A comprehensive evaluation method and system for the anti-internal charging performance of a medium

Abstract

The present invention belongs to the technical field of analysis of the deep charge and discharge characteristics of insulating dielectrics under electron radiation, and discloses a comprehensive evaluation method for the anti-intracavity charging performance of dielectrics based on a combination of simulation calculations and experimental measurements. The comprehensive evaluation method for the anti-intracavity charging performance of dielectrics provided by the present invention provides a favorable test scheme and evaluation means for the research on the deep charge and discharge of dielectrics under electron radiation and the research on the improvement of the anti-intracavity charging performance of dielectrics. It solves the problem of low credibility in current research relying solely on theoretical simulation calculations, provides an intuitive and feasible comparison and evaluation scheme for the anti-intracavity charging performance of dielectrics, selects eight key factors that can reflect the anti-intracavity charging performance of dielectrics to intuitively judge its anti-intracavity charging performance, and can be compared and verified with the results of simulation calculations, greatly improving the accuracy of the evaluation results. Moreover, the theoretical model can be corrected and improved according to specific experimental results, and the accuracy of the theoretical calculation results can be further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of research on the deep charging and discharging characteristics of insulating dielectrics under electron radiation, and particularly relates to a comprehensive evaluation method for the anti-intra-charging performance of dielectrics based on the combination of simulation calculation and experimental measurement. Background Art

[0002] At present, in the space environment, the interaction between high-energy particles and spacecraft will induce various abnormal phenomena, among which the deep charging and discharging phenomenon of dielectrics under the action of high-energy electrons is the most serious. Deep charging and discharging of dielectrics, also known as intra-charging of dielectrics, refers to high-energy electrons (0.1 - 10 MeV) penetrating the shielding layer and the dielectric surface of a spacecraft and depositing inside the dielectric. Due to the extremely low conductivity of the dielectric material, the charge release rate is much smaller than the charge deposition rate, so the deposited charges accumulate continuously inside the dielectric, resulting in local electric field concentration. When the electric field generated by the deposited charges exceeds the breakdown threshold of the material, electrostatic discharge will occur. Deep charging and discharging of dielectrics will cause deterioration of the dielectric material properties, and at the same time, the electromagnetic pulse generated during the discharge process will cause abnormal operation of spacecraft electronic equipment, seriously affecting the safe operation of spacecraft.

[0003] From the perspective of materials, studying the deep charging and discharging mechanism and key influencing factors of dielectrics under electron radiation, so as to improve the performance of dielectric materials and enhance their anti-deep charging and discharging performance is a current research hotspot.

[0004] However, current research mainly focuses on the research of the charge transport mechanism of dielectrics under electron radiation (theoretical model research) and the simulation calculation of deep charging and discharging of dielectrics (simulation calculation research), lacking a targeted and effective test and evaluation method for the deep charging and discharging performance of dielectrics.

[0005] Currently, for verifying the anti-deep charging and discharging performance of dielectric materials after modification, the simulation calculation method is mostly used for comparative verification (mainly comparing the amplitude of the internal electric field of the dielectric under the same radiation conditions); and the experimental tests mainly focus on parameters such as the conductivity, permittivity, and electrical strength of the samples, lacking the comparative test of the charging and discharging performance of dielectric materials under real electron radiation conditions. The current method cannot intuitively reflect the anti-deep charging and discharging performance of dielectrics before and after modification, and there is an urgent need to construct a corresponding experimental test and performance comprehensive evaluation scheme.

[0006] Through the above analysis, the problems and defects existing in the prior art are as follows:

[0007] (1) Most of the prior art conducts research from the perspective of simulation calculation or side experimental verification, lacking targeted experimental verification of the anti-intra-charging performance of dielectric materials under real electron radiation conditions.

[0008] (2) The prior art lacks a targeted and effective experimental test scheme for deep charging and discharging of dielectrics and an evaluation method for anti-intra-charging performance. Summary of the Invention

[0009] Aiming at the problems existing in the prior art, the present invention provides a technology applicable to the research field of deep charging and discharging characteristics of insulating dielectrics under electron radiation, and particularly relates to a comprehensive evaluation method for the anti-intra-charging performance of dielectrics based on the combination of simulation calculation and experimental measurement.

[0010] The present invention is implemented as follows. A method for evaluating the deep charging and discharging performance of a dielectric includes: simulating the internal electric field simulation calculation of the dielectric under electron radiation, and testing the deep charging and discharging performance of the dielectric under electron radiation; using Geant4 to simulate the electron radiation process, using COMSOL to calculate the charge transport process, and then performing the electrostatic discharge test of the specimen under real electron radiation; determining the charge distribution and the internal electric field distribution in the dielectric, recording the electrostatic discharge waveform and experimental data of the dielectric, and determining the evaluation index.

[0011] Further, the method for evaluating the deep charging and discharging performance of a dielectric includes the following steps:

[0012] Step 1, simulating the internal electric field of the dielectric based on the dielectric parameters of the dielectric material;

[0013] Step 2, testing and analyzing the deep charging and discharging performance of the dielectric under electron radiation experiments;

[0014] Step 3, comprehensively evaluating the deep charging and discharging performance of the dielectric under electron radiation.

[0015] Further, the simulation calculation of the internal electric field of the dielectric based on the dielectric parameters of the dielectric material in Step 1 includes:

[0016] (1) Experimentally measuring parameters such as the density ρ, intrinsic conductivity δ0, high-field conductivity δ, radiation-induced conductivity δ, dielectric constant ε, and breakdown field strength E of each specimen; E and radiation-induced conductivity δ RIC of each specimen; b and other parameters;

[0017] (2) Using the open-source Monte Carlo simulation software Geant4 to simulate the electron radiation process of the dielectric material under a set space radiation environment; programming and constructing a three-dimensional simulation model corresponding to the specimen according to the specimen material properties and three-dimensional dimensions in Geant4, and dividing it into small volume elements for detecting the electrons and energy deposited during the radiation process; setting the initial energy of the incident electrons and the number of simulated incident electrons to 3×10 6 pieces, and in Geant4, the total charge deposition number E n and energy deposition E g in each volume element are counted through the functions G4PSCellCharge3D and G4PSEnergyDeposit3D.

[0018] Next, the counted number of charge depositions E n and the energy deposition E g need to be converted into the charge deposition rate ρ d and the dose rate

[0019] The conversion method is as follows:

[0020] When the number of incident electrons is N; the incident electron beam current density is J0, A / m 2 ; the electron source area is A0, m 2 ; then the virtual radiation time T is:

[0021]

[0022] where, e q is the electron charge, set to 1.6×10 -19 C; the corresponding charge deposition rate in the medium under the actual beam current is:

[0023]

[0024] The dose rate in the medium is:

[0025]

[0026] (3) Through step (2), the charge deposition rate ρ d and the dose rate at each position inside the sample under the set electron radiation conditions can be obtained. Next, the finite element method is used to calculate the charge distribution and electric field strength distribution inside the medium at different irradiation times.

[0027] The charge transport equations inside the medium are as follows:

[0028]

[0029] The charge transport equations are, from top to bottom, the Poisson equation, the current continuity equation, and Ohm's law; where, E is the electric field strength, with the unit V / m; ρ s is the net charge density in the medium, with the unit C / m 3 ; ε is the dielectric constant of the medium, with the unit F / m; J is the net current density, with the unit A / m 2 ; ρd is the charge deposition rate in the medium, with the unit C / m 3 ·s, which is the calculation result obtained by the radiation simulation program developed based on Geant4 in step (2); δ E is the conductivity related to the electric field, with the unit S / m, which is the test measurement value in step (1).

[0030] (4) Calculate and solve

[0031] Export the charge deposition rate and dose rate at each position in the sample obtained in step (2) to a.txt file, and then import it into COMSOL using the interpolation method; set the grounding condition and working voltage according to the actual working condition of the sample, then set the radiation time, and select the MUMPS type solver based on LU decomposition to perform the solution calculation to obtain the internal charge and electric field distribution of the sample within the set radiation time under the actual working condition.

[0032] Obtain two key quantities, the maximum internal charge density and the maximum internal electric field strength, by calculating and comparing the charge distribution and internal electric field distribution of each sample under the same radiation conditions; among them, the same radiation conditions refer to the same electron energy, beam current, and radiation time during the radiation test; the greater the maximum internal charge density in the medium, the more serious the charge accumulation in the medium and the easier it is to trigger dielectric electrostatic discharge; the greater the maximum internal electric field strength, the easier it is to exceed the breakdown threshold of the dielectric material and trigger electrostatic discharge; through simulation calculation, a preliminary determination of the anti-internal charging performance of each sample can be made.

[0033] Furthermore, use the finite element analysis software COMSOL to solve the charge transport equations, including:

[0034] 1) Establish a three-dimensional model of the sample in COMSOL and import the corresponding material parameters;

[0035] 2) Construct the charge transport equations in step (3) in COMSOL; select the partial differential equation interface in the mathematics module to customize the equations to be solved; select the partial differential equation and modify the coefficients of the partial differential equation and the Poisson equation respectively according to the charge transport model equations in step (3).

[0036] The structure of the partial differential equation is as follows:

[0037]

[0038]

[0039] 3) Set the boundary conditions and divide the mesh in COMSOL; analyze the specific working conditions of the sample, including factors such as the grounding state, grounding position of the sample, and the amplitude and application position of the working voltage. The working conditions of the sample correspond to the initial state and boundary conditions of the partial differential equation system; in COMSOL, various initial states are set by modifying the initial conditions of the custom equation and adding Dirichlet boundary conditions; the mesh division uses automatic free tetrahedral mesh division.

[0040] Further, the dielectric deep charging and discharging performance test and analysis based on electron radiation test in step two include:

[0041] (1) Pretreat the specimen and the specimen platform: Ultrasonically clean the specimen and the specimen platform with anhydrous ethanol and deionized water. After cleaning, wrap them with aluminum foil, connect the grounding wire, and place them in a vacuum drying oven at 90°C for 2 hours.

[0042] (2) Design a shielding disk and specimen disk matching scheme according to the test requirements to form a test flow chart.

[0043] (3) Place the specimen on the corresponding area of the specimen disk according to the specimen placement method designed in step (2). Cover the bottom surface of each specimen relative to the radiation surface with copper tape and connect it to the lead wire at the specimen boss. The other end of each lead wire is grounded through a 50-ohm resistor, and the far-end of the 50-ohm resistor is led out and connected to an oscilloscope. When the input interface of the oscilloscope is insufficient, multiple oscilloscopes are used for simultaneous testing. After the circuit connection is completed, use a multimeter to check whether the test circuit connection is correct.

[0044] (4) After the specimen is placed and the test circuit is checked to be correct, close the vacuum test tank, turn on the vacuum pump to pump vacuum until the vacuum degree of the vacuum test tank is <5×10 -4 Pa.

[0045] (5) Conduct the test according to the designed test flow chart, and use the oscilloscope to record and collect the discharge waveform data of the corresponding specimen.

[0046] (6) Test data analysis scheme: Collect and record all the electrostatic discharge waveforms of the specimen under electron radiation through the oscilloscope, and select the number of electrostatic discharges, discharge waveforms, peak discharge current, average discharge current, peak single discharge charge amount, and total discharge charge amount as indicators to evaluate the anti-deep charging and discharging performance of the specimen.

[0047] Further, the comprehensive evaluation of the dielectric deep charging and discharging performance under electron radiation in step three includes:

[0048] Obtain the maximum value of the internal charge density and the maximum value of the internal electric field strength of the dielectric inside each specimen under the same radiation conditions through the dielectric internal electric field simulation calculation process based on the dielectric parameters of the dielectric material; record and extract the number of electrostatic discharges, discharge waveforms, peak discharge current, average discharge current, peak single discharge charge amount, and total discharge charge amount of each specimen under the same radiation conditions through the radiation test.

[0049] Another object of the present invention is to provide a dielectric deep charging and discharging performance evaluation system applying the dielectric deep charging and discharging performance evaluation method described above. The dielectric deep charging and discharging performance evaluation system includes:

[0050] The electron gun, as the radiation source for electron radiation tests, is located in the vacuum chamber; the vacuum degree of the vacuum chamber is pumped down to a vacuum degree < 5×10 -4 Pa, and then the electron gun is turned on; during the test, different incident electron energies and electron beam currents are set according to the incident electron energy and beam current range to be measured and the parameters of the electron gun.

[0051] The vacuum test chamber. Electron radiation tests are used to simulate the interaction process between high-energy electrons and dielectric materials in a space environment. The electron gun and the specimen platform are placed in the vacuum test chamber, and a vacuum environment is pumped by a vacuum pump for test measurements.

[0052] The vacuum pump is used to pump the vacuum for the vacuum test chamber to create a vacuum environment.

[0053] The oscilloscope is used to monitor and record the discharge pulse signals during the deep charging and discharging process of the dielectric specimen under electron irradiation.

[0054] The specimen platform is used to place the specimen to be tested. It consists of a rotatable shielding disk at the upper end and a non-rotatable specimen disk. Both the shielding disk and the specimen disk are evenly divided into 12 regions. The shielding disk is marked as D1 - D12, and the specimen disk is marked as Y1 - Y12. The regions of the upper and lower disks correspond one by one; among them, D1 - D12 are removable shielding blocks. When the corresponding shielding block is removed, the specimen below can be directly irradiated, and when the shielding block is inserted, the corresponding specimen is shielded and not irradiated; among them, when D1, D3, and D5 are removed from the shielding disk, the specimens Y1, Y3, and Y5 on the corresponding specimen disk are irradiated, and the rest of the samples are shielded; and the shielding disk can be driven by a stepping motor to rotate clockwise or counterclockwise, and the rotation angle for each movement is 30°; through the mutual cooperation of the shielding disk and the specimen disk, different types of specimens can be simultaneously tested under different radiation conditions, and up to 12 samples can be tested at one time.

[0055] The discharge signal lead wire leads out from the vacuum chamber and connects to the bottom of the specimen and the oscilloscope. It is the transmission line for the specimen discharge signal; the transmission line is a multi-core shielded cable. A total of 12 branch lines are respectively led out to the vicinity of the 12 raised specimen platforms on the specimen disk. The bottom surface of the specimen to be tested is firmly bonded to the corresponding lead wire with copper tape; the other end of each lead wire is grounded through a 50-ohm resistor, and is led out and connected to the oscilloscope at the far end of the 50-ohm resistor. When the input interface of the oscilloscope is insufficient, multiple oscilloscopes are used to simultaneously test and store the electrostatic discharge data and waveforms of each specimen.

[0056] The specimen platform grounding terminal is used for the discharge signal lead wire to be grounded and to shield interference signals at the same time.

[0057] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by the present invention are:

[0058] The present invention proposes a complete set of methods for testing and comprehensive evaluation of the anti-intra-charging performance of dielectrics applicable to the research on the regulation of the anti-intra-charging performance of dielectrics under electron radiation by combining theoretical simulation calculations and radiation test measurements. It can provide feasible test means and comprehensive evaluation schemes for the in-depth charge-discharge research of dielectrics under electron radiation, and the accuracy of the evaluation results can be greatly improved through the mutual verification of the simulation calculation results and the radiation test measurement results.

[0059] Based on the in-depth charge-discharge test and analysis scheme of dielectrics under electron radiation, the present invention mainly uses real electron radiation tests to intuitively measure and compare the anti-intra-charging performance of specimens before and after modification, so as to verify and judge the advantages and disadvantages of the modification effect. This provides an intuitive and feasible measurement method and judgment basis for the research on improving the anti-intra-charging performance of dielectrics under electron radiation. The present invention combines the in-depth electric field simulation calculation scheme of dielectrics based on material dielectric parameters and the in-depth charge-discharge test and analysis scheme of dielectrics under electron radiation to construct a comprehensive evaluation scheme for the anti-intra-charging performance of dielectrics under electron radiation. The present invention can evaluate and analyze the anti-intra-charging performance of dielectrics from two perspectives: theoretical simulation calculation and real electron radiation test.

[0060] The present invention proposes a feasible comprehensive evaluation scheme for the anti-intra-charging performance of dielectrics under electron radiation by combining theoretical simulation calculations and real radiation test measurements. Eight key indicators related to the anti-intra-charging performance of dielectrics under electron radiation are selected, and the anti-intra-charging performance of dielectrics is comprehensively evaluated from two aspects: theoretical calculation and test measurement. This is lacking in current research, and the simulation calculation results and real electron radiation test measurement results of this scheme are not only complementary to each other but also can be mutually verified, greatly improving the accuracy of the evaluation results.

[0061] The comprehensive evaluation method for the anti-intra-charging performance of dielectrics of the present invention provides a favorable test scheme and evaluation means for the in-depth charge-discharge research of dielectrics under electron radiation and the improvement research of the anti-intra-charging performance of dielectrics. It solves the problem of low credibility in current research relying only on theoretical simulation calculations, provides an intuitive and feasible comparison and evaluation scheme for the anti-intra-charging performance of dielectrics, and selects eight key factors that can reflect the anti-intra-charging performance of dielectrics to intuitively judge its anti-intra-charging performance, and can be compared and verified with the simulation calculation results, greatly improving the accuracy of the evaluation results. Moreover, the theoretical model can be corrected and improved according to specific test results, and the accuracy of the theoretical calculation results can be further improved.

[0062] The technical solution of the present invention fills the technical gaps at home and abroad: the present invention solves the problem of the lack of test measurement schemes in the current research on deep charge and discharge of dielectrics. Through a large number of test measurement studies, this patent proposes a feasible and intuitive method for measuring and evaluating the anti-intra-charging performance of dielectrics by combining theoretical calculations and test measurements. Based on the traditional calculation of the internal electric field of dielectrics, this method designs an internal charging test device and scheme for dielectrics, and selects eight key parameters related to the anti-intra-charging performance of dielectrics to comprehensively compare and evaluate the anti-intra-charging performance of dielectrics. This is a research lacking in China at present and has a certain degree of advancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0064] Figure 1 is the flowchart of the method for evaluating the deep charge and discharge performance of dielectrics provided by the embodiments of the present invention;

[0065] Figure 2 is the schematic diagram of the method for evaluating the deep charge and discharge performance of dielectrics provided by the embodiments of the present invention;

[0066] Figure 3 is the structural diagram of the deep charge and discharge test device for dielectric materials under sub-radiation provided by the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0067] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0068] In view of the problems existing in the prior art, the present invention provides a comprehensive evaluation method for the anti-intra-charging performance of dielectrics based on the combination of simulation calculation and test measurement.

[0069] The present invention provides a comprehensive evaluation method for the anti-intra-charging performance of dielectrics based on the combination of simulation calculation and test measurement. The following describes the present invention in detail with reference to the drawings.

[0070] In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands and explains the technical solutions of the claims.

[0071] As Figure 1 shown, the method for evaluating the deep charge and discharge performance of dielectrics provided by the embodiments of the present invention includes the following steps:

[0072] S101, Simulation calculation of the internal electric field in the dielectric based on the dielectric parameters of the dielectric material;

[0073] S102, Performance test and analysis of deep charging and discharging of the dielectric under electron radiation test;

[0074] S103, Comprehensive evaluation of the deep charging and discharging performance of the dielectric under electron radiation.

[0075] The method for evaluating the deep charging and discharging performance of the dielectric provided by the embodiment of the present invention consists of two parts. One is the simulation calculation scheme of the internal electric field in the dielectric based on the dielectric parameter test of the dielectric, and the other is the performance test and analysis scheme of the deep charging and discharging of the dielectric under electron radiation test. Then, a comprehensive evaluation scheme is constructed by comprehensively analyzing the two.

[0076] I. Simulation calculation scheme of the internal electric field in the dielectric based on the dielectric parameters of the dielectric material

[0077] Step 1: Experimentally measure the density (ρ), intrinsic conductivity (δ0), strong-field conductivity (δ E ), radiation-induced conductivity (δ RIC ), dielectric constant (ε), breakdown field strength (E b ) and other parameters of each specimen.

[0078] Step 2: Use the open-source Monte Carlo simulation software Geant4 to simulate the electron radiation process of the dielectric material in the set space environment. First, according to the specimen material properties and three-dimensional dimensions, construct a three-dimensional simulation model corresponding to the specimen and divide it into small volume elements for detecting the electrons and energy deposited during the radiation process. Then, set the initial energy of the incident electrons and the number of incident electrons to be simulated (set to 3×10 6 in this scheme). In Geant4, the total charge deposition number E n and energy deposition E g in each volume element are statistically obtained through the functions G4PSCellCharge3D and G4PSEnergyDeposit3D.

[0079] Next, the statistically obtained charge deposition number E n and energy deposition E g need to be converted into the charge deposition rate ρ d and dose rate

[0080] The conversion method is as follows:

[0081] Assume that the number of incident electrons is N; the incident electron beam current density is J0, A / m 2 , and the electron source area is A0, m 2 ; then the virtual radiation time T is:

[0082]

[0083] where e q is the elementary charge of an electron (1.6×10 -19 C), and the corresponding charge deposition rate in the medium under the actual beam current is:

[0084]

[0085] The dose rate in the medium is:

[0086]

[0087] Step 3:

[0088] By simulating the electron radiation process of the specimen in Step 2, the charge deposition rate (ρ d ) and dose rate at each position inside the specimen under the set radiation conditions can be obtained. Next, the finite element method is used to calculate the charge distribution and electric field strength distribution inside the medium under electron radiation. The charge transport equations inside the medium are as follows:

[0089]

[0090] From top to bottom, this set of equations is the Poisson equation, the current continuity equation, and Ohm's law. Among them, E is the electric field strength, V / m (quantity to be solved); ρ s is the net charge density in the medium, C / m 3 , (quantity to be solved); ε is the dielectric constant of the medium, F / m, (using the test results in Step 1); J is the net current density, A / m 2 , (quantity to be solved); ρ d is the charge deposition rate in the medium, C / m 3 ·s, (using the calculation results of the radiation simulation program developed based on Geant4 in Step 2); δ E is the conductivity related to the electric field, S / m, (using the calculation test results in Step 1).

[0091] The solution of this part of the charge transport equations needs to be solved using the finite element method. Relevant programs can be written in MATLAB, or mature commercial finite element analysis software such as COMSOL or Ansys can be used for solving: In this solution, COMSOL 5.6 is selected to solve this set of charge transport equations:

[0092] Specifically as follows:

[0093] (1) Establish a three-dimensional model of the specimen in COMSOL and import the corresponding material parameters.

[0094] (2) Construct the charge transport equations in step 3 in COMSOL.

[0095] Instead of using the built-in modules in COMSOL to calculate the electric field, this solution selects the partial differential equation interface in the mathematics module to customize the equations to be solved. In this example, the general form of the partial differential equation is selected, and its specific structure is as follows:

[0096]

[0097]

[0098] Just modify the coefficients of this partial differential equation according to the charge transport model equations in step 3 respectively, and the Poisson equation can also be rewritten from this equation.

[0099] (3) Set the boundary conditions and divide the mesh in COMSOL

[0100] In the simulation calculation process of this example, the specific working conditions of the specimen also need to be considered, mainly including factors such as the grounding state of the specimen, the grounding position, the amplitude of the working voltage, and the application position, etc. These correspond to the initial state and boundary conditions of the partial differential equation system. In COMSOL, various initial states can be set by modifying the initial conditions of the custom equation and adding Dirichlet boundary conditions. The mesh division adopts automatic division of free tetrahedral meshes.

[0101] (4) Calculate and solve

[0102] Export the two key parameters, the charge deposition rate and the dose rate, at each position in the specimen obtained in step 2 to a.txt file, and then import them into COMSOL by interpolation. Then set the grounding conditions and the working voltage according to the actual working conditions of the specimen, and then set the radiation time. Select the MUMPS type solver based on LU decomposition for the solution calculation. Finally, the internal charge and electric field distribution of the specimen within the set radiation time under the actual working conditions can be obtained.

[0103] By calculating and comparing the charge distribution and the internal electric field distribution of each specimen under the same radiation conditions (the same radiation conditions refer to the same electron energy, beam current, and radiation time during the radiation test), the two key quantities, the maximum value of the internal charge density of the dielectric and the maximum value of the internal electric field strength, can be obtained. Among them, the larger the maximum value of the internal charge density of the dielectric, the more serious the charge accumulation inside the dielectric, and the easier it is to trigger dielectric electrostatic discharge; the larger the maximum value of the internal electric field strength, the easier it is to exceed the breakdown threshold of the dielectric material and thus trigger electrostatic discharge. Therefore, through the simulation calculation method, a preliminary judgment of the anti-internal charging performance of each specimen can be made.

[0104] II. Test and Analysis Scheme for the Internal Charging Resistance Performance of Dielectrics Based on Real Electron Radiation Tests

[0105] This part mainly uses real electron radiation tests to compare the internal charging resistance performance of specimens before and after modification, so as to verify and evaluate the quality of the modification effect. Thus, it provides a feasible evaluation method and judgment basis for the research on improving the internal charging resistance performance of dielectrics under electron radiation.

[0106] Test Scheme for the Internal Charging Resistance Performance of Dielectrics under Electron Radiation

[0107] The structural diagram of the test device for the internal charging resistance performance of dielectric materials under electron radiation is as Figure 3 shown.

[0108] The test system includes:[[]]

[0109] 1. Electron gun

[0110] As the radiation source for electron radiation tests, it is located in the vacuum chamber. The vacuum chamber needs to be pumped down to the required vacuum degree (generally required to be less than a vacuum degree better than 5×10 -4 Pa) before the electron gun can be turned on. During the test, different incident electron energies and electron beam currents are set according to the test requirements (the range of incident electron energies and beam currents that can be tested is determined by the parameters of the electron gun).

[0111] 2. Vacuum test chamber

[0112] Electron radiation tests are mainly used to simulate the interaction process between high-energy electrons and dielectric materials in the space environment. Therefore, the general test environment needs to be a vacuum environment. This requires the use of a vacuum test chamber. The electron gun, specimen platform, etc. are placed in the vacuum chamber, and a vacuum environment is pumped through a vacuum pump for test measurement.

[0113] 3. Vacuum pump

[0114] It is mainly used to pump the vacuum test chamber to create a vacuum environment. The vacuum degree in the vacuum chamber of this test needs to be <5×10 -4 Pa.

[0115] 4. Oscilloscope

[0116] It is used to monitor and record the discharge pulse signals during the deep charging and discharging process of dielectric specimens under electron irradiation.

[0117] 5. Specimen platform

[0118] It is used to place the test specimens, which mainly consists of a rotatable shielding disk at the upper end and a non-rotatable specimen disk. Both the shielding disk and the specimen disk are evenly divided into 12 regions. The shielding disk is marked as D1 - D12, and the specimen disk is marked as Y1 - Y12. The regions of the upper and lower disks correspond to each other one by one. Among them, D1 - D12 are removable shielding blocks. When the corresponding shielding block is removed, the specimen below can be directly irradiated. When the shielding block is inserted, the corresponding specimen is shielded and not irradiated. For example, if D1, D3, and D5 are removed from the shielding disk, the specimens Y1, Y3, and Y5 on the corresponding specimen disk are irradiated, and the rest of the samples are shielded. Moreover, the shielding disk can be driven by a stepping motor to rotate clockwise or counterclockwise, and the rotation angle for each movement is 30°. Through the mutual cooperation of the shielding disk and the specimen disk, different types of specimens can be tested simultaneously under different radiation conditions, greatly improving the test efficiency. Up to 12 samples can be tested at one time.

[0119] 6. Discharge signal lead wire

[0120] It is led out from the vacuum chamber and connected to the bottom of the specimen and the oscilloscope, and is the transmission line of the specimen discharge signal. The transmission line is a multi-core shielded cable. A total of 12 branch lines are respectively led to near the 12 protruding specimen platforms of the specimen disk. The bottom surface of the test specimen is firmly bonded to the corresponding lead wire with copper tape. The other end of each lead wire is grounded through a 50-ohm resistor, and is led to the oscilloscope at the far end of the 50-ohm resistor. When the input interface of the oscilloscope is insufficient, multiple oscilloscopes can be used to test and store the electrostatic discharge data and waveforms of each specimen simultaneously.

[0121] 7. Specimen platform grounding terminal

[0122] It is used for grounding the discharge signal lead wire and shielding interference signals at the same time.

[0123] Test steps:

[0124] Step 1: To ensure the accuracy of the test results, the specimens and the specimen platforms need to be pretreated: First, the specimens and the specimen platforms are ultrasonically oscillated and cleaned with anhydrous ethanol and deionized water. After cleaning, they are wrapped with aluminum foil and connected to the ground wire and placed in a vacuum drying oven at a temperature of 90 °C for 2 hours (the main purpose is to ensure that the specimens are dry, clean and have no residual charge).

[0125] Step 2: Design the cooperation scheme of the shielding disk and the specimen disk according to the test requirements to form a test flow chart.

[0126] Step 3: Place the specimens on the corresponding areas of the specimen tray according to the specimen placement method designed in Step 2. The bottom surface of each specimen (relative to the radiation surface) needs to be covered with copper tape and connected to the lead wire at the boss of the specimen. The other end of each lead wire is grounded through a 50-ohm resistor, and the far-end of the 50-ohm resistor is led out and connected to an oscilloscope. When the input interface of the oscilloscope is insufficient, multiple oscilloscopes can be used for simultaneous testing. After the circuit connection is completed, use a multimeter to check whether the test circuit connection is correct.

[0127] Step 4: After the specimens are placed and the test circuit is checked to be correct, close the vacuum test chamber, turn on the vacuum pump to pump vacuum until the vacuum degree of the vacuum test chamber < 5×10 -4 Pa.

[0128] Step 5: Conduct tests according to the designed test flow chart, and use an oscilloscope to record and collect the discharge waveform data of the corresponding specimens.

[0129] Test data analysis plan: All the electrostatic discharge waveforms of the specimens under electron radiation can be collected and recorded by an oscilloscope. This plan mainly selects the following several indicators to evaluate the anti-internal charging performance of the specimens.

[0130] Record the following indicators of the specimens under the same radiation conditions (the same radiation conditions mean that the electron energy, beam current, and radiation time during the radiation test are the same):

[0131] 1. The number of electrostatic discharges;

[0132] 2. Discharge waveforms;

[0133] 3. Peak discharge current;

[0134] 4. Average discharge current;

[0135] 5. Peak value of the charge quantity per single discharge;

[0136] 6. Total discharge charge.

[0137] Among them, under the same radiation conditions, the incident electron energy, beam current, and radiation time are the same, and it can be considered that the number of electrons interacting with each specimen is the same, that is, the total number of incident electrons is the same.

[0138] (1) The number of electrostatic discharges most intuitively reflects the anti-deep charging and discharging performance of the specimens. The more the number of discharges, the more serious the electric field concentration inside the dielectric, the charges are released in the form of local breakdown, forming more discharge pulses, and the greater the impact on the electronic equipment of aerospace equipment;

[0139] (2) The discharge waveform also intuitively reflects the characteristics of the discharge. The internal charges in the dielectric can be determined to be released mildly or in a breakdown manner with strong randomness through characteristics such as the smoothness and repeatability of the waveform. Among them, the random release is more harmful; the more waveform burrs, the more intense the discharge, which belongs to the breakdown type of discharge and is more harmful to the dielectric material; the smoother the waveform, the milder the discharge process and it tends to be conductive discharge.

[0140] (3) The peak value of the discharge current reflects the intensity of the dielectric electrostatic discharge. The larger the peak value of the discharge current, the greater the released energy and the greater the harm to the electronic device. The smaller its value, the less charge accumulates inside the dielectric, and the better the anti-internal charging performance of the corresponding dielectric.

[0141] (4) The average value of the discharge current can comprehensively compare and evaluate the destructiveness of the electrostatic discharge of each specimen. The smaller its value, the better the anti-internal charging performance of the dielectric.

[0142] (5) The peak value of the single-shot discharge charge reflects the amount of charge of each specimen in a single discharge. The more discharge charge, the more serious the charge accumulation inside the dielectric, and at the same time, the larger the discharge current shown, and the greater the harm.

[0143] (6) The total discharge charge is used to macroscopically compare the anti-deep charge and discharge performance of each specimen. The less the total discharge charge, the less charge accumulates inside the dielectric. More deposited charges are slowly leaked through the way of conductance rather than instantaneously released through the way of electrostatic discharge. Therefore, the less the total discharge charge, the better the anti-internal charging performance of the corresponding specimen can be considered.

[0144] III. Comprehensive Evaluation Scheme for the Deep Charge and Discharge Performance of Dielectrics under Electron Radiation

[0145] This scheme combines "I. Dielectric Internal Electric Field Simulation Calculation Scheme Based on Dielectric Parameters of Dielectric Materials" and "II. Test and Analysis Scheme for the Deep Charge and Discharge Performance of Dielectrics under Electron Radiation Test" to construct an evaluation scheme for the deep charge and discharge performance of dielectrics under electron radiation, and can evaluate and analyze the anti-internal charging performance of each specimen from the perspectives of theoretical simulation calculation and electron radiation test.

[0146] The overall evaluation scheme is as follows:

[0147] First, through the dielectric internal electric field simulation calculation process based on the dielectric parameters of the dielectric material, obtain the two indicators of the maximum internal charge density and the maximum internal electric field strength of each specimen under the same radiation condition; then record and extract the six indicators of the number of electrostatic discharges, discharge waveform, peak value of discharge current, average value of discharge current, peak value of single-shot discharge charge, and total discharge charge of each specimen under the same radiation condition through the radiation test; a total of eight indicators constitute the key evaluation indicators of this scheme.

[0148] Then, first analyze the simulation calculation results. Under the same radiation conditions, the greater the charge density in the dielectric, the more serious the internal charge accumulation, and the worse the internal charging resistance; the greater the internal electric field strength of the dielectric, the more serious the electric field distortion inside the dielectric, the more charge accumulation, and the worse the internal charging resistance. Through these two factors, a preliminary evaluation of the internal charging resistance of the test sample can be made.

[0149] Next, compare and analyze the electron radiation measurement results:

[0150] Among them, (1) the number of electrostatic discharges most intuitively reflects the deep charging and discharging resistance of the sample. The more discharge times, the more serious the electric field concentration inside the dielectric. The charges are released in the form of local breakdown, forming more discharge pulses, which has a greater impact on the electronic equipment of aerospace equipment.

[0151] (2) The discharge waveform intuitively reflects the characteristics of the discharge. The smoothness, repeatability and other characteristics of the waveform can be used to determine whether the charge inside the dielectric is released gently or in a breakdown manner with strong randomness. Among them, the random release is more harmful; the more waveform burrs, the more violent the discharge, which belongs to the breakdown type discharge and is more harmful to the dielectric material; the smoother the waveform, the milder the discharge process and it tends to be a conductive discharge.

[0152] (3) The peak value of the discharge current reflects the intensity of the dielectric electrostatic discharge. The greater the peak value of the discharge current, the greater the released energy and the greater the harm to the electronic equipment. The smaller its value, the less charge accumulates inside the dielectric, and the better the internal charging resistance of the corresponding dielectric.

[0153] (4) The average value of the discharge current can comprehensively compare and evaluate the destructive size of the electrostatic discharge of each sample. The smaller its value, the better the internal charging resistance of the dielectric.

[0154] (5) The peak value of the single discharge charge reflects the size of the single discharge charge of each sample. The more discharge charge, the more serious the internal charge accumulation in the dielectric, and at the same time, the greater the discharge current shown, and the greater the harm.

[0155] (6) The total discharge charge macroscopically compares the deep charging and discharging resistance of each sample. The less the total discharge charge, the less the internal charge accumulation in the dielectric. More deposited charges are slowly leaked through the way of conductance rather than instantaneously released through the way of electrostatic discharge. Therefore, the less the total discharge charge, the better the internal charging resistance of the corresponding sample can be considered.

[0156] By comparing these six indicators of each sample, the advantages and disadvantages of the internal charging resistance of each sample can be further compared and evaluated. Then, combined with the results of simulation calculations, the test results are compared and verified. Generally, the greater the charge density in the dielectric, the greater the internal electric field. For the specific discharge characteristics, the breakdown field strength of each sample needs to be considered. The lower the breakdown field strength, the easier it is to discharge under the same electric field strength. Based on this, the internal charging resistance of each sample can be comprehensively evaluated. The overall flow chart of the evaluation scheme is as Figure 2 shown.

[0157] The present invention proposes a feasible deep charging and discharging resistance scheme for dielectrics under electron radiation by combining simulation calculations and experimental tests. Eight key indicators related to the deep charging and discharging performance of dielectrics under electron radiation are selected, and the deep charging and discharging resistance performance of dielectrics is comprehensively evaluated from two aspects of theoretical calculation and experimental test, which is lacking in existing research. Moreover, the simulation calculation results and experimental test results complement each other and can be mutually verified, improving the accuracy of the evaluation results. The present invention provides a favorable evaluation method and test scheme for the research on deep charging and discharging of dielectrics under electron radiation and the improvement of the deep charging and discharging resistance performance of dielectrics.

[0158] To prove the creativity and technical value of the technical solution of the present invention, this part is an application example of the technical solution of the claims on specific products or related technologies.

[0159] Taking a polyimide (PI) sample as an example, using the evaluation method proposed in the embodiment of the present invention, the internal charging resistance characteristics of pure PI samples and micron zinc oxide (ZnO) modified samples are calculated and tested respectively. The brief description is as follows:

[0160] First, the maximum value of the internal electric field of the two samples was calculated under the radiation conditions of (incident electron energy 0.3 MeV, beam current 5 μA).

[0161] When the beam current is 5 μA, the maximum value of the internal electric field of the pure PI sample increases rapidly with the increase of radiation time and exceeds 1×10 8 V / m in a short time, and the electric field growth rate is basically unchanged. The change trend of the internal electric field of the micron zinc oxide modified sample is different from that of the pure PI sample. With the increase of radiation time, the internal electric field of the modified sample first increases continuously, but the electric field growth rate gradually decreases. Finally, the maximum value of the electric field tends to be stable, the internal electric field reaches equilibrium and no longer changes with the change of radiation time, and the amplitude of the electric field strength of the modified sample is less than that of the pure PI sample. Therefore, it is preliminarily determined that the internal charging resistance characteristics of the micron zinc oxide modified sample are better than those of the pure PI sample.

[0162] Then, radiation tests were carried out. The radiation conditions were set as incident electron energy 0.3 MeV, beam current 5 μA, and radiation time 20 min. The typical discharge waveforms collected are as follows:

[0163]

[0164] It can be obtained from the radiation test results that:

[0165] For the modified sample with micron zinc oxide, several key indicators such as the number of discharges, discharge waveform, peak discharge current, average discharge current, peak charge of single discharge, and total charge of discharge are all superior to those of the pure PI sample. The test results are consistent with the theoretical calculation results. Considering both, it shows that the anti-internal charging performance of the modified sample is superior to that of the pure PI sample.

[0166] As mentioned above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention.

Claims

1. A comprehensive evaluation method for the anti-internal charging performance of a medium, characterized in that, The method for evaluating the deep charging and discharging performance of the dielectric includes: simulating the electric field simulation calculation in the dielectric under electron radiation, and testing the deep charging and discharging performance of the dielectric under electron radiation; using Geant4 to simulate the electron radiation process, using COMSOL to calculate the charge transport process, and then testing the electrostatic discharge of the specimen under real electron radiation; determining the charge distribution in the dielectric and the electric field distribution in the dielectric, recording the electrostatic discharge waveform and test data of the dielectric, and determining the evaluation index; The method for evaluating the deep charging and discharging performance of the dielectric includes the following steps: Step 1, simulating the electric field calculation in the dielectric based on the dielectric parameters of the dielectric material; Step 2, testing and analyzing the deep charging and discharging performance of the dielectric under electron radiation test; Step 3, comprehensively evaluating the deep charging and discharging performance of the dielectric under electron radiation; The testing and analysis of the deep charging and discharging performance of the dielectric under electron radiation test in Step 2 includes: (1) Pretreating the specimen and the specimen platform: ultrasonically oscillating and cleaning the specimen and the specimen platform with anhydrous ethanol and deionized water, wrapping them with aluminum foil and connecting the ground wire after cleaning, and putting them into a vacuum drying oven at 90 °C for 2 h; (2) Designing the cooperation scheme of the shielding disk and the specimen disk according to the test requirements to form a test flow chart; (3) Placing the specimen on the corresponding area of the specimen disk according to the specimen placement method designed in step (2). The bottom surface of each specimen is covered with copper tape relative to the radiation surface and connected to the lead wire at the boss of the specimen. The other end of each lead wire is grounded through a 50-ohm resistor, and the far-end of the 50-ohm resistor is led out and connected to an oscilloscope; when the input interface of the oscilloscope is insufficient, multiple oscilloscopes are used for simultaneous testing; after the circuit connection is completed, use a multimeter to check whether the test circuit connection is correct; (4) After the specimen is placed and the test circuit is checked to be correct, close the vacuum test tank, turn on the vacuum pump to evacuate the air until the vacuum degree of the vacuum test tank is <5×10 -4 Pa; (5) Conducting the test according to the designed test flow chart, and using an oscilloscope to record and collect the discharge waveform data of the corresponding specimen; (6) Test data analysis scheme: Collecting and recording all the electrostatic discharge waveforms of the specimen under electron radiation through the oscilloscope, and selecting the number of electrostatic discharges, discharge waveform, peak discharge current, average discharge current, peak single discharge charge amount, and total discharge charge amount as indicators to evaluate the anti-deep charging and discharging performance of the specimen; The comprehensive evaluation of the deep charging and discharging performance of the dielectric under electron radiation in Step 3 includes: Obtaining the indexes of the maximum internal charge density and the maximum internal electric field strength of each specimen under the same radiation condition through the dielectric internal electric field simulation calculation process based on the dielectric parameters of the dielectric material; recording and extracting the indexes of the number of electrostatic discharges, discharge waveform, peak discharge current, average discharge current, peak single discharge charge amount, and total discharge charge amount of each specimen under the same radiation condition through the radiation test.

2. The comprehensive evaluation method for the anti-internal charging performance of the medium according to claim 1, characterized in that The simulation calculation of the electric field in the dielectric based on the dielectric parameters of the dielectric material in Step 1 includes: (1) Experimentally determine the parameters of density ρ, intrinsic conductivity δ0, high-field conductivity δ, radiation-induced conductivity δ, dielectric constant ε, and breakdown field strength E of each sample. E , radiation-induced conductivity δ RIC , dielectric constant ε, and breakdown field strength E b ; (2) Use the open-source Monte Carlo simulation software Geant4 to simulate the electron radiation process of dielectric materials in a set space environment; according to the properties and three-dimensional dimensions of the specimen material, construct a three-dimensional simulation model corresponding to the specimen, and divide it into small volume elements for detecting the electrons and energy deposited during the radiation process; set the initial energy of the incident electrons and the number of incident electrons simulated to be 3×10 6 pieces, and in Geant4, the total charge deposition number E n and energy deposition E g in each volume element are counted through the functions G4PSCellCharge3D and G4PSEnergyDeposit3D; Among them, the conversion method of the beam current density of the incident electrons is as follows: When the number of incident electrons is N; the incident electron beam current density is J0, in A / m 2 , the electron source area is A0, in m 2 , then the virtual radiation time T is: where e q is the electronic charge, set to 1.6×10 -19 C; the corresponding charge deposition rate in the medium under the actual beam current is: The dose rate in the dielectric is: (3) By simulating the electron radiation process of the specimen in step (2), the charge deposition rate ρ at each position inside the specimen under the set radiation conditions is obtained d and the dose rate The finite element method is used to calculate the charge distribution and electric field intensity distribution inside the medium under electron radiation. The charge transport equations inside the medium are as follows: The charge transport equations from top to bottom are the Poisson equation, the current continuity equation, and Ohm's law; where, E is the electric field strength with the unit of V / m; ρ s is the net charge density in the medium with the unit of C / m 3 ; ε is the dielectric constant of the medium with the unit of F / m; J is the net current density with the unit of A / m 2 ; ρ d is the charge deposition rate in the medium with the unit of C / m 3 ·s, which is the calculation result of the radiation simulation program developed based on Geant4 in step (2); δ E is the conductivity related to the electric field with the unit of S / m, which is the calculation and test result of step (1); (4) Calculating and solving Export the charge deposition rate and dose rate at each position in the sample obtained in step (2) as a.txt file, and then import it into COMSOL using the interpolation method; set the grounding condition and working voltage according to the actual working condition of the sample, then set the radiation time, and select the MUMPS type solver based on LU decomposition for solving calculation to obtain the internal charge and electric field distribution of the sample within the set radiation time under the actual working condition.

3. The comprehensive evaluation method for the anti-internal charging performance of the medium according to claim 2, wherein, Use the finite element analysis software COMSOL to solve the charge transport equations, including: 1) Establish a three-dimensional model of the sample in COMSOL and import the corresponding material parameters; 2) Construct the charge transport equations in step (3) in COMSOL; select the partial differential equation interface in the mathematics module to customize the equations to be solved; select the partial differential equation, and modify the coefficients of the partial differential equation and the Poisson equation respectively according to the charge transport model equations in step (3); The structure of the partial differential equation is as follows: 3) Set the boundary conditions and divide the mesh in COMSOL; analyze the specific working conditions of the sample, including the grounding state, grounding position of the sample, and the factors of the amplitude and application position of the working voltage. The working conditions of the sample correspond to the initial state and boundary conditions of the partial differential equation system; in COMSOL, various initial states are set by modifying the initial conditions of the custom equation and adding Dirichlet boundary conditions; the mesh division uses automatic free tetrahedral mesh.

4. A comprehensive evaluation system for the internal charging resistance of a dielectric, which applies the comprehensive evaluation method for the internal charging resistance of a dielectric according to any one of claims 1 to 3, characterized in that The comprehensive evaluation system for the internal charging resistance of the dielectric includes: The electron gun, serving as a radiation source for electron radiation tests, is located in a vacuum chamber; the vacuum degree of the vacuum chamber is pumped down to a vacuum degree <5×10 -4 Pa, and then the electron gun is turned on; during the test, different incident electron energies and electron beam currents are set according to the parameters of the electron gun for the measured incident electron energy and beam current range. A vacuum test chamber. The electron radiation test is used to simulate the interaction process between high-energy electrons and dielectric materials in the space environment. Place the electron gun and the sample platform in the vacuum test chamber, and use a vacuum pump to extract the vacuum environment for test; A vacuum pump, used to pump vacuum for the vacuum test chamber to construct a vacuum environment; An oscilloscope, used to monitor and record the discharge pulse signals during the deep charging and discharging process of the dielectric sample under electron irradiation; A sample platform, used to place the sample to be tested, consisting of a rotatable shielding disk at the upper end and a non-rotatable sample disk; Discharge signal lead wires, leading out from the vacuum chamber and connecting the bottom of the sample and the oscilloscope, which are the transmission lines of the sample discharge signals; the transmission lines are multi-core shielded cables, and 12 branch lines are respectively led out to the vicinity of the 12 raised sample platforms of the sample disk. The bottom surface of the sample to be tested is firmly bonded to the corresponding lead wire with copper tape; the other end of each lead wire is grounded through a 50-ohm resistor, and the far-end of the 50-ohm resistor is led out and connected to the oscilloscope; when the input interface of the oscilloscope is insufficient, multiple oscilloscopes are used to simultaneously test and store the electrostatic discharge data and waveforms of each sample; The grounding terminal of the sample platform, used for grounding the discharge signal lead wire and shielding interference signals.

5. The comprehensive evaluation system for the internal charging resistance performance of the medium according to claim 4, characterized in that Both the shielding disk and the specimen disk are evenly divided into 12 regions. The shielding disk is marked as D1 - D12, and the specimen disk is marked as Y1 - Y12. The regions of the upper and lower disks correspond to each other one by one. Among them, D1 - D12 are removable shielding blocks. When the corresponding shielding block is removed, the specimen below can be directly irradiated. When the shielding block is inserted, the corresponding specimen is shielded and not irradiated. Among them, when D1, D3, and D5 are removed from the shielding disk, the specimens Y1, Y3, and Y5 on the corresponding specimen disk are irradiated, and the rest of the samples are shielded. Moreover, the shielding disk can be driven by a stepper motor to rotate clockwise or counterclockwise, and the rotation angle for each movement is 30°. By the mutual cooperation of the shielding disk and the specimen disk, different types of specimens can be simultaneously tested under different radiation conditions, and up to 12 samples can be tested at one time.

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