CN116818261A - Plasma probe measurement method for rolling moment of electric thruster - Google Patents
Plasma probe measurement method for rolling moment of electric thruster Download PDFInfo
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- 239000000523 sample Substances 0.000 title claims abstract description 89
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- 150000002500 ions Chemical class 0.000 claims description 115
- 238000006073 displacement reaction Methods 0.000 claims description 42
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- 238000011065 in-situ storage Methods 0.000 claims description 21
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- 239000004973 liquid crystal related substance Substances 0.000 claims description 6
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/06—Measuring arrangements specially adapted for aerodynamic testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0028—Force sensors associated with force applying means
Abstract
The invention provides a plasma probe measuring method for the rolling moment of an electric thruster. According to the method, an electric thruster rolling moment measuring turntable is used, parameters such as electron temperature, electron density, ion density and the like at different positions in a plume field are measured through a Mach probe method, and ion current densities of radial points at different axial distances are obtained through a negative bias test method, so that ion velocity distribution is obtained; and calculating plasma parameters by using electric thruster rolling moment calculation software, so as to obtain thrust and moment performances of the electric thruster in a steady-state ignition process, and finally, realizing indirect measurement of the rolling moment of the electric thruster. The invention realizes the measurement of the rolling moment in the mu N m order, and has important significance for the design and development of the electric thruster and the application of the electric thruster on a spacecraft. The invention has high measurement accuracy, the measurement accuracy of steady-state thrust can reach 1%, and the measurement accuracy of rolling moment can reach within 5%; the measurement range is large, and the measurement of thrust and rolling moment of electric thrusters with different sizes in any range can be satisfied.
Description
Technical Field
The invention relates to the technical field of electric propulsion, in particular to a plasma probe measuring method of the rolling moment of an electric thruster.
Background
The space electric propulsion technology is used as an advanced propulsion technology, has the characteristics of higher than impulse, small thrust, low cost and the like, can realize the requirements of attitude control, orbit transfer, north-south position maintenance, repositioning and the like of the spacecraft, and is widely applied to the spacecraft in recent years.
In operation, an electric thruster generates a rolling moment about the thruster axis, typically of the order of a few μn·m to tens of μn·m. The rolling moment generated by the thruster mainly comes from the assembly error of the grid electrode of the electric thruster and tangential lorentz force in the beam current, so that the rolling moment cannot be avoided in design. The roll moment brings momentum accumulation on the spacecraft, and the momentum accumulation is eliminated by consuming the load cost of the spacecraft, so that the measurement of the roll moment generated by the electric thruster has important significance for the application of the electric thruster on the spacecraft.
The conventional rolling moment measuring method comprises a micro rolling moment strain balance method, an air bearing or free rolling method of the air bearing, an air bearing balance method and the like, but the technologies are mainly concentrated on the rolling moment measurement of missiles and reentry aircrafts, the measuring range is large, the measuring range is generally in the order of N.m, and the measuring requirement of electric thrusters from a few mu N.m to tens mu N.m cannot be met. Therefore, a measurement method capable of measuring the mu N-m order rolling moment is needed to be designed for the electric thruster so as to meet the measurement requirement of the rolling moment of the electric thruster.
Disclosure of Invention
In view of the above, the invention provides a plasma probe measurement method for the roll moment of an electric thruster. According to the method, an electric thruster rolling moment measuring turntable is used, parameters such as electron temperature, electron density, ion density and the like at different positions in a plume field are measured through a Mach probe method, and ion current densities of radial points at different axial distances are obtained through a negative bias test method, so that ion velocity distribution is obtained; and calculating plasma parameters by using electric thruster rolling moment calculation software, so as to obtain thrust and moment performances of the electric thruster in a steady-state ignition process, and finally, realizing indirect measurement of the rolling moment of the electric thruster.
To achieve the above object, the present invention comprises the steps of:
s1: the electric thruster rolling moment measuring turntable and the electric thruster are arranged in a vacuum cabin, and the vacuum cabin is operated to vacuumize;
s2: when an experiment starts, after the vacuum degree is determined to meet the requirement, the electric thruster is ignited, and the electric thruster enters a stable working condition;
s3: operating a displacement mechanism, moving the Faraday probe to the selected measuring point, and recording the serial number of the measuring point;
s4: operating a probe in-situ scanning device, enabling the Faraday probe to perform rotary scanning on the selected measuring point, finding the position with the largest collecting current, and recording the displacement of the probe in-situ scanning device at the moment to obtain the displacement angle theta and the corresponding beam current density i;
s5: operating a displacement mechanism to enable the blocking energy analyzer to be aligned with the measuring point selected in the step S3, wherein the probe in-situ scanning device is kept unchanged at the moment so as to ensure that the blocking energy analyzer and the Faraday probe are aligned in the same direction;
s6: applying scanning voltage to the retarding energy analyzer to obtain an ion current curve, and recording a file serial number corresponding to the current curve of the measuring point;
s7: operating the probe in-situ scanning device to enable the Faraday probe to return to the horizontal position;
s8: operating the displacement mechanism, selecting the next measuring point, and repeating the steps S3-S7;
s9: ending the measurement, outputting the current curve of each measuring point, performing differential processing to obtain and record the speed v of each measuring point, and calculating the angular speed v by using the displacement angle and the measuring point speed az ；
S10: and calculating the torque density obtained by each measuring point by using the particle speed and the particle speed direction, and integrating to obtain the total torque.
In one possible implementation manner, in the plasma probe measurement method of the electric thruster rolling moment provided by the invention, the electric thruster rolling moment measurement turntable comprises a plume ion parameter data acquisition device, a displacement sliding table, a power supply control component, a calibration system and calculation software.
In a possible implementation manner, in the plasma probe measurement method of the electric thruster rolling moment provided by the invention, the plume ion parameter data acquisition device comprises a faraday probe test system and a blocking energy analyzer test system, wherein the faraday probe test system is used for measuring beam current density, and the blocking energy analyzer is used for measuring ion velocity.
In one possible implementation manner, in the plasma probe measurement method of the electric thruster rolling moment provided by the invention, the faraday probe test system comprises a faraday probe body, a probe mounting frame, a bias power supply, a diagnosis circuit and an acquisition and storage system.
In one possible implementation manner, in the plasma probe measurement method of the rolling moment of the electric thruster provided by the invention, the displacement mechanism uses a linear displacement sliding table for adjusting the radial and axial positions of probe measuring points.
In one possible implementation manner, in the method for measuring the rolling torque of the electric thruster provided by the invention, the measuring point selected in the step S3 is located on the diameter of the plume of the electric thruster at the beam section in the vertical axial direction, and the measuring point selection rule is as follows: the density of the central area is large, and the interval is about 5mm-10mm; the density of the two side areas is small, and the interval is about 10mm-20mm.
In a possible implementation manner, in the plasma probe measurement method of the rolling moment of the electric thruster provided by the invention, the probe in-situ scanning device is assembled by two displacement rotating tables, and 360-degree spherical scanning of probe orientation can be completed.
In one possible implementation manner, in the method for measuring the rolling torque of the electric thruster provided by the invention, the assembly method of the displacement rotary table is that the measuring point of the probe is positioned at the intersection of the two displacement rotary tables.
In one possible implementation manner, in the plasma probe measurement method of the rolling moment of the electric thruster provided by the invention, the differential processing principle of the current curve is as follows:
the blocking energy analyzer collects a distributed expression of the current available ion velocity:
wherein A is c Q for collector effective collection area i N is the electric quantity carried by the ions i The ion number density is V, and the ion blocking grid potential in the blocking energy analyzer; v i For ion velocity, f (u i ) As a function of ion velocity distribution.
According to the energy conservation equation, the kinetic energy of the ions and the internal blocking electric field of the blocking energy analyzer do conservation of the functional quantity, so that the ion energy analyzer has the following functions of
Where mi is the ion mass. Differentiating the two sides of the (2) to obtain
Substituting the formula (2) and the formula (3) into the formula (1), and obtaining a collection current expression after processing:
differentiating the ion blocking gate potential V across equation (4) to obtain:
wherein f (V) is ion energy distribution. From equation (5), it is known that the ion energy distribution function can be obtained by differentiating the ion current with respect to the scanning voltage. From f (V), the maximum value of the distribution function, i.e. the ion most probable energy, and the corresponding scan voltage value can be found. The most probable ion energy is used in the calculation to represent the average ion energy at the station, from which the kinetic energy and velocity of the corresponding ion can be obtained. The ion velocity can be calculated by the following method: the most probable ion energy corresponds to the scan voltage V i Substituting the ion velocity v into the formula (2) to obtain the ion velocity v at the current measuring point.
In one possible implementation manner, in the plasma probe measurement method of the electric thruster rolling moment provided by the invention, the angular velocity v az The calculation method of (2) is as follows:
the angle between the direction of the maximum collection current measured in the step S4 and the horizontal plane is theta, the ion current curve under the angle theta is measured in the step S6, and the ion velocity v under the angle theta is obtained by processing according to the processing method of claim 9. Ion velocity v and angular velocity v az Axial velocity v z The following geometrical relationship exists:
v az ＝vsinθ (6)
v z ＝vcosθ (7)
from this, the angular velocity v can be calculated az Axial velocity v z 。
In one possible implementation manner, in the method for measuring the rolling torque of the electric thruster provided by the invention, the method for calculating the total torque includes:
the ion current density measured at the measuring point with the distance r from the central axis of the electric thruster is i, and the ion angular velocity is v az An axial velocity v z Angular ion current density i az An axial ion current density of i z 。
Wherein, the liquid crystal display device comprises a liquid crystal display device,
i z ＝icosθ (8)
i az ＝isinθ (9)
at any measuring point, the axial thrust generated by the beam current in unit area is
Where e is the charge amount per charge, M is the mass of a single ion, and ds is the area infinitesimal.
By analogy, the axial thrust generated on the circular ring with the distance r from the central axis and the width dr is
Integrating the axial thrust to obtain the total axial thrust:
similarly, the angular ion current at any one of the stations will also produce a force and a roll moment on the electric thruster. Due to the axial symmetry of the electric thruster, it can be considered that the angular velocity of the ions at each point on a circular ring of radius r centered on the electric thruster axis is identical to the point of measurement on this ring, these angular velocities of the ions acting together to generate the rolling moment:
wherein A is p The area of the disk was collected for the faraday probe.
The invention has the following advantages:
(1) The method measures the plasma parameters of the plume region of the electric thruster by a plasma probe diagnosis method, further calculates the rolling moment of the electric thruster by using the plasma parameters, and solves the problem that the rolling moment of the electric thruster cannot be measured.
(2) The rolling moment of the electric thruster and the corresponding plume region parameters are measured, which is beneficial to the design of the electric thruster and the application of the electric thruster on an aerospace vehicle.
(3) The measuring precision is high, and the measuring precision of the rolling moment can reach within 5 percent.
(4) The measuring range is large, the application range is wide, and in theory, the measurement of the thrust and the rolling moment of electric thrusters with different sizes in any range can be satisfied by adjusting the size, the position and the moving distance of the displacement table.
Drawings
Fig. 1 is a flow chart of a plasma probe measurement method of the rolling moment of the electric thruster.
FIG. 2 is a schematic diagram of an electric thruster roll torque plasma probe measurement apparatus according to an embodiment of the present invention
FIG. 3 is a schematic diagram of a probe in-situ scanner according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of a probe station arrangement according to one embodiment of the present invention.
Fig. 5 is a schematic diagram of a faraday probe measurement method according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of a method for measuring the blocking energy analyzer according to an embodiment of the present invention.
The components denoted by reference numerals in the figures are as follows,
1. vacuum chamber 2, displacement mechanism 300, probe in-situ scanning device 4 and ion electric thruster
5. No. 1 displacement rotary table 6, fixing mechanism 7, faraday probe 8 and blocking energy analyzer
9. No. 2 displacement rotary table 10, electric thruster plume 11 and set measuring point positions
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict. The following detailed description of specific embodiments of the invention refers to the accompanying drawings and detailed description. The following examples or figures are illustrative of the invention and are not intended to limit the scope of the invention.
The embodiment of the invention provides a plasma probe measuring method of the rolling moment of an electric thruster, which is shown in fig. 1 and comprises the following steps:
s1: the electric thruster rolling moment measuring turntable and the electric thruster 4 are arranged in the vacuum chamber 1, and the vacuum chamber 1 is operated to vacuumize.
In particular implementations, a measurement apparatus installation schematic is shown in fig. 2, and an electric thruster roll moment measurement turntable is installed downstream of the plume region of the electric thruster 4, wherein the electric thruster roll moment measurement turntable includes the displacement mechanism 2 and the probe in-situ scanner 300, and in addition, includes a matched power control assembly, calibration system, and calculation software, which are not shown in fig. 2. The probe in-situ scanner 300 is used to acquire plume ion parameter data.
S2: and (3) when the experiment starts, after the vacuum degree meets the requirement, the electric thruster 4 is ignited, and the electric thruster enters a stable working condition.
S3: the displacement mechanism 2 is operated to move the Faraday probe 7 to the selected measuring point 11, and the measuring point serial number is recorded.
In specific implementation, as shown in fig. 4, the selected measuring point 11 is located on the diameter of the plume of the electric thruster at the beam section in the vertical axial direction, and the measuring point selection rule is as follows: the density of the central area is large, and the interval is about 5mm-10mm; the density of the two side areas is small, and the interval is about 10mm-20mm.
S4: and operating the probe in-situ scanning device 300 to enable the Faraday probe 7 to perform rotary scanning on the selected measuring point, finding the position with the largest collecting current, and recording the displacement of the probe in-situ scanning device 300 at the moment to obtain the displacement angle theta and the corresponding beam current density i.
In a specific implementation, the probe in-situ scanner 300 is mounted at a position shown in fig. 3, and includes a No. 1 displacement rotary table 5, a fixing mechanism 6, a faraday probe 7, a retardation energy analyzer 8, and a No. 2 displacement rotary table 9. The faraday probe 7 is used to measure beam current density and the blocking energy analyzer 8 is used to measure ion velocity. The probe in-situ scanning device 300 is installed so that the probe measuring point is at the intersection of the two displacement rotating tables, and 360-degree spherical scanning of the Faraday probe 7 and the blocking energy analyzer 8 can be realized through the two displacement rotating tables 5 and 9.
In practice, the faraday probe 7 also requires a supporting probe mount, bias power supply, diagnostic circuitry, and acquisition and storage system. The Faraday probe 7 is arranged in the plume 10 of the electric thruster, and negative bias voltage-30V is applied to the collector of the Faraday probe 7 when measuring the ion current, so that electrons can be repelled to collect ions, the current value of the ions is obtained, and the current density of the ions is obtained by dividing the current value of the ions by the collector area
Wherein V is a measured bias voltage; r is a shunt resistance value; a is that p Is the area of the collection disk in the faraday probe 7.
In a specific implementation, as shown in fig. 5, the faraday probe 7 is rotated by the displacement rotating tables 5 and 9 to find the displacement angle θ corresponding to the position of the maximum collecting current, which is the direction of the jet of the electric thruster at the measuring point. .
S5: the displacement mechanism 2 is operated to align the blocking energy analyzer 8 with the measuring point selected in step S3, and the probe in-situ scanning device 300 is kept unchanged at this time, so as to ensure that the blocking energy analyzer 8 and the faraday probe 7 are aligned in the same direction.
In a specific implementation, as shown in fig. 6, the measurement process of the blocking energy analyzer 8 is that the direction of the blocking energy analyzer 8 is the same as the displacement angle θ measured in step S4, and the direction of the jet of the electric thruster at the measuring point is aligned
S6: and applying scanning voltage to the blocking energy analyzer 8 to obtain an ion current curve, and recording a file serial number corresponding to the current curve of the measuring point.
S7: operating the original probe in-situ scanner 300 to return the faraday probe 7 to the horizontal position;
s8: operating the displacement mechanism 2, selecting the next measuring point, and repeating the steps S3-S7;
s9: ending the measurement, outputting the current curve of each measuring point, performing differential processing to obtain and record the speed v of each measuring point, and calculating the angular speed v by using the displacement angle and the measuring point speed az 。
In specific implementation, the differential processing principle of the current curve and the calculation method of the measuring point speed are as follows:
the blocking energy analyzer collects a distributed expression of the current available ion velocity:
wherein A is c Q for collector effective collection area i Carried by ionsElectric quantity n i The ion number density is V, and the ion blocking grid potential in the blocking energy analyzer; v i For ion velocity, f (u i ) As a function of ion velocity distribution.
According to the energy conservation equation, the kinetic energy of the ions and the internal blocking electric field of the blocking energy analyzer do conservation of the functional quantity, so that the ion energy analyzer has the following functions of
Where mi is the ion mass. Differentiating the two sides of the (2) to obtain
Substituting the formula (2) and the formula (3) into the formula (1), and obtaining a collection current expression after processing:
differentiating the ion blocking gate potential V across equation (4) to obtain:
wherein f (V) is ion energy distribution. From equation (5), it is known that the ion energy distribution function can be obtained by differentiating the ion current with respect to the scanning voltage. From f (V), the maximum value of the distribution function, i.e. the ion most probable energy, and the corresponding scan voltage value can be found. The most probable ion energy is used in the calculation to represent the average ion energy at the station, from which the kinetic energy and velocity of the corresponding ion can be obtained. The ion velocity can be calculated by the following method: the most probable ion energy corresponds to the scan voltage V i Substituting the ion velocity v into the formula (2) to obtain the ion velocity v at the current measuring point.
In the concrete implementation, the measuring point speedThe direction of the degree v is shown in fig. 6 and is in the jet direction of the electric thruster. Angular velocity v az Can be obtained by calculation of geometric relations, and the specific method comprises the following steps: the angle between the direction of the maximum collection current measured in the step S4 and the horizontal plane is theta, the ion current curve under the angle theta is measured in the step S6, and the ion velocity v under the angle theta is obtained by processing according to the processing method of claim 9. Ion velocity v and angular velocity v az Axial velocity v z The following geometrical relationship exists:
v az ＝vsinθ (19)
v z ＝vcosθ (20)
from this, the angular velocity v can be calculated az Axial velocity v z 。
S10: and calculating the torque density obtained by each measuring point by using the particle speed and the particle speed direction, and integrating to obtain the total torque.
In specific implementation, the method for calculating the total torque comprises the following steps: the ion current density measured at the measuring point with the distance r from the central axis of the electric thruster is i, and the ion angular velocity is v az An axial velocity v z Angular ion current density i az An axial ion current density of i z 。
Wherein, the liquid crystal display device comprises a liquid crystal display device,
i z ＝icosθ (21)
i az ＝isinθ (22)
at any measuring point, the axial thrust generated by the beam current in unit area is
Where e is the charge amount per charge, M is the mass of a single ion, and ds is the area infinitesimal.
By analogy, the axial thrust generated on the circular ring with the distance r from the central axis and the width dr is
Integrating the axial thrust to obtain the total axial thrust:
similarly, the angular ion current at any one of the stations will also produce a force and a roll moment on the electric thruster. Due to the axial symmetry of the electric thruster, it can be considered that the angular velocity of the ions at each point on a circular ring of radius r centered on the electric thruster axis is identical to the point of measurement on this ring, these angular velocities of the ions acting together to generate the rolling moment:
wherein A is p The area of the disk was collected for the faraday probe.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (11)
1. The plasma probe measuring method for the rolling moment of the electric thruster is characterized by comprising the following steps of:
s1: the electric thruster rolling moment measuring turntable and the electric thruster are arranged in a vacuum cabin, and the vacuum cabin is operated to vacuumize;
s2: when an experiment starts, after the vacuum degree is determined to meet the requirement, the electric thruster is ignited, and the electric thruster enters a stable working condition;
s3: operating a displacement mechanism, moving the Faraday probe to the selected measuring point, and recording the serial number of the measuring point;
s4: operating a probe in-situ scanning device, enabling the Faraday probe to perform rotary scanning on the selected measuring point, finding the position with the largest collecting current, and recording the displacement of the probe in-situ scanning device at the moment to obtain the displacement angle theta and the corresponding beam current density i;
s5: operating a displacement mechanism to enable the blocking energy analyzer to be aligned with the measuring point selected in the step S3, wherein the probe in-situ scanning device is kept unchanged at the moment so as to ensure that the blocking energy analyzer and the Faraday probe are aligned in the same direction;
s6: applying scanning voltage to the retarding energy analyzer to obtain an ion current curve, and recording a file serial number corresponding to the current curve of the measuring point;
s7: operating the probe in-situ scanning device to enable the Faraday probe to return to the horizontal position;
s8: operating the displacement mechanism, selecting the next measuring point, and repeating the steps S3-S7;
s9: ending the measurement, outputting the current curve of each measuring point, performing differential processing to obtain and record the speed v of each measuring point, and calculating the angular speed v by using the displacement angle and the measuring point speed az ；
S10: and calculating the torque density obtained by each measuring point by using the particle speed and the particle speed direction, and integrating to obtain the total torque.
2. The method for measuring the rolling moment of the electric thruster of claim 1, wherein the turntable for measuring the rolling moment of the electric thruster comprises a plume ion parameter data acquisition device, a displacement slipway, a power supply control assembly, a calibration system and calculation software.
3. The plume ion parameter data acquisition device of claim 2 comprising a faraday probe test system for measuring beam current density, a blocking energy analyzer for measuring ion velocity.
4. The faraday probe testing system of claim 3, comprising a faraday probe body, a probe mount, a bias power supply, a diagnostic circuit, and a collection storage system.
5. The method for measuring the rolling moment of the electric thruster plasma probe according to claim 1, wherein the displacement mechanism uses a linear displacement sliding table for adjusting the radial and axial positions of the probe measuring points.
6. The method for measuring the rolling moment of the electric thruster by using the plasma probe according to claim 1, wherein the measuring points selected in the step S3 are located on the diameter of the plume of the electric thruster at the beam cross section in the vertical axial direction, and the measuring points are selected according to the following rule: the density of the central area is large, and the interval is about 5mm-10mm; the density of the two side areas is small, and the interval is about 10mm-20mm.
7. The method for measuring the rolling moment of the electric thruster plasma probe according to claim 1, wherein the probe in-situ scanning device is assembled by two displacement rotating tables, and can complete 360-degree spherical scanning of probe orientation.
8. The probe in-situ scanner of claim 7, wherein the displacement turntable is assembled by positioning the probe station at the intersection of two displacement turntable.
9. The method for measuring the rolling moment of the electric thruster by using the plasma probe according to claim 1, wherein the differential processing principle of the current curve is as follows:
the blocking energy analyzer collects a distributed expression of the current available ion velocity:
wherein A is c Q for collector effective collection area i N is the electric quantity carried by the ions i The ion number density is V, and the ion blocking grid potential in the blocking energy analyzer; v i For ion velocity, f (u i ) As a function of ion velocity distribution.
According to the energy conservation equation, the kinetic energy of the ions and the internal blocking electric field of the blocking energy analyzer do conservation of the functional quantity, so that the ion energy analyzer has the following functions of
Where mi is the ion mass. Differentiating the two sides of the (2) to obtain
Substituting the formula (2) and the formula (3) into the formula (1), and obtaining a collection current expression after processing:
differentiating the ion blocking gate potential V across equation (4) to obtain:
wherein f (V) is ion energy distribution. From equation (5), it is known that the ion energy distribution function can be obtained by differentiating the ion current with respect to the scanning voltage. From f (V), the maximum value of the distribution function, i.e. the ion most probable energy, and the corresponding scan voltage value can be found. The most probable ion energy is used in the calculation to represent the average ion energy at the station, from which the kinetic energy and velocity of the corresponding ion can be obtained. The ion velocity can be calculated by the following method: the most probable ion energy corresponds to the scan voltage V i Substituting the ion velocity v into the formula (2) to obtain the ion velocity v at the current measuring point.
10. The method for measuring the rolling moment of an electric thruster by a plasma probe according to claim 1, wherein the angular velocity v az The calculation method of (2) is as follows:
the angle between the direction of the maximum collection current measured in the step S4 and the horizontal plane is theta, the ion current curve under the angle theta is measured in the step S6, and the ion velocity v under the angle theta is obtained by processing according to the processing method of claim 9. Ion velocity v and angular velocity v az Axial velocity v z The following geometrical relationship exists:
v az ＝vsinθ (6)
v z ＝vcosθ (7)
from this, the angular velocity v can be calculated az Axial velocity v z 。
11. The method for measuring the rolling moment of the electric thruster by using the plasma probe according to claim 1, wherein the total torque calculation method is as follows:
the ion current density measured at the measuring point with the distance r from the central axis of the electric thruster is i, and the ion angular velocity is v az An axial velocity v z Angular ion current density i az An axial ion current density of i z 。
Wherein, the liquid crystal display device comprises a liquid crystal display device,
i z ＝icosθ (8)
i az ＝isinθ (9)
at any measuring point, the axial thrust generated by the beam current in unit area is
Where e is the charge amount per charge, M is the mass of a single ion, and ds is the area infinitesimal.
By analogy, the axial thrust generated on the circular ring with the distance r from the central axis and the width dr is
Integrating the axial thrust to obtain the total axial thrust:
similarly, the angular ion current at any one of the stations will also produce a force and a roll moment on the electric thruster. Due to the axial symmetry of the electric thruster, it can be considered that the angular velocity of the ions at each point on a circular ring of radius r centered on the electric thruster axis is identical to the point of measurement on this ring, these angular velocities of the ions acting together to generate the rolling moment:
wherein A is p The area of the disk was collected for the faraday probe.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117425259A (en) * | 2023-12-19 | 2024-01-19 | 哈尔滨工业大学 | Device and method for measuring spatial distribution of propeller plume ion energy spectrum |
| CN117451238A (en) * | 2023-12-19 | 2024-01-26 | 哈尔滨工业大学 | On-orbit optical detection method and device for propeller thrust fluctuation based on neural network |
| CN117590140A (en) * | 2024-01-18 | 2024-02-23 | 国科大杭州高等研究院 | Measurement method suitable for measuring response time of electric thruster and readable storage medium |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117425259A (en) * | 2023-12-19 | 2024-01-19 | 哈尔滨工业大学 | Device and method for measuring spatial distribution of propeller plume ion energy spectrum |
| CN117451238A (en) * | 2023-12-19 | 2024-01-26 | 哈尔滨工业大学 | On-orbit optical detection method and device for propeller thrust fluctuation based on neural network |
| CN117451238B (en) * | 2023-12-19 | 2024-04-09 | 哈尔滨工业大学 | On-orbit optical detection method and device for propeller thrust fluctuation based on neural network |
| CN117425259B (en) * | 2023-12-19 | 2024-04-23 | 哈尔滨工业大学 | Device and method for measuring spatial distribution of propeller plume ion energy spectrum |
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