An optimization method for the grid structure of a microgrid gas detector
By optimizing the grid structure parameters and arrangement of the microgrid gas detector, the problems of long time consumption and high cost of traditional design methods are solved, and efficient optimization of microscopic physical processes is achieved, thereby improving the performance and stability of the detector.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN CNNC NUCLEAR INSTRUMENT CO LTD
- Filing Date
- 2025-11-25
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional microgrid gas detector design methods are time-consuming, costly, and difficult to optimize the internal microscopic physical processes of the detector, thus failing to meet the requirements for high-performance detection.
By establishing a finite element model and optimizing grid structure parameters such as aperture ratio and arrangement, combined with electric field uniformity index, the movement trajectories of electrons and ions are simulated. A multi-objective optimization strategy is adopted to determine the optimal grid configuration, including square and rectangular double-layer arrangements, and extended to a double-layer composite grid configuration to enhance electron penetration and ion blocking ability.
Significantly reduces trial-and-error costs, improves electron penetration and enhances ion blocking capabilities, improves signal pulse width and detector stability, and provides customized design solutions to meet the high-performance requirements of different application scenarios.
Smart Images
Figure CN121562285B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microgrid gas detector optimization technology, specifically relating to a method for optimizing the grid structure of a microgrid gas detector. Background Technology
[0002] Microgrid gas detectors have significant engineering application value in high-intensity thermal neutron measurements, such as those in reactors. In the field of microgrid gas detector technology, at the microscopic level, their detection performance is primarily determined by key parameters such as electron transmittance, ion feedback suppression capability, and effective electron gain. These key parameters are fundamentally constrained by the grid structure, specifically encompassing structural elements such as the grid aperture size, wire spacing, wire diameter, and arrangement. The mesh count is one of the key parameters affecting performance. A higher mesh count reduces the grid aperture, leading to a decrease in electron transmittance, but simultaneously, the denser grid enhances the blocking effect on ions, more effectively suppressing ion feedback. A lower mesh count is beneficial for increasing electron transmittance, but it exacerbates the ion feedback effect. The mesh count also affects electron gain. A denser grid typically generates higher local electric field inhomogeneities, thereby improving electron multiplication efficiency at appropriate voltages. However, excessively high mesh counts may lead to uneven electric field distribution or increased electron loss, thus reducing the effective gain.
[0003] Traditional design methods involve macroscopic physical fabrication and experimental testing processes, which are lengthy and time-consuming from design to final product testing. The economic costs are high, and the costs of material consumption and equipment use during the physical fabrication process accumulate continuously. Furthermore, it is difficult to deeply explore and precisely control the microscopic physical processes inside the detector, which greatly limits the depth and efficiency of performance optimization and fails to meet the growing demand for high-performance detection. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide an optimization method for the grid structure of a microgrid gas detector, addressing the shortcomings of the prior art.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an optimization method for the grid structure of a microgrid gas detector, characterized in that the method includes the following steps:
[0006] Step 1: Establish the finite element model of the microgrid gas detector, which includes a cathode, drift region, grid, amplification region, and anode. Select grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector. The grid structure parameters include the grid aperture ratio and the grid arrangement. The grid arrangement includes a square single-layer arrangement, a square double-layer arrangement, a rectangular single-layer arrangement, and a rectangular double-layer arrangement.
[0007] The selection of grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector includes: under the condition of fixed grid aperture ratio, determining the effect mechanism of grid mesh number change on electric field distortion near the grid, selecting the grid mesh number that can satisfy the electric field uniformity index, and based on this, adjusting the grid arrangement, obtaining numerical solutions of static electric field and potential distribution under different parameter combinations, and screening out the target candidate structure set;
[0008] Step 2: Convert the target candidate structure set obtained in Step 1 into a Garfield++ readable format and import it. Select a suitable working gas from the Garfield++ built-in gas database and set the ambient temperature and pressure parameters.
[0009] Step 3: Generate a specified number and spatially distributed initial ionized electrons in the drift region and track their drift trajectories from the generation location to the grid, recording the drift time and position of each electron; determine whether the electrons are captured by the grid based on accurate electric field data, count the proportion of electrons that penetrate the grid and enter the avalanche region, calculate the electron penetration rate, and plot the relationship between the electron penetration rate and the grid parameters.
[0010] Step 4: Avalanche multiplication of penetrating electrons generates secondary electrons. Random sampling is used to track the movement trajectories of secondary electrons and ions. The final number and spatial distribution of electrons and ions are recorded, and the electron gain and the proportion of ions fed back to the drift region, i.e., the ion feedback coefficient, are calculated.
[0011] Step 5: Combining the charge motion information obtained in Step 4, convolve the charge motion with the weighted field to output the original current signal; input the original current signal to the electronics response module to obtain the output voltage pulse signal and extract the pulse width;
[0012] Step 6: Analyze multiple performance indicators obtained under different grid structure parameters, including electron transmittance, electron gain, ion feedback coefficient, and output signal pulse width; comprehensively evaluate the performance of the microgrid gas detector using a multi-objective optimization strategy, and determine the optimal configuration of grid structure parameters by using the analytic hierarchy process (AHP) to determine the comprehensive score.
[0013] The above-mentioned optimization method for the grid structure of a microgrid gas detector is characterized in that: the electric field uniformity index condition is an electric field uniformity index. ,in, , Number the grid points and , This represents the total number of grid points in the grid. For the first The electric field strength at each grid point The average electric field strength is denoted as .
[0014] The above-mentioned method for optimizing the grid structure of a microgrid gas detector is characterized in that: the working gas includes a mixture of argon and carbon dioxide.
[0015] The above-mentioned method for optimizing the grid structure of a microgrid gas detector is characterized in that: the electron transmittance , The number of electrons passing through the grid. This represents the initial number of electrons.
[0016] The above-mentioned method for optimizing the grid structure of a microgrid gas detector is characterized in that: the electronic gain , The total number after electron avalanche; the ion feedback coefficient , The number of ions that pass through the grid and reach the drift region. The number of ions after an avalanche.
[0017] The above-mentioned method for optimizing the grid structure of a microgrid gas detector is characterized in that: the original current signal , For charge quantity, For carrier velocity, The electronic response module comprises a charge-sensitive preamplifier circuit, a pole-zero cancellation circuit, and an RC differential filter shaping circuit connected in sequence.
[0018] The above-mentioned method for optimizing the grid structure of a microgrid gas detector is characterized in that: the comprehensive scoring determines the optimal configuration of the grid structure parameters. , This is a weighting coefficient for electron transmittance. This is the weighting coefficient for the ion feedback coefficient. This is the weighting coefficient for electronic gain. The pulse width. This is the weighting coefficient for the pulse width.
[0019] The beneficial effects of this invention are that, through electric field distribution simulation, electron transport characteristic analysis, and electrostatic induction analysis, it achieves, for the first time, optimization of the grid structure from the microscopic electronic behavior process. This significantly reduces trial-and-error costs and deeply integrates physical simulation and parameter optimization functions. By selecting appropriate combinations of grid aperture ratio (the ratio of aperture to aperture plus wire diameter) and grid mesh count, it significantly improves electron transmittance, reduces primary electron loss, and effectively enhances the physical blocking ability against feedback ions, thereby directly suppressing ion feedback and improving signal pulse width and long-term detector stability. The method of this invention is scalable, allowing for the use of rectangular asymmetric grids for arrangement along the electron path. The drift direction is widened to further improve electron transmission efficiency and ensure more electrons participate in avalanche multiplication, while a smaller spacing is maintained in the lateral direction to enhance ion blocking. Moreover, this scheme can be further extended into a double-layer composite grid configuration. Through the synergy of electric fields and shielding effect between the two grid layers, the ion feedback intensity is further reduced while maintaining high electron penetration, thereby significantly improving net electron gain and gain uniformity. This overcomes the contradiction between the difficulty of balancing gain and ion suppression in traditional single-layer grids. Customized design schemes can be quickly generated for different application scenarios, providing a reliable theoretical basis for the design of high-performance microgrid gas detectors and facilitating their widespread use.
[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0021] Figure 1 This is a flowchart of the method of the present invention.
[0022] Figure 2 This is a schematic diagram of the microgrid gas detector of the present invention.
[0023] Figure 3 This is a diagram showing the electron drift trajectory and avalanche distribution when the grid arrangement in this embodiment of the invention uses a square single-layer arrangement.
[0024] Figure 4 This is a graph showing the changing trends of electron transmittance and ion feedback with the number of grid meshes when the grid arrangement is a square single-layer arrangement in an embodiment of the present invention.
[0025] Figure 5 This is a waveform diagram of the current signal generated by a single electron when the grid arrangement is a square single-layer arrangement in an embodiment of the present invention.
[0026] Figure 6 This is a waveform diagram of the voltage signal generated by a single electron when the grid arrangement in an embodiment of the present invention is a square single-layer arrangement. Detailed Implementation
[0027] like Figures 1 to 6 As shown, the present invention provides a method for optimizing the grid structure of a microgrid gas detector, comprising the following steps:
[0028] Step 1: Establish the finite element model of the microgrid gas detector, which includes a cathode, drift region, grid, amplification region, and anode. Select grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector. The grid structure parameters include the grid aperture ratio and the grid arrangement. The grid arrangement includes a square single-layer arrangement, a square double-layer arrangement, a rectangular single-layer arrangement, and a rectangular double-layer arrangement.
[0029] The selection of grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector includes: under the condition of fixed grid aperture ratio, determining the effect mechanism of grid mesh number change on electric field distortion near the grid, selecting the grid mesh number that can satisfy the electric field uniformity index, and based on this, adjusting the grid arrangement, obtaining numerical solutions of static electric field and potential distribution under different parameter combinations, and screening out the target candidate structure set;
[0030] Step 2: Convert the target candidate structure set obtained in Step 1 into a Garfield++ readable format and import it. Select a suitable working gas from the Garfield++ built-in gas database and set the ambient temperature and pressure parameters.
[0031] Step 3: Generate a specified number and spatially distributed initial ionized electrons in the drift region and track their drift trajectories from the generation location to the grid, recording the drift time and position of each electron; determine whether the electrons are captured by the grid based on accurate electric field data, count the proportion of electrons that penetrate the grid and enter the avalanche region, calculate the electron penetration rate, and plot the relationship between the electron penetration rate and the grid parameters.
[0032] Step 4: Avalanche multiplication of penetrating electrons generates secondary electrons. Random sampling is used to track the movement trajectories of secondary electrons and ions. The final number and spatial distribution of electrons and ions are recorded, and the electron gain and the proportion of ions fed back to the drift region, i.e., the ion feedback coefficient, are calculated.
[0033] Step 5: Combining the charge motion information obtained in Step 4, convolve the charge motion with the weighted field to output the original current signal; input the original current signal to the electronics response module to obtain the output voltage pulse signal and extract the pulse width;
[0034] Step 6: Analyze multiple performance indicators obtained under different grid structure parameters, including electron transmittance, electron gain, ion feedback coefficient, and output signal pulse width; comprehensively evaluate the performance of the microgrid gas detector using a multi-objective optimization strategy, and determine the optimal configuration of grid structure parameters by using the analytic hierarchy process (AHP) to determine the comprehensive score.
[0035] In this embodiment, the electric field uniformity index condition is the electric field uniformity index. ,in, , Number the grid points and , This represents the total number of grid points in the grid. For the first The electric field strength at each grid point The average electric field strength is denoted as .
[0036] In this embodiment, the working gas includes a mixture of argon and carbon dioxide.
[0037] In this embodiment, the electron transmittance , The number of electrons passing through the grid. This represents the initial number of electrons.
[0038] In this embodiment, the electronic gain , The total number after electron avalanche; the ion feedback coefficient , The number of ions that pass through the grid and reach the drift region. The number of ions after an avalanche.
[0039] In this embodiment, the original current signal , For charge quantity, For carrier velocity, The electronic response module comprises a charge-sensitive preamplifier circuit, a pole-zero cancellation circuit, and an RC differential filter shaping circuit connected in sequence.
[0040] In this embodiment, the comprehensive scoring determines the optimal configuration of the grid structure parameters. , This is a weighting coefficient for electron transmittance. This is the weighting coefficient for the ion feedback coefficient. This is the weighting coefficient for electronic gain. The pulse width. This is the weighting coefficient for the pulse width.
[0041] In using this invention, a finite element model of the microgrid gas detector is established in the COMSOL Multiphysics environment, and corresponding boundary conditions and material properties are set. The grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector are selected, and the optimal configuration of the grid structure parameters is determined by comprehensive scoring. In, the weighting coefficient of electron penetration The weighting coefficient of the ion feedback system is set to 0.3. The weighting coefficient for electronic gain is set to 0.3. The weighting coefficient for pulse width is set to 0.2. Using a value of 0.2, in this embodiment, the grid arrangement adopts a square single-layer arrangement, the cathode size is 197mm × 197mm, the wire radius is 10.5um, the aperture ratio is 0.7, and the grid mesh count is 36. Figures 3 to 6 The following are the electron drift trajectory and avalanche distribution effect under a square single-layer grid arrangement, the trend of electron penetration and ion feedback with the grid mesh number, the current signal waveform generated by a single electron, and the voltage signal waveform generated by a single electron.
[0042] In this embodiment, the grid arrangement is extended to a rectangular asymmetric grid unit structure. The cathode size is 197mm×197mm, the wire radius is 10.5um, 2000 wires are arranged in the longitudinal direction, and 3000 wires are arranged in the lateral direction. Under these conditions, the mesh count in the longitudinal direction is about 26 meshes and the aperture ratio is about 0.7; the mesh count in the lateral direction is about 39 meshes and the aperture ratio is about 0.7.
[0043] Furthermore, this scheme can be further extended to a dual-layer composite grid configuration. Through the synergy of electric fields and shielding effect between the two grid layers, the ion feedback intensity is further reduced while maintaining high electron transmittance, thereby significantly improving net electron gain and gain uniformity. This overcomes the contradiction between gain and ion suppression that is difficult to achieve simultaneously in traditional single-layer grids. Customized design schemes can be quickly generated for different application scenarios, providing a reliable theoretical basis for the design of high-performance microgrid gas detectors.
[0044] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A method for optimizing the grid structure of a microgrid gas detector, characterized in that, The method includes the following steps: Step 1: Establish the finite element model of the microgrid gas detector, which includes a cathode, drift region, grid, amplification region, and anode. Select grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector. The grid structure parameters include the grid aperture ratio and the grid arrangement. The grid arrangement includes a square single-layer arrangement, a square double-layer arrangement, a rectangular single-layer arrangement, and a rectangular double-layer arrangement. The selection of grid structure parameters that satisfy the electric field uniformity index in the microgrid gas detector includes: under the condition of fixed grid aperture ratio, determining the effect mechanism of grid mesh number change on electric field distortion near the grid, selecting the grid mesh number that can satisfy the electric field uniformity index, and based on this, adjusting the grid arrangement, obtaining numerical solutions of static electric field and potential distribution under different parameter combinations, and screening out the target candidate structure set; Step 2: Convert the target candidate structure set obtained in Step 1 into a Garfield++ readable format and import it. Select the working gas from the Garfield++ built-in gas database and set the ambient temperature and pressure parameters. Step 3: Generate a specified number and spatially distributed initial ionized electrons in the drift region and track their drift trajectories from the generation location to the grid, recording the drift time and position of each electron; determine whether the electrons are captured by the grid based on accurate electric field data, count the proportion of electrons that penetrate the grid and enter the avalanche region, calculate the electron penetration rate, and plot the relationship between the electron penetration rate and the grid parameters. Step 4: Avalanche multiplication of penetrating electrons generates secondary electrons. Random sampling is used to track the movement trajectories of secondary electrons and ions. The final number and spatial distribution of electrons and ions are recorded, and the electron gain and the proportion of ions fed back to the drift region, i.e., the ion feedback coefficient, are calculated. Step 5: Combining the charge motion information obtained in Step 4, convolve the charge motion with the weighted field to output the original current signal; input the original current signal to the electronics response module to obtain the output voltage pulse signal and extract the pulse width; Step 6: Analyze multiple performance indicators obtained under different grid structure parameters, including electron transmittance, electron gain, ion feedback coefficient, and output signal pulse width; comprehensively evaluate the performance of the microgrid gas detector using a multi-objective optimization strategy, and determine the optimal configuration of grid structure parameters by using the analytic hierarchy process (AHP) to determine the comprehensive score.
2. The method for optimizing the grid structure of a microgrid gas detector according to claim 1, characterized in that: The electric field uniformity index condition is the electric field uniformity index. ,in, , Number the grid points and , This represents the total number of grid points in the grid. For the first The electric field strength at each grid point The average electric field strength is denoted as .
3. The method for optimizing the grid structure of a microgrid gas detector according to claim 1, characterized in that: The working gas includes a mixture of argon and carbon dioxide.
4. The method for optimizing the grid structure of a microgrid gas detector according to claim 1, characterized in that: electron transmittance , The number of electrons passing through the grid. This represents the initial number of electrons.
5. The method for optimizing the grid structure of a microgrid gas detector according to claim 4, characterized in that: The electronic gain , The total number after the electron avalanche; The ion feedback coefficient , The number of ions that pass through the grid and reach the drift region. The number of ions after an avalanche.
6. The method for optimizing the grid structure of a microgrid gas detector according to claim 5, characterized in that: The original current signal , For charge quantity, For carrier velocity, The electronic response module comprises a charge-sensitive preamplifier circuit, a pole-zero cancellation circuit, and an RC differential filter shaping circuit connected in sequence.
7. The method for optimizing the grid structure of a microgrid gas detector according to claim 6, characterized in that: The comprehensive score determines the optimal configuration of the grid structure parameters. , This is a weighting coefficient for electron transmittance. The weighting coefficient for the ion feedback coefficient. This is the weighting coefficient for electronic gain. The pulse width. This is the weighting coefficient for the pulse width.