Optimization Method for Propulsion Performance of Target-Belt Pulsed Laser Microthruster

Abstract

Based on large-sample experimental data, the present invention optimizes the propulsion performance of a target-belt pulsed laser microthruster from three aspects: First, under the constraints of given volume and weight, to provide the micro-nano satellite platform with the most sustained kinetic energy for attitude and orbit changes, the total impulse of the laser microthruster needs to be increased. Second, under given energy and mass requirements, to achieve greater kinetic energy conversion, that is, to convert electrical energy into kinetic energy, the efficiency of the laser microthruster needs to be optimized. Third, to meet the application needs of micro-nano satellite emergency response, the laser microthruster needs to provide the satellite platform with rapid maneuvering and orbit change capabilities under the constraints of given power. This method can meet the typical long-life, strong maneuverability, and high-efficiency satellite platform requirements for laser microthrusters. The method is highly operational and can be directly used for the design of laser microthruster performance, which has important application value for the practical application of laser microthrusters.

Description

Technical Field

[0001] The invention relates to a laser micro-propulsion performance design method, belonging to the technical field of spacecraft electric propulsion. Background Art

[0002] Micro- and nanosatellites, a new type of spacecraft designed for Earth orbit or space exploration missions, offer advantages such as small size, light weight, ease of manufacture, and low cost. Their diverse missions require precise, controllable, and continuous thrust output to enable orbit transfers, attitude adjustments, and rapid maneuvers. For microsatellites, a compact, highly integrated, and thrust-adjustable propulsion system is essential for practical engineering. Conventional chemical rocket propulsion systems are bulky and inefficient, making them unsuitable for these small spacecraft. Consequently, new micropropulsion systems tailored to the diverse functions of microsatellites have emerged. As an alternative, laser propulsion systems offer high specific impulse, low power consumption, compact size and weight, controllable thrust, and high efficiency, earning them a unique position in the field of micropropulsion systems.

[0003] The target-belt pulsed laser microthruster is a new type of microthruster. The advantage of transmission laser ablation is that it avoids laser contamination, making it more practical for engineering applications. A high-energy laser penetrates the target's transparent PET layer (PET boasts high light transmittance, high strength, and high-temperature resistance) and is deposited on the target's fuel layer (GAP), an energetic polymer. Through heat conduction, the GAP undergoes ionization and vaporization, forming a high-speed jet plume, generating impulse and providing power for the micro-nano satellite. Due to limitations in target belt preparation technology, the current maximum target belt thickness can only be 300μm, while ensuring uniformity in the target fuel layer.

[0004] During the development of laser microthrusters, the mission attributes of micro-nanosatellites play a crucial role in the design of their propulsion performance parameters. To meet the diverse mission requirements and application scenarios of micro-nanosatellites, laser microthrusters must provide varying propulsion capabilities. However, previous research methods have focused on limited data optimization and ablation mechanism analysis under specific parameters, lacking a systematic optimization approach based on large-scale experimental data. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for optimizing the propulsion performance of a target-belt pulsed laser microthruster, which satisfies different application scenarios through parameter design. The specific method is as follows:

[0006] A method for optimizing the propellant performance of a target-belt pulsed laser microthruster is proposed. The method is characterized in that the laser microthruster needs to provide different propulsion capabilities for different mission requirements and application scenarios of micro-nano satellites. Given volume and weight constraints, in order to provide the micro-nano satellite platform with the most sustained kinetic energy for attitude and orbit changes, the total impulse of the laser microthruster needs to be increased:

[0007] 1.1, fitting the linear equation of the maximum specific impulse and laser pulse width under different target fuel layer thicknesses

[0008] The orthogonal test method is used. Based on the test data, the relationship between the laser pulse width and the specific impulse is plotted with the laser pulse as the horizontal axis and the specific impulse as the vertical axis under different target fuel layer thicknesses. It is found that under the same laser pulse width, the thinner the target fuel layer, the larger the average specific impulse; under the same target fuel layer thickness, the specific impulse has a maximum value as the laser pulse width increases; the thicker the target fuel layer, the smaller the specific impulse maximum value, and the corresponding pulse width is also larger; the specific impulse maximum points under different target fuel layer thicknesses are connected, and the linear equation (1) of the specific impulse maximum value corresponding to different target fuel layer thicknesses and the linear equation of the specific impulse maximum value and the laser pulse width under different target fuel layer thicknesses are fitted:

[0009] I spmax =f(h) (1)

[0010] τ=f(h) (2)

[0011] Among them, the maximum value of specific impulse is I spmax , the laser pulse width is τ, and the target fuel layer thickness is h;

[0012] 1.2, Optimize specific impulse and target band thickness

[0013] As shown in 1.1, the thinner the target fuel layer, the higher the specific impulse. However, in actual engineering applications, the target fuel layer needs to be attached to a target substrate film of a specific thickness. The thinner the target fuel layer, the smaller the proportion of effective fuel in a certain volume. Therefore, optimizing the total impulse requires a comprehensive optimization of the specific impulse and the target thickness:

[0014] For a laser ablation microthruster with a limited volume, the target tape is wound on a ring with a radius of r and a thickness of D. The maximum outer diameter of the target tape is 2R. The total volume occupied by the target tape is:

[0015] V tape =π*(R 2 -r 2 )*D (3)

[0016] Assuming that the thickness of the target fuel layer is h, the thickness of the transparent substrate is H, and the density of the target fuel layer is ρ, the total impulse I is:

[0017] I=V tape *h / (h+H)*ρ*g*I sp max (4)

[0018] Substituting formula (1) into formula (4), we can obtain the functional relationship between the total impulse I and the target fuel layer thickness h:

[0019] I=V tape *h / (H+h)*ρ*g*f(h) (5)

[0020] Let d(I) = 0, and find the optimal target fuel layer thickness h opt According to formula (2), the corresponding laser pulse width τ is deduced opt Finally, the result is substituted into formula (5) to obtain the optimal total impulse I opt .

[0021] Furthermore, when energy and mass constraints are given, in order to achieve greater kinetic energy conversion, it is also necessary to optimize the efficiency of the laser microthruster. The specific impulse and impulse coupling coefficient are coupled to achieve the optimal laser ablation efficiency:

[0022] 2.1 Ablation efficiency η AB , impulse coupling coefficient C m and specific impulse I sp The relationship is

[0023] 2η AB =C m v E =C m I sp g (6) where the dimensionless parameter ablation efficiency η AB Defined as the efficiency of converting laser pulse energy into jet kinetic energy v E is the jet velocity, and g is the acceleration due to gravity.

[0024] 2.2. It can be seen from formula (6) that the product of impulse coupling coefficient and specific impulse has an upper limit. Through the orthogonal test method, the relationship diagram of target fuel layer thickness, laser pulse width and impulse coupling coefficient is drawn. Combined with formula (6), the optimal value of ablation efficiency is obtained. Then, combined with the experimental data, the corresponding target fuel layer thickness and laser pulse width are obtained.

[0025] Furthermore, in order to meet the application requirements of micro-nano satellite emergency response, the laser microthruster needs to provide the satellite platform with rapid maneuvering and trajectory change capabilities under the constraints of a given power:

[0026] 3.1, Optimizing thrust with known power consumption limits

[0027] Through orthogonal experiments, it can be found that under the same target fuel layer thickness, the larger the laser pulse width, the larger the single pulse impulse; under the same laser pulse width, the larger the target fuel layer thickness, the larger the single pulse impulse; under the same target fuel layer thickness, the single pulse impulse P and the laser pulse width τ have a linear functional relationship:

[0028] P=f(τ) (7)

[0029] For each target fuel layer thickness, the laser pulse width τ needs to meet the following requirements:

[0030] τ≥t (8)

[0031] Where t is the minimum laser pulse width that can burn through a target fuel layer of a certain thickness;

[0032] Assume that the average power consumption of the laser microthruster is limited to W max , the laser pulse width is τ, in μs, the single pulse impulse is P, the laser power density is E, the spot area is Q, the laser ablation frequency is f, and the average power consumption W needs to satisfy the following relationship:

[0033] W=Q*E*f*τ*10 -6 ≤W max (9)

[0034] Combining formulas (7)-(9), the maximum average thrust F under limited power consumption is obtained max :

[0035] F max =W max *P / (Q*E*τ*10 -6 ) (10)

[0036] With the goal of increasing maneuverability, under the same laser pulse width, the thicker the target fuel layer, the larger the single pulse impulse P. From formula (10), it can be seen that the maximum average thrust F at this time is max The larger the thrust, the better. Therefore, the steps to optimize thrust when the power consumption limit is known are:

[0037] (1) Select the maximum target dye layer thickness h within the target dye layer design range;

[0038] (2) Reduce the laser pulse width τ within the performance range of the laser;

[0039] (3) Optimize the ablation frequency f according to formula (9);

[0040] 3.2 Optimizing Power Consumption Under Known Thrust Requirements

[0041] Under the premise of meeting the thrust requirements, the power consumption of the laser microthruster needs to be reduced;

[0042] Assuming the target layer thickness is h, the optimization is performed under the constraints of laser power density E and spot area Q, and the mission required thrust is F need ,Right now

[0043] f*P=F need (11)

[0044] Combining formulas (7), (9) and (11), the minimum power consumption can be obtained as:

[0045] W min =Q*E*F need *τ*10 -6 / f(τ)(τ≥t) (12)

[0046] That is, when the target layer thickness is determined and the thrust F is satisfied, the power consumption W can be reduced by reducing the laser pulse width τ.

[0047] The above three approaches are used to design and optimize the performance of laser microthrusters to meet the different mission requirements of micro-nano satellite platforms.

[0048] Beneficial effects:

[0049] This paper provides a systematic method for designing the propulsion performance of laser-ablated microthrusters, capable of meeting the design requirements for different laser microthruster applications. The proposed propulsion performance design method addresses typical satellite platform requirements for laser microthrusters, including long life, high maneuverability, and high performance. The method is highly operational and can be directly applied to the design of laser microthruster performance, thus possessing significant practical value for the practical application of laser microthrusters. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Design and optimization method of propulsion performance of target-belt pulsed laser microthruster

[0051] Figure 2 Variation of specific impulse with pulse width and target thickness

[0052] Figure 3 Functional relationship between fuel layer thickness and total impulse

[0053] Figure 4 Impulse coupling coefficient under different laser pulse widths and different target fuel layer thicknesses

[0054] Figure 5 Ablation efficiency corresponding to different laser pulse widths and target fuel layer thicknesses

[0055] Figure 6 Effects of laser pulse width and target fuel layer thickness on single pulse impulse

[0056] Figure 7Curve of the effect of laser pulse width on single pulse impulse

[0057] Figure 8 Relationship curve between laser pulse width and power consumption Specific embodiments

[0058] The optimization method of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0059] like Figure 1 As shown in the figure, the optimization design of the propulsion performance of the target-belt pulsed laser micro-inferencer is mainly implemented from three aspects.

[0060] First, to provide the micro-nano satellite platform with the most sustained kinetic energy for attitude and orbit changes within given volume and weight constraints, the total impulse of the laser microthruster needs to be increased. Second, to achieve greater kinetic energy conversion (converting electrical energy into kinetic energy) within given energy and mass requirements, the efficiency of the laser microthruster needs to be optimized. Third, to meet the application needs of micro-nano satellites in emergency response situations, the laser microthruster needs to provide the satellite platform with rapid maneuvering and trajectory change capabilities within given power constraints.

[0061] like Figure 2 、 3 As shown in the figure, under the constraints of given volume and weight, in order to provide the micro-nano satellite platform with the most sustained kinetic energy for attitude and orbit changes, the total impulse of the laser microthruster needs to be increased. The linear equation of the maximum specific impulse and laser pulse width under different target fuel layer thicknesses is fitted:

[0062] Specifically, an orthogonal test method was used. Based on the test data, the laser pulse was used as the horizontal coordinate and the specific impulse was used as the vertical coordinate to draw a relationship diagram between the laser pulse width and the specific impulse under different target fuel layer thicknesses. It was found that under the same laser pulse width, the thinner the target fuel layer, the larger the average specific impulse; under the same target fuel layer thickness, the specific impulse has a maximum value as the laser pulse width increases. The thicker the target fuel layer, the smaller the specific impulse maximum value, and the corresponding pulse width is also larger; the specific impulse maximum points under different target fuel layer thicknesses are connected, and the linear equation (1) of the specific impulse maximum value corresponding to different target fuel layer thicknesses is fitted, as well as the linear equation of the specific impulse maximum value and the laser pulse width under different target fuel layer thicknesses:

[0063] I spmax =f(h) (1)

[0064] τ=f(h) (2)

[0065] Among them, the maximum value of specific impulse is I spmax, the laser pulse width is τ, and the target fuel layer thickness is h. According to experimental results, the thinner the target fuel layer, the higher the specific impulse. However, in actual engineering applications, the target fuel layer needs to be attached to a target substrate film of a specific thickness. The thinner the target fuel layer, the smaller the proportion of effective fuel within a given volume. Therefore, optimizing the total impulse requires a comprehensive optimization of both the specific impulse and the target thickness.

[0066] Assuming a laser ablation microthruster with a limited volume, the target ribbon is wrapped around a ring with a radius of r and a thickness of D, and the maximum outer diameter of the target ribbon is 2R. Therefore, the total volume occupied by the target ribbon is approximately:

[0067] V tape =π*(R 2 -r 2 )*D (3)

[0068] Assuming that the thickness of the target fuel layer is h, the thickness of the transparent substrate is H, and the density of the target fuel layer is ρ, the total impulse I should be:

[0069] I=V tape *h / (h+H)*ρ*g*I sp max (4)

[0070] Substituting formula (1) into formula (4), we can obtain the functional relationship between the total impulse I and the target fuel layer thickness h:

[0071] I=V tape *h / (H+h)*ρ*g*f(h) (5)

[0072] Let d(I) = 0, and find the optimal target fuel layer thickness h opt According to formula (2), the corresponding laser pulse width τ can be deduced opt Finally, the result is substituted into formula (5) to obtain the optimal total impulse I opt .

[0073] Specifically, it is assumed that the laser microthruster has a volume of 1U, the radius r of the target ribbon winding ring is 15mm, the thickness is 13mm, the maximum outer diameter 2R of the target ribbon winding is 80mm, the thickness D of the target ribbon transparent substrate is 100μm, and the fuel density ρ is 1.3*10 -3 kg / cm 3 , then formula (5) becomes a function of the total impulse I and the target fuel layer thickness d: I = 1 / (d + 100) * (314.67d - 0.58d 2 ).

[0074] Plotting formula (5), the function graph is as follows: Figure 3As shown in the figure, the optimal total impulse is 136.63 N·s, and the corresponding target fuel layer thickness is about 153 μm. Then, according to formula (2), we can deduce that the corresponding laser pulse width is about 191 μs.

[0075] Of course, when optimizing the total impulse of the laser microthruster, different target winding disk volumes, different target transparent base layer thicknesses, and different target fuel layer selections will result in different optimal total impulses, and the corresponding pulse widths and target thicknesses will also be different, but this method can all be used for optimization design.

[0076] like Figure 4 、 Figure 5 As shown, under given energy and mass requirements, in order to achieve greater kinetic energy conversion, that is, converting electrical energy into kinetic energy, the efficiency of the laser microthruster needs to be optimized.

[0077] The specific impulse and impulse coupling coefficient are coupled to achieve the optimal laser ablation efficiency:

[0078] Ablation efficiency η AB , impulse coupling coefficient C m and specific impulse I sp The relationship is

[0079] 2η AB =C m v E =C m I sp g (6)

[0080] The dimensionless parameter ablation efficiency η AB Defined as the efficiency of converting laser pulse energy into jet kinetic energy

[0081] From formula (6), it can be seen that the impulse coupling coefficient and the specific impulse product have an upper limit. Through the orthogonal test method, a relationship diagram of the target fuel layer thickness, laser pulse width and impulse coupling coefficient is drawn. Combined with formula (6), the optimal value of the ablation efficiency is obtained. Then, combined with the experimental data, the corresponding target fuel layer thickness and laser pulse width are obtained.

[0082] Specifically, from Figure 5As can be seen from the figure, the target fuel layer thickness significantly influences the maximum ablation efficiency. The highest ablation efficiency is achieved when the target fuel layer is 200μm thick, reaching 35.41%, corresponding to a laser pulse width of 200μs. According to the calculations in the first section, the target fuel layer thickness corresponding to the maximum total impulse is 150μm, at which point the maximum ablation efficiency is also high, approximately 31.35%. Therefore, we can conclude that the target fuel layer thickness corresponding to the optimal ablation efficiency is neither the thickness that optimizes the specific impulse nor the thickness corresponding to the impulse coupling coefficient. Optimizing ablation efficiency is crucial for micro-nano satellites, where power consumption is limited.

[0083] like Figure 7 、 8 As shown in the figure, in order to meet the application requirements of micro-nano satellites in emergency response situations, laser micro-thrusters need to provide the satellite platform with rapid maneuvering and orbit change capabilities under the constraints of given power.

[0084] 3.1, Optimizing thrust with known power consumption limits

[0085] After a large number of experiments, it was found that at the same target fuel layer thickness, the larger the laser pulse width, the greater the single pulse impulse; at the same laser pulse width, the thicker the target fuel layer, the greater the single pulse impulse; at the same target fuel layer thickness, the single pulse impulse P and the laser pulse width τ have a linear functional relationship:

[0086] P=f(τ) (7)

[0087] For each target fuel layer thickness, the laser pulse width τ needs to meet the following requirements:

[0088] τ≥t (8)

[0089] Where t is the minimum laser pulse width that can burn through a target fuel layer of a certain thickness;

[0090] Assume that the average power consumption of the laser microthruster is limited to W max , the laser pulse width is τ, in μs, the single pulse impulse is P, the laser power density is E, the spot area is Q, the laser operating frequency is f, and the average power consumption W needs to satisfy the following relationship:

[0091] W=Q*E*f*τ*10 -6 ≤W max (9)

[0092] From formulas (7)-(9), the maximum average thrust F under limited power consumption is obtained max :

[0093] F max =W max *I / Q*E*τ*10 -6(10)

[0094] With the goal of increasing maneuverability, under the same laser pulse width, the thicker the target fuel layer, the larger the single pulse impulse P. From formula (10), it can be seen that the maximum average thrust F at this time is max The larger the thrust, the better. Therefore, the steps to optimize thrust when the power consumption limit is known are:

[0095] (1) Within the design range of the target dye layer, select the maximum target dye layer thickness h.

[0096] (2) Reduce the laser pulse width τ within the performance range of the laser.

[0097] (3) Optimize the ablation frequency f according to formula (9).

[0098] Specifically, taking the target fuel layer thickness of 150 μm as an example, the obtained data is fitted, such as Figure 7 As shown, the functional relationship between the single pulse impulse I and the laser pulse width τ is:

[0099] I=0.0158*τ+3.43(τ≥100μs)

[0100] When the laser pulse width is too small, it is impossible to completely ablate the 150μm thick fuel layer, so t = 100μs, that is, τ ≥ 100μs.

[0101] We designed the power consumption limit to be 10W, and the laser power density is about 5*10 6 W / cm 2 , the laser spot area is about 1.77*10 -4 cm 2 We can get: F = 0.0158*f*τ + 3.43*f

[0102] At this point, the maximum value of the average thrust F is approximately 601.4 μN. Of course, the maximum thrust varies under different constraint powers. The thrust can also be adjusted in real time based on actual thrust requirements.

[0103] 3.2 Optimizing thrust under known thrust requirements

[0104] Under the premise of meeting the thrust requirements, the power consumption of the laser microthruster is reduced.

[0105] Assuming the target layer thickness is hμm, the optimization is performed under the constraints of laser power density E and spot area Q, and the mission required thrust is F need ,Right now

[0106] f*P=F need (11)

[0107] Combining formulas (7), (9) and (11), the minimum power consumption can be obtained as:

[0108] W min =Q*E*F need *τ*10 -6 / f(τ)(τ≥t) (12)

[0109] That is, when the target layer thickness is determined, under the condition of satisfying the thrust F, the smaller the laser pulse width t, the lower the power consumption W. Under different target layer thicknesses and different thrust requirements, the lowest power consumption can be obtained according to the above method.

[0110] Specifically, assuming that the target strip thickness is still 150 μm, the laser power density is E (the laser power density is about 5*10 6 W / cm 2 ), the spot area is Q (the laser spot area used is about 1.77*10 -4 cm 2 Assume that the mission thrust F is 300μN, that is, f*I=300μN, and the power consumption W is: W=8.85*10 -4 *f*t, combined with formulas (7), (9) and (11), we can get the inverse proportional function:

[0111] W=0.2655*t / (0.0158*t+3.34)(t≥100μs)

[0112] Fit the above function to get the following Figure 8 As shown in the curve, it can be seen from the figure that when the laser pulse width is 100μs, the power consumption is the lowest, at this time the power consumption W is about 5.39W, and the corresponding frequency f is about 61Hz. In summary, we can conclude that under the condition of satisfying the thrust F, the smaller the laser pulse width t, the lower the power consumption W. Of course, corresponding to different thicknesses of the target belt fuel layer, there is a minimum laser pulse width t. The optimal total impact target belt fuel layer thickness is 150μm, and the minimum burn-through pulse width is 100μs. Under this working condition, the optimal power consumption W min The relationship between it and the thrust F is:

[0113] W min =0.0179*F

[0114] Therefore, under different target tape thicknesses and different thrust requirements, the lowest power consumption can be obtained according to the above method.

[0115] The above description and embodiments are only specific embodiments of the present invention and do not constitute any limitation to the present invention. Any changes made under the inventive concept of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for optimizing the propulsion performance of a target-belt pulsed laser microthruster. This method is characterized by the fact that, for different mission requirements and application scenarios of micro-nano satellites, the laser microthruster needs to provide different propulsion capabilities. Given the volume and weight constraints, in order to provide the micro-nano satellite platform with the most sustained kinetic energy for attitude and orbit changes, the total impulse of the laser microthruster needs to be increased: 1.1, fitting the linear equation of the maximum specific impulse and laser pulse width under different target fuel layer thicknesses The orthogonal test method is used. Based on the test data, the relationship between the laser pulse width and the specific impulse is plotted with the laser pulse as the horizontal axis and the specific impulse as the vertical axis under different target fuel layer thicknesses. It is found that under the same laser pulse width, the thinner the target fuel layer, the larger the average specific impulse; under the same target fuel layer thickness, the specific impulse has a maximum value as the laser pulse width increases; the thicker the target fuel layer, the smaller the specific impulse maximum value, and the corresponding pulse width is also larger; the specific impulse maximum points under different target fuel layer thicknesses are connected, and the linear equation (1) of the specific impulse maximum value corresponding to different target fuel layer thicknesses and the linear equation of the specific impulse maximum value and the laser pulse width under different target fuel layer thicknesses are fitted: I spmax =f(h) (1) τ=f(h) (2) in, The maximum specific impulse is I spmax , the laser pulse width is τ, and the target fuel layer thickness is h; 1.2, Optimize specific impulse and target band thickness As shown in 1.1, the thinner the target fuel layer, the higher the specific impulse. However, in actual engineering applications, the target fuel layer needs to be attached to a target substrate film of a specific thickness. The thinner the target fuel layer, the smaller the proportion of effective fuel in a certain volume. Therefore, optimizing the total impulse requires a comprehensive optimization of the specific impulse and the target thickness: For a laser ablation microthruster with a limited volume, the target tape is wound on a ring with a radius of r and a thickness of D. The maximum outer diameter of the target tape is 2R. The total volume occupied by the target tape is: V tape Zπ*(R 2 -r 2 )*D (3) Assuming that the thickness of the target fuel layer is h, the thickness of the transparent substrate is H, and the density of the target fuel layer is ρ, the total impulse I is: I=V tape *h / (h+H)*ρ*g*I spmax (4) Substituting formula (1) into formula (4), we can obtain the functional relationship between the total impulse I and the target fuel layer thickness h: I=V tape *h / (H+h)*ρ*g*f(h) (5) Let d(I) = 0, and find the optimal target fuel layer thickness h opt According to formula (2), the corresponding laser pulse width τ is deduced opt Finally, the result is substituted into formula (5) to obtain the optimal total impulse I opt .

2. The optimization method according to claim 1, wherein: When energy and mass constraints are given, in order to achieve greater kinetic energy conversion, it is necessary to optimize the efficiency of the laser microthruster. The following method uses the mutual coupling design of specific impulse and impulse coupling coefficient to achieve the optimal laser ablation efficiency: 2.1, Ablation efficiency η AB , impulse coupling coefficient C m and specific impulse I sp The relationship is 2η AB =C m v E =C m I sp g (6) Among them, v E is the jet velocity, g is the acceleration due to gravity; 2.

2. It can be seen from formula (6) that the product of impulse coupling coefficient and specific impulse has an upper limit. Through the orthogonal test method, the relationship diagram of target fuel layer thickness, laser pulse width and impulse coupling coefficient is drawn. Combined with formula (6), the optimal value of ablation efficiency is obtained. Then, combined with the experimental data, the corresponding target fuel layer thickness and laser pulse width are obtained.

3. The optimization method according to claim 1 or 2, characterized in that: In order to meet the application requirements of micro-nano satellite emergency response, when the laser micro-thruster is at a given power, it is necessary to provide the satellite platform with rapid maneuvering and orbit change capabilities: 3.1, Optimizing thrust with known power consumption limits Through orthogonal experiments, it can be found that under the same target fuel layer thickness, the larger the laser pulse width, the larger the single pulse impulse; under the same laser pulse width, the larger the target fuel layer thickness, the larger the single pulse impulse; under the same target fuel layer thickness, the single pulse impulse P and the laser pulse width τ have a linear functional relationship: P=f(τ) (7) For each target fuel layer thickness, the laser pulse width τ needs to meet the following requirements: τ≥t (8) Where t is the minimum laser pulse width that can burn through a target fuel layer of a certain thickness; Assume that the average power consumption of the laser microthruster is limited to W max , the laser pulse width is τ, in μs, the single pulse impulse is P, the laser power density is E, the spot area is Q, the laser ablation frequency is f, and the average power consumption W needs to satisfy the following relationship: W=Q*E*f*τ*10 -6 ≤W max (9) Combining formulas (7)-(9), the maximum average thrust F under limited power consumption is obtained max : F max =W max *P / (Q*E*τ*10 -6 ) (10) With the goal of increasing maneuverability, under the same laser pulse width, the thicker the target fuel layer, the larger the single pulse impulse P. From formula (10), it can be seen that the maximum average thrust F at this time is max The larger the thrust, the better. Therefore, the steps to optimize thrust when the power consumption limit is known are: (1) Select the maximum target dye layer thickness h within the target dye layer design range; (2) Reduce the laser pulse width τ within the performance range of the laser; (3) Optimize the ablation frequency f according to formula (9); 3.2 Optimizing Power Consumption Under Known Thrust Requirements Under the premise of meeting the thrust requirements, it is necessary to reduce the power consumption of the laser microthruster Assuming the target layer thickness is h, the optimization is performed under the constraints of laser power density E and spot area Q, and the mission required thrust is F need ,Right now f*P=F need (11) Combining formulas (7), (9) and (11), the minimum power consumption can be obtained as: W min =Q*E*F need *t*10 -6 / f(τ) (12) where τ ≥ t That is, when the target layer thickness is determined and the thrust F is satisfied, the power consumption W can be reduced by reducing the laser pulse width τ.

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