A method for plasma toroidal current ramp-up

Abstract

This application relates to the field of space electric propulsion technology, specifically to a method for enhancing plasma circumferential current. By calculating the influence of electromagnetic parameters, structural parameters, and gas supply parameters on the plasma circumferential current, key factors are selected for experimental adjustment to construct a mapping relationship between the influence of each factor on the plasma circumferential current, thereby achieving the goal of quantifying the enhancement of the plasma circumferential current. This application uses the Shapley value method to quantify the individual and joint contributions of different factors, assessing the marginal gain of each factor on the response, reducing the risk of traditional feature selection potentially missing low-frequency but high-impact interaction terms, and improving the accuracy of key factor identification. Furthermore, through a staged sampling strategy during the experiment, the impact of parameter drift and noise changes on the measured results can be effectively reduced, improving the adjustment accuracy of the plasma circumferential current.

Description

Technical Field

[0001] This application relates to the field of space electric propulsion technology, and more specifically, to a method for boosting plasma circumferential current. Background Technology

[0002] Space electric propulsion utilizes electrical energy provided by space solar cells or nuclear power sources to ionize propellant into plasma, which is then accelerated electrostatically, electromagnetically, or electrothermally and ejected at high speed to generate thrust. Currently, the power of space electric propulsion systems is mainly concentrated below 10kW, which is insufficient to meet the application requirements of advanced space propulsion technologies with both N-level or higher thrust and high specific impulse (over 4000s) for missions such as main propulsion for manned deep space exploration, orbit maintenance by space solar power stations, large-scale rapid orbital maneuvers of spacecraft, and high-payload deep space cargo transport. Therefore, conducting research on 100kW high-power electric propulsion technology can both meet the application requirements of advanced space propulsion technologies in future mission planning and conform to the objective laws of current space electric propulsion technology development.

[0003] Compared to other high-power electric propulsion systems, the field-reverse configuration electromagnetic thruster, as an emerging electric propulsion device, integrates advantages such as long lifespan, high thrust-to-weight ratio, variable power, and a wide range of working propellant options. It is also easy to combine with other types of thrusters to form a composite propulsion system, and has become one of the mainstream technical solutions for 100kW~MW-class high-power electric propulsion systems internationally.

[0004] Improving the performance of field-reverse configuration electromagnetic thrusters is a key area of ​​continuous research and iteration both domestically and internationally. Plasma circumferential current, as a breakthrough point for performance enhancement, requires in-depth research into its generation mechanism and the coupling mechanism of influencing factors to achieve positive performance improvements. This is a critical issue that urgently needs to be addressed. The generation of plasma circumferential current involves the coupling effects between multidimensional discrete-continuous design parameters, including electromagnetic parameters such as the amplitude and frequency of the rotating field antenna current, physical parameters such as the radius and density of the plasma cluster, and structural parameters such as the radius of the discharge cavity and the shape of the coil. Furthermore, the high coupling dimension, the difficulty of decoupling, and the complexity of the mechanism make it difficult to achieve improvements through single-factor mechanism modeling and engineering modifications alone. Summary of the Invention

[0005] This application provides a plasma circumferential current enhancement method, which quantifies the individual and joint contributions of different factors based on the Shapley value method, evaluates the marginal gain of each factor on the response, and improves the accuracy of key factor identification.

[0006] To achieve the above objectives, this application provides a method for enhancing plasma circumferential current, comprising the following steps: Step 1: Establishing a dataset of factors influencing plasma circumferential current, including an input parameter set and an output parameter set; the input parameter set consists of electromagnetic parameters, structural parameters, and gas supply parameters; the output parameter set is the plasma circumferential current set; Step 2: Calculating the influence of each factor on the plasma circumferential current based on the Shapley value method according to different input values ​​of electromagnetic parameters, structural parameters, and gas supply parameters and corresponding measured values ​​of plasma circumferential current; Step 3: Selecting factors whose influence on plasma circumferential current is at or above the lower quartile as key factors to design an adjustment matrix for enhancing plasma circumferential current; Step 4: Conducting adjustment experiments based on the adjustment matrix, and collecting different input values ​​of electromagnetic parameters, structural parameters, and gas supply parameters and corresponding measured values ​​of plasma circumferential current using a phased updating sampling strategy during continuous experiments; Step 5: Establishing a mapping model between plasma circumferential current and electromagnetic parameters, structural parameters, and gas supply parameters based on the measured data from the adjustment experiments in Step 4, serving as the quantitative basis for enhancing plasma circumferential current.

[0007] Furthermore, in step 1, the electromagnetic parameters include the amplitude of the rotating magnetic field antenna current, the frequency of the rotating magnetic field, the pulse width of the rotating magnetic field antenna current, the radio frequency power of the pre-ionization source, and the steady-state magnetic field strength; the structural parameters include the radius of the discharge chamber and the divergence angle of the steady-state magnetic field; and the gas supply parameters include the gas flow rate, the type of working medium, and the gas pressure of the discharge chamber.

[0008] Furthermore, the electromagnetic parameters are adjusted through the power control module, and the actual output results are fed back in real time through an oscilloscope and a gaussmeter; the structural parameters are achieved by setting and processing discharge chamber cavities of different shapes; the gas supply parameters are adjusted through the flow control module, and the actual output results are fed back in real time through a flow meter; the output parameter is the plasma circumferential current, which is measured through a Roco coil, and the actual output results are fed back in real time through an oscilloscope.

[0009] Furthermore, in step 2, the influence of various factors on the plasma circumferential current is investigated. It can be quantified as: , Where T represents the set of factors influencing the plasma circumferential current, t represents the total number of factors, B represents all subsets of set T containing i, and |B| represents the number of elements in subset B. Let i be the marginal gain of factor i.

[0010] Furthermore, in step 2, in calculating the marginal gain... At that time, the low, median, and high levels of each factor were taken separately for calculation, and the corresponding influence values ​​were obtained as follows: , and ,Pick The final calculated value of factor i is used as the central level value of the factor in the subsequent adjustment matrix design.

[0011] Furthermore, the range of values ​​for all factor levels was determined before conducting the adjustment experiment; the adjustment experiment was set up using the response surface methodology in DOE theory.

[0012] Furthermore, in step 5, the mapping relationship between the plasma circumferential current and the influencing factors of electromagnetic parameters, structural parameters, and gas supply parameters is as follows: , Where X represents the influencing factors, and Y represents the plasma circumferential current. For random disturbance terms, For constant terms, , and The fitting coefficients for each term are . , and is the significance coefficient for each item.

[0013] The plasma circumferential current enhancement method provided in this application has the following beneficial effects: This application quantifies the individual and joint contributions of different factors based on the Shapley value method, evaluates the marginal gain of each factor on the response, reduces the risk of traditional feature selection missing low-frequency but high-impact interaction terms, and improves the accuracy of key factor identification. Furthermore, through a staged sampling strategy during the experiment, the impact of parameter drift and noise changes on the measured results can be effectively reduced, and the adjustment accuracy of plasma circumferential current can be improved. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a schematic diagram of the steps of the plasma circumferential current enhancement method provided in the embodiments of this application. Detailed Implementation

[0015] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0016] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0018] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0019] In addition, the term "multiple" should mean two or more.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] like Figure 1As shown, this application provides a method for increasing plasma circumferential current. By calculating the influence values ​​of electromagnetic parameters, structural parameters, and gas supply parameters on plasma circumferential current, key factors are selected for experimental adjustment to construct a mapping relationship between the influence of each factor on plasma circumferential current, thereby achieving the purpose of quantitatively increasing plasma circumferential current. The specific steps include the following: Step 1: Establish a dataset of factors influencing plasma circumferential current, including an input parameter set and an output parameter set; the input parameter set consists of electromagnetic parameters, structural parameters, and gas supply parameters; the output parameter set is the plasma circumferential current set. Specifically, the electromagnetic parameters include the rotating magnetic field antenna current amplitude X1, rotating magnetic field frequency X2, rotating magnetic field antenna current pulse width X3, pre-ionization source RF power X4, and steady-state magnetic field strength X5, which are adjusted through the power control module, and the actual output results are fed back in real time through an oscilloscope and a gaussmeter; the structural parameters include the discharge chamber radius X6 and the steady-state magnetic field divergence angle X7, which are achieved by setting and processing discharge chamber cavities of different shapes; the gas supply parameters include the gas flow rate X8, working fluid type X9, and discharge chamber gas pressure X1. 10 The flow is adjusted by the flow control module and the actual output result is fed back in real time by the flow meter; the output parameter is the plasma circumferential current Y, which is measured by the Roco coil and the actual output result is fed back in real time by the oscilloscope.

[0022] Step 2: Based on the different input values ​​of electromagnetic parameters, structural parameters, and gas supply parameters, and the corresponding measured values ​​of plasma circumferential current, calculate the influence of each factor on the plasma circumferential current using the Shapley value method; Specifically, based on the Shapley value method, the influence of various factors on the plasma circumferential current can be quantified as follows: , Where T represents the set of factors influencing the plasma circumferential current, t represents the total number of factors, B represents all subsets of set T containing i, and |B| represents the number of elements in subset B. The marginal gain of factor i; in calculating the marginal gain At that time, the low, median, and high levels of each factor were taken separately for calculation, and the corresponding influence values ​​were obtained as follows: , and ,Pick The final calculated value of factor i is used as the central level value of the factor in the subsequent adjustment matrix design.

[0023] More specifically, in the embodiments of this application, the low, medium, and high levels of each parameter within the range of values ​​are determined based on the power output characteristics and the conditions of the ground experimental vacuum chamber, as shown in Table 1: Table 1. Low, medium, and high level values ​​for each parameter within its range. The influence values ​​of each of the above factors at the three different value levels are calculated as shown in Table 2: Table 2. Calculated influence values ​​of each factor Therefore, based on the calculation results of the above influence values ​​and The corresponding level values ​​for each factor, and the median value of each factor's level when designing the adjustment matrix, are shown in the last column of Table 2.

[0024] Step 3: Select factors whose influence on the plasma circumferential current is at or above the lower quartile as key factors to design the adjustment matrix for boosting the plasma circumferential current; Specifically, in this embodiment, based on the maximum value of each factor's influence, the lower quartile is calculated to be 0.74. Therefore, the factors included in the adjustment matrix are: rotating magnetic field antenna current amplitude X1, rotating magnetic field frequency X2, pre-ionization source RF power X4, steady-state magnetic field strength X5, discharge chamber radius X6, ventilation volume X8, working fluid type X9, and discharge chamber pressure X1. 10 .

[0025] Step 4: Conduct adjustment experiments based on the adjustment matrix, and during the continuous experiment, adopt a sampling strategy of updating factor levels in stages to collect different input values ​​of electromagnetic parameters, structural parameters and gas supply parameters and corresponding measured values ​​of plasma circumferential current, thereby reducing the impact of parameter drift and noise changes on the measured results; Specifically, the regulation experiment was set up using the response surface methodology in DOE theory. Before conducting the regulation experiment, it was necessary to determine the value ranges of all factor levels. Based on theoretical analysis and experimental constraints, the value ranges of all factors were determined as follows: ,in, and These represent the upper and lower boundaries of the factor value levels. To minimize the influence of dimensions, the interval boundaries and center of each factor level are taken, and a unit space is established based on the Min-Max normalization method. ,Right now: , Since variables have a deterministic response to performance, directly normalizing the variables will weaken the response effect. Therefore, variables should be processed as needed.

[0026] Step 5: Based on the measured data of the adjustment experiment in Step 4, establish a mapping model between plasma circumferential current and electromagnetic parameters, structural parameters and gas supply parameters, as a quantitative basis for the improvement of plasma circumferential current.

[0027] Specifically, in the embodiments of this application, the mapping relationship between the plasma circumferential current and the influencing factors of electromagnetic parameters, structural parameters, and gas supply parameters is as follows: , Where X represents the influencing factors, and Y represents the plasma circumferential current. For random disturbance terms, For constant terms, , and The fitting coefficients for each term are denoted as . , and Let be the significance coefficients of each item. Based on the importance level of the variable, it is defined as a binary variable, i.e.: , Based on the results of short-term experimental tests, the mapping relationship between key factors and plasma circumferential current is constructed as follows: , This can serve as a quantitative basis for improving plasma circumferential current. Subsequent iterative optimization will yield a more accurate mapping model between key factors and plasma circumferential current that better reflects engineering practice, thereby guiding engineering practices for improving plasma circumferential current.

[0028] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for increasing the circumferential current of plasma, characterized in that, Includes the following steps: Step 1: Establish a dataset of factors influencing plasma circumferential current, including input parameter sets and output parameter sets; The input parameter set consists of electromagnetic parameters, structural parameters, and gas supply parameters; The output parameter set is a plasma circumferential current set; Step 2: Based on the different input values ​​of electromagnetic parameters, structural parameters, and gas supply parameters, and the corresponding measured values ​​of plasma circumferential current, calculate the influence of each factor on the plasma circumferential current using the Shapley value method; Step 3: Select factors whose influence on the plasma circumferential current is at or above the lower quartile as key factors to design the adjustment matrix for boosting the plasma circumferential current; Step 4: Conduct adjustment experiments based on the adjustment matrix, and during the continuous experiment, adopt a sampling strategy of updating factor levels in stages to collect different input values ​​of electromagnetic parameters, structural parameters and gas supply parameters and corresponding measured values ​​of plasma circumferential current. Step 5: Based on the measured data of the adjustment experiment described in Step 4, establish a mapping model between plasma circumferential current and electromagnetic parameters, structural parameters, and gas supply parameters, as a quantitative basis for increasing plasma circumferential current.

2. The plasma circumferential current enhancement method according to claim 1, characterized in that, In step 1, the electromagnetic parameters include the amplitude of the rotating magnetic field antenna current, the frequency of the rotating magnetic field, the pulse width of the rotating magnetic field antenna current, the radio frequency power of the pre-ionization source, and the steady-state magnetic field strength; the structural parameters include the radius of the discharge chamber and the divergence angle of the steady-state magnetic field; and the gas supply parameters include the gas flow rate, the type of working medium, and the gas pressure of the discharge chamber.

3. The plasma circumferential current enhancement method according to claim 2, characterized in that, In step 2, the electromagnetic parameters are adjusted by the power control module, and the actual output results are fed back in real time by an oscilloscope and a gaussmeter; the structural parameters are achieved by setting and processing discharge chamber cavities of different shapes; the gas supply parameters are adjusted by the flow control module, and the actual output results are fed back in real time by a flow meter; the output parameter is the plasma circumferential current, which is measured by a Roco coil, and the actual output results are fed back in real time by an oscilloscope.

4. The plasma circumferential current enhancement method according to claim 3, characterized in that, In step 2, the influence of various factors on the plasma circumferential current. It can be quantified as: ， Where T represents the set of factors influencing the plasma circumferential current, t represents the total number of factors, B represents all subsets of set T containing i, and |B| represents the number of elements in subset B. Let i be the marginal gain of factor i.

5. The plasma circumferential current enhancement method according to claim 4, characterized in that, In step 2, the marginal gain is calculated. At that time, the low, median, and high levels of each factor were taken separately for calculation, and the corresponding influence values ​​were obtained as follows: , and ,Pick The final calculated value of factor i is used as the central level value of the factor in the subsequent adjustment matrix design.

6. The plasma circumferential current enhancement method according to claim 5, characterized in that, In step 4, the range of values ​​for all factor levels is determined before conducting the adjustment experiment; the adjustment experiment is set up using the response surface methodology in DOE theory.

7. The plasma circumferential current enhancement method according to claim 6, characterized in that, In step 5, the mapping relationship between the plasma circumferential current and the influencing factors of electromagnetic parameters, structural parameters, and gas supply parameters is as follows: ， Where X represents the influencing factors, and Y represents the plasma circumferential current. For random disturbance terms, For constant terms, and The fitting coefficients for each term are denoted as . , and is the significance coefficient for each item.

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