease in emissivity, and an increased operating temperature, which results in high energy consumption, heat loss, and relatively low energy efficiency.

The present invention is the creation of an electric propulsion having a simple design, more economical, generally efficient and reliable in operation. According to the invention, a positive effect is achieved in increasing the efficiency of using electric energy of electric propulsion, and as a result, a quantitative indicator of energy efficiency - energy efficiency of the engine is increased.

Alternatively, the electric propulsion contains:

a) photoemission cathodes - sources of electrons that produce the emission of a stream of secondary photoelectrons in a vacuum;

b) a photodetector of light radiation, which generates a signal when registering photons;

c) photoelectronic panels that generate electrical energy when irradiated with photons.

These photoactive devices (a, b, c) are installed mainly near the boundary of the accelerating channel and are connected to the on-board power supply and control system. They are designed to use the luminance of photon radiation arising from the operation of the engine at the boundary of the ion acceleration region, in the field of neutralization by electrons and in the field of torch extraction. Radiation is associated with the emission of photons from ions during their neutralization by electrons, as well as with the relaxation of excited neutral particles that lose energy upon transition to the ground state.

The use of photoemission cathodes - electron sources, a photodetector and photoelectronic panels can significantly improve the performance of the electric propulsion, and, in particular, provides:

- the formation of neutralizing electrons due to photoelectron emission;

- control of engine functioning;

- return to the on-board network of part of the energy spent on ionization.

The object of the invention is solved in the design variants of the electric propulsion described in the claims.

According to paragraphs 1-3 Formulas, the claimed ERE having a drive with a consumable working fluid in it, an extractor-injector, an accelerator chamber for accelerating ions and ejection of a torch, a cathode-compensator for neutralizing ions. The disadvantages of the prototype are eliminated in this invention by optimizing the processes in the reactor chamber and in the field of neutralization due to the fact that mainly in the near region of ion neutralization and ejection of the torch there are devices for collecting light radiation and converting this radiation, as an option: into a stream of photoelectrons; into the signal controlling the motion of the spacecraft; into electrical voltage. For example, photocathodes are mounted - electron sources in the form of photoemissive panels, there is a photodetector of light radiation, photoelectronic panels are installed.

In FIG. 1. shows a schematic representation of the electric propulsion with an example of the installation of structural elements: 1 - drive working fluid; 2 - transportation channel; 3 -extractor injector; 4 - control voltage generator connected to the extractor-injector 3; 5 - region of surface ionization and plasma; 6 is an acceleration chamber containing electrodes for creating an electromagnetic field (not shown in the figure); 7 - cathode-compensator; 8 is a slice of the acceleration chamber in the region of the ion flux exit from the engine; 9 - region of ion neutralization and flare ejection. The dash-dotted line indicates the region of the reactor chamber.

In FIG. 2 schematically shows the region of the exit of the ion flux from the engine with the elements: 8 - section of the acceleration chamber in the region of the exit of the ion flux from the engine; 9 - region of ion neutralization and flare emission (photon radiation source); 10 - photoemission cathode - an electron source that produces the emission of secondary photoelectrons into the ion flux; 11 - photon; 12 - secondary photoelectron; 13 - photodetector of the light flux for collecting light radiation connected to the spacecraft motion control system (not shown in the figure); 14 - photoelectronic panels connected to the spacecraft power supply system (not shown in the figure).

According to paragraph 1 of the Formula, mainly in the near region of ion neutralization and flare ejection there are photocathodes - electron sources in the form of photoemissive panels. In contrast to the known analogues and prototype, in the proposed device, the neutralization is carried out, including photoelectrons. The principle of operation is based on the implementation of the theory of the external photoelectric effect (photoelectric effect). The glow emitted by the torch is emitted in the form of photons with a certain energy. Upon reaching the photocathode, in the surface layer of its material, the photon meets the electron and transfers its energy to it (absorbed by the electron). If the received energy is enough to complete the work function, then the electron leaves the material from which the photocathode is made, becomes free and can be used to neutralize the ion flux. Each substance (material) has its own work function. Preferred materials for the photoemission cathode are potassium, cesium with a work function of 2.2 and 1.8 eV, respectively, and preferably BaO or Ba ₃ WO ₅ with a work function close to 1 eV. It becomes possible to create the most favorable ion neutralization scheme, which allows to simplify the engine design, increase efficiency and reliability.

According to paragraph 2 of the Formula, the problem is solved as follows: mainly in the near region of ion neutralization and ejection of the torch there is a photodetector of light radiation connected to the spacecraft motion control system. Rational use of the signal received from the photodetector will allow for remote monitoring of the functioning of the engine, as well as its use in the automatic control system of the spacecraft.

According to paragraph 3 of the Formula, mainly in the near field of ion neutralization and flare ejection there are photoelectronic panels - electric energy generators connected to the electrical network on board the spacecraft.

According to paragraph 4 of the Formula, mainly in the area closest to the photoemission / photoelectronic panels there is at least one optical device focusing light radiation on them from the ion neutralization region and the torch ejection region. This allows you to increase the intensity of the useful exposure of the panels.

We consider the operation of electric propulsion on specific examples of the design and operating modes.

When transferred to a working state, an energetic effect (for example, heating) is applied to the working fluid in drive 1 (Fig. 1) and a flow of neutral atomic, molecular, cluster, small or microparticles of the working fluid is formed. The flow of neutral particles of the working fluid from the accumulator 1 through the transport channel 2 is transmitted to the extractor injector 3, to which the control voltage generator is connected 4. In region 5, a plasma is formed consisting of ions and electrons. Using the electrodes contained in the accelerating chamber 6, an electromagnetic field is created, under the influence of which the ions are accelerated and thrown into the torch. In the field of neutralization of ions and ejection of the torch 9, the field of the space charge is compensated by emission of free electrons into this region. The relaxation of excited atoms (molecules) to the ground state and ion recharging is accompanied by the emission of photons and, as a whole, by bright emission in the visible and ultraviolet parts of the spectrum. In analogues and prototype, this radiation is scattered and lost in space, without any benefit. The claimed invention proposes to extract a positive effect from this phenomenon, which is created by the fact that:

1. A device in the form of photoemission cathodes - electron sources under the influence of photon radiation forms a photoelectron flux in vacuum, which is drawn by the electric field of ions into the ion flux, where it neutralizes the specified ion flux. This device is supposed to be used with the cathode-compensator described in the prototype invention, and is intended to significantly reduce its power consumption, loss of its emission ability, heat loss. This will favorably affect the ERD resource. At the same time, an important factor is the reduction in energy consumption, and, consequently, the increase in efficiency. In addition, the device in the form of photoemission cathodes - electron sources is a duplicate (parallel) system for neutralizing the ion flux, therefore, the use of such a scheme helps to increase the reliability of the apparatus.

2. The device in the form of a photodetector of light radiation works as a photodetector - a signal generator, with which it is possible to remotely monitor the functioning of the engine. In this case, it becomes possible to control: the fact and stability of starting / not starting the engine, i.e. creating the necessary conditions for the implementation of the ionization process and the formation of the torch; the intensity of the engine; duration and possible malfunctions / interruptions during engine operation. Alternatively, this signal can be transmitted to the engine management system. Incorrect engine operation will be detected in a timely manner and an operational decision will be made, for example, to restart. In addition, the use of the device appears to be effective with high-precision control of the spacecraft in orbit, helping to reduce unnecessary maneuvers, which means saving not only energy resources, but also the RT.

3. A device in the form of photoelectronic panels when irradiating photocells with photons produces additional electrical energy, which is sent to the on-board electrical network. Such energy recovery is especially important when the intensity of illumination of the solar panels of the spacecraft is weak (the period the spacecraft is in the shadowed region of the planets, the spacecraft is far removed from the light source, and the spacecraft is disoriented). The photoelectric conversion coefficient of modern silicon and gallium panels reaches 24-25%, and gallium-based multilayer panels (GalnP / GaAs / Ge) - 32%. Given the efficiency of solar cells, the proportion of recuperated energy can reach decent values.

In order to increase the efficiency of photoemission and photoelectronic panels, radiation is additionally focused using an optical device (Clause 4 of the Formula).

To confirm the feasibility of the invention, the authors conducted practical experiments. When firing tests of an ionic electric rocket engine in a vacuum chamber (10 ^-4 -10 ^-5 mm Hg), near the area of the flare, photoelectronic panels were installed - the elements of the solar battery of the spacecraft. The conductors from the photoelectronic panels were sealed to the outside of the chamber using pressure connectors. When the ion engine was operating in various modes, the presence and level of the signal were controlled using a measuring device. With the formation of the torch, an electrical signal arose, and its level increased with increasing intensity of the engine, i.e. brightness of the glow of the torch. Further use of such a signal does not present great difficulties and is a feasible technical task.

The positive effect of the application of the design variants of the electric propulsion engine according to the invention, which consists in increasing the efficiency of use of on-board electric energy, as a result, increasing energy efficiency, contributes to an increase in the overall and continuous operation time of the apparatus, increasing the resource, reliability, stability and efficiency of traction characteristics. The invention is aimed at overcoming the common disadvantages of electric propulsion: low reproducibility of traction pulses, low reliability of inclusion after a pause, insufficient achievable pulse duration, limited service life.

Claims (4)

1. An electric rocket engine having a storage medium for the working fluid, an extractor injector, an accelerator chamber for accelerating ions and ejecting a torch, a cathode-compensator for neutralizing ions, characterized in that there are mainly photocathodes in the near field of ion neutralization and ejection electrons in the form of photoemission panels. 2. An electric rocket engine having a storage medium for the working fluid, an extractor injector, an accelerator chamber for accelerating ions and ejecting a torch, a cathode-compensator for neutralizing ions, characterized in that there is a light detector in the near region of ion neutralization and ejection of a torch in the form of photoelectronic panels connected to a spacecraft motion control system. 3. An electric rocket engine having an accumulator of a working fluid, an extractor injector, an accelerator chamber for accelerating ions and ejecting a torch, a cathode-compensator for neutralizing ions, characterized in that there are photoelectronic panels in the near region of ion neutralization and ejection of a torch connected to the spacecraft’s power supply system. 4. The device according to paragraphs. 1-3, characterized in that mainly in the area closest to the photoemission / photoelectronic panels there is at least one optical device focusing light radiation on them from the ion neutralization region and the torch ejection area.

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