A thermal design method for laser cavity with heat shielding and weight reduction effects

Abstract

The application discloses a heat design method for a laser cavity, which considers heat shielding and weight reduction effects, and relates to the technical field of heat design optimization. The method comprises the following steps: S1, determining an initial structure of a multi-layer nested heat shielding laser cavity; S2, performing thermal analysis on the cavity structure to obtain all heat design parameters and calculate the thermal time constant of a silicon crystal; S3, calculating the weight of the cavity according to the initial structure; S4, evaluating the heat shielding effect according to the time constant, evaluating the weight reduction effect, and performing multi-objective Pareto optimization on the heat design parameters; and S5, obtaining the optimal heat design method after weighing the two effects. The application improves the heat design efficiency of the laser cavity, improves the heat shielding effect, and saves the weight cost.

Description

Technical Field

[0001] This invention belongs to the field of thermal design optimization technology, specifically relating to a thermal design method for laser cavities that balances thermal shielding and weight reduction. Background Technology

[0002] Spaceborne optical clocks are crucial payloads for ensuring high-accuracy time and frequency references in space quantum science. The frequency stability of these clocks requires ultra-stable lasers to reduce external thermal noise. Typically, an ultra-stable laser cavity is used to improve thermal shielding and provide a stable and reliable temperature environment for the ultra-stable laser. Meanwhile, onboard resources are very limited. Statistics show that the thermal control system accounts for 3% to 5% of the satellite's total mass. Therefore, weight reduction design must be implemented while ensuring effective thermal shielding during thermal design.

[0003] From a thermal perspective, a larger heat capacity results in a slower temperature change and a better thermal shielding effect. However, a large heat capacity requires increased material mass, thus creating a conflict between the goals of effective thermal shielding and weight reduction. Current thermal design optimization methods rely on the experience of thermal design engineers, making it difficult to efficiently iterate and calculate solutions, and it is challenging to find an optimal solution that balances two conflicting design objectives. This can lead to either poor thermal shielding or excessive time and weight costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a thermal design method for laser cavities that balances thermal shielding and weight reduction. By determining the calculation method for the thermal time constant, and using the thermal time constant and weight as objective functions, the Pareto front is used to obtain a multi-objective optimal solution, thereby efficiently achieving a thermal design solution that balances thermal shielding and weight reduction.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A thermal design method for laser cavities that combines thermal shielding and weight reduction, the method comprising:

[0007] Step S1: Determine the initial structure of the multi-layer heat shield cavity;

[0008] Step S2: Perform thermal analysis on the initial structure of the multilayer thermal shielding cavity and calculate the thermal time constant of the silicon crystal;

[0009] Step S3: Calculate the weight of the cavity based on the initial structure of the multi-layer heat shield cavity to obtain the total weight of the cavity;

[0010] Step S4: Perform multi-objective Pareto optimization based on thermal time constant and total cavity weight to obtain Pareto front curve;

[0011] Step S5: Analyze the Pareto front curve to find the optimal thermal design scheme that balances thermal shielding and weight reduction.

[0012] In a second aspect, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned thermal design method for a laser cavity that combines thermal shielding and weight reduction.

[0013] Thirdly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned thermal design method for a laser cavity that combines thermal shielding and weight reduction.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention utilizes Laplace transform to calculate the thermal time constant and total weight, combined with Pareto front analysis, to develop a method for efficiently designing optimal thermal structures for multi-layered thermally shielded cavities. Equivalent thermal conductivity is obtained through thermal analysis, and the thermal time constant is calculated using Laplace transform in Matlab for rapid iterative thermal design. Through Pareto front analysis, a thermal design scheme that reduces weight and time costs is ultimately achieved while maintaining good thermal shielding performance. Attached Figure Description

[0016] Figure 1 This is a flowchart of a thermal design method for a laser cavity that combines thermal shielding and weight reduction, according to the present invention.

[0017] Figure 2 This is a simplified model diagram of the multi-layer heat shield cavity in an embodiment of the present invention;

[0018] Figure 3 This is the Pareto front curve in an embodiment of the present invention.

[0019] Figure label:

[0020] 101. Vacuum layer; 102. External temperature control layer; 103. Internal temperature control layer; 104. Shielding layer; 105. Support frame; 106. Silicon crystal; 107. Support rod; 108. Interlayer support; 109. Epoxy fiberglass cup-shaped support. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] like Figure 1The diagram shown is a flowchart of a thermal design method for a laser cavity that combines thermal shielding and weight reduction, comprising the following steps:

[0023] Step S1: Determine the initial structure of the multi-layer heat shield cavity;

[0024] Step S2: Perform thermal analysis on the initial structure of the multilayer thermal shielding cavity and calculate the thermal time constant of the silicon crystal;

[0025] Step S3: Calculate the weight of the cavity based on the initial structure of the multi-layer heat shield cavity to obtain the total weight of the cavity;

[0026] Step S4: Perform multi-objective Pareto optimization based on thermal time constant and total cavity weight to obtain Pareto front curve;

[0027] Step S5: Analyze the Pareto front curve to find the optimal thermal design scheme that balances thermal shielding and weight reduction.

[0028] Preferably, in step S1, such as Figure 2 As shown, determining the initial structure of the multi-layer thermal shielding cavity includes: determining the first structural parameters of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105 arranged sequentially from the outside to the inside. The first structural parameters include at least one of the following: bottom area, height, thickness, material thermal conductivity, density, specific heat capacity, and surface radiation properties. Preferably, all first structural parameters of each layer are determined. The silicon crystal 106 is surrounded by the support frame 105 by the support rod 107. The interlayer supports 108 are located between the outer temperature control layer 102 and the inner temperature control layer 103, and the inner temperature control layer 104 and the inner temperature control layer 105 are respectively located between the outer temperature control layer 102 and the inner temperature control layer 103. Between the control layer 103 and the shielding layer 104, and between the shielding layer 104 and the support frame 105, the support rod 107 is a polyimide thermal insulation column, and the interlayer support 108 adopts a polyimide screw sleeve thermal insulation structure for support; the second structural parameters of the support rod 107, the interlayer support 108, and the epoxy fiberglass cup-shaped support 109 are determined, and the second structural parameters include at least one of length, contact area, and thickness. Preferably, all the second structural parameters of each support structure are determined; the outermost vacuum layer 101 and the outer temperature control layer 102 are supported by the epoxy fiberglass cup-shaped support 109.

[0029] The vacuum layer 101 is also connected to a vacuum system, which evacuates the system to a vacuum level below 10⁻⁹ mbar.

[0030] The interlayer support 108 includes two polyimide insulating pads and a screw. The two connecting surfaces are connected by the screw, and the contact surfaces are insulated by the polyimide insulating pads.

[0031] Preferably, step S2 includes the following steps:

[0032] Step S201: Calculate the equivalent heat transfer coefficient of each connection structure, such as the equivalent heat transfer coefficient of support rod 107, interlayer support 108, and epoxy fiberglass cup-shaped support 109.

[0033] Step S202: Calculate the equivalent radiative heat transfer coefficient between each layer, such as the equivalent radiative heat transfer coefficient of the outer temperature control layer 102, the inner temperature control layer 103, the shielding layer 104, and the support frame 105.

[0034] Step S203: Calculate the interlayer equivalent thermal conductivity based on steps S201 and S202;

[0035] Step S204: Based on the specific heat capacity and interlayer equivalent thermal conductivity, implement the Laplace transform in Matlab using code to obtain the temperature response formula and temperature response curve of silicon crystal 106 as a function of external temperature.

[0036] Step S205: When the external temperature rises by 1K, the time taken for the temperature to rise by (1-1 / e)K in the temperature response curve of the silicon crystal 106 is the thermal time constant.

[0037] Preferably, step S3 includes the following steps:

[0038] Step S301: Calculate the volume of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104 and support frame 105 respectively based on the material bottom area, height and thickness of each layer;

[0039] Step S302: Multiply the volume of each layer by the material density to obtain the weights of the outer temperature control layer 102, the inner temperature control layer 103, the shielding layer 104, and the support frame 105 respectively.

[0040] Step S303: Add the weights of the outer temperature control layer 102, the inner temperature control layer 103, the shielding layer 104, and the support frame 105 together to obtain the total weight.

[0041] Preferably, step S4 includes the following steps:

[0042] Step S401: Maximize the thermal time constant obtained in step S205 as the objective function to measure the thermal shielding effect;

[0043] Step S402: Minimize the total weight obtained in step S303 as the objective function to measure the weight reduction effect;

[0044] Step S403: Modify the material and thickness of each layer of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104 and support frame 105; modify the surface radiation properties of each layer of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104 and support frame 105; modify the length, thickness, contact area, etc. of the connection structure of each layer to change the equivalent thermal conductivity; design an experiment; and use the ilaplace function in Matlab to iteratively calculate the thermal time constant and total weight to obtain the dataset.

[0045] Step S404: Process the dataset using the Pareto front method based on intersection of normal boundaries to obtain Pareto front curves for different materials.

[0046] Preferably, step S5 includes the following steps:

[0047] Step S501: Analyze the Pareto front curves of different materials, and find a solution that balances thermal shielding and weight reduction while meeting thermal design requirements.

[0048] Step S502: Compare the results before and after optimization to obtain the optimal thermal design scheme.

[0049] Example

[0050] Step S1, Press Figure 2 The diagram shows the initial structure of the multi-layered heat-shielding cavity;

[0051] Step S2: Thermal analysis of the cavity and calculation of the thermal time constant;

[0052] First, calculate the equivalent heat transfer coefficient of the connection structure between each layer. :

[0053] ,

[0054] Where λ is the thermal conductivity of the material, A is the contact area, L is the length, and n is the number of identical connection structures in each layer.

[0055] Then calculate the equivalent radiative heat transfer coefficient between each layer. :

[0056] ,

[0057] Among them, B ij A represents the viewpoint factor from surface i to surface j. j Let ε represent the area of ​​surface j. j Indicates the emissivity of surface j. T represents the Boltzmann constant. i and T jThese are the temperatures of surface i and surface j, respectively, with the superscript r indicating radiative heat transfer. This represents the radiative heat exchange between surface i and surface j.

[0058] Finally, the equivalent thermal conductivity between each layer was calculated. :

[0059] ,i,j=1,2,3,4,i<j,

[0060] Let the cavity extend from silicon crystal 106 to outer temperature control layer 102, with temperatures ranging from T1 to T4 and heat capacities ranging from C1 to C4. Then, when the temperature stabilizes, the heat balance equation is:

[0061] ,

[0062] In the formula, the superscript · denotes the first time derivative of the temperature function;

[0063] Perform a Laplace transform:

[0064] ,

[0065] In the formula, s represents the Laplace operator, and the superscript ~ represents the temperature function after the Laplace transform;

[0066] The temperature change relationship between silicon crystal 106 and outer temperature control layer 102 can be derived:

[0067] ,

[0068] The outer wall of the external temperature control layer 102 provides a step response. This allows us to obtain the temperature of silicon crystal 106. Dependency:

[0069] ,

[0070] Substituting the heat capacity from step S1 and the equivalent heat transfer coefficient calculated in step S2, and performing a Laplace transform, we obtain the following form:

[0071] ,

[0072] The above formula represents the temperature response curve of silicon crystal 106, where t represents time. This process can be solved in Matlab using the ilaplace function. Then, plot this curve, and when the temperature rises to (1-1 / e) K, read the time at that point; this is the thermal time constant. .

[0073] Step S3: Calculate the weight of the cavity;

[0074] Calculate the volume of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105 based on the bottom area, height, and thickness of each layer. Multiply the volume of each layer by the material density to obtain the weight of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105. Add the weights of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105 to obtain the total weight W.

[0075] ,

[0076] In the formula, i represents the i-th layer of the cavity structure, which consists of four layers: an outer temperature control layer 102, an inner temperature control layer 103, a shielding layer 104, and a support frame 105. This represents the density of the i-th layer of material. Indicates the thickness of the i-th layer. This represents the surface area of ​​the i-th layer.

[0077] Step S4: Multi-objective Pareto optimization of thermal design parameters;

[0078] First, modify the material and thickness of each layer of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105. Then, modify the surface radiation properties of each layer of the outer temperature control layer 102, inner temperature control layer 103, shielding layer 104, and support frame 105. Finally, modify the length, thickness, and contact area of ​​the connection structure of each layer to change the equivalent thermal conductivity. These parameters are called thermal design parameters. Conduct experimental design, iteratively calculate the thermal time constant and total weight, and obtain the dataset.

[0079] Then, two main optimization objectives are defined: the objective of heat shielding effect and the objective of weight reduction effect. The objective function for heat shielding effect is... Expressed in terms of thermal time constant:

[0080] ,

[0081] In the formula, m represents the total number of iterations, and a represents the a-th calculation. There are a total of q thermal design parameters. This represents the value of the q-th thermal design parameter in the a-th calculation. This represents the matrix of values ​​for all thermal design parameters in the a-th calculation. This represents the thermal time constant calculated at this time, which indicates how the silicon crystal 106 changes with the external environment. This represents the objective function for the heat shielding effect in the a-th calculation. m calculations were performed, and all iterative calculations were obtained. The resulting matrix. Indicates taking The maximum value in the matrix, i.e. the largest thermal time constant of silicon crystal 106, indicates that silicon crystal 106 is least affected by external temperature changes and has the best thermal shielding effect.

[0082] The objective function for weight loss is represented by weight:

[0083] ,

[0084] In the formula, This represents the total weight of the system in the a-th calculation. This represents the objective function for weight loss in a single instance. m calculations were performed, and all iterative calculations were obtained. The resulting matrix. Representative take The minimum value in the matrix represents the minimum system weight, at which point the weight reduction effect is optimal.

[0085] The dataset was processed using the Pareto front method based on intersection of normal boundaries to obtain Pareto front curves for different materials, such as... Figure 3 By moving along the Pareto front curve, all Pareto optimal solutions to this biobjective problem can be found.

[0086] Step S5: Obtain the optimal thermal design scheme;

[0087] according to Figure 3 Analysis shows that the Pareto front curve for aluminum is located to the lower right of copper, indicating that under the same thermal design, copper has a shorter thermal response time and lower weight compared to aluminum. This suggests that aluminum can achieve better thermal shielding performance at a lower weight cost. However, the temperature gradient of the copper structure may be smaller compared to the aluminum structure. Specifically, for copper, a thermal time constant of 95 hours and a minimum weight of approximately 19.62 kg can be achieved. For aluminum, a thermal time constant of 190 hours and a minimum weight of 10.77 kg can be achieved. The optimal design scheme for aluminum is analyzed to obtain the best thermal design solution.

[0088] In a second aspect, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned thermal design method for a laser cavity that combines thermal shielding and weight reduction.

[0089] Thirdly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned thermal design method for a laser cavity that combines thermal shielding and weight reduction.

[0090] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal design method for laser cavities that combines thermal shielding and weight reduction, characterized in that, The method includes: Step S1: Determine the initial structure of the multi-layer heat shield cavity; the initial structure of the multi-layer heat shield cavity includes a vacuum layer, an outer temperature control layer, an inner temperature control layer, a shielding layer, and a support frame arranged sequentially from the outside to the inside; the silicon crystal is surrounded by the support frame through support rods, and the interlayer supports are located between the outer temperature control layer and the inner temperature control layer, between the inner temperature control layer and the shielding layer, and between the shielding layer and the support frame, respectively. The vacuum layer and the outer temperature control layer are supported by epoxy fiberglass cup-shaped supports. Step S2: Perform thermal analysis on the initial structure of the multilayer thermal shielding cavity, and calculate the thermal time constant of the silicon crystal using Laplace transform and inverse transform; including: Step S201: Calculate the equivalent heat transfer coefficients of the support rods, interlayer supports, and epoxy fiberglass cup supports; Step S202: Calculate the equivalent radiative heat transfer coefficient between each layer; Step S203: Calculate the interlayer equivalent thermal conductivity based on the equivalent heat transfer coefficient and the equivalent radiation heat transfer coefficient; Step S204: Based on the specific heat capacity and interlayer equivalent thermal conductivity, perform Laplace transform and inverse Laplace transform to obtain the temperature response formula and temperature response curve of silicon crystal as a function of external temperature. Step S205: When the external temperature rises by 1K, the time when the temperature rises by (1-1 / e)K in the temperature response curve of the silicon crystal is read, which is the thermal time constant. Step S3: Calculate the weight of the cavity based on the initial structure of the multi-layer heat shield cavity to obtain the total weight of the cavity; Step S4: Construct an objective function for the thermal shielding effect based on the thermal time constant. ， In the formula, m represents the total number of iterations, and a represents the a-th calculation. There are a total of q thermal design parameters. This represents the value of the q-th thermal design parameter in the a-th calculation. This represents the matrix of values ​​for all thermal design parameters in the a-th calculation. This represents the thermal time constant calculated at this point. This represents the objective function for the heat shielding effect in the a-th calculation. This indicates performing m calculations to obtain all iterative calculations. The resulting matrix, Indicates taking The maximum value in the matrix; Construct an objective function for weight reduction based on the total weight of the cavity: ， In the formula, This represents the total weight of the system in the a-th calculation. This represents the objective function for weight loss in a single instance. This indicates performing m calculations to obtain all iterative calculations. The resulting matrix, Representative take The minimum value in the matrix; By combining the Pareto front curve based on the intersection of the normal boundary, the Pareto optimal solution of the two objective functions is found; Step S5: Perform steps S1-S4 on different materials to obtain and analyze the Pareto optimal solution for different materials, and find the optimal thermal design scheme that takes into account both thermal shielding effect and weight reduction effect.

2. The thermal design method for a laser cavity that combines thermal shielding and weight reduction according to claim 1, characterized in that, In step S1, determining the initial structure of the multi-layer thermal shielding cavity includes determining the first structural parameters of the outer temperature control layer, inner temperature control layer, shielding layer, and support frame. The first structural parameters include at least one of the following: bottom area, height, thickness, material thermal conductivity, density, specific heat capacity, and surface radiation properties. The second structural parameters of the support rod, interlayer support, and epoxy fiberglass cup-shaped support are also determined. The second structural parameters include at least one of the following: length, contact area, and thickness.

3. The thermal design method for a laser cavity that combines thermal shielding and weight reduction according to claim 2, characterized in that, The support rod is a polyimide heat-insulating column; the interlayer support adopts a polyimide screw sleeve heat-insulating structure, including two polyimide insulating pads and a screw, the two connecting surfaces are connected by the screw, and the contact surfaces are heat-insulated by the polyimide insulating pads.

4. The thermal design method for a laser cavity that combines thermal shielding and weight reduction according to claim 3, characterized in that, Step S3 includes: Step S301: Calculate the volume of the outer temperature control layer, inner temperature control layer, shielding layer and support frame respectively based on the material bottom area, height and thickness of each layer; Step S302: Multiply the volume of each layer by the material density to obtain the weights of the outer temperature control layer, inner temperature control layer, shielding layer, and support frame respectively; Step S303: Add up the weights of the outer temperature control layer, inner temperature control layer, shielding layer, and support frame to obtain the total weight.

5. A thermal design method for a laser cavity that combines thermal shielding and weight reduction according to claim 4, characterized in that, Step S4 further includes: The materials and thicknesses of the outer temperature control layer, inner temperature control layer, shielding layer, and support frame were modified. The surface radiation properties of the outer temperature control layer, inner temperature control layer, shielding layer, and support frame were also modified. The length, thickness, and contact area of ​​the connecting structures of each layer were modified. An experimental design was carried out, and the thermal time constant and total weight were iteratively calculated using the ilaplace function in Matlab to obtain the dataset. The Pareto front method based on intersection of normal boundaries is used to process the dataset to obtain Pareto front curves for different materials. By combining the Pareto front curves, the Pareto optimal solution for the two objective functions is found.

6. A thermal design method for a laser cavity that combines thermal shielding and weight reduction according to claim 5, characterized in that, Step S5 includes: Step S501: Analyze the Pareto optimal solution for different materials. Under the premise of meeting the thermal design index, select the material that takes into account both thermal shielding effect and weight reduction effect as the optimal thermal design scheme.

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