A polyimide degradation analysis method and system under the synergistic action of multiple stresses

Abstract

The present application is about a polyimide degradation analysis method and system under the synergistic action of multiple stresses, wherein the method comprises: establishing a deep space environment, obtaining the charge accumulation characteristics of the polyimide to be tested under the deep space environment; constructing a fine description model of the charge behavior of the polyimide material to be tested under the deep space environment according to the trap energy state distribution characteristics of the polyimide material to be tested under the deep space environment; constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested under the deep space environment according to the electrostatic discharge characteristics of the polyimide material to be tested under the deep space environment; according to the microscopic molecular structure of the polyimide material to be tested under the deep space environment, the fine description model of charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics, the degradation trend of the polyimide insulation performance is obtained. The present application provides a polyimide degradation analysis method and system under the synergistic action of multiple stresses, which can obtain the degradation trend of the polyimide insulation performance under the long-term synergistic action of multiple stresses.

Description

Technical Field

[0001] The present application relates to the technical field of material analysis, and in particular to a method and system for analyzing polyimide degradation under the synergistic action of multiple stresses. Background Art

[0002] As my country's deep space exploration strategy advances, flexible solar wings have become the preferred option for deep space spacecraft due to their higher power-to-weight ratio. However, due to the complex environment of deep space exploration, deep space spacecraft will lose the protection of the Earth's magnetic field and will be severely exposed to electron radiation. In the short term, the potential of the dielectric material on the surface of the spacecraft will increase, and charge accumulation will occur inside the polyimide material that constitutes the flexible solar wing, accumulating a large number of electrons. As the electron irradiation time increases, the transported charges are trapped in deep and shallow traps, and the released energy is transferred to the second electron through the Auger effect and other means. Through the transfer method, the subsequent electrons are gradually "heated" to become high-energy particles, triggering a discharge process, which in turn leads to spacecraft system failures and abnormalities.

[0003] In the existing technology, NASA has conducted research on flexible solar panels based on the "Long-Term Exposure Facility" (LDEF) experimental platform, and found that under the action of thermal radiation, the average temperature change rate of the polyimide material that constitutes the flexible solar panel reaches 2°C / min. The ambient temperature will have a major impact on the temperature rise of the flexible device itself, causing the device performance to decline. However, since the dielectric properties of polymer dielectric materials are very sensitive to temperature changes, repeated rapid changes in temperature can easily lead to charge accumulation and migration in polymer dielectric materials, thereby causing spacecraft failure accidents.

[0004] The above analysis scheme only studies and explains the environmental factors that affect polyimide materials in the deep space environment, and cannot obtain the degradation trend of polyimide materials in the deep space environment.

[0005] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0007] The purpose of the embodiments of the present disclosure is to provide a method and system for analyzing polyimide degradation under the synergistic action of multiple stresses, thereby overcoming one or more problems caused by the limitations and defects of related technologies at least to a certain extent.

[0008] In a first aspect, the present application provides a method for analyzing polyimide degradation under the synergistic action of multiple stresses, comprising:

[0009] Establishing a simulated deep space environment, placing the polyimide material to be tested in the simulated deep space environment, thereby obtaining the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics;

[0010] According to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, the electron incident trajectory and the electron energy deposition distribution are obtained, so as to obtain the electron deposition depth distribution. Through the electron deposition depth distribution and the charge accumulation characteristics, a fine description model of the charge behavior of the polyimide material to be tested in the simulated deep space environment is constructed, and the fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation and an electron release rate equation;

[0011] Obtaining electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and obtaining mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters;

[0012] According to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the detailed description model of charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics, the degradation trend of the polyimide insulation performance is obtained.

[0013] In a possible implementation, the step of establishing a simulated deep space environment, placing the polyimide material to be tested in the simulated deep space environment, and thereby obtaining charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics, comprises:

[0014] Establishing a simulated deep space environment with multiple stresses that are continuously adjustable and controllable, wherein the multiple stresses include temperature, field strength, tension, electron energy and beam density;

[0015] The surface potential, charge accumulation density, dissipation characteristics, surface flashover, conductivity, relative dielectric constant, charge mobility, surface trap characteristics and barrier energy level distribution of the polyimide to be tested under the action of multiple stresses alone and in combination are obtained.

[0016] In a possible implementation, the electron incident trajectory and the electron energy deposition distribution are obtained according to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, thereby obtaining the electron deposition depth distribution, and constructing a fine description model of the charge behavior of the polyimide material to be tested in the simulated deep space environment through the electron deposition depth distribution and the charge accumulation characteristics. The fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation, and an electron release rate equation, including the following steps:

[0017] The charge properties and trap energy states of the polyimide material to be tested in a simulated deep space environment were obtained by using a high-field intensity, wide-temperature spectrum thermal stimulation current and space charge joint experiment.

[0018] The electron incident trajectory and electron energy deposition distribution are obtained by Monte Carlo method, and the electron deposition depth distribution of the polyimide to be tested is obtained;

[0019] According to the electron deposition depth distribution and charge accumulation characteristics of the polyimide to be tested, a detailed description model of the charge behavior of the polyimide material to be tested in a simulated deep space environment is constructed.

[0020] In a possible implementation, the step of obtaining electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, obtaining mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters includes:

[0021] According to the charge accumulation characteristics of the polyimide material to be tested, the potential distribution, surface flashover and charging rate tests are performed on the surface of the polyimide material to be tested, so as to obtain the electrostatic discharge performance of the polyimide material under the synergistic action of multiple stresses; the electrostatic discharge performance includes potential distribution, surface flashover and charging rate;

[0022] According to the charge behavior fine description model of the polyimide material to be tested, the mesoscopic parameters of the polyimide material to be tested are obtained; the mesoscopic parameters include activation energy, relaxation time, trap density, trap energy level, trap distribution and trap filling speed;

[0023] According to the charge accumulation characteristics, mesoscopic parameters and electrostatic discharge performance of the polyimide to be tested, the correlation between the charge accumulation characteristics and electrostatic discharge characteristics of the polyimide material to be tested under the synergistic action of multiple stresses is established.

[0024] In a possible implementation, the step of obtaining the degradation trend of the insulation performance of the polyimide according to the microscopic molecular structure of the polyimide material to be tested, the fine description model of the charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics in the simulated deep space environment includes:

[0025] Acquire the microscopic molecular structure of the polyimide material to be tested in a simulated deep space environment; the microscopic molecular structure of the polyimide material to be tested includes short-range structural information and long-range structural information;

[0026] According to the correlation between the microscopic molecular structure of the polyimide material to be tested and the charge accumulation and discharge characteristics of the polyimide material to be tested, the degradation trend of the polyimide insulation performance is obtained; the degradation trend of the polyimide insulation performance is:

[0027] ;

[0028] in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

[0029] In a possible implementation, the step of obtaining the surface potential, charge accumulation density, dissipation characteristics, surface flashover, conductivity, relative dielectric constant, charge mobility, surface trap characteristics and barrier energy level distribution of the polyimide to be tested under the action of multiple stresses alone and in combination includes:

[0030] Under the action of multiple stresses individually and in combination, the surface potential is collected through the polyimide material to be tested, and the charge accumulation density, dissipation characteristics and surface flashover are analyzed.

[0031] Under the action of multiple stresses individually and in combination, the conductivity, relative dielectric constant and charge mobility are obtained through the first formula, the second formula and the third formula; the first formula is: ;in, is the initial conductivity, is the correction factor, is the free charge density (C m -3 ), is the charge trapping probability (s -1 ), is the charge trapping probability (s -1 ), is the electron charge, is the trap density (m -3 ), is the action time; the second formula is: ;in, is the capacitance, is the dielectric constant, is the plate area, is the electrostatic force constant, is the plate spacing; the third formula is: ;in, is the corresponding voltage at the current time, is the initial charge, is the charge mobility, is the electric field strength, is the carrier lifetime, L is the thickness of the polyimide material to be measured, is the capacitance, is the current time, For the crossing time;

[0032] Under the action of multiple stresses individually and in combination, the surface trap characteristics and barrier energy level distribution of the polyimide material to be tested were obtained through surface potential decay method and atomic force microscopy technology.

[0033] In a possible implementation, the charge behavior fine description model of the polyimide material to be tested includes:

[0034] ;

[0035] in, , ;

[0036] is the charge current density, is the electron charge, is the electron concentration, is the charge mobility, is the electric field strength, is the absolute temperature, is the mechanical stress, is the irradiation dose rate, is the rate of electron-hole pair generation by thermal excitation, is the radiation ionization rate, is the carrier lifetime, is the room temperature band gap, is the temperature coefficient, is the Boltzmann constant, is the electron deposition depth distribution, is the dynamic recombination rate, is the electron concentration, is the hole concentration, is the electric field strength, is the trap density, is the electron capture rate, is the speed of thermal motion, To capture the cross section, is the electron release rate, To release the cross section, is the trap level.

[0037] In a possible implementation, the correlation between charge accumulation and discharge characteristics of the polyimide material to be tested under the synergistic action of multiple stresses includes:

[0038] ;

[0039] in, is the breakdown field strength, is the charge accumulation density, is the conductivity, is the relative dielectric constant, is the activation energy, is the trap density, is the trap level, is the charge mobility, is the gas constant, T is the absolute temperature, , , , is the fitting parameter.

[0040] In a possible implementation, the step of obtaining the microscopic molecular structure of the polyimide material to be tested in a simulated deep space environment, wherein the microscopic molecular structure of the polyimide material to be tested includes short-range structural information and long-range structural information, comprises:

[0041] Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and nuclear magnetic resonance were used to obtain short-range structural information such as functional groups, energy level structure, and element valence state of polyimide materials;

[0042] Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy were used to obtain long-range structural information such as thermal enthalpy, specific heat, crystallization behavior, and radiation damage of polyimide materials.

[0043] In a second aspect, the present application provides a polyimide degradation analysis system under the synergistic action of multiple stresses, the system is used to perform the above-mentioned polyimide degradation analysis method under the synergistic action of multiple stresses, and the system comprises:

[0044] An environmental simulation module is used to establish a simulated deep space environment, and place the polyimide material to be tested in the simulated deep space environment, so as to obtain the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics;

[0045] A model building module is used to obtain the electron incident trajectory and the electron energy deposition distribution according to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, so as to obtain the electron deposition depth distribution, and to construct a charge behavior fine description model of the polyimide material to be tested in the simulated deep space environment through the electron deposition depth distribution and the charge accumulation characteristics, wherein the fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation, and an electron release rate equation;

[0046] A correlation construction module is used to obtain electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and to obtain mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and to construct a correlation relationship between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters;

[0047] The degradation analysis module is used to obtain the degradation trend of the insulation performance of polyimide according to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics; the degradation trend of the insulation performance of polyimide is:

[0048] ;

[0049] in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

[0050] The technical solution provided by this application may have the following beneficial effects:

[0051] Through the polyimide degradation analysis method and system under the synergistic action of multiple stresses of the present application, it is possible to analyze the charge accumulation characteristics of the flexible substrate polyimide material under the action of electricity, heat, force and radiation in the deep space environment, establish a refined description model of charge behavior, and clarify the correlation mechanism between the charge accumulation characteristics and the discharge characteristics. Based on the refined description model of charge behavior and the microscopic molecular structure, the degradation trend of the insulation performance of polyimide under the long-term synergistic action of multiple stresses is obtained, which provides a basis for the material performance improvement method and structural optimization of the flexible solar wings of deep space exploration spacecraft, thereby promoting the development and application of flexible solar wings for deep space exploration spacecraft.

[0052] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0054] Figure 1 A flow chart showing a method for analyzing polyimide degradation under the synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure;

[0055] Figure 2 A detailed flow chart of step S100 of the polyimide degradation analysis method under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0056] Figure 3 A detailed flow chart of step S200 of the method for analyzing polyimide degradation under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0057] Figure 4 A detailed flow chart of step S300 of the polyimide degradation analysis method under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0058] Figure 5 A detailed flow chart of step S400 of the polyimide degradation analysis method under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0059] Figure 6 A schematic diagram showing a solar wing structure and a charge accumulation process of a polyimide degradation analysis method under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0060] Figure 7 The technical roadmap of the polyimide degradation analysis method under the synergistic effect of multiple stresses in the exemplary embodiment of the present disclosure is shown;

[0061] Figure 8 A schematic diagram of a multi-stress synergistic loading experimental platform for a polyimide degradation analysis method under synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0062] Fig. 9 A schematic diagram showing electron irradiation and potential acquisition of a polyimide degradation analysis method under the synergistic effect of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0063] Fig.10 A schematic diagram of a HFWT-TSC-PEA joint testing system for analyzing polyimide degradation under the synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0064] Fig.11 A schematic diagram of a method for testing the dynamic evolution law of space charge of a polyimide degradation analysis method under the synergistic action of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0065] Fig.12 A schematic diagram of a charge behavior refinement description model of a polyimide degradation analysis method under the synergistic effect of multiple stresses in an exemplary embodiment of the present disclosure is shown;

[0066] Fig.13 A schematic diagram of the structure of a polyimide material showing a method for analyzing polyimide degradation under the synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure;

[0067] Fig.14 A schematic diagram showing the degradation trend mechanism of polyimide materials in a method for analyzing polyimide degradation under the synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure;

[0068] Fig.15 A schematic structural diagram of a polyimide degradation analysis system under the synergistic effects of multiple stresses in an exemplary embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0069] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0070] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0071] like Figure 6 As shown in the figure, the electrode structure of the traditional rigid solar wing has an increased amount of polyimide charge accumulation under the synergistic effect of electricity, heat and radiation compared with a single stress, and the surface insulation performance is significantly reduced. The electric field and mechanical stress borne by the flexible solar wing are more complex than those of the traditional rigid solar wing. On the one hand, under the synergistic effect of the working electric field on the surface of the solar wing and the charged particles of space radiation, the charge will be injected into the dielectric material. Compared with the vacuum / dielectric / electrode interface system of the traditional solar wing, the vacuum / dielectric / vacuum structure of the flexible solar wing makes it more difficult to release the injected charge. On the other hand, the flexible substrate is subjected to a certain tension to maintain the rigidity required by the solar wing in space. Mechanical stress will cause changes in the local morphological structure and trap distribution characteristics of the polyimide material, accelerating the charge accumulation process. The electric field distortion caused by charge accumulation will induce electrostatic discharge to damage the insulating medium, and in severe cases, it will cause the spacecraft to be scrapped.

[0072] In this exemplary embodiment, a method for analyzing polyimide degradation under the synergistic action of multiple stresses is first provided. The method can be applied to a terminal device, such as a mobile phone, a desktop computer, a personal digital assistant, a laptop computer, a tablet computer, a smart watch, or other mobile terminal. Figure 1 As shown in , the method may include the following steps:

[0073] Step S100: establishing a simulated deep space environment, placing the polyimide material to be tested in the simulated deep space environment, thereby obtaining the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics.

[0074] Step S200: According to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, the electron incident trajectory and the electron energy deposition distribution are obtained to obtain the electron deposition depth distribution, and the charge behavior fine description model of the polyimide material to be tested in the simulated deep space environment is constructed through the electron deposition depth distribution and the charge accumulation characteristics. The fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation and an electron release rate equation.

[0075] Step S300: obtaining electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and obtaining mesoscopic parameters through a detailed description model of the charge behavior of the polyimide material to be tested, and constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters.

[0076] Step S400: Obtain the degradation trend of the insulation performance of the polyimide according to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of the charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics.

[0077] Through the above method, such as Figure 7 As shown, by simulating the deep space environment, the charge accumulation characteristics of the polyimide material under the action of electricity, heat, force and radiation can be obtained, so as to establish a refined description model of the charge behavior of the polyimide material under the synergistic action of multiple stresses, and through the refined description model of the charge behavior and the charge accumulation characteristics, the correlation mechanism between the charge accumulation characteristics and the electrostatic discharge characteristics can be clarified. Finally, based on the correlation mechanism and the microscopic molecular structure, the degradation trend of the insulation performance of the polyimide under the long-term synergistic action of multiple stresses can be obtained.

[0078] Next, we will refer to Figures 1 to 5 Each step of the above method in this example implementation is described in more detail.

[0079] In step S100, a simulated deep space environment is established, and a polyimide material to be tested is placed in the simulated deep space environment, so as to obtain charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics.

[0080] It can be understood that the surface charge characteristics include: surface potential, charge accumulation density, dissipation characteristics, surface trap characteristics, flashover conditions and barrier energy level distribution; space charge characteristics include: conductivity, relative dielectric constant and charge mobility; based on the structure of deep space exploration spacecraft components, a simulated deep space environment is established to make the flexible substrate polyimide material withstand field strength, temperature, tension and radiation stress, and the following can be designed: Figure 8 The multi-stress collaborative loading device in the multi-stress collaborative loading experimental platform shown includes an electric field loading system, a temperature control system, a mechanical loading and sensing system, a vacuum and irradiation environment simulation system, which can realize continuous adjustment and controllability of temperature, field strength, tension, electron energy and beam density.

[0081] In one embodiment, Figure 2 As shown, step S100 may include the following sub-steps:

[0082] In step S110, a simulated deep space environment with multiple stresses continuously adjustable and controllable is established, wherein the multiple stresses include temperature, field intensity, tension, electron energy and beam density.

[0083] It should be noted that based on the extremely complex space environment and component structure faced by the flexible solar wing of deep space exploration spacecraft, the harsh space radiation, rapid alternating temperature cycles of hot and cold, extremely high working field strength and mechanical stress that the surface of the flexible solar wing needs to withstand in deep space are analyzed. According to the potential field strength, temperature, tension and radiation (including electron energy, beam density) stress, a multi-stress collaborative loading device is designed, including electric heating controller, temperature sensor, high-voltage power supply, high-voltage pulse source, force sensor, electrometer, oscilloscope probe and other equipment, such as Figure 8 The difficulty of this experimental platform is that the electron irradiation applied during the test will cause signal interference to the experimental platform itself, resulting in errors in the experimental results. Therefore, this application uses a multi-layer insulation structure of insulating paint impregnation and aluminum foil stacking and wrapping for shielding to avoid interference of electron irradiation on the test results.

[0084] The voltage waveform is regulated by the signal generator and the power amplifier. The temperature is controlled by the high-sensitivity temperature sensor and the PID controller. The tensile force is adjusted by the high-precision force sensor to control the stepper motor. The Schottky thermal emission principle is adopted to control the electron emitter current and the accelerating electrode voltage to achieve electron irradiation with different beam currents and energies. The platform can meet the requirements of continuous adjustment and control of temperature, field strength, tension, electron energy and beam density. The voltage range is 0~±20kV, the current range is 0~20mA, the rising edge is >350V / μs, the temperature control range is -100~100℃, the rate reaches 2℃ / min of continuous temperature regulation, the mechanical force range is 0.1~1000N, the electron energy is in the range of 1~10keV, and the beam density is 0~25nA / cm 2Continuously adjust within the range to meet the requirements of the steps of this method.

[0085] In step S120, the surface potential, charge accumulation density, dissipation characteristics, surface flashover, conductivity, relative dielectric constant, charge mobility, surface trap characteristics and barrier energy level distribution of the polyimide to be tested under the action of multiple stresses alone and in combination are obtained.

[0086] It should be noted that, based on the multi-stress collaborative loading experimental device, the three-electrode method and the bridge method were used to build a conductivity and relative dielectric constant measurement platform, and the transit time algorithm and the electroacoustic pulse method were used to build a temperature and field intensity controllable material carrier or ion mobility (including positive and negative ions, holes, electrons, etc.) measurement platform, respectively measuring the conductivity, relative dielectric constant, charge mobility and other internal charge characteristics of polyimide under the action of multiple stresses alone and in synergy. The surface potential decay (SPD) and atomic force microscopy and other testing techniques were used to measure the surface trap characteristics of polyimide and the change of barrier energy level distribution with temperature, field strength, tension and irradiation intensity.

[0087] Furthermore, step S120 may include the following sub-steps:

[0088] In step S121, under the action of multiple stresses individually and in combination, the surface potential is collected through the polyimide material to be tested, and the charge accumulation density, dissipation characteristics and surface flashover are analyzed to obtain.

[0089] Optionally, specifically, before the test begins, the capacitance probe is moved to the surface of the polyimide material to measure the initial potential. After the initial surface potential of the sample is obtained, the electron irradiation module begins to preheat. After 10 minutes of preheating, the potentials of the accelerating electrode and the confinement electrode are adjusted to the set values. The action instructions are transmitted to the motion control component through the Labview host computer software, and the cross arm is moved so that the electron irradiation device moves to the top of the sample to start the irradiation experiment phase. Fig. 9As shown, the potential collection stage begins every 2 minutes of irradiation. In the first stage, the motion control component is driven by the Labview host computer software command to quickly move the electron irradiation device to the top of the sample to start the irradiation experiment. The potential collection stage begins 2 minutes after irradiation. The control component drives the capacitor probe to the edge of the sample at high speed to lay out the subsequent precise collection. This stage is a quick battle to reduce the impact of transient interference and ensure that the collected potential accurately reflects the charge state of the material. In the second stage, the host computer activates the signal acquisition system and synchronously regulates the motion mechanism to run at an appropriately low speed to ensure that the capacitor probe scans the sample at a uniform speed to collect the potential. When the probe reaches the center of the irradiation, the potential collection reaches the critical node. Immediately terminate the acquisition to avoid charge dissipation interference and ensure that the potential peak is collected accurately and reliably. This stage is the core of data acquisition and is related to the potential distribution, charge accumulation density and dissipation parameter accuracy. In the third stage, the center point acquisition is completed, and the control component immediately drives the capacitance probe to return to the initial position at high speed to prepare for the next round of irradiation, maintain the continuity of the experiment, reduce the impact of experimental cycle fluctuations on the results, and ensure that the data collected in each round are comparable. After multiple rounds of repeated experiments, the potential, charge accumulation density, dissipation parameters and surface flashover data under different field strengths, temperatures, tensions, and irradiation intensities are accumulated, and a multi-stress influence database is constructed to deeply analyze the charge behavior characteristics and surface flashover mechanism of polyimide. In order to avoid charge dissipation during the test, the total time of the entire test working potential measurement stage is less than 10s. Through repeated experiments, the surface potential, charge accumulation density, dissipation and other parameters of polyimide materials under different field strengths, different temperatures, different tensions, and different irradiation intensities are tested separately and synergistically.

[0090] In step S122, under the action of multiple stresses individually and in combination, the conductivity, relative dielectric constant and charge mobility are obtained by the first formula, the second formula and the third formula;

[0091] The first formula is:

[0092] ;

[0093] in, is the initial conductivity, is the correction factor, is the free charge density (C m -3 ), is the charge trapping probability (s -1 ), is the charge trapping probability (s -1 ), is the electron charge, is the trap density (m -3 ), is the action time;

[0094] The second formula is: ;in, is the capacitance, is the dielectric constant, is the plate area, is the electrostatic force constant, is the plate spacing;

[0095] The third formula is: ;in, is the corresponding voltage at the current time, is the initial charge, is the charge mobility, is the electric field strength, is the carrier lifetime, L is the thickness of the polyimide material to be measured, is the capacitance, is the current time, For the crossing time;

[0096] It should be noted that the correction factor It can be determined through experimental measurement and data fitting. Dielectric properties refer to the response characteristics of bound charges in material molecules to an applied stress field. They are important parameters for describing material performance, including conductivity, dielectric constant, dielectric loss, etc. Optionally, based on a multi-stress collaborative loading device, a conductivity and relative dielectric constant measurement platform is built using a three-electrode method and a bridge method. The test sample that has been strictly pretreated is placed in the test cavity, and the test cavity is heated according to the test requirements. Using a Keithley 6517B electrometer, after pressurization, the first and second formulas are used to obtain the variation of key dielectric properties of polyimide materials such as conductivity and relative dielectric constant with temperature, field strength, mechanical force and irradiation under the working conditions to be tested; using the transit time algorithm, that is, the third formula and the electroacoustic pulse method, a temperature and field strength controllable material carrier or ion mobility (including positive and negative ions, holes, electrons, etc.) measurement platform is built, and a heating unit and insulation layer are designed, and the temperature real-time feedback system is connected to achieve reasonable regulation of the temperature of the polyimide material. The temperature control range is -100~100℃, and the control accuracy is 0.1℃. The mobility of carriers of different polarities is tested by measuring the charge accumulation rate, and the change of the charge mobility of polyimide and other internal charge characteristics of the material under multiple stresses alone and in synergy is measured.

[0097] In step S123, under the action of multiple stresses individually and in concert, the surface trap characteristics and barrier energy level distribution of the polyimide material to be tested are obtained by using a surface potential decay method and atomic force microscopy technology.

[0098] It should be noted that physical phenomena such as charge injection, trapping, detrapping, and migration determine the surface potential decay process. By establishing a model to analyze the dynamic characteristics of surface potential decay, parameters such as the trap energy level distribution on the sample surface can be obtained. Atomic force microscopy (AFM) is used to analyze changes in the surface structure of solid materials, including insulators. The surface structure and properties of materials are studied by detecting the extremely weak atomic interaction force between the sample surface and a micro-force sensitive element. A pair of micro-cantilevers that are extremely sensitive to weak forces are fixed at one end, and the tiny needle tip at the other end is close to the sample. At this time, it will interact with it, and the force will cause the micro-cantilever to deform or change its motion state. When scanning the sample, the sensor is used to detect these changes, and the force distribution information can be obtained, thereby obtaining surface morphology structure information and surface roughness information with nanometer resolution, which helps to improve the understanding of the charge distribution and trap information inside the polyimide material. Therefore, measurement techniques such as surface potential decay (SPD) and atomic force microscopy are used for test analysis, and the corresponding test platform, including needle electrode, gate, sample, back electrode and power supply part, is improved. The SPD experimental system uses a heating plate connected to a high-precision temperature control and feedback system to achieve real-time temperature control of the sample, and to measure the surface trap characteristics of polyimide and the variation of the barrier energy level distribution with temperature, field strength, tension and radiation intensity.

[0099] In step S200, according to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, the electron incident trajectory and the electron energy deposition distribution are obtained to obtain the electron deposition depth distribution, and the electron deposition depth distribution and the charge accumulation characteristics are used to construct a fine description model of the charge behavior of the polyimide material to be tested in the simulated deep space environment. The fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation, and an electron release rate equation.

[0100] It is understandable that the high field strength and wide temperature spectrum thermally stimulated current and space charge combined experiment (HFWT-TSC-PEA) is used to distinguish the charge properties and trap energy levels, so as to obtain the influence of electrical, thermal, mechanical and irradiation stresses alone and synergistically on mesoscopic trap parameters such as activation energy, relaxation time, trap density, and trap filling speed. Based on the distribution characteristics of polyimide trap energy states under multi-stress synergy, that is, charge properties and trap energy levels, the Monte Carlo method is combined to study the electron incident trajectory, obtain the electron deposition depth distribution characteristics, and comprehensively consider the surface potential of polyimide and the generation, migration and accumulation characteristics of space charge, propose modeling principles and methods that can describe the charge behavior of polyimide, and construct a refined description model for characterizing the charge behavior of polyimide materials.

[0101] In one embodiment, Figure 3 As shown, step S200 may include the following sub-steps:

[0102] In step S210, a high-field-strength, wide-temperature-spectrum thermal stimulation current and space charge joint experiment is performed to obtain the charge properties and trap energy states of the polyimide material to be tested in a simulated deep space environment.

[0103] It is understandable that under the separate or synergistic effects of field strength, temperature, tension and irradiation, charges will be injected into the material and bound by the traps in the material, and impurities in the material will also generate traps. Therefore, one of the major difficulties in exploring the charge accumulation of dielectric materials is the need for an in-depth understanding of the changes in trap distribution inside the dielectric material. Therefore, the trap energy state distribution characteristics of polyimide under the separate and synergistic effects of electrical, thermal, mechanical and irradiation stresses are studied, and the trap characteristics of polyimide materials are measured using the high field strength wide temperature spectrum thermal stimulation current and space charge joint experiment (HFWT-TSC-PEA) joint test platform to distinguish trap charges at different energy levels. The thermal stimulation current is tested under different bias voltages. During the measurement, bias voltages of different polarities and amplitudes are applied to both ends of the material. The different change trends of the thermal stimulation current curve are compared, and combined with the dielectric spectrum test results, the three different types of charges in the thermal stimulation current curve, namely the dipole steering polarization peak, thermionic polarization peak and the trap charge detrapping peak, are distinguished. Combined with the dielectric spectrum test results, the curve was fitted by Origin software, and the charge released by each charge peak was calculated after peak separation. The relationship between the charge released by each charge peak and the bias voltage under different bias voltages was compared to identify the charge properties corresponding to each current peak. The HFWT-TSC-PEA joint test system is mainly composed of a temperature control module, an electrode module, a signal acquisition module, and a high-voltage power supply module. The test system is as follows: Fig.10 As shown, this is used to explore the influence of electrical, thermal, mechanical and irradiation stresses alone and in combination on mesoscopic trap parameters such as activation energy, relaxation time, trap density, and trap filling speed. The size of the activation energy can reflect the difficulty of a chemical reaction. The activation energy Ea is calculated using the Arrhenius formula, which represents the height of the potential barrier. The relaxation time is used to represent the relaxation characteristics of the material. The trap density also reflects the corresponding concentration of deep and shallow traps, and the trap filling speed also represents the depth of the deep and shallow traps. The Arrhenius formula is: ;in, is the frequency factor, is the gas constant, with a value of 8.314 J / (mol·K), is the relaxation activation energy.

[0104] In step S220, the electron incident trajectory and the electron energy deposition distribution are obtained by using the Monte Carlo method to obtain the electron deposition depth distribution of the polyimide to be tested.

[0105] It is understandable that in exploring a series of physical processes such as the migration changes of polyimide materials after electron incidence under electron irradiation, the changes in interface potential barriers affecting charge conduction, etc., the Monte Carlo method tracks the movement of a large number of incident electrons through computer simulation by simulating electron irradiation of dielectric materials, and adopts the continuous slowing-down assumption. The collision between the incident electron and the target atomic nucleus of the material is described by a two-body collision. This part mainly causes the tortuosity of the motion trajectory of the incident ion. The energy loss comes from the elastic energy loss part, and between the two two-body collisions, it is assumed that the incident electron and the electron in the material continuously and uniformly lose energy. Therefore, based on the distribution characteristics of traps at different energy levels, Geant4 simulation software based on the Monte Carlo method is used to simulate the transport process of particles in the material, and the electron scattering trajectory of the electron incident on the polyimide material is studied in combination with finite element electrodynamics. The charge generation, incidence, reflection, energy deposition distribution characteristics and interface barrier changes under electron irradiation are analyzed; the charge diffusion migration process under the synergistic action of electric field, thermal field, force field and electron irradiation is analyzed, and the changes in material parameters such as conductivity, thermal conductivity and dielectric constant caused by charge diffusion migration are analyzed, and the dynamic evolution law of the charge of the polyimide material under the synergistic action of multiple stresses is obtained. Its test methods are as follows: Fig.11 shown.

[0106] In step S230, a detailed description model of the charge behavior of the polyimide material to be tested in a simulated deep space environment is constructed according to the electron deposition depth distribution and charge accumulation characteristics of the polyimide to be tested.

[0107] It is understandable that, depending on the different types of defects, traps inside the material under the action of various stresses can capture electrons or holes injected into the material, but each different charge carrier trap corresponds to a different energy level. The charge accumulation of dielectric materials is a key factor in exploring the aging phenomenon of materials. Therefore, it is necessary to establish a model that can accurately describe the charge behavior to simulate the charge morphology inside the dielectric material. By comprehensively considering the surface potential and spatial charge generation, accumulation and migration characteristics of polyimide, modeling principles and methods that can describe the charge generation, accumulation and transport characteristics of polyimide are proposed, and the generation mechanism of the charge accumulation mode of polyimide materials under the action of multiple stresses alone is clarified. The parameters such as the trapping rate of charge trapping, the ratio of deep and shallow traps, the total number of trapped charges, and the de-trapping rate are adjusted to finely describe the charge behavior of polyimide materials. A refined description model, such as Fig.12 shown.

[0108] Furthermore, the detailed description model of the charge behavior of the polyimide material to be tested includes:

[0109] ;

[0110] in, , ;

[0111] is the charge current density, is the electron charge, is the electron concentration, is the charge mobility, is the electric field strength, is the absolute temperature, is the mechanical stress, is the irradiation dose rate, is the rate of electron-hole pair generation by thermal excitation, is the radiation ionization rate, is the carrier lifetime, is the room temperature band gap, is the temperature coefficient, is the Boltzmann constant, is the electron deposition depth distribution, is the dynamic recombination rate, is the electron concentration, is the hole concentration, is the electric field strength, is the trap density, is the electron capture rate, is the speed of thermal motion, To capture the cross section, is the electron release rate, To release the cross section, is the trap level.

[0112] It can be understood that the charge current density is related to the electric field, electron concentration and mobility as follows: . Mobility under multiple stresses will change, thus obtaining the dynamic charge transport equation ( is the absolute temperature, For mechanical stress, is the irradiation dose rate), reflecting that the charge transport driven by multi-stress electric field is subject to the multi-factor coupling law.

[0113] According to the Boltzmann distribution, the rate of electron-hole pairs generated by thermal excitation is , under thermal stress , will change, and the rate of electron-hole pairs generated by thermal excitation is obtained , which is an important source of charge generation, especially at high temperatures, it dominates charge generation. , is the irradiation dose rate, is the ionization efficiency, which is related to the irradiation type, energy and material interaction, and takes into account the electron deposition depth distribution , construct the irradiance generation term with depth variable , reflecting the charge generation distribution characteristics under irradiation. According to the dominant Shockley-Read-Hall recombination, the recombination rate ( is the electron lifetime, is the hole lifetime, Determined by the trap energy level, According to the Fermi level, is the intrinsic carrier concentration). Charge accumulation induces electric field, carrier concentration changes affect recombination, electric field promotes recombination, according to Poisson's equation ( is the dielectric constant) and the charge continuity equation Solve the dynamic compound rate by combining the above equations. , accurately describe the process of charge dynamic balance being disturbed by multiple factors. ( is the effective mass of the carriers), mechanical stress and irradiation will change and , the electric field will The variable promotes charge detrapping, thus establishing the dynamic equation of charge capture and release, which represents the evolution of the interaction between charge and trap with the environment.

[0114] In step S300, the electrostatic discharge characteristics are obtained according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and the mesoscopic parameters are obtained through a detailed description model of the charge behavior of the polyimide material to be tested. The correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested is constructed through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters.

[0115] In one embodiment, Figure 4 As shown, step S300 may include the following sub-steps:

[0116] In step S310, according to the charge accumulation characteristics of the polyimide material to be tested, the potential distribution, surface flashover and charging rate tests are performed on the surface of the polyimide material to be tested, so as to obtain the electrostatic discharge performance of the polyimide material under the synergistic action of multiple stresses; the electrostatic discharge performance includes potential distribution, surface flashover and charging rate.

[0117] It is understandable that based on the charge accumulation characteristics of the polyimide material to be tested, tests such as surface potential distribution, surface flashover, and charging rate of the polyimide material are carried out under the synergistic effects of different field strengths, different temperatures, different tensions, and different irradiation intensities. The changes in charging and discharging parameters such as surface potential, charging speed, breakdown threshold, discharge field strength, pulse width, and discharge energy are analyzed to obtain the evolution law of the electrostatic discharge performance of the polyimide material under the synergistic effect of multiple stresses.

[0118] In step S320, mesoscopic parameters of the polyimide material to be tested are obtained according to the charge behavior fine description model of the polyimide material to be tested; the mesoscopic parameters include activation energy, relaxation time, trap density, trap energy level, trap distribution and trap filling speed.

[0119] It is understandable that the trap level and trap density pass and , using surface potential decay method and atomic force microscopy technology to measure different depths z The dynamic data of charge capture and release at Distribution and With absolute temperature T ,electric field E Equi-stress variation relationship, such as inverse calculation of charge capture at multiple times under a specific stress combination , calculated based on the capture and release current changes, laying the foundation for subsequent parameter derivation, because traps are the key to charge accumulation, and their density energy levels determine the energy state of charge capture storage scale; activation energy is determined by middle, Related to the activation energy of the material, under thermal stress The change of contains activation energy information, which is determined by the different temperatures The slope of the experimental value fitting curve is obtained, and the relaxation time is obtained from the charge recombination dynamics R It can be deduced that according to different carrier concentrations n , p Lower compound rate R The experimental values ​​of , , which reflects the relaxation speed of charge from the excited state to the equilibrium state, helps to analyze the stability of charge dynamic equilibrium and the rhythm of accumulation and dissipation; the trap distribution and trap filling speed are combined and The solution is obtained.

[0120] In step S330, a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested under the synergistic effect of multiple stresses is established according to the charge accumulation characteristics, mesoscopic parameters and electrostatic discharge performance of the polyimide to be tested.

[0121] It is understandable that based on the refined description model of polyimide charge behavior, the evolution of mesoscopic parameters such as traps and charge mobility of the material is analyzed. Combined with the experiments on the generation, accumulation, migration characteristics and electrostatic discharge characteristics of polyimide surface charge and space charge under multi-stress synergy, the correlation between charge accumulation and discharge characteristics of polyimide under multi-stress synergy is established.

[0122] Furthermore, the correlation between the charge accumulation and discharge characteristics of the polyimide material to be tested under the synergistic effect of multiple stresses includes:

[0123] ;

[0124] in, is the breakdown field strength, is the charge accumulation density, is the conductivity, is the relative dielectric constant, is the activation energy, is the trap density, is the trap level, is the charge mobility, is the gas constant, T is the absolute temperature, , , , is the fitting parameter.

[0125] Understandably, , , , , , , , , , , are fitting parameters, obtained through data fitting, activation energy , trap density , trap level and charge mobility It is the key mesoscopic parameter. According to the Arrhenius formula, the thermal stimulation current experiment ( is the reaction rate constant, is the pre-exponential factor, is the gas constant, is the absolute temperature) is obtained by fitting; and Determined by combining thermal stimulation current and dielectric spectrum curves with HFWT-TSC-PEA experiment; Measured by the transit time algorithm and the electroacoustic pulse method, these mesoscopic parameters reflect the charge behavior characteristics and the mechanism of influence on accumulation and discharge at the microscopic level. , discharge energy and surface flashover voltage Characterize the discharge performance. It is the electric field strength threshold when the material breaks down; According to the discharge process current i(t) and voltage v(t) Points calculation ( , is the discharge start and end time); It is the critical voltage for flashover to occur along the surface of the material, and it directly reflects the material's ability to withstand and generate discharge under multiple stresses.

[0126] In step S400, the degradation trend of the insulation performance of the polyimide is obtained according to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of the charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics.

[0127] It should be noted that based on the evolution of the microscopic molecular structure and the correlation between charge accumulation and discharge characteristics, when the microscopic molecular structure changes, it will affect the distribution and characteristics of the charge trap, thereby changing the charge accumulation and discharge characteristics. As time goes by and the synergistic effect of multiple stresses continues, if the breakdown field strength gradually decreases, the discharge energy gradually increases, and the surface flashover voltage gradually decreases, these change trends can be combined to reflect the degradation trend of the insulation performance of the polyimide material. That is, by long-term monitoring of the changes in these parameters and combining them with the evolution of the microscopic molecular structure, the degradation trend of the polyimide material can be evaluated and predicted.

[0128] In one embodiment, Figure 5 As shown, step S400 may include the following sub-steps:

[0129] In step S410, the microscopic molecular structure of the polyimide material to be tested in a simulated deep space environment is obtained; the microscopic molecular structure of the polyimide material to be tested includes short-range structural information and long-range structural information.

[0130] Furthermore, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and nuclear magnetic resonance were used to obtain short-range structural information such as functional groups, energy level structure, and element valence state of polyimide materials;

[0131] Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy were used to obtain long-range structural information such as thermal enthalpy, specific heat, crystallization behavior, and radiation damage of polyimide materials.

[0132] It should be noted that Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) are used to study the short-range structural information of polyimide materials, such as functional groups, energy level structure, and element valence state. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to study the long-range structural information of polyimide materials, such as thermal enthalpy, specific heat, crystallization behavior, and radiation damage, in order to clarify the evolution of molecular structural characteristics of polyimide at different scales, such as Fig.13 shown.

[0133] In step S420, the degradation trend of the insulation performance of the polyimide is obtained according to the correlation between the microscopic molecular structure of the polyimide material to be tested and the charge accumulation and discharge characteristics of the polyimide material to be tested; the degradation trend of the insulation performance of the polyimide is:

[0134] ;

[0135] in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

[0136] It should be noted that the aging of dielectric materials is usually manifested in multiple levels, and the change law of characteristic parameters characterized by each level and the fault connection between each level are the key to revealing the performance degradation mechanism of dielectric materials. Therefore, according to the intrinsic connection between the microscopic molecular structure, mesoscopic trap energy state, and macroscopic electrostatic discharge characteristics of polyimide materials under the long-term synergistic action of multiple stresses, the contribution weight of the change of characteristic parameters at different levels under the single and synergistic action of multiple stresses to the degradation performance of dielectric materials is explained, revealing the degradation mechanism of the insulation performance of polyimide materials under the long-term synergistic action of multiple stresses. Schematic diagram of the research idea of ​​the degradation mechanism, as shown in Fig.14 shown.

[0137] Changes in the microscopic molecular structure can affect the trap properties. , if the content of a functional group in the molecular structure increases, resulting in an increase in the trap density, then ; If the change in molecular structure causes the trap energy level to increase, then ,in, is the initial trap level, is a parameter determined based on experimental data. It indicates the change of molecular structure relative to the initial state.

[0138] , , , , , , is the weight coefficient, which reflects the relative importance of each factor to the degradation trend; high charge accumulation, multiple traps and deep trap energy levels may reduce the breakdown field strength. As the breakdown field strength decreases, the degree of material degradation increases. At this time, the degradation trend is reflected through the second reaction in the degradation trend; high charge density, high mobility and low activation energy may increase the discharge energy. As the discharge energy increases, the degree of material degradation increases. At this time, the degradation trend is reflected through the third reaction in the degradation trend; high charge density, low conductivity and high dielectric constant may reduce the surface flashover voltage. As the surface flashover voltage decreases, the degree of material degradation increases. At this time, the degradation trend is reflected through the fourth reaction in the degradation trend.

[0139] Furthermore, in this exemplary embodiment, a polyimide degradation analysis system under the synergistic effect of multiple stresses is also provided. Fig.15 As shown in , the system may include:

[0140] The environmental simulation module is used to establish a simulated deep space environment and place the polyimide material to be tested in the simulated deep space environment, so as to obtain the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics.

[0141] The model building module is used to obtain the electron incident trajectory and the electron energy deposition distribution according to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, so as to obtain the electron deposition depth distribution. Through the electron deposition depth distribution and the charge accumulation characteristics, a fine description model of the charge behavior of the polyimide material to be tested in the simulated deep space environment is constructed. The fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation and an electron release rate equation.

[0142] The correlation construction module is used to obtain electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and to obtain mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and to construct a correlation relationship between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters.

[0143] The degradation analysis module is used to obtain the degradation trend of the insulation performance of polyimide according to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics; the degradation trend of the insulation performance of polyimide is:

[0144] ;

[0145] in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

[0146] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0147] It should be noted that although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the present disclosure, the features and functions of two or more modules or units described above can be concretized in one module or unit. Conversely, the features and functions of a module or unit described above can be further divided into multiple modules or units for concretization. The components displayed as modules or units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the disclosed solution. Those of ordinary skill in the art can understand and implement it without paying creative work.

[0148] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A method for analyzing polyimide degradation under the synergistic action of multiple stresses, characterized in that: include: Establishing a simulated deep space environment, placing the polyimide material to be tested in the simulated deep space environment, thereby obtaining the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics; According to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, the electron incident trajectory and the electron energy deposition distribution are obtained, so as to obtain the electron deposition depth distribution. Through the electron deposition depth distribution and the charge accumulation characteristics, a fine description model of the charge behavior of the polyimide material to be tested in the simulated deep space environment is constructed. The fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation and an electron release rate equation; the specific steps are: The charge properties and trap energy states of the polyimide material to be tested in a simulated deep space environment were obtained by using a high-field intensity, wide-temperature spectrum thermal stimulation current and space charge joint experiment. The electron incident trajectory and electron energy deposition distribution are obtained by Monte Carlo method, and the electron deposition depth distribution of the polyimide to be tested is obtained; According to the electron deposition depth distribution and charge accumulation characteristics of the polyimide to be tested, a detailed description model of the charge behavior of the polyimide material to be tested in a simulated deep space environment is constructed; Obtaining electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and obtaining mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters; According to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of the charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics, the degradation trend of the polyimide insulation performance is obtained; the specific steps are: Acquire the microscopic molecular structure of the polyimide material to be tested in a simulated deep space environment; the microscopic molecular structure of the polyimide material to be tested includes short-range structural information and long-range structural information; According to the correlation between the microscopic molecular structure of the polyimide material to be tested and the charge accumulation and discharge characteristics of the polyimide material to be tested, the degradation trend of the polyimide insulation performance is obtained; the degradation trend of the polyimide insulation performance is: ； in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

2. The method for analyzing polyimide degradation under the synergistic effect of multiple stresses according to claim 1, characterized in that: The step of establishing a simulated deep space environment and placing the polyimide material to be tested in the simulated deep space environment, thereby obtaining the charge accumulation characteristics of the polyimide material to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics, comprises: Establishing a simulated deep space environment with multiple stresses that are continuously adjustable and controllable, wherein the multiple stresses include temperature, field intensity, tension, electron energy and beam density; The surface potential, charge accumulation density, dissipation characteristics, surface flashover, conductivity, relative dielectric constant, charge mobility, surface trap characteristics and barrier energy level distribution of the polyimide to be tested under the action of multiple stresses alone and in combination are obtained.

3. The method for analyzing polyimide degradation under the synergistic effects of multiple stresses according to claim 1, characterized in that: The steps of obtaining electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in the simulated deep space environment, obtaining mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and constructing a correlation between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters include: According to the charge accumulation characteristics of the polyimide material to be tested, the potential distribution, surface flashover and charging rate tests are performed on the surface of the polyimide material to be tested, so as to obtain the electrostatic discharge performance of the polyimide material under the synergistic action of multiple stresses; the electrostatic discharge performance includes potential distribution, surface flashover and charging rate; According to the charge behavior fine description model of the polyimide material to be tested, the mesoscopic parameters of the polyimide material to be tested are obtained; the mesoscopic parameters include activation energy, relaxation time, trap density, trap energy level, trap distribution and trap filling speed; According to the charge accumulation characteristics, mesoscopic parameters and electrostatic discharge performance of the polyimide to be tested, the correlation between the charge accumulation characteristics and electrostatic discharge characteristics of the polyimide material to be tested under the synergistic action of multiple stresses is established.

4. The method for analyzing polyimide degradation under the synergistic effect of multiple stresses according to claim 2, characterized in that: The step of obtaining the surface potential, charge accumulation density, dissipation characteristics, surface flashover, conductivity, relative dielectric constant, charge mobility, surface trap characteristics and barrier energy level distribution of the polyimide to be tested under the action of multiple stresses alone and in combination comprises: Under the action of multiple stresses individually and in combination, the surface potential is collected through the polyimide material to be tested, and the charge accumulation density, dissipation characteristics and surface flashover are analyzed. Under the action of multiple stresses individually and in combination, the conductivity, relative dielectric constant and charge mobility are obtained through the first formula, the second formula and the third formula; the first formula is: ;in, is the initial conductivity, is the correction factor, is the free charge density, is the charge trapping probability, is the charge trapping probability, is the electron charge, is the trap density, is the action time; the second formula is: ;in, is the capacitance, is the dielectric constant, is the plate area, is the electrostatic force constant, is the plate spacing; the third formula is: ;in, is the corresponding voltage at the current time, is the initial charge, is the charge mobility, is the electric field strength, is the carrier lifetime, L is the thickness of the polyimide material to be measured, is the capacitance, is the current time, For the crossing time; Under the action of multiple stresses individually and in combination, the surface trap characteristics and barrier energy level distribution of the polyimide material to be tested were obtained through surface potential decay method and atomic force microscopy technology.

5. The method for analyzing polyimide degradation under the synergistic effects of multiple stresses according to claim 1, characterized in that: The detailed description model of the charge behavior of the polyimide material to be tested includes: ； in, , ; is the charge current density, is the electron charge, is the electron concentration, is the charge mobility, is the electric field strength, is the absolute temperature, is the mechanical stress, is the irradiation dose rate, is the rate of electron-hole pair generation by thermal excitation, is the irradiation ionization rate, is the carrier lifetime, is the room temperature band gap, is the temperature coefficient, is the Boltzmann constant, is the electron deposition depth distribution, is the dynamic recombination rate, is the electron concentration, is the hole concentration, is the electric field strength, is the trap density, is the electron capture rate, is the speed of thermal motion, To capture the cross section, is the electron release rate, To release the cross section, is the trap level.

6. The method for analyzing polyimide degradation under the synergistic effects of multiple stresses according to claim 3, characterized in that: The correlation between the charge accumulation and discharge characteristics of the polyimide material to be tested under the synergistic action of multiple stresses includes: ； in, is the breakdown field strength, is the charge accumulation density, is the conductivity, is the relative dielectric constant, is the activation energy, is the trap density, is the trap level, is the charge mobility, is the gas constant, T is the absolute temperature, , , , is the fitting parameter.

7. The method for analyzing polyimide degradation under the synergistic effects of multiple stresses according to claim 1, characterized in that: The step of obtaining the microscopic molecular structure of the polyimide material to be tested under the simulated deep space environment, wherein the microscopic molecular structure of the polyimide material to be tested includes short-range structural information and long-range structural information, comprises: Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and nuclear magnetic resonance were used to obtain the functional groups, energy level structure and element valence state short-range structural information of polyimide materials; Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy were used to obtain the thermal enthalpy, specific heat, crystallization behavior and radiation damage remote structural information of polyimide materials.

8. A polyimide degradation analysis system under the synergistic action of multiple stresses, characterized in that: The system is used to execute the method according to any one of claims 1 to 7, and the system comprises: An environmental simulation module is used to establish a simulated deep space environment, and place the polyimide material to be tested in the simulated deep space environment, so as to obtain the charge accumulation characteristics of the polyimide to be tested in the simulated deep space environment, wherein the charge accumulation characteristics include surface charge characteristics and space charge characteristics; A model building module is used to obtain the electron incident trajectory and the electron energy deposition distribution according to the trap energy state distribution characteristics of the polyimide material to be tested in the simulated deep space environment, so as to obtain the electron deposition depth distribution, and to construct a charge behavior fine description model of the polyimide material to be tested in the simulated deep space environment through the electron deposition depth distribution and the charge accumulation characteristics, wherein the fine description model includes: an electron concentration change rate equation, a charge current density equation, a hole concentration change rate equation, an electron capture rate equation, and an electron release rate equation; A correlation construction module is used to obtain electrostatic discharge characteristics according to the charge accumulation characteristics of the polyimide material to be tested in a simulated deep space environment, and to obtain mesoscopic parameters through a fine description model of the charge behavior of the polyimide material to be tested, and to construct a correlation relationship between the charge accumulation characteristics and the electrostatic discharge characteristics of the polyimide material to be tested through the charge accumulation characteristics, the electrostatic discharge characteristics and the mesoscopic parameters; The degradation analysis module is used to obtain the degradation trend of the insulation performance of polyimide according to the microscopic molecular structure of the polyimide material to be tested in the simulated deep space environment, the fine description model of charge behavior, and the correlation between the charge accumulation characteristics and the electrostatic discharge characteristics; the degradation trend of the insulation performance of polyimide is: ； in, is the initial degradation degree, is the proportionality constant, is the weight coefficient, is the charge accumulation density, is the initial value of charge accumulation density, is the trap density, is the initial value of trap density, is the trap level, is the initial value of the trap level, is the charge mobility, is the initial value of charge mobility, is the activation energy, is the initial value of activation energy, is the conductivity, is the initial value of conductivity, is the relative dielectric constant, is the initial value of relative dielectric constant, is the breakdown field strength, is the discharge energy, is the initial value of discharge energy, is the surface flashover voltage.

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