RO133741A2 - Installation and process for producing energetic beams of metal ions to be applied in electric propulsion in space - Google Patents

Abstract

The invention relates to an installation and a process for producing energetic beams of metal ions of controllable flow, to be applied in electric propulsion in space. According to the invention, the installation consists of a cylindrical enclosure (1) made of stainless steel, depressurized to a pressure lower than 10Pa by a system consisting of a turbomolecular pump (2) and a dry mechanical pump (3), wherein there is introduced a system (9) which maintains a constant distance of about 1 cm between a metallic anode (5) situated on the axle of the cylindrical enclosure (1) and heated by bombardment with electrons produced by a stainless steel Wehnelt tube (8) and a tungsten filament (7) with the role of cathode placed at an angle of about 60° related to the axle and heated by a current source, the electrons being accelerated in an electric field generated between the cathode (7) and the anode (5) with a voltage of about 2000 V applied from a power source (10). The claimed process consists in that the metallic vapours, produced by the vaporization of an anode heated by electron bombardment, are ionized and accelerated by a double layer of plasma confining a volume of plasma generated around the anode.

Description

STATE OFFICE FOR INVENTIONS Trademark Application for a patent

Nr. ......

Filing date .... P.,

INSTALLATION AND PROCESS FOR OBTAINING ENERGY BODIES

METAL IONS WITH APPLICATION IN ELECTRIC PROPULSION IN SPACE

The present invention relates to an installation and a process for obtaining energy beams of metal ions with controllable flows, with application in electric propulsion in space. Electric propulsion encompasses all propulsion technologies in which electricity is used to increase the fuel discharge rate, in order to increase the propulsion force. Compared to other conventional propulsion methods (for example, chemical propulsion), the high rate of fuel escape in the case of electric propulsion results in a significant reduction in the amount of fuel required for a space mission or application, and consequently a reduction in costs or duration. time needed to complete the mission. The main functional parameters that define the performance of an electric propeller are: propulsion force (7), specific impulse (I _sp ) and total efficiency (ηΤ). Of all the types of electric propellers, the most efficient and often used in space applications are those of type Ion Thruster and Hali Thruster. Both types of propellants use xenon (Xe) as a fuel, which is first ionized and then expelled at very high speeds, using different techniques. The major difference between the operation of the two thrusters is that Ion Thruster uses electrostatic grids to increase the ionization rate of gas expulsion, while in the case of Hali Thruster a magnetic field is used which increases the ionization rate of the gas. and the appearance of a strong electric field that accelerates ions outside the propeller. In both cases, the expelled ion beam is neutralized using the plasma of a cavity cathode discharge to prevent the return of the ions to the spacecraft or satellite. The electric power consumed by these thrusters is of the order of hundreds or thousands of W, thus obtaining specific impulses of the order of thousands of seconds, propulsion forces of the order of tens or hundreds of mN and total efficiencies of over 50%. Due to their small propulsion forces, these propellers cannot be used in space launch missions on Earth, but are used to maintain or modify the orbits of artificial satellites used in telecommunications and long-range space missions conducted outside the area of influence. of intense gravitational fields, in this case the terrestrial one.

The main problems faced by both types of thrusters are:

to 2018 00304

02/05/2018

High fuel costs, costs related to both the production price (depending on the purity, one liter of Xe costs between $ 5 and $ 30), as well as bottling, transportation, storage, distribution and gas flow control systems ;

- The erosion of the acceleration grids (in the case of Ion Thuster) and of the walls of the thrusters (Hali Thruster) due to ion bombardment;

- Difficulty in controlling the propulsion force and the specific impulse independently. For example, high satellite momentum and low propulsion force are required to keep a satellite in orbit. In the case of classic propellers, the value of the specific impulse increases with the increase of the propulsion force, which leads to the increase of the fuel and energy consumption.

In order to overcome these limitations, it is necessary to find an alternative solution to electric propulsion using the classical ion engines (Ion Thruster and Hali Thruster). Thus, it is necessary to develop a new type of ionic propeller, with performances (specific impulse, propulsion force and total efficiency) comparable or even better than those obtained so far by classical ion engines, but which offers the possibility of independent impulse control. specific and the propulsion force, requiring lower costs for manufacture and operation (fuel, energy and maintenance). The solution proposed in the present invention relates to an installation and a process for obtaining energy beams of metal ions, which allows independent control of energy and ion density. The process of obtaining the ion beams with controllable flows, with application in the electric propulsion in space, according to the invention, consists in using the thermionic arc technique, in pulsed regime, for the ablation and ionization of a metallic material and its evacuation at very high speeds. . The present invention brings a series of novelty elements, the most important of which is the operation, for the first time, of the thermionic arc in pulsed regime. To date, the thermo-ionic arc has been operated only under DC (DC) regime, being mainly used for depositing thin metal layers. A characteristic of the thermo-ionic arc is the generation of a strong double layer (V.

Tiron, L. Mihaescu, C.P. Lungu, G, Popa, Rom. Journ. Phys., 56 (2011) 41-46), which allows the acceleration of plasma ions at very high speeds, of the order of hundreds or even thousands of eV. However, the low degree of plasma ionization (a few percent) results in relatively low opulence. The operation of the thermo-ionic arc in pulsed regime allows cr efcf to be defined as well

to 2018 00304

02/05/2018 of the ionization degree of the metal vapors, as well as of their energy. thus greatly improving propulsion performance.

The embodiment of the invention relates to an installation and a process for obtaining energy beams of metal ions, in order to optimize the performances of the ionic motors used in space propulsion and to reduce the manufacturing and operating costs, the installation and the process for obtaining the energy beams. using the thermionic arc in pulsed current regime, as well as the specific performance parameters are described in this invention. Process! used allows to increase the degree of ionization of the plasma and the creation, in the plasma of the thermo-ionic arc, of a double layer with a very high potential drop which can ensure the acceleration of the plasma ions at energies of the order keV. For certain values of the operating parameters of the discharge of the thermo-ionic arc, quasi-monoenergetic beams of metal ions are obtained whose energy and density can be controlled by means of the electric parameters of the discharge. The installation and process are suitable for obtaining ion beams of pure metals, such as: Be, Al, Ti, Cr, Ni, Cu, Zn, Ag, In, W, Au, etc.

The discharge of the thermo-ionic arc in high-power pulses is ensured by a high-power pulse generator or an external control high-voltage DC source that allows the application of positive high-voltage pulses (1-3 kV) in short intervals. (several tens or hundreds of microseconds). The chamber in which the plasma of the thermo-ionic arc is produced in metallic vapors consists of a stainless steel working chamber which is depressurized to a lower pressure limit of IO ' ⁵ Pa using a depressurization system consisting of a dry mechanical pump and a turbomolecular pump.

The principle of the method

Thermo-ionic vacuum arc (known in the literature as Thermionic Vacuum Arc - VAT) is an electric discharge produced in the metal vapors of a material from which an electrode with an anode of discharge is made (G. Musa, A. Baltog, A Popescu, N. Betiu, I. Mustata, Plasma Contr. Phys. 26 (3) (1986) 171). Metallic vapors are produced by electron bombardment in the presence of an electric field applied between the cathode and the anode, a field that accelerates the electrons emitted by a filament (hot cathode) towards the anode. The filament is made of tungsten wire (W) and is surrounded by a Wehnelt cylinder at an appropriate reference potential (referred to as a reference), usually the cathode, which focuses the electron beam on its surface.

to 2018 00304

02/05/2018

The assembly consisting of the filament and the Wehnelt cylinder is referred to as the electron cannon and can have various sizes and / or shapes (H. Ehrich, J. Schuhmann, G. Musa, A. Popescu, I. Mustata, Thin Solid Films 333 (1998) 95-102), (P. Lungu, C. Porosnicu, 1. Jepu, P. Chiru, A. M. Lungu, V. N. Zaroschi, V. Tiron, R. Vlădoiu, V. Ciupina, '' Beryllium nanostructured alloy, Patent ROI27300-A0 2012). The voltage on the discharge anode is in the order of hundreds or even thousands of volts and can be applied continuously (DC) or pulsed. The anode usually consists of a crucible (cradle) made of refractory material (W, C, Mo, Ta or TiB) in which is found the material used to feed the plasma of the thermo-ionic arc. The discharge anode can also be in the form of a bar in the case of materials with very high melting point (C, Mo, Ta, W) or with very low thermal conductivity (B, Ti), in which case the platform can be dropped. The electrode system is placed in a metal enclosure coupled to a pumping system that ensures a lower limit pressure of less than ⁰ Pa. In order to be able to adjust the distance between the discharge electrodes, it is necessary that what! at least one of the electrodes is fixed to a displacement system. In order to ignite and maintain the discharge, it is necessary that the thermoelectrons originating from the filament be focused and accelerated towards the anode so as to produce the melting and evaporation of the anodic material, and in the interelectrode space a sufficiently high vapor pressure of the material used to supply the plasma is realized. of the thermo-ionic arc. For certain values of the voltage applied between the discharge electrodes, as well as the pressure of the metal vapors, a stable electric discharge in the metal vapors of the material in the nacelle is lit. Due to the very low pressure in the enclosure, but also the high rate of evaporation of the material subjected to the electronic bombardment, a very intense plasma is produced above the anode, a plasma whose shape is quasi-spherical due to the very high concentration of metal vapor concentration. The fact that the walls of the enclosure and the cathode (filament) are connected to the reference potential of the electrical circuit of the electric discharge causes the anode and also the plasma produced in the metal vapors to be at a positive potential much higher than that of the electrode. reference. For some experimental conditions, such as low values of the discharge current intensity and the intensity of the electronic thermo-emission current, but high values of the voltage applied to the anode, the plasma formation is surrounded by a well-defined potential structure indicating the presence of a double layer. very strong (sVsd >> kT _e , where e represents the electric charge of the electron, Vsd - the potential fall on Boltzmann, and T _e - temperature of the electrons). Therefore, the ions

to 2018 00304

02/05/2018 of potential will receive energies comparable to the potential drop (by the order of hundreds or even thousands of volts) on the double layer of electric discharge. The flux (energy and density) of metal ions can be adjusted by changing the value of the voltage on the anode, the discharge current, the heat-emitting current on the filament, as well as by changing the geometry and the distance between the electrodes. In the case of electric propulsion, the value of the specific impulse depends linearly on the ion speed, and that of the propulsion sheet depends on the product between the velocity and the ion density in the beam. In the case of the thermionic arc, both the energy and the density of metal ions depend on the electrical parameters of the discharge which, in turn, are strongly dependent on the nature of the evaporated material. Thus, in the case of high melting point materials (W, Ta, Re), metal ions have very high energy (velocity), but their concentration in the total flux of particles is low, and in the case of low melting point materials (Zn) , In, Sn, Pb), the metal ions have low energy, but very high concentration.

The installation and process for obtaining energy beams of metal ions, according to the invention, has the following advantages:

V reduced cost of the material used for generating metal ions compared to the gas used in conventional ion engines (Xe);

V reduced costs for transporting and storing material used to generate energy ions due to the reduced volume of metal compared to that of gases used for conventional propulsion devices (Jon Thruster and Hali Thruster). For example, compared to Xe (compressed at 200 atm.), The same mass of Cu occupies a volume 10 times smaller;

V elimination of the acceleration / deceleration grids used in the case of conventional ionic motors, which, over time, erode and affect the performances of the devices;

V precise and independent control of the energy and concentration of metal ions in the propulsion beam;

V performance parameters (specific impulse, propulsion force, total efficiency) comparable or superior to the classic propulsion devices;

I can use a very diverse range of materials for ion production

to 2018 00304

02/05/2018

V the proposed system can be used both for maintaining or modifying the orbits of artificial satellites used in telecommunications and long-term space missions, but also for obtaining very compact thin metal layers in the laboratory;

V the proposed system works in the extraterrestrial space and does not require enclosure and depressurization system like those used in laboratory experiments;

V the possibility of using a carousel-type displacement system, which allows the selection of the material corresponding to the independent control of the specific impulse or propulsion force;

V reduced cost of the solution adopted by the present invention due to the simplicity of the proposed device.

The following is an example of an embodiment of the invention in connection with FIG. 1, ... 6, which represents:

Fig. 1. Schematic of the installation used to obtain in the laboratory of energy beams of metal ions using the pulsed thermo-ionic arc in high power pulses.

Fig. 2. Temporal evolution of the discharge voltage in the case of the pulsed thermo-ionic arc.

Fig. 3. Temporal evolutions of the intensity of the electric current by discharge in the case of the pulsed thermo-arc.

Fig. 4. Temporal evolutions of ionic current density in the case of pulsed thermo-ionic arc.

Fig. 5. Axial distribution of the potential of the plasma of the thermo-ionic arc operating in DC regime.

Fig. 6. The temporal evolution of the potential of the thermionic arc plasma measured at different positions relative to the anode. The discharge parameters of the thermo-ionic arc are: the amplitude of the voltage pulse applied on the cathode of approximately +1.45 kV, the duration of the voltage pulse of about 400 ps, the repetition frequency of the voltage pulses of 1 kHz.

The installation (Fig. 1), according to the invention, is composed of a stainless steel enclosure 1 in the form of a cylindrical enclosure with a diameter of 80 cm and a height of 40 cm, provided with various ports on which windows for visualization and optical diagnostics are mounted. of plasma, electrical bypasses for electrical plasma diagnostics and monitoring systems of ion beam parameters. The enclosure may be depressurized up to a limit pressure irti ^ ixsr ^ idjș ^^^ a / * £ »ΝΓ · '

to 2018 00304

02/05/2018 using a system for producing low pressures (vacuum or depressurization system) consisting of a turboinolecular pump 2 and a dry mechanical pump 3. The vacuum system is connected to the deposition chamber 1 by means of an insulation hatch. 4. in the enclosure is mounted a platform 5. in the form of a boat, with anode of discharge. The material 6 used to feed the plasma of the thermo-ionic arc comes in the form of paralepipedic copper pellets, with dimensions of 2 mm * 3 mm> -5 mm. The material is melted using an electron gun made of tungsten filament 7 and stainless steel Wehnelt cylinder 8, fixed to a displacement system 9 and fed from a pulsed DC voltage source 10. The thermo-ionic arc is operated in DC mode. pulsed using a high voltage positive pulse generator 11 or a high voltage DC source with positive polarity and external control.

The defined parameters of the discharge of the thermo-ionic arc in high power pulses are: the nature of the material used to produce the metal ions (in this case, Cu), the amplitude of the voltage pulse applied to the anode, the repetition frequency of the voltage pulse and the duration of the pulse. voltage, the value of the intensity of the electric current on discharge, the value of the intensity of the current through the filament of the electron gun, the distance between the nacelle and the electron cannon, as well as the angle between the normal surface of the nacelle and the axis of the electron cannon. To operate the pulsed thermo-ion arc proceed as follows: heat up the filament of the electron gun by applying a voltage, in DC mode, to its ends, then apply high voltage pulses and positive polarity between the anode in W, which contains Cu pellets (granules), and the electron gun that is connected, together with the enclosure walls, to the reference electrode. It adjusts the process parameters (amplitude of the voltage pulse applied to the anode, the frequency of repetition of the voltage pulse and the duration of the voltage pulse, the value of the current intensity through the filament of the electron cannon, the distance between the nacelle and the electron cannon) so that during the arc operation thermo-ionic so that no uncontrollable fluctuations of the electrical parameters of the discharge appear. The spatial distribution and temporal evolution of the plasma potential were measured using an emissive probe. The energy of the metal ions was measured using a magnetic field deflection spectrometer (Dempster spectrometer). The flux of metal ions was measured using a 50 mm diameter disc-shaped manifold polarized with 100 V reference. The total flux of particles, ions and neutral, was determirjat-rjlj ^ jiQruI a micobalanţe quartz, and the rate of consumption of the material of the platform and ^/ ^^>âBterfrimătQ', by gravimetric measurements.

to 2018 00304

05/02/2018 in Fig. 2 shows the temporal evolution of the voltage applied to the discharge, measured using a 1: 100 voltage probe. For this, the plasma of the thermo-ionic arc is ignited in metallic copper vapors by applying voltage pulses with a voltage pulse amplitude ranging from 0.8 to 1.2 kV, with a duration of about 100 us and a repetition frequency of 3 kHz. The distance between the platform and the electron gun was 10 mm, and the angle between the normal surface of the platform and the axis of the electron gun was 60 ^li . By changing the value of the intensity of the average current on discharge between 0.2 and 0.5 A, the maximum value of the voltage during the voltage pulse increases from 800 to 1050 V. In certain conditions, for example, by reducing the repetition frequency to 1 kHz, they can reach voltage values on discharge of +3 kV.

The intensity of the electric current by discharge (Fig. 3), measured by means of a current probe (transforming factor 1 V / l A), undergoes large variations both during the voltage pulse and after the voltage breakdown on the discharge. During the voltage pulse, the intensity of the electric current increases with the increase of the voltage on the discharge, reaching the maximum value of 1.2 A, and for values of the voltage on the pulse of 2 kV, the maximum value of the current intensity is 2 A.

The ionic current density (Fig. 4), measured at the distance of 200 mm from the surface of the platform using a electrostatic collector polarized at -100 V relative to the reference, also undergoes changes during the high voltage pulse. The maximum value of ionic current density reaches the value of 1.12 mA / cm for voltage and discharge current values of 1050 V, respectively 1.2 A. The increase of the saturation ionic current density is due to the ionization processes of the copper atoms. evaporated under the action of electrons from both the plasma of the thermionic arc and from the electron cannon.

in FIG. 5 shows the axial distribution of the plasma potential of the thermionic arc operating in DC regime. The discharge parameters of the thermo-ionic arc are: voltage applied on anode of about -t-850 V, the intensity of the discharge current of 200 mA, the distance between the platform and the electron gun of about 10 mm, and the angle between the normal at the surface of the platform and the axis of the cannon of 60 ° electrons. The axial distribution of the plasma potential indicates the presence of a strong double layer with comparable voltage drop values or even greater than the voltage applied to the discharge. The double layer formed in the plasma of the thermal arc ^ diddfacilitate '* or some \ k & V) of 2018 00304

02/05/2018 being comparable to the energy gained by ions in the potential double layer drop. Furthermore, the electrical measurements made using the Dempster spectrometer showed that the ion beam is quasi-monoenergetic, the potential drop on the double layer being approximately equal to the voltage applied to the anode (V. Tiron, M. Dobromir, V. Pohoata and G. Popa, IEEE Transaction on Plasma Science 39 (2011) 1403-1407).

in FIG. 6 are presented the temporal evolutions of the potential of the thermionic arc plasma in pulsed regime, measured at different distances of anode (nacelle). The discharge parameters of the thermo-ionic arc are: the amplitude of the voltage pulse applied on the cathode of approximately +1450 V, the duration of the voltage pulse of about 400 μ5, the frequency of repetition of the voltage pulses of 1 kHz. The distance between the platform and the electron gun was 10 mm, and the angle between the normal surface of the platform and the axis of the electron gun was 60 °. Among the features shown in Fig. 6, the spatial-temporal distributions of the plasma potential (similar to those in Fig. 5) can be obtained, which highlight the presence of a strong double layer, with potential drops of approximately 1500 V, at different time points. The corroboration of the data presented in Fig. 5 and 6 show that the plasma in the region of the anode, respectively the double layer associated with it, expands into the depressurized enclosure where the pressure at the walls is 10 ' ^J Pa, with the average supersonic speed of about 450 m / s.

The experimental results shown in Fig. 1-6, as well as the results obtained with the help of electrostatic collector (ion flux), quartz microbalance (total particle flux) and Dempster spectrometer (metal ion energy) provide the information needed to calculate the specific performance parameters for the electric propellant. Next, the performance parameter values are defined and computed (Table 1): propulsion force (7), specific impulse (Z _v ) and total efficiency (η _τ ) (Dan M. Goebel and Ira Katz, Fundamentals of Electric Propulsion : Ion and Hali Thrusters, JPL SPACE SCIENCE AND TECHNOLOGY SERIES, 2008).

The propulsion force (7) is defined as the force exerted by the propeller on the spacecraft and is equal to the time variation of the mechanical impulse due to fuel consumption ”which, in the present case is the material evaporated from the anode, multiplied by Zug ^ correction factor γ:

τ = (m _c v _ev ) = Y ~ v _ev = ynî _c v _ev

to 2018 00304

02/05/2018 i where m _c is the fuel consumption rate, expressed in kg / s, v _ev is the rate of escape of the fuel which, in the present case, is the speed of the ions in the beam generated by the system. If the ion beam is unidirectional, mono-energetic and consists of only electrically charged ions, this velocity is constant over time, γ represents the correction factor of the propulsion force.

The correction factor γ is equal to the product of two factors, one due to the divergence of the ion beam, and the other due to the fact that the ion beam is made up of a mixture of ions that can be single-charge or multiple-charge electric. Therefore, γ - F _t where F _t is the divergence factor, and a is the factor due to ionic species with multiple charges. F _t = cos Θ, where Θ represents half the value of the divergence angle of the beam.

In the case of the thermo-ionic arc, the fuel consists of Cu ions (m _c = mj, and the rate of escape of the fuel is equal to the speed of the copper ions (v _c = i ';) which are accelerated in the potential drop of the layer. For a given set of process parameters of the thermo-ion arc, such as the value of the 1 kV arc voltage (Fig. 2) and the value of the electric current intensity during the pulse of 1.2 A (Fig. 3), the kinetic energy value of Cu ions (measured using the Dempster spectrometer) was around 1 keV, which corresponds to a speed of approximately 55 km / s. For the same set of process parameters, taking into account the measurement results on the rate of consumption of the material from the platform (calculated using the gravimetric method), the deposition rate and the density of ionic current (Fig. 4), the fuel consumption rate, that is, of Cu ions, is about 9 ^X IO ' ⁷ kg / s. If the beam is taken into account the ion beam consists of ions with only one electrical charge (a = 1), and the divergence angle of the ion beam is 60 °, resulting in a correction factor γ = 0.866. Taking all these values into account, a propulsion force T = ym _L Vj of about 43 rnN results. For values of the voltage and intensity of the electric current of discharge of 2 kV, respectively 2 A, values of the propulsion force of up to 87 mN can be reached. Considering that the value of the propulsion force depends on the electric power consumed by the propeller, in order to compare the performance of the electric propulsors, it is indicated that the propulsion force is normalized to the electric power consumed by the propeller. In the case of the thermo-ionic arc, the total electrical power consumed to obtain 1 kV arc voltages and intensities of the electric current ^ d ^ Ț ^ / ^ Lt. is about 450 W. The average electric power consumed by the discharge is

to 2018 00304

02/05/2018 of approximately 330 W, and that consumed by the electron cannon of about 120 W (voltage of 17 V, current of 7 A). Therefore, the propulsion force normalized to the consumed power is about 95.5 mN / kW. The electrical power consumed by the electron gun can be greatly diminished by the use of filaments made of very high emissivity materials, such as thoriated tungsten, lanthanium oxide-coated tungsten or lanthanium hexaboride (LaB6).

The specific impulse (Isp) represents the efficiency of the propulsion force and is defined as the ratio between the propulsion force and the product between the fuel consumption rate used for propulsion and the gravitational acceleration, g:

T

Ist> ~ m- _c g

Considering that T = γιή ^, it turns out r _ Y ^ Vț ^sp m _c g ·

Report - = T) _m defines the mass of the fuel utilization efficiency and fuel fraction is m _c converted into ions which are used for their propulsion accelerating electric fields.

Therefore,

T - WmVj ^sp g · In the case of the thermo-ionic arc, for values of the 1 kV arc voltage and the electric current intensity during the pulse of 1.2 A, the efficiency of using the evaporated and ionized material is about 20%, and the value of the specific impulse is 975 s. It is very important to mention that this value was calculated for the case when we are in the immediate vicinity of the Earth and the average gravitational acceleration has the value of 9.81 m / s ² . In the case of geostationary satellites, for example, located at altitudes of approximately 35 000 km, taking into account the variation of gravitational acceleration with altitude, this decreases to the value of 0.23 m / s ^2, which would lead to a specific impulse value of 42.65 times higher, - The efficiency of using the evaporated material was estimated from the ratio between the flux with the help of the electrostatic collector) and the total flux of particles (measured with /Mjjt)ru|^ij^îO.b^^țpi a 2018 00304

05/05/2018 with quartz). For 2 kV arc voltage values and 2 A pulse current intensity, the efficiency of using evaporated and ionized material is about 70% and the specific impulse value is 4825 s.

The total efficiency of the propeller fif) defines the ratio between the power of the ion jet and the total power consumed by the propeller and has the expression:

VT = where η »represents the electric efficiency of the propellant and is defined as the ratio between the power of the ion beam and the total power consumed by the electric propeller.

In the case of the thermal-ionic vacuum arc, for values of the arc voltage between I and 2 kV and values of the electric current intensity between 1.2 and 2 A, the electric efficiency varies between 75 and 90%, and the total one between 11 and 47%.

Table 1 compares the experimental and performance parameters of the thermionic arc plasma with those obtained in the case of classical ionic engines of type XIPS Ion Thruster and STP Hali Thuster. For certain experimental conditions, the performance parameters of the thermionic arc plasma are comparable or higher (I _sp and T / Pţ larger) to those of the classic ionic type XIPS Ion Thruster and STP Hali Thuster engines.

Table 1 Comparison between the experimental and performance parameters of the thermionic arc plasma and those obtained in the case of Ιοη-Thruster or Hali Thuster ion motors.

Specific parameters XIPS ion thruster STP Hali thruster TVA thruster Power (W) 2000 - 4300 350 - 1350 450 - 1350 Specific impulse I _sp (s) (calculated for g = 9.81 m / s ² ) 3420 - 3550 1100 - 1600 975 - 4825 Thrust T (mN) 80- 166 20-80 43-87 Overall efficiency η _τ (%) 67.0 - 68.8 35-50 11-47 Electrical efficiency η _β (%) 87.0 - 87.5 - 75-90

to 2018 00304

02/05/2018

Mass efficiency of η _[η (%) 80.0 - 82.5 - 20-70 T / P-r (nm / kW) 40.0 - 38.6 57-59 95.5 -64.4 Acceleration voltage (V) 1215 300 1000-2000 Ionic current (A) 1.45 to 3.05 1.17 to 4.50 1 -2

to 2018 00304

02/05/2018

Claims (2)

INSTALLATION AND METHOD FOR OBTAINING ENERGY METHODS OF METAL IONS APPLIED TO ELECTRICAL PROPULSION IN SPACE 1. Installation and process for obtaining the energy beams of metal ions with controllable flows, with application in the electric propulsion in space, characterized in that they use the plasma of the pulsed thermo-ionic arc, the ablation of the metallic materials and the control of the energy and the density of the metal ions in the beam. . 2. Method for obtaining the metal ion energy beams according to claim 1, characterized in that operating the thermionic arc in pulsed regime can control the energy of the ions in the range 0.8 - 3 keV without using grids for acceleration or magnetic fields. . 3. Electric propulsion plant according to claim 1, characterized in that the performance parameters (specific impulse and propulsion force) can be controlled in a wide range by: appropriate choice of metal which, by its nature (melting point, atomic mass) allows independent control of the specific impulse or propulsion force; convenient choice of the pulse configuration (duration, frequency, voltage and intensity of the electrical current on the pulse) of the thermo-emission current of the filament; respectively, the convenient choice of electrode geometry and their arrangement. to 2018 00304 02/05/2018 Fig. L Schematic of the installation used to obtain energy beams of meuic ions using the pulsed thermo-ionic arc in high power pulses. to 2018 00304 05/02/2018 no (V) t (με) Fig. 2. The temporal evolution of the discharge voltage in the case of the pulsed thermo-ionic arc. to 2018 00304 02/05/2018 Discharge current (A) Fig. 3·. Temporal evolutions of the intensity of the electric current on discharge in the baths of the pulsed thermo-arc. to 2018 00304 02/05/2018 t UlS) Fig. 4. Temporal evolutions of ionic current density in the pulsed thermo-ionic arc.