A method and apparatus for diagnosing electric propulsion plume parameters based on a composite Mach probe.
Patent Information
- Application Number
- CN202611261486.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-19
- Publication Date
- 2026-10-27
AI Technical Summary
[0008]本发明的目的在于，提供一种基于复合马赫探针的电推进羽流参数诊断方法、装置、电推进羽流参数诊断系统、存储介质和计算机程序产品，以解决相关方案中传统背靠背马赫探针在超音速电推进羽流环境下适用性不足，以及朗缪尔探针与马赫探针分离测量或简单组合测量过程中存在的参数独立求解、缺乏统一关联反演机制、诊断结果时空一致性和物理自洽性不足的问题，达到实现电推进羽流多参数的联合求解与自洽诊断，提高羽流诊断结果的准确性、一致性、可靠性及工程应用价值的效果
[0022]本发明的方案，针对离子温度远小于电子温度、非磁化或弱磁化的超音速定向电推进羽流环境建立适用的马赫数与流速反演模型，有效克服传统背靠背马赫探针模型在超音速定向流场中适用性不足的问题，从而提高电推进羽流诊断的精度、可靠性和工程适用性。
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Figure CN122994986A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of plasma diagnostics and electric propulsion plume testing technology, specifically relating to a method, device, system, storage medium, and computer program product for diagnosing electric propulsion plume parameters based on a composite Mach probe. Background Technology
[0002] When an electric propulsion device is in operation, it ejects a supersonic, high-speed, directional plasma plume. Electron temperature, ion density, Mach number, and plasma velocity are key parameters characterizing the plume's properties, and their accurate measurement is an important basis for evaluating and optimizing electric propulsion performance.
[0003] Currently, the aforementioned plasma parameter measurements mainly employ diagnostic methods such as the Langmuir probe and the Mach probe. The Langmuir probe can measure electron temperature and ion density, but cannot obtain plasma velocity; the Mach probe is primarily used to measure plasma velocity or Mach number. However, traditional Mach probes are mostly back-to-back symmetrical structures, and their theoretical models are applicable to subsonic or near-sonic plasmas. They have poor applicability in supersonic directional flow fields, low velocity inversion accuracy, and are insufficient to meet the precise diagnostic requirements of electrically propelled plumes.
[0004] To obtain various plasma parameters of a plume, current techniques typically employ separate measurements using Langmuir and Mach probes. Since these two types of probes are independent diagnostic devices, they often need to be deployed separately or measured in stages. This makes them susceptible to factors such as probe positioning errors, plume fluctuations, and differences in measurement timing. Consequently, the measurement times and locations for parameters like electron temperature, ion density, Mach number, and flow velocity become inconsistent, affecting the accuracy and comparability of the diagnostic results.
[0005] Furthermore, even when Langmuir probes and Mach probes are simply integrated or combined for measurement, electron temperature, ion density, Mach number, and flow rate still originate from different measurement models and independent parameter solution processes. There is a lack of a unified correlation and inversion mechanism among the parameters, making it difficult to establish the intrinsic relationship between electron temperature, ion density, Mach number, and flow rate. This makes it impossible to achieve joint solution and cross-validation of parameters, resulting in insufficient physical self-consistency of the diagnostic results.
[0006] Therefore, there is an urgent need for a multi-parameter measurement method suitable for supersonic electric propulsion plume environments, capable of joint inversion and self-consistent diagnosis of electron temperature, ion density, Mach number, and plasma velocity under the same measurement system, in order to improve the accuracy, reliability, and engineering applicability of electric propulsion plume diagnostic results.
[0007] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention
[0008] The purpose of this invention is to provide a method, device, system, storage medium, and computer program product for diagnosing electric propulsion plume parameters based on a composite Mach probe. This addresses the shortcomings of traditional back-to-back Mach probes in supersonic electric propulsion plume environments, as well as the problems of independent parameter solving, lack of a unified correlation and inversion mechanism, and insufficient spatiotemporal consistency and physical self-consistency of diagnostic results during separate or simple combined measurements of Langmuir and Mach probes. The aim is to achieve joint solving and self-consistent diagnosis of multiple parameters in electric propulsion plumes, thereby improving the accuracy, consistency, reliability, and engineering application value of plume diagnostic results.
[0009] This invention provides a method for diagnosing electric propulsion plume parameters based on a composite Mach probe. The composite Mach probe includes a first collection surface and a second collection surface. The diagnostic method includes: placing the composite Mach probe in a plasma flow field, such that the normal of the first collection surface is perpendicular to the plasma flow field direction and the normal of the second collection surface is parallel to the plasma flow field direction; applying a bias voltage to the first collection surface to obtain a current-voltage characteristic curve; obtaining the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction based on the current-voltage characteristic curve; applying a preset bias voltage to the second collection surface to obtain an ion saturation current parallel to the flow field direction; and determining the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction.
[0010] In some embodiments, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained based on the current-voltage characteristic curve, including: determining the electron temperature based on the slope of the electron current exponential region of the current-voltage characteristic curve; obtaining the ion saturation current perpendicular to the flow field direction based on the ion saturation current of the current-voltage characteristic curve, and inverting the ion density.
[0011] In some implementations, determining the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction includes: constructing the ratio of the ion saturation current parallel to the flow field direction to the ion saturation current perpendicular to the flow field direction, and determining the flow field Mach number by combining a correction factor; and calculating the plasma velocity based on the flow field Mach number and the ion sound velocity.
[0012] In some implementations, the correction factor is related to electron temperature, ion temperature, and plasma thermodynamic parameters.
[0013] In some embodiments, the plasma flow field is a non-magnetized supersonic electric propulsion plume plasma flow field with an electron temperature higher than the ion temperature.
[0014] In conjunction with the above method, another aspect of the present invention provides a diagnostic device for electric propulsion plume parameters based on a composite Mach probe. The composite Mach probe includes a first collection surface and a second collection surface. The diagnostic device includes: a positioning unit configured to place the composite Mach probe in a plasma flow field, such that the normal of the first collection surface is perpendicular to the plasma flow field direction and the normal of the second collection surface is parallel to the plasma flow field direction; a detection and calculation unit configured to apply a bias voltage scan to the first collection surface to obtain a current-voltage characteristic curve; and based on the current-voltage characteristic curve, to obtain the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction; a current acquisition unit configured to apply a preset bias voltage to the second collection surface to obtain the ion saturation current parallel to the flow field direction; and a parameter calculation unit configured to determine the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction.
[0015] In some implementations, the detection and calculation unit obtains the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction based on the current-voltage characteristic curve, including: determining the electron temperature based on the slope of the electron current exponential region of the current-voltage characteristic curve; obtaining the ion saturation current perpendicular to the flow field direction based on the ion saturation current of the current-voltage characteristic curve, and inverting it to obtain the ion density.
[0016] In some implementations, the parameter calculation unit determines the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction, including: constructing the ratio of the ion saturation current parallel to the flow field direction and perpendicular to the flow field direction, and determining the flow field Mach number in combination with a correction factor; and calculating the plasma velocity based on the flow field Mach number and the ion sound velocity.
[0017] In some implementations, the correction factor is related to electron temperature, ion temperature, and plasma thermodynamic parameters.
[0018] In some embodiments, the plasma flow field is a non-magnetized supersonic electric propulsion plume plasma flow field with an electron temperature higher than the ion temperature.
[0019] In conjunction with the above-mentioned device, the present invention further provides an electric propulsion plume parameter diagnostic system, comprising: the electric propulsion plume parameter diagnostic device based on the composite Mach probe described above.
[0020] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the above-described method for diagnosing electric propulsion plume parameters based on a composite Mach probe.
[0021] In conjunction with the above method, the present invention further provides a computer program product comprising a computer program that, when processed and executed, implements the steps of the above-described method for diagnosing electric propulsion plume parameters based on a composite Mach probe.
[0022] The present invention establishes a suitable Mach number and velocity inversion model for supersonic directional electric propulsion plume environments where the ion temperature is much lower than the electron temperature and the flow is unmagnetized or weakly magnetized. This effectively overcomes the problem of insufficient applicability of traditional back-to-back Mach probe models in supersonic directional flow fields, thereby improving the accuracy, reliability and engineering applicability of electric propulsion plume diagnosis.
[0023] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.
[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0025] Figure 1 This is a schematic flowchart of an embodiment of the electric propulsion plume parameter diagnosis method based on a composite Mach probe of the present invention.
[0026] Figure 2 This is a schematic diagram of an embodiment of the electric propulsion plume parameter diagnostic device based on a composite Mach probe of the present invention.
[0027] Figure 3 This is a schematic diagram of the cross-sectional structure of the composite Mach probe.
[0028] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:
[0029] 1a-First collecting surface; 1b-Second collecting surface; 101-Positioning unit; 102-Detection and calculation unit; 103-Current acquisition unit; 104-Parameter calculation unit. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0031] According to embodiments of the present invention, a method for diagnosing electric propulsion plumes based on a composite Mach probe is provided. This method addresses the poor applicability of traditional back-to-back Mach probe theory in supersonic electric propulsion plumes, and the problems of temporal inconsistency, spatial inconsistency, and insufficient parameter correlation in the separate measurement process of traditional Langmuir and Mach probes. By using a single composite Mach probe to simultaneously acquire the current-voltage characteristic curves, the ion saturation current perpendicular to the flow field direction, and the ion saturation current parallel to the flow field direction at the same measurement location, a correlation inversion relationship is constructed for electron temperature, ion density, Mach number, and plasma velocity, establishing a unified multi-parameter inversion system to achieve synchronous and self-consistent diagnosis of multiple parameters in electric propulsion plumes. This method is particularly suitable for applications where the ion temperature is much lower than the electron temperature (…). ), unmagnetized or weakly magnetized, and supersonic directional electric propulsion plume plasma environment.
[0032] The composite Mach probe, serving as a diagnostic carrier, simultaneously measures and inverts parameters such as electron temperature, ion density, Mach number, and plasma velocity in an electrically propelled plume. Its structure mainly comprises a probe body and a first and a second collection surface disposed at the end of the probe body. The first and second collection surfaces are arranged orthogonally to each other, with the normal of the first collection surface perpendicular to the plasma flow field direction, and the normal of the second collection surface parallel to the plasma flow field direction. The first collection surface is used for bias scanning to obtain current-voltage characteristic curves, and the second collection surface is used to obtain ion saturation current under a preset bias condition.
[0033] The current-voltage characteristic curves obtained from the first collecting surface are used to invert electron temperature and ion density, and to obtain the ion saturation current perpendicular to the flow field direction; the ion saturation current parallel to the flow field direction is obtained from the second collecting surface. Furthermore, a parameter inversion model is constructed by combining the measurement results from the two collecting surfaces to achieve simultaneous diagnosis of electron temperature, ion density, Mach number, and plasma velocity.
[0034] Composite Mach probes serve as diagnostic carriers, suitable for supersonic, high-speed directional plasma plumes generated by electric propulsion devices. For example... Figure 3 As shown, the composite Mach probe includes a probe body and core components for collecting plasma currents disposed at the end of the probe body: a first collecting surface 1a and a second collecting surface 1b.
[0035] The normal of the first collecting surface 1a is perpendicular to the plume flow direction. Its core principle is that when the collecting surface normal is perpendicular to the high-speed directional flow field, the component of the macroscopic flow velocity in the collecting surface normal direction is significantly reduced, thus greatly weakening its influence on the ion saturation current. The collection process of the ion saturation current is mainly constrained by the Bohm criterion. Under the conditions that the electron temperature is much higher than the ion temperature and the plume is unmagnetized or weakly magnetized, the ion saturation current obtained by this collecting surface can be approximately described using a planar Langmuir probe collecting model. The measurement process is as follows: a continuous bias voltage scan from negative to positive is applied to the first collecting surface 1a, and the corresponding current signal is acquired to generate a complete current-voltage characteristic curve. Based on the slope of the exponential region of the electron current in this curve, the electron temperature can be inverted; based on the current in the ion saturation region, the ion density can be inverted; and simultaneously, the ion saturation current perpendicular to the flow field direction is obtained.
[0036] The normal of the second collecting surface 1b is parallel to the plume flow direction. Its core principle is that when the collecting surface normal is parallel to the high-speed directional flow field, the pre-sheath of the collecting surface tends to disappear. This can be approximated as ions being collected by the collecting surface at a macroscopic flow velocity, and the magnitude of the ion saturation current is positively correlated with the flow field velocity. The measurement process involves applying a preset fixed negative bias voltage to the second collecting surface 1b and stably collecting the ion saturation current parallel to the flow field direction. This current is mainly related to the plume velocity and ion density and can be directly used for subsequent Mach number and velocity inversion.
[0037] The probes for the first collecting surface 1a and the second collecting surface 1b are electrically connected to independent bias power supplies and sampling circuits to achieve synchronous acquisition of signals from the two collecting surfaces within the same time window. Specifically, the first collecting surface 1a is connected to an adjustable scanning bias circuit to acquire the current-voltage characteristic curve; the second collecting surface 1b is connected to a fixed negative bias circuit to acquire the parallel ion saturation current when entering the ion saturation region.
[0038] This invention obtains electron temperature, ion density, and vertical ion saturation current through a first collection surface 1a, and parallel ion saturation current through a second collection surface 1b. Based on the ratio of the ion saturation currents in the two directions, a Mach number and velocity inversion relationship is established, thereby achieving simultaneous diagnosis of electron temperature, ion density, Mach number, and plasma velocity using the same probe and at the same spatial location. This solves core technical problems such as the spatiotemporal inconsistency between traditional split Langmuir and Mach probe measurements, and the unsuitability of traditional Mach probes for supersonic electrically propelled plumes. Simultaneously, it significantly reduces the disturbance to the plume field caused by probe insertion, improving measurement accuracy and result consistency. It is adaptable to high-speed directional, non-thermal equilibrium, unmagnetized, or weakly magnetized plasma environments of electrically propelled plumes, exhibiting higher measurement reliability and engineering applicability.
[0039] like Figure 1The flowchart of an embodiment of the method of the present invention is shown. The electric propulsion plume parameter diagnosis method based on a composite Mach probe may include steps S110 to S140.
[0040] In step S110, the composite Mach probe is placed in the plasma flow field, such that the normal of the first collection surface is perpendicular to the direction of the plasma flow field, and the normal of the second collection surface is parallel to the direction of the plasma flow field. The plasma flow field is a supersonic electric propulsion plume plasma flow field with an electron temperature higher than the ion temperature and which is unmagnetized or weakly magnetized.
[0041] Specifically, the probe body is inserted into the region of the electrically propelled plume to be tested, and the position and direction of the probe are adjusted by the displacement mechanism and the attitude adjustment mechanism so that the first collecting surface 1a is perpendicular to the direction of the plume flow and the second collecting surface 1b is parallel to the direction of the plume flow.
[0042] In step S120, a bias voltage scan is applied to the first collection surface to obtain the current-voltage characteristic curve; based on the current-voltage characteristic curve, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained.
[0043] In some embodiments, a complete current-voltage characteristic curve, encompassing the ion saturation region to the electron saturation region, is obtained by applying a sinusoidal scanning bias voltage to the first collection surface 1a. The current-voltage characteristic curve is then processed: the slope is fitted in the exponential region of the electron current to obtain the electron temperature; a stable current value is taken in the ion saturation region to obtain the vertical ion saturation current; and the ion density is further obtained by combining the electron temperature and the ion saturation current.
[0044] In some embodiments, step S120, based on the current-voltage characteristic curve, obtains the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction, including: determining the electron temperature based on the slope of the electron current exponential region of the current-voltage characteristic curve; obtaining the ion saturation current perpendicular to the flow field direction based on the ion saturation current of the current-voltage characteristic curve, and inverting it to obtain the ion density.
[0045] Specifically, the electron current exponential region (generally a voltage range where the scanning voltage is greater than the suspension potential and less than the plasma space potential) is selected in the current-voltage characteristic curve, and the electron temperature is determined by the slope of this region. The formula is:
[0046] , (1)
[0047] in, The current collected by the first collecting surface 1a This is the bias voltage. When the voltage... Electron temperature, measured in volts by The above formula holds true when the unit is denoted as .
[0048] In the ion saturation region, the vertical ion saturation current is almost unaffected by the plasma flow velocity. In the unmagnetized or weakly magnetized region, the ion temperature is much lower than the electron temperature. In the case of non-thermal equilibrium, the vertical ion saturation current can be approximately described using a planar Langmuir probe collection model.
[0049] Based on the planar Langmuir probe sheath theory, in situations where the ion temperature is much lower than the electron temperature ( Under conditions of non-magnetization or weak magnetization and negligible collision effects, ions satisfy the Bohm criterion at the edge of the sheath and move at a velocity not less than that of the Bohm. Entering the sheath. At this point, the ion saturation current is mainly determined by the ion flux passing through the edge of the sheath, and the ion saturation current in the vertical direction can be approximated as:
[0050] , (2)
[0051] in, The charge of an electron. To measure the ion density at the probe location. The effective collection area of the first collection surface. This represents the propellant ion mass. This can be obtained from the Bohm sheath criterion. .
[0052] The ion density can be inverted from formula (2):
[0053] , (3)
[0054] In step S130, a preset bias voltage is applied to the second collection surface to obtain an ion saturation current parallel to the flow field direction.
[0055] A preset negative bias voltage is applied to the second collection surface 1b to make the probe work in the ion current saturation region, and a stable current value is collected and recorded. This current is the ion saturation current parallel to the flow field direction.
[0056] Under high-speed directional plume conditions (the plasma velocity is typically supersonic, i.e., Mach number...), The ion flux at the second collecting surface 1b is dominated by the macroscopic flow rate, and the pre-sheath is almost non-existent. Neglecting the accelerating effect of the pre-sheath on the ions, the ions can be considered to move at the macroscopic flow rate. Upon reaching the probe surface, the ion saturation current collected therefrom It can be approximated as:
[0057] , (4)
[0058] in, This represents the effective collection area of the second collecting surface. Here, it is assumed that the collecting surface collects only single-charged ions. It should be noted that... and You can set them to be equal or unequal depending on the situation.
[0059] In step S140, the Mach number and plasma velocity are determined based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction. This establishes a unified inversion system among electron temperature, ion density, Mach number, and plasma velocity, enabling joint solution and self-consistent diagnosis of multiple parameters in an electric propulsion plume, and achieving accurate inversion of Mach number and plasma velocity under supersonic electric propulsion plume conditions.
[0060] Specifically, the vertical and parallel ion saturation currents are substituted into a unified physical model to calculate the current ratio and solve for the Mach number of the flow field. Then, the plasma velocity is obtained by combining the Mach number with the ion sound velocity, ultimately achieving simultaneous inversion of multiple parameters such as electron temperature, ion density, Mach number, and plasma velocity. This method ensures that the measurements of fundamental parameters conform to Langmuir probe theory and overcomes the limitation of traditional Mach probes in poor applicability in supersonic flow fields, significantly improving the accuracy, consistency, and environmental adaptability of electric propulsion plume diagnosis.
[0061] In some embodiments, step S140, determining the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction, includes: constructing the ratio of the ion saturation current parallel to the flow field direction to the ion saturation current perpendicular to the flow field direction, and determining the flow field Mach number by combining a correction factor; calculating the plasma velocity based on the flow field Mach number and the ion sound velocity. The correction factor is related to the electron temperature, ion temperature, and plasma thermodynamic parameters.
[0062] Establish a model for the ratio of ion saturation current in the parallel and perpendicular directions:
[0063] , (5)
[0064] Further introduce ion sound velocity:
[0065] , (6)
[0066] in, and These are the electron and ion heat transfer coefficients, respectively. and These are the electron and ion temperatures, respectively.
[0067] Inversion of the feather flow Mach number for:
[0068] , (7)
[0069] in, As a correction factor, it is related to the ion temperature. Electronic temperature and plasma thermodynamic parameters and related.
[0070] In an electrically propelled plume field, the plasma temperature characteristics satisfy the electron heat transfer coefficient. The ion temperature is much smaller than the electron temperature. (Non-thermal equilibrium conditions). In this case, Correction factor It can be approximated as a constant. Formula (7) can be further simplified to:
[0071] , (8)
[0072] Calculate plasma velocity based on Mach number and speed of sound:
[0073] , (9)
[0074] In an electrically propelled plume field and , We can obtain:
[0075] , (10)
[0076] This achieves electronic temperature Ion density ,Mach number and flow rate Synchronous and self-consistent output.
[0077] This invention is particularly applicable to electron temperatures much higher than ion temperatures ( The plasma flow field of unmagnetized or weakly magnetized and supersonic directional electric propulsion plumes is studied. Taking advantage of the characteristic that the flow field velocity has a weak effect on the ion saturation current perpendicular to the flow field direction but a significant effect on the ion saturation current parallel to the flow field direction, a ratio model of the ion saturation current in the parallel and perpendicular directions is constructed to achieve stable inversion of the flow field Mach number and plasma velocity.
[0078] This invention combines bias scanning measurement on the first collection surface with stable negative bias measurement on the second collection surface. Using a single composite Mach probe, it simultaneously acquires current-voltage characteristic curves, vertical ion saturation current, and parallel ion saturation current at the same measurement location and within the same time window. Based on this, a correlation inversion relationship is established between electron temperature, ion density, Mach number, and plasma velocity. Unlike the traditional method of separately measuring and independently solving parameters using Langmuir and Mach probes, this invention employs a unified measurement system to achieve multi-parameter joint inversion. This ensures that all parameters originate from the same set of original measurement data, thereby guaranteeing the temporal consistency, spatial consistency, and physical self-consistency of parameter acquisition.
[0079] Using the technical solution of this embodiment, electron temperature, ion density, Mach number, and plasma velocity are no longer obtained separately by different probes and measurement systems. Instead, they are jointly solved and cross-validated through a unified parameter inversion framework, achieving integrated diagnosis of multiple parameters of electrically propelled plumes. Compared with traditional stepwise measurement methods using Langmuir and Mach probes, as well as simple combined measurement methods, this invention not only reduces errors caused by flow field disturbances, measurement position deviations, and differences in measurement timing, but also establishes intrinsic correlations between parameters, improving the reliability, self-consistency, and measurement efficiency of diagnostic results.
[0080] According to embodiments of the present invention, an electric propulsion plume parameter diagnostic device based on a composite Mach probe is also provided, corresponding to the electric propulsion plume parameter diagnostic method based on a composite Mach probe. See also Figure 2 The schematic diagram of an embodiment of the device of the present invention shown below shows that the electric propulsion plume parameter diagnosis device based on a composite Mach probe may include: a positioning unit 101, a detection and calculation unit 102, a current acquisition unit 103, and a parameter calculation unit 104.
[0081] The positioning unit 101 is configured to place the composite Mach probe in the plasma flow field such that the normal of the first collection surface is perpendicular to the direction of the plasma flow field and the normal of the second collection surface is parallel to the direction of the plasma flow field.
[0082] Specifically, the probe body is inserted into the region of the electrically propelled plume to be tested, and the position and direction of the probe are adjusted by the displacement mechanism and the attitude adjustment mechanism so that the first collecting surface 1a is perpendicular to the direction of the plume flow and the second collecting surface 1b is parallel to the direction of the plume flow.
[0083] The detection and calculation unit 102 is configured to apply a bias voltage scan to the first collection surface to obtain a current-voltage characteristic curve; based on the current-voltage characteristic curve, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained.
[0084] In some embodiments, a complete current-voltage characteristic curve, encompassing the ion saturation region to the electron saturation region, is obtained by applying a sinusoidal scanning bias voltage to the first collection surface 1a. The current-voltage characteristic curve is then processed: the slope is fitted in the exponential region of the electron current to obtain the electron temperature; a stable current value is taken in the ion saturation region to obtain the vertical ion saturation current; and the ion density is further obtained by combining the electron temperature and the ion saturation current.
[0085] In some embodiments, the detection and calculation unit 102 obtains the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction based on the current-voltage characteristic curve, including: determining the electron temperature based on the slope of the electron current exponential region of the current-voltage characteristic curve; obtaining the ion saturation current perpendicular to the flow field direction based on the ion saturation current of the current-voltage characteristic curve, and inverting to obtain the ion density.
[0086] Specifically, the electron current exponential region (generally a voltage range where the scanning voltage is greater than the suspension potential and less than the plasma space potential) is selected in the current-voltage characteristic curve, and the electron temperature is determined by the slope of this region. The formula is:
[0087] , (1)
[0088] in, The current collected by the first collecting surface 1a This is the bias voltage. When the voltage... Electron temperature, measured in volts by The above formula holds true when the unit is denoted as .
[0089] In the ion saturation region, the vertical ion saturation current is almost unaffected by the plasma flow velocity. In the unmagnetized or weakly magnetized region, the ion temperature is much lower than the electron temperature. In the case of non-thermal equilibrium, the vertical ion saturation current can be approximately described using a planar Langmuir probe collection model.
[0090] Based on the planar Langmuir probe sheath theory, in situations where the ion temperature is much lower than the electron temperature ( Under conditions of non-magnetization or weak magnetization and negligible collision effects, ions satisfy the Bohm criterion at the edge of the sheath and move at a velocity not less than that of the Bohm. Entering the sheath. At this point, the ion saturation current is mainly determined by the ion flux passing through the edge of the sheath, and the ion saturation current in the vertical direction can be approximated as:
[0091] , (2)
[0092] in, The charge of an electron. To measure the ion density at the probe location. The effective collection area of the first collection surface. This represents the propellant ion mass. This can be obtained from the Bohm sheath criterion. .
[0093] The ion density can be inverted from formula (2):
[0094] , (3)
[0095] The current acquisition unit 103 is configured to apply a preset bias voltage to the second collection surface to obtain an ion saturation current parallel to the flow field direction.
[0096] A preset negative bias voltage is applied to the second collection surface 1b to make the probe work in the ion current saturation region, and a stable current value is collected and recorded. This current is the ion saturation current parallel to the flow field direction.
[0097] Under high-speed directional plume conditions (the plasma velocity is typically supersonic, i.e., Mach number...), The ion flux at the second collecting surface 1b is dominated by the macroscopic flow rate, and the pre-sheath is almost non-existent. Neglecting the accelerating effect of the pre-sheath on the ions, the ions can be considered to move at the macroscopic flow rate. Upon reaching the probe surface, the ion saturation current collected therefrom It can be approximated as:
[0098] , (4)
[0099] in, This represents the effective collection area of the second collecting surface. Here, it is assumed that the collecting surface collects only single-charged ions. It should be noted that... and You can set them to be equal or unequal depending on the situation.
[0100] The parameter calculation unit 104 is configured to determine the Mach number and plasma velocity of the flow field based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction. This constructs a unified inversion system among electron temperature, ion density, Mach number, and plasma velocity, enabling joint solution and self-consistent diagnosis of multiple parameters in an electric propulsion plume, and achieving accurate inversion of Mach number and plasma velocity under supersonic electric propulsion plume conditions.
[0101] Specifically, the vertical and parallel ion saturation currents are substituted into a unified physical model to calculate the current ratio and solve for the Mach number of the flow field. Then, the plasma velocity is obtained by combining the Mach number with the ion sound velocity, ultimately achieving simultaneous inversion of multiple parameters such as electron temperature, ion density, Mach number, and plasma velocity. This method ensures that the measurements of fundamental parameters conform to Langmuir probe theory and overcomes the limitation of traditional Mach probes in poor applicability in supersonic flow fields, significantly improving the accuracy, consistency, and environmental adaptability of electric propulsion plume diagnosis.
[0102] In some embodiments, the parameter calculation unit 104 determines the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction. This includes: constructing the ratio of the ion saturation current parallel to the flow field direction to the ion saturation current perpendicular to the flow field direction, and determining the flow field Mach number by combining it with a correction factor; and calculating the plasma velocity based on the flow field Mach number and the ion sound velocity. The correction factor is related to the electron temperature, ion temperature, and plasma thermodynamic parameters.
[0103] Establish a model for the ratio of ion saturation current in the parallel and perpendicular directions:
[0104] , (5)
[0105] Further introduce ion sound velocity:
[0106] , (6)
[0107] in, and These are the electron and ion heat transfer coefficients, respectively. and These are the electron and ion temperatures, respectively.
[0108] Inversion of the feather flow Mach number for:
[0109] , (7)
[0110] in, As a correction factor, it is related to the ion temperature. Electronic temperature and plasma thermodynamic parameters and related.
[0111] In an electrically propelled plume field, the plasma temperature characteristics satisfy the electron heat transfer coefficient. The ion temperature is much smaller than the electron temperature. (Non-thermal equilibrium conditions). In this case, Correction factor It can be approximated as a constant. Formula (7) can be further simplified to:
[0112] , (8)
[0113] Calculate plasma velocity based on Mach number and speed of sound:
[0114] , (9)
[0115] In an electrically propelled plume field and , We can obtain:
[0116] , (10)
[0117] This achieves electronic temperature Ion density ,Mach number and flow rate Synchronous and self-consistent output.
[0118] This invention is particularly applicable to electron temperatures much higher than ion temperatures ( The plasma flow field of unmagnetized or weakly magnetized and supersonic directional electric propulsion plumes is studied. Taking advantage of the characteristic that the flow field velocity has a weak effect on the ion saturation current perpendicular to the flow field direction but a significant effect on the ion saturation current parallel to the flow field direction, a ratio model of the ion saturation current in the parallel and perpendicular directions is constructed to achieve stable inversion of the flow field Mach number and plasma velocity.
[0119] This invention combines bias scanning measurement on the first collection surface with stable negative bias measurement on the second collection surface. Using a single composite Mach probe, it simultaneously acquires current-voltage characteristic curves, vertical ion saturation current, and parallel ion saturation current at the same measurement location and within the same time window. Based on this, a correlation inversion relationship is established between electron temperature, ion density, Mach number, and plasma velocity. Unlike the traditional method of separately measuring and independently solving parameters using Langmuir and Mach probes, this invention employs a unified measurement system to achieve multi-parameter joint inversion. This ensures that all parameters originate from the same set of original measurement data, thereby guaranteeing the temporal consistency, spatial consistency, and physical self-consistency of parameter acquisition.
[0120] Since the processing and functions implemented by the device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.
[0121] By employing the technical solution of this invention, electron temperature, ion density, Mach number, and plasma velocity are no longer obtained separately by different probes and measurement systems. Instead, they are jointly solved and cross-validated through a unified parameter inversion framework, achieving integrated diagnosis of multiple parameters in electrically propelled plumes. Compared to traditional stepwise measurement methods using Langmuir and Mach probes, as well as simple combined measurement methods, this invention not only reduces errors caused by flow field disturbances, measurement position deviations, and differences in measurement timing, but also establishes intrinsic correlations between parameters, improving the reliability, self-consistency, and measurement efficiency of the diagnostic results.
[0122] According to embodiments of the present invention, an electric propulsion plume parameter diagnostic system corresponding to an electric propulsion plume parameter diagnostic device based on a composite Mach probe is also provided. This electric propulsion plume parameter diagnostic system may include: the electric propulsion plume parameter diagnostic device based on a composite Mach probe described above.
[0123] Since the processing and functions implemented by the electric propulsion plume parameter diagnosis system in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned device, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.
[0124] According to an embodiment of the present invention, a storage medium corresponding to the electric propulsion plume parameter diagnosis method based on a composite Mach probe is also provided. The storage medium includes a stored program, wherein, when the program is executed, the device where the storage medium is located executes the electric propulsion plume parameter diagnosis method based on a composite Mach probe as described above.
[0125] Since the processing and functions implemented by the storage medium in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.
[0126] According to an embodiment of the present invention, a computer program product corresponding to the method for diagnosing electric propulsion plume parameters based on a composite Mach probe is also provided. The computer program product includes a computer program that, when processed and executed, implements the steps of the above-described method for diagnosing electric propulsion plume parameters based on a composite Mach probe.
[0127] Since the processing and functions implemented by the computer program product in this embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.
[0128] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.
[0129] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.
Claims
1. A method for diagnosing electric propulsion plume parameters based on a composite Mach probe, characterized in that, The composite Mach probe includes a first collecting surface and a second collecting surface; the diagnostic method includes: The composite Mach probe is placed in the plasma flow field, with the normal of the first collection surface perpendicular to the direction of the plasma flow field and the normal of the second collection surface parallel to the direction of the plasma flow field. A bias voltage scan is applied to the first collecting surface to obtain the current-voltage characteristic curve; based on the current-voltage characteristic curve, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained. A preset bias voltage is applied to the second collection surface to obtain an ion saturation current parallel to the flow field direction; Based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction, the flow field Mach number and plasma velocity are determined.
2. The method for diagnosing electric propulsion plume parameters based on a composite Mach probe according to claim 1, characterized in that, Based on the current-voltage characteristic curve, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained, including: The electron temperature is determined based on the slope of the exponential region of the current-voltage characteristic curve. Based on the current-voltage characteristic curve, the ion saturation current perpendicular to the flow field direction is obtained from the ion saturation current in the ion saturation region, and the ion density is obtained by inversion.
3. The method for diagnosing electric propulsion plume parameters based on a composite Mach probe according to claim 1, characterized in that, Based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction, the flow field Mach number and plasma velocity are determined, including: The ratio of ion saturation current parallel to the flow field direction to that perpendicular to the flow field direction is constructed, and the flow field Mach number is determined by combining the correction factor. The plasma velocity was calculated based on the Mach number of the flow field and the sound velocity of the ions.
4. The self-consistent multi-parameter diagnostic method for electrically propelled plumes based on a composite Mach probe according to claim 3, characterized in that, The correction factor is related to electron temperature, ion temperature, and plasma thermodynamic parameters.
5. The self-consistent multi-parameter diagnostic method for electrically propelled plumes based on a composite Mach probe according to claim 1, characterized in that, The plasma flow field is a non-magnetized supersonic electrically propelled plume plasma flow field with an electron temperature higher than the ion temperature.
6. A diagnostic device for electric propulsion plume parameters based on a composite Mach probe, characterized in that, The composite Mach probe includes a first collecting surface and a second collecting surface; the diagnostic device includes: The positioning unit is configured to place the composite Mach probe in the plasma flow field, such that the normal of the first collection surface is perpendicular to the direction of the plasma flow field and the normal of the second collection surface is parallel to the direction of the plasma flow field. The detection and calculation unit is configured to apply a bias voltage scan to the first collection surface to obtain a current-voltage characteristic curve; based on the current-voltage characteristic curve, the electron temperature, ion density, and ion saturation current perpendicular to the flow field direction are obtained. The current acquisition unit is configured to apply a preset bias voltage to the second collection surface to obtain an ion saturation current parallel to the flow field direction; The parameter calculation unit is configured to determine the flow field Mach number and plasma velocity based on the ion saturation current perpendicular to the flow field direction and the ion saturation current parallel to the flow field direction.
7. A diagnostic system for electric propulsion plume parameters, characterized in that, include: The electric propulsion plume parameter diagnostic device based on a composite Mach probe as described in claim 6.
8. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the electric propulsion plume parameter diagnosis method based on the composite Mach probe as described in any one of claims 1 to 5.
9. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the electric propulsion plume parameter diagnosis method based on a composite Mach probe as described in any one of claims 1 to 5.