Prediction method for insulating strength of ultrahigh-pressure helium and electronic equipment
By establishing a plasma fluid simulation model and numerical calculation method, the problem of predicting the insulation strength of helium under high temperature and high pressure was solved, and accurate prediction of helium insulation strength was achieved, reducing equipment costs and simplifying breakdown judgment.
Patent Information
- Application Number
- CN202511040243.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-11
AI Technical Summary
Existing technologies struggle to accurately predict helium insulation strength under high temperature and pressure conditions, necessitating a large margin in design, increasing equipment costs. Furthermore, traditional methods yield predictions that differ significantly from actual values under ultra-high pressure.
A plasma fluid simulation model was established, considering a multi-particle, multi-reaction system. Helium breakdown was determined by numerical calculation, and the potential boundary conditions were scanned using the bisection method to accurately simulate the insulation performance of helium.
It improves the accuracy of helium insulation strength prediction, reduces equipment costs, provides theoretical support under high temperature and high pressure conditions, and simplifies breakdown judgment.
Smart Images
Figure CN120930540A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of insulation performance testing technology, and in particular to a method for predicting the insulation strength of ultra-high pressure helium gas and an electronic device. Background Technology
[0002] Nuclear energy, due to its cleanliness, high efficiency, and enormous energy output, has gradually become a key alternative to traditional fossil fuels. High-temperature gas-cooled reactors (HTGRs) possess inherent safety, economic efficiency, high thermal efficiency, and great flexibility in nuclear fuel cycle, making them one of the representative reactor types of fourth-generation reactors. The main helium blower, as one of the most critical pieces of equipment in an HTGR, drives an appropriate flow of coolant through the reactor core under various operating conditions, including reactor startup, normal power operation, power regulation, and shutdown. This coolant transfers the heat generated by nuclear fission to the steam generator to produce steam, which in turn drives the turbine generator to generate electricity. Ensuring the stability of the main helium blower is essential for the safe operation of an HTGR nuclear power plant. Helium, an inert gas, possesses advantages such as a small neutron absorption surface, chemical stability, high specific heat, and high thermal conductivity, making it the preferred choice for both the coolant and insulating medium in the reactor loop.
[0003] However, helium, as a monatomic gas, has relatively low insulation strength. To ensure insulation strength and improve heat density, the helium pressure in the main helium blower can reach up to 7 MPa, while the temperature of the helium in the circuit can reach up to 750°C. Under such high temperature and high pressure conditions, the insulation performance of helium in various electrical structures such as electromagnetic bearings, helium blowers, electrical penetrations, and drive motor stator windings operating in the pressure shell is still unclear, requiring a large margin to be reserved in the design, thus increasing the production cost of the equipment.
[0004] In high-temperature and high-pressure environments, the insulation of helium gaps is affected by a variety of factors, including: the uniformity of the electric field in the gap space, electrode surface processes, gas flow and thermal field distribution, impurity gas composition, and the temperature-pressure correlation of particle transport parameters. Therefore, the breakdown of the gap is a complex multiphysics process.
[0005] Current research on the insulating strength of helium primarily focuses on pressure parameters ranging from low to atmospheric pressure. Few studies report helium breakdown voltage parameters at such high pressures, and research on the insulating strength of helium at pressures up to 70 atmospheres has yet to develop into a mature system. At high pressures, the mean free path of electrons shortens, making it difficult for them to accumulate sufficient energy for effective collisional ionization. Simultaneously, high pressure may force some helium atoms (ions) to condense, thus affecting the transport properties of charged particles. A deeper understanding of the inherent insulating properties of high-pressure helium necessitates considering the impact and corrections these factors have on classical breakdown theory.
[0006] Traditional gas insulation performance prediction methods are based on fitting empirical formulas to experimental data. This method cannot reflect the essential mechanism of gas discharge. Furthermore, under ultra-high pressure, the mean free path of electrons is shortened and some helium atoms condense, causing the predicted results to differ significantly from the actual values. Summary of the Invention
[0007] To address the aforementioned technical problems, this invention proposes a method and electronic device for predicting the insulation strength of ultra-high pressure helium gas. This method can predict the breakdown voltage of helium gas under different pressures and gaps, thus solving the problem that the predicted results differ significantly from the actual values in existing technologies.
[0008] This invention is achieved through the following technical solution: A method for predicting the insulation strength of ultra-high pressure helium gas includes the following steps: Step S1. Establish a plasma fluid simulation model; Step S2. Consider a multi-particle, multi-reaction system; Step S3. Obtain the mobility and diffusion coefficient of all particles and input them into the simulation model; Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium; Step S5. Set the potential boundary conditions for the simulation model; Step S6. Perform simulation model calculations using numerical calculation methods to determine whether breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
[0009] The plasma fluid simulation model in step S1 has a geometric structure of one-dimensional parallel plate electrodes, with helium gas filling the space between the electrodes. One side of the plate is grounded, and the other side is connected to a power source. The mathematical governing equations of the simulation model include: the electron density continuity equation, the electron energy conservation equation, and the heavy particle multi-component diffusion equation. By coupling and solving the Poisson equation of the electric field, the simulation model achieves self-consistency.
[0010] The particles in step S2 include electrons, helium molecules, metastable particles, and elementary ions. The metastable particles are He* and He2*, and the elementary ion is He. + and He2 + The reactions include: elastic collisions, collision ionization and excitation reactions between electrons and helium molecules; ionization and attachment reactions between electrons and metastable particles; quenching of metastable particles into helium molecules and ions on the electrode surface and the initiation of secondary electron emission reactions on the electrode surface.
[0011] Step S3 specifically refers to: obtaining the electron mobility by solving the two Boltzmann approximation equations, and obtaining the electron diffusion coefficient according to the generalized Einstein relation.
[0012] Step S3 further includes calculating the mobility of the elementary ion and then calculating the diffusion coefficient of the elementary ion according to the Einstein relation; the method for calculating the mobility of the elementary ion is as follows: , In the formula, μ i The mobility of the basic ions, m g and m i These are the molar masses of gases and elementary ions, respectively. α Polarizability a 0 is the Bohr radius. p It refers to air pressure; Step S3 further includes calculating the diffusion coefficient of neutral particles, wherein the neutral particles include helium molecules and metastable particles; the method for calculating the diffusion coefficient of neutral particles is as follows: , In the formula, D n The diffusion coefficient of neutral particles is denoted as . T For gas temperature, m n The molar mass of a neutral particle. m g The molar mass of the gas. p For air pressure, σ LJ Let Ω be the Lennard-Jones radius. LJ For the collision integral.
[0013] The environmental parameters include air pressure, temperature, and electrode spacing.
[0014] When setting the potential boundary conditions of the simulation model, the breakdown voltage determined by the Paschen curve of helium is set as the initial potential boundary based on the electrode spacing and gas pressure parameters.
[0015] The numerical calculation method for model calculation includes: analyzing the electron density continuity equation, the electron energy density continuity equation, the heavy particle multi-component diffusion equation, and the Poisson equation; based on the calculation results, the electron density variation curve over time is obtained.
[0016] Determine whether the electron density increases geometrically continuously. If it does, the circuit is considered to have broken down; otherwise, it is considered not to have broken down.
[0017] Determine whether the waveform of electron density shows obvious pulse spikes. If so, it is judged as breakdown; if not, it is judged as non-breakdown.
[0018] An electronic device includes a processor and a memory; the memory stores computer-readable instructions that, when executed by the processor, implement the above-described prediction method.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention addresses the complex multi-particle reaction system in helium discharge by establishing a plasma fluid model that accurately simulates the actual working environment of helium, enabling the prediction of breakdown voltage. This method, starting from the physical mechanism of breakdown, specifically considers the influence of field emission on the helium discharge process and proposes a novel method for evaluating the insulation strength of helium under ultra-high pressure conditions, based on the final electron density multiplication as the criterion. This method is primarily used to predict the insulation strength of helium at 7 MPa pressure, providing solid theoretical support for the design of main helium blowers.
[0020] Specifically, this invention establishes a breakdown model for uniform fields and uses numerical calculation methods to simulate the model, verifying its effectiveness in predicting the insulation strength of helium under ultra-high pressure conditions, thereby significantly improving the accuracy of the prediction results. By constructing a fully self-consistent simulation model to predict the breakdown voltage of helium, no experimental measurement data is required. Only environmental parameters (such as pressure and temperature) need to be adjusted to flexibly predict the breakdown voltage under different operating conditions, and the prediction accuracy far exceeds that of traditional empirical formulas.
[0021] Furthermore, this invention successfully avoids the high equipment costs and potential safety risks faced by traditional experimental methods when dealing with extreme conditions such as high pressure and high temperature, while significantly improving computational efficiency, making it possible to quickly and accurately evaluate the insulation performance of helium under various extreme conditions.
[0022] 2. This invention uses simulation to predict the insulation strength of helium under ultra-high pressure, and the prediction effect is accurate.
[0023] 3. The breakdown determination method in this invention is simpler and more accurate. Attached Figure Description
[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein: Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 This is a schematic diagram of the relationship between electron density and time in this invention; Figure 3This is a schematic diagram comparing the prediction results of the present invention with those of a traditional gas insulation performance prediction scheme. Figure 1 ; Figure 4 This is a schematic diagram comparing the prediction results of the present invention with those of a traditional gas insulation performance prediction scheme. Figure 2 . Detailed Implementation
[0025] Example 1 As a basic embodiment of the present invention, the present invention includes a method for predicting the insulation strength of ultra-high pressure helium gas, comprising the following steps: Step S1. Establish a plasma fluid simulation model.
[0026] Step S2. Consider a multi-particle, multi-reaction system.
[0027] Step S3. Obtain the mobility and diffusion coefficient of all particles and input them into the simulation model.
[0028] Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium.
[0029] Step S5. Set the potential boundary conditions for the simulation model.
[0030] Step S6. Perform simulation model calculations using numerical methods to determine if breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
[0031] Example 2 In a preferred embodiment of the present invention, the present invention includes a method for predicting the insulation strength of ultra-high pressure helium gas, comprising the following steps: Step S1. Establish a plasma fluid simulation model. The geometry of the plasma fluid simulation model is a one-dimensional parallel plate electrode, with helium gas filling the space between the electrodes. One side of the plate is grounded, and the other side is connected to a power source. The mathematical governing equations of the simulation model include: the electron density continuity equation, the electron energy conservation equation, and the heavy particle multi-component diffusion equation. By coupling and solving the Poisson equation of the electric field, the simulation model achieves self-consistency.
[0032] Step S2. Consider a multi-particle, multi-reaction system. The particles include electrons, helium molecules, metastable particles, and elementary ions. The metastable particles are He* and He2*, and the elementary ion is He. + and He2 + The reactions include: elastic collisions, collisional ionization and excitation reactions between electrons and helium molecules; ionization and attachment reactions between electrons and metastable particles; quenching of metastable particles into helium molecules and ions on the electrode surface; and secondary electron emission reactions initiated on the electrode surface.
[0033] Step S3. Obtain the mobility and diffusion coefficient of all particles and input them into the simulation model. Specifically, the electron mobility can be obtained by solving the two Boltzmann approximation equations, and the electron diffusion coefficient can be obtained according to the generalized Einstein relation.
[0034] Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium.
[0035] Step S5. Set the potential boundary conditions for the simulation model.
[0036] Step S6. Perform simulation model calculations using numerical methods to determine if breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
[0037] Example 3 In another preferred embodiment of the present invention, the present invention includes a method for predicting the insulation strength of ultra-high pressure helium gas, comprising the following steps: Step S1. Establish a plasma fluid simulation model.
[0038] Step S2. Consider a multi-particle, multi-reaction system.
[0039] Step S3. Obtain the mobility and diffusion coefficient of all particles and input them into the simulation model.
[0040] Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium. The environmental parameters include gas pressure, temperature, and electrode spacing.
[0041] Step S5. Set the potential boundary conditions for the simulation model. Specifically, based on the electrode spacing and gas pressure parameters, determine the approximate breakdown voltage using the Paschen curve of helium, and set it as the initial potential boundary.
[0042] Step S6. Perform simulation model calculations using numerical methods to determine if breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
[0043] The numerical calculation methods used in the model calculations include: analyzing the electron density continuity equation, the electron energy density continuity equation, the heavy particle multi-component diffusion equation, and the Poisson equation; based on the calculation results, the electron density versus time curve is obtained. The presence or absence of breakdown is determined based on the electron density versus time curve.
[0044] Example 4 Under a uniform electric field, the breakdown voltage of the air gap UWith pressure p and air gap spacing d The product is related. U and pd The functional relationship is the famous Paschen curve, which shows the expression of the inherent breakdown properties of the discharge medium (usually a gas) in a uniform electric field. Traditional gas insulation performance prediction schemes are based on fitting experimental data to the Paschen empirical formula. However, this method cannot reflect the essential mechanism of gas discharge and takes into account the millimeter-level gap between the stator bars of the main helium blower and the ultra-high gas pressure of 7 MPa. pd The value will reach a very high level. Under these conditions, the mean free path of electrons will be shortened, making it difficult for them to accumulate enough energy for effective collisional ionization. At the same time, high pressure may force some helium atoms (ions) to condense, thereby affecting the transport characteristics of charged particles. This causes the breakdown characteristics of high-pressure helium to deviate from the Paschen curve.
[0045] Based on this, as another preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1 This invention includes a method for predicting the insulation strength of ultra-high pressure helium gas, comprising the following steps: Step S1. Establish a plasma fluid simulation model. The geometry of the plasma fluid simulation model is a one-dimensional parallel plate electrode structure. The width between the electrodes is... d mm, d It is a constant, and the space between the electrodes is filled with helium. One electrode is grounded, and the other is connected to a power source. The gas temperature is set to 300K, which is room temperature, and processes such as gas heating caused by discharge are not considered.
[0046] The mathematical governing equations of the simulation model include: the electron density continuity equation, the electron energy conservation equation, and the heavy particle multi-component diffusion equation. By coupling and solving the Poisson equation of the electric field, the simulation model achieves self-consistency.
[0047] Step S2. Consider a multi-particle, multi-reaction system. The particles include electrons, helium molecules, metastable particles, and elementary ions. The metastable particles are He* and He2*, and the elementary ion is He. + and He2 + The reactions include: elastic collisions, collisional ionization and excitation reactions between electrons and helium molecules; ionization and attachment reactions between electrons and metastable particles; quenching of metastable particles into helium molecules and ions on the electrode surface; and secondary electron emission reactions initiated on the electrode surface.
[0048] The electrons can be analyzed using equations (1) and (2): (1) (2) Equation (1) is the electron density continuity equation, and equation (2) is the electron energy density continuity equation. In the equations, n e and n ε These are the electron number density and electron energy, respectively, with initial values set to 2 × 10⁻⁶ for spatial uniformity. 13 m –3 and 2eV; Г e and Г ε These are the electron number density flux and electron energy flux under the migration-diffusion approximation, respectively; E The local electric field intensity in space S e The source term represents the net increase in electron density, and its value is obtained through a comprehensive calculation involving electron collisions. S ε The source term refers to the energy of electrons, representing the total amount of energy exchanged during all collisions.
[0049] The remaining heavy particles (excluding helium molecules) are analyzed using equation (3): (3) Equation (3) is the diffusion equation for heavy particles in multiple components. In the equation, where, ρ For the gas density; for the first i Heavy particles, Γ i For migration and diffusion flux, S i For source terms, ω i This represents the quality score.
[0050] The aforementioned equations relating electrons and heavy particles are solved by coupling the Poisson equation for the electric field, thus achieving self-consistency in the model, i.e.: , In the above formula, ε r It is the relative permittivity of the material (the air gap). ε r Set to 1); φ It is electrical potential; ρ v It is the space charge density.
[0051] Step S3. Obtain the mobility and diffusion coefficients of all particles and input them into the simulation model, including calculating the mobility and diffusion coefficients of electrons, the mobility and diffusion coefficients of basic ions, and the diffusion coefficients of neutral particles. Neutral particles include helium molecules and metastable particles.
[0052] Specifically, the electron mobility can be obtained by solving the two approximation equations of Boltzmann, and then the electron diffusion coefficient can be obtained according to the generalized Einstein relation. Among them, the Boltzmann equation is the state distribution function equation of the particle in the six-dimensional phase space, and the coordinates of the phase space (position state and velocity state) are six relatively independent variables.
[0053] The Boltzmann equation is as follows: .
[0054] In the formula, f Let be the particle state distribution function; the right-hand side of the equation The term represents the collision terms between particles and other particles during the motion; the left column of the equation represents the diffusion of particles in phase space and the drift motion driven by macroscopic forces (here, electric field force). m It is electronic quality. E It is the electric field strength. v It is the electron velocity. It is the velocity gradient operator. r It refers to the electronic position state. It is the position gradient operator. t It is a time variable. However, due to the complexity and huge computational cost of integrating the Boltzmann equation, it is necessary to simplify the Boltzmann equation extensively. Finally, two approximations are used to simplify it into two Boltzmann equations.
[0055] The mobility of basic ions is calculated as follows: , In the formula, μ i The mobility of the basic ions, m g and m i The molar masses (in g / mol) of gases and elementary ions, respectively. α Polarizability a 0 is the Bohr radius. p This refers to air pressure (unit: MPa).
[0056] Therefore, it is approximately considered that μ i ∝1 / p The diffusion coefficient of the basic ion D i Based on Einstein's relationship μ i The calculation yielded: , In the formula, k b Boltzmann's constant, T iThis is the ion temperature (equal to the gas temperature). q i This represents the ionic charge (unit: C). Therefore, the diffusion coefficient of a basic ion is also inversely proportional to the gas pressure.
[0057] The diffusion coefficient of neutral particles is calculated as follows: , In the formula, D n The diffusion coefficient of neutral particles is denoted as . T Gas temperature (unit: K). m n The molar mass of a neutral particle (unit: g / mol). m g This represents the molar mass of the gas (unit: g / mol). p For air pressure, σ LJ Lennard-Jones radius (in Å), Ω LJ This is the collision integral (dimensionless). Therefore, the diffusion coefficient of neutral particles is also inversely proportional to air pressure.
[0058] The dispersion coefficients and mobilities of helium molecules, metastable particles, and basic ions can also be calculated based on existing calculation methods. For example, the "Experiment and Simulation of High Temperature and High Pressure Helium Breakdown in Non-Uniform Electric Field" published by You Qi, Liu Xingnan, et al. in 2020 can be used as a reference, and the calculation methods published in the reference can be used for calculation.
[0059] Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium. The environmental parameters include gas pressure, temperature, and electrode spacing.
[0060] Step S5. Set the potential boundary conditions for the simulation model. Specifically, based on the electrode spacing and gas pressure parameters, determine the approximate breakdown voltage using the Paschen curve of helium, and set it as the initial potential boundary.
[0061] Step S6. Perform simulation model calculations using numerical methods to determine if breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
[0062] The numerical calculation methods used for model calculations include: analyzing the electron density continuity equation, the electron energy density continuity equation, the heavy particle multi-component diffusion equation, and the Poisson equation; based on the calculation results, the electron density versus time curve is obtained.
[0063] One method to determine whether breakdown has occurred is by analyzing the electron density versus time curve. Specifically, there are two criteria: one is to assess whether the electron density increases geometrically continuously; if so, it's considered breakdown; otherwise, it's considered non-breakdown. The other is to assess whether the electron density waveform shows a significant pulse spike; if so, it's considered breakdown; otherwise, it's considered non-breakdown. Either criterion can be chosen; a pulse spike will always appear if the electron density shows a continuous geometric increase.
[0064] The potential boundary conditions are corrected using a bisection method for voltage parameter scanning. Specifically, initially, the input voltage of the simulation model is denoted as... U a The input voltage resolution is 10V. If the helium gas is not broken down at this point, the input voltage is increased and the calculation is repeated. If it is still not broken down, then... U a Update the input voltage to the new time step; continue increasing the breakdown voltage. If the helium gas breaks down at this point, record the input voltage at this time as [value missing]. U b The input voltage to be calculated by the simulation model next is ( U a + U b Repeat the above process until the input voltage is equal to the critical breakdown voltage of helium (e.g., the input voltage is 2). U c This causes the helium gas to break down, but the input voltage ( U c If -10V cannot break down helium, then U c (Critical breakdown voltage).
[0065] Example 5 In a preferred embodiment of the present invention, the present invention includes an electronic device comprising a processor and a memory. The memory stores computer-readable instructions. When executed by the processor, the computer-readable instructions implement the prediction method described in any of embodiments 1 to 4. Example 6 As a specific embodiment of the present invention, taking atmospheric pressure as an example, the input simulation model parameters are: air pressure 1 atm, air gap length... d The sample size is 5 mm, the temperature is 300 K, and the power supply frequency is 0 Hz. Then, input the electron mobility obtained from two Boltzmann equations, followed by the electron diffusion coefficient obtained from the generalized Einstein relation. Finally, input the ion diffusion coefficient and ion mobility obtained from the literature.
[0066] At this point, the product of air pressure and gap... pdThe breakdown voltage of helium is approximately 100 Pa·m. According to the Paschen curve, the breakdown voltage of helium is approximately 760 V. Therefore, the initial power supply of the model is set to 760 V.
[0067] Then, the model was calculated using the finite element method. No increase in charged particles was observed in the gap, indicating that the helium gas was not broken down at a voltage of 760V.
[0068] The critical breakdown voltage of helium is obtained by continuously refining the potential boundary conditions through a binary voltage parameter scanning calculation. If breakdown does not occur at 760V, the input voltage is increased to 1000V, at which point the gap electron density doubles and helium breaks down. The input voltage value for the next calculation is then corrected using the binary voltage parameter scanning method to 880V, at which point breakdown occurs. The next voltage parameter is then set to 820V, at which point breakdown also occurs. This process is repeated, and the final calculation result is shown in the appendix to the instruction manual. Figure 2 As shown. (Attached to the instruction manual) Figure 2 It can be seen that at a voltage of 800V, the electron density in the gap does not double, and the helium is not broken down; while at a voltage of 810V, the electron density doubles, and the helium is broken down. Therefore, at atmospheric pressure and a 1mm gap, the critical breakdown voltage of helium is 810V.
[0069] The data from "Experiment and Simulation of High-Temperature and High-Pressure Helium Breakdown in Non-Uniform Electric Field" published by You Qi, Liu Xingnan, et al. in 2020 was used as experimental and simulation references, and its results were presented as experimental and existing simulation results. This invention validated the ultra-high pressure helium breakdown model by comparing the results with experimental and existing simulation results at three pressures: 0.1 MPa, 1 MPa, and 7 MPa. The results are shown in the appendix to the specification. Figure 3 Included with instruction manual Figure 4 As shown.
[0070] The comparison shows that at a pressure of 0.1 MPa, the simulation results presented in this paper are in good agreement with the experimental results and are even superior to existing simulation results. Only at a pressure of 0.3 mm does the simulation result deviate significantly from the experimental result. Based on the trend of breakdown voltage and the Paschen curve, the breakdown characteristic curve at this point is located on the right half of the U-shaped Paschen curve, meaning that the breakdown voltage increases with the increase of pd (pressure × spacing), and the slope of the increase is lower when pd is small. Therefore, it can be concluded that the experimental results at 0.3 mm do not conform to reality, while the simulation results presented in this paper better match the trend of the Paschen curve.
[0071] When the air pressure increases to 1 MPa and 7 MPa, the simulation results of the prediction method in this paper still agree well with the experimental results, as shown in the appendix to the instruction manual. Figure 4As shown, under high pressures of 0.1 MPa, the breakdown voltage increases approximately linearly with increasing pd. Furthermore, compared to existing simulation results used as a reference, the simulation results of the proposed method show smaller deviations from the experimental results. Therefore, the proposed prediction method can be considered to possess high prediction accuracy across the pressure range of 0.1 MPa to 7 MPa.
[0072] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.
Claims
1. A method for predicting the insulation strength of ultra-high pressure helium gas, characterized in that: Includes the following steps: Step S1. Establish a plasma fluid simulation model; Step S2. Consider a multi-particle, multi-reaction system; Step S3. Obtain the mobility and diffusion coefficient of all particles and input them into the simulation model; Step S4. Set the environmental parameters in the simulation model according to the actual working conditions of helium; Step S5. Set the potential boundary conditions for the simulation model; Step S6. Perform simulation model calculations using numerical calculation methods to determine whether breakdown has occurred. If not, use the bisection method to scan and correct the potential boundary conditions, and recalculate the simulation model. If yes, obtain the critical breakdown voltage of helium.
2. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 1, characterized in that: The plasma fluid simulation model in step S1 has a geometric structure of one-dimensional parallel plate electrodes, with helium gas filling the space between the electrodes. One side of the plate is grounded, and the other side is connected to a power source. The mathematical governing equations of the simulation model include: the electron density continuity equation, the electron energy conservation equation, and the heavy particle multi-component diffusion equation. By coupling and solving the Poisson equation of the electric field, the simulation model achieves self-consistency.
3. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 2, characterized in that: The particles in step S2 include electrons, helium molecules, metastable particles, and elementary ions. The metastable particles are He* and He2*, and the elementary ion is He. + and He2 + The reactions include: elastic collisions, collision ionization and excitation reactions between electrons and helium molecules; ionization and attachment reactions between electrons and metastable particles; quenching of metastable particles into helium molecules and ions on the electrode surface and the initiation of secondary electron emission reactions on the electrode surface.
4. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 3, characterized in that: Step S3 includes: obtaining the electron mobility by solving the two Boltzmann approximation equations, and obtaining the electron diffusion coefficient according to the generalized Einstein relation.
5. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 3, characterized in that: Step S3 further includes calculating the mobility of the elementary ion and then calculating the diffusion coefficient of the elementary ion according to the Einstein relation; the method for calculating the mobility of the elementary ion is as follows: ， In the formula, μ i The mobility of the basic ions, m g and m i These are the molar masses of gases and elementary ions, respectively. α Polarizability a 0 is the Bohr radius. p This refers to air pressure.
6. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 3, characterized in that: Step S3 further includes calculating the diffusion coefficient of neutral particles, wherein the neutral particles include helium molecules and metastable particles; the method for calculating the diffusion coefficient of neutral particles is as follows: ， In the formula, D n The diffusion coefficient of neutral particles is denoted as . T For gas temperature, m n The molar mass of a neutral particle. m g The molar mass of the gas. p For air pressure, σ LJ Let Ω be the Lennard-Jones radius. LJ For the collision integral.
7. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 3, characterized in that: The environmental parameters include air pressure, temperature, and electrode spacing.
8. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 7, characterized in that: When setting the potential boundary conditions of the simulation model, the breakdown voltage determined by the Paschen curve of helium is set as the initial potential boundary based on the electrode spacing and gas pressure parameters.
9. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 3, characterized in that: The numerical calculation method for model calculation includes: analyzing the electron density continuity equation, the electron energy density continuity equation, the heavy particle multi-component diffusion equation, and the Poisson equation; based on the calculation results, the electron density variation curve over time is obtained.
10. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 9, characterized in that: Determine whether the electron density increases geometrically continuously. If it does, the circuit is considered to have broken down; otherwise, it is considered not to have broken down.
11. The method for predicting the insulation strength of ultra-high pressure helium gas according to claim 9, characterized in that: Determine whether the waveform of electron density shows obvious pulse spikes. If so, it is judged as breakdown; if not, it is judged as non-breakdown.
12. An electronic device, characterized in that: It includes a processor and a memory; the memory stores computer-readable instructions, which, when executed by the processor, implement the prediction method according to any one of claims 1 to 11.