Method and device for predicting emission capability of X-ray tube flat plate filament, and storage medium
By establishing a three-dimensional simulation model and mesh generation of the X-ray tube, and combining the coupling model and the emission current calculation model, the problem of accurately predicting the emission capability of the flat filament of the X-ray tube was solved, enabling reliable evaluation in the design stage and improving design efficiency and accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies cannot accurately quantify the emission capability of X-ray tube flat filaments, especially under different structural shapes and heating conditions. The lack of quantitative prediction methods from applied current to emission current makes it difficult to accurately assess its performance and reliability during the design phase.
A three-dimensional simulation model of the X-ray tube was established and meshed. Using a coupled model and an emission current calculation model, the steady-state temperature field distribution and emission current under the applied current were determined through multi-physics field coupling analysis. A current relationship model was established to achieve accurate prediction of the emission capability of the flat filament.
Accurate prediction of the emission capability of flat filaments was achieved during the X-ray tube design phase, which improved design efficiency, shortened the R&D cycle, provided reliable quantitative basis, and ensured the system correlation of emission performance.
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Figure CN121835166A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of current prediction of an X-ray tube, and in particular, to a method and device for predicting the emission capability of a flat filament of an X-ray tube and a storage medium. BACKGROUND
[0002] In an X-ray tube, the cathode flat filament serves as a thermal emission source, and its emission capability directly determines its performance and reliability.
[0003] However, the related art does not consider key factors such as the grid attribute and temperature field distribution of the flat filament, and thus cannot accurately quantify the emission capability difference of the flat filament under different structural shapes and heating conditions. In addition, the related art mainly focuses on the material and configuration improvement of the filament itself, lacks a quantitative prediction method from the loading current to the emission current, and thus cannot directly deduce the emission performance in the design stage through electrical parameters.
[0004] Therefore, it is difficult to quickly and accurately evaluate the emission capability of the flat filament of the X-ray tube by using the related art. SUMMARY
[0005] Embodiments of the present disclosure provide a method and device for predicting the emission capability of a flat filament of an X-ray tube and a storage medium to at least solve the technical problem that the emission capability of the flat filament of the X-ray tube is difficult to predict in the prior art.
[0006] According to an aspect of an embodiment of the present disclosure, a method for predicting the emission capability of a flat filament of an X-ray tube is provided, including: establishing a three-dimensional simulation model of the X-ray tube including a flat filament whose emission capability is to be predicted, and performing mesh division on the three-dimensional simulation model; for a plurality of different numerical loading currents preset, determining the predicted emission current of the flat filament under the different numerical loading currents based on the three-dimensional simulation model after mesh division, by using a pre-constructed coupling model and an emission current calculation model; and establishing a current relationship model for evaluating the emission capability of the flat filament according to the numerical loading currents and the corresponding predicted emission currents; wherein the coupling model is used to couple the electro-thermal conversion relationship of the flat filament and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube to determine the steady-state temperature field distribution of the flat filament under each numerical loading current; and the emission current calculation model is established based on the thermionic emission theory and takes the steady-state temperature field distribution as an input parameter.
[0007] According to another aspect of an embodiment of the present disclosure, a storage medium is also provided, which includes a stored program, wherein the program is executed by a processor when running.
[0008] According to another aspect of the embodiments of the present disclosure, a device for predicting the emission capability of a flat filament of an X-ray tube is also provided, which comprises: a processing module configured to establish a three-dimensional simulation model of the X-ray tube including the flat filament whose emission capability is to be predicted, and to perform meshing on the three-dimensional simulation model; a first determining module configured to, for a plurality of different values of a loading current, determine the predicted emission current of the flat filament under the different values of the loading current based on the meshed three-dimensional simulation model, by using a pre-constructed coupling model and an emission current calculation model; and a constructing module configured to establish a current relationship model for evaluating the emission capability of the flat filament according to the different values of the loading current and the corresponding predicted emission current; wherein the coupling model is configured to couple the solution of the electro-thermal conversion relationship of the flat filament and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, so as to determine the steady-state temperature field distribution of the flat filament under the different values of the loading current; and the emission current calculation model is established based on the thermionic emission theory and takes the steady-state temperature field distribution as an input parameter.
[0009] According to another aspect of the embodiments of the present disclosure, a device for predicting the emission capability of a flat filament of an X-ray tube is also provided, which comprises: a processing module configured to establish a three-dimensional simulation model of the X-ray tube including the flat filament whose emission capability is to be predicted, and to perform meshing on the three-dimensional simulation model; a first determining module configured to, for a plurality of different values of a loading current, determine the predicted emission current of the flat filament under the different values of the loading current based on the meshed three-dimensional simulation model, by using a pre-constructed coupling model and an emission current calculation model; and a constructing module configured to establish a current relationship model for evaluating the emission capability of the flat filament according to the different values of the loading current and the corresponding predicted emission current; wherein the coupling model is configured to couple the solution of the electro-thermal conversion relationship of the flat filament and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, so as to determine the steady-state temperature field distribution of the flat filament under the different values of the loading current; and the emission current calculation model is established based on the thermionic emission theory and takes the steady-state temperature field distribution as an input parameter.
[0010] In the embodiments of the present disclosure, firstly, a three-dimensional simulation model containing the flat filament to be predicted is established and meshed, providing an accurate geometric structure and spatial discrete basis for subsequent high-precision multi-physical field coupling analysis, ensuring that the key attributes such as the specific structure shape and size of the filament can be completely included in the calculation system. Then, for multiple loaded current values, based on the meshed model, the filament's electric-thermal conversion and the heat radiation between the filament and the electron beam channel are simultaneously solved by using the coupling model, to accurately obtain the steady-state temperature field distribution of the filament under different currents, breaking through the limitation of only considering the filament's own heating, and realizing the real simulation of the key thermal behavior in the actual working environment. The obtained steady-state temperature field distribution is input into the emission current calculation model based on the thermal electron emission theory, to realize the direct and theoretical quantitative calculation of the filament emission current, so that the prediction of the emission capacity has a solid physical theory basis. Finally, the current relationship model is established according to the correspondence between the loaded current and the predicted emission current, providing a clear and quantifiable mapping relationship between the input and output for evaluating the emission capacity of the flat filament. Thus, the emission capacity of the flat filament in the real thermal environment can be accurately predicted during the design stage of the X-ray tube, and the structure design, thermal boundary conditions and the final emission performance are systematically and reliably associated, providing a reliable quantitative basis for research and development. Moreover, through batch simulation of multiple loaded currents and establishment of the current relationship model, the research and development personnel can quickly query the emission capacity under different working conditions without repeated simulation, thereby improving the design efficiency and shortening the research and development cycle. Further, the technical problem of being difficult to predict the emission capacity of the flat filament of the X-ray tube in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS
[0011] The drawings described herein are used to provide further understanding of the present disclosure, and constitute a part of the present application. The illustrative embodiments of the present disclosure and their descriptions serve to explain the present disclosure, and do not constitute an improper limitation on the present disclosure. In the drawings: Figure 1 is a hardware structure block diagram of a computing device for implementing the method according to Embodiment 1 of the present disclosure; Figure 2 shows a three-dimensional simulation model schematic diagram for implementing the method for predicting the emission capacity of the flat filament of the X-ray tube according to the present embodiment; Figure 3A shows a structure schematic diagram of the flat filament according to the present embodiment; Figure 3B shows a structure schematic diagram of the meshed flat filament according to the present embodiment; Figure 4A shows a flowchart of a method for predicting the emission capacity of the flat filament of the X-ray tube; Figure 4BA temperature distribution diagram of the X-ray tube flat filament according to the present embodiment is shown. Figure 4C A correlation curve representing the current relationship in the X-ray tube flat filament according to the present embodiment is shown. Figure 5 A schematic diagram of the prediction device for the emission capability of the X-ray tube flat filament according to the present embodiment is shown. Figure 6 A schematic diagram of the prediction device for the emission capability of the X-ray tube flat filament according to the present embodiment is shown. DETAILED DESCRIPTION
[0012] In order to make the technical personnel in the art better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor should be within the scope of protection of the present disclosure.
[0013] It should be noted that the terms "first", "second" and the like in the specification and claims of the present disclosure and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.
[0014] First, some nouns or terms that appear in the description of the embodiments of the present disclosure are applicable to the following explanations: X-ray tube flat filament: a hot electron emission cathode with a flat, non-spiral structure in a vacuum electron tube for generating X-rays. In the present specification, it is an evaluation object for evaluating the current emission capability.
[0015] Three-dimensional simulation model: a digital model established in a computer for simulating the geometric shape and assembly relationship of a real X-ray tube (including key components such as filaments and electron beam channels).
[0016] Steady-state temperature field distribution: The temperature distribution state of the filament's interior and surface points in space, which no longer changes with time, when the filament's heat generation power and heat dissipation power reach a dynamic balance. This is the key intermediate physical state that connects the electrical input and the electron emission output.
[0017] Electro-thermal relationship: The physical relationship describing the conversion of electrical energy into thermal energy (Joule heat Pf), which in this embodiment is used to indicate the Joule's law between the resistance value of each grid element and the loading current of the flat filament.
[0018] Resistance value: The resistance of the grid element, which is a material property of the flat filament. It needs to be understood that the resistance value changes with the change of the temperature of the grid element.
[0019] Thermal radiation heat dissipation relationship: The physical relationship describing the heat radiation from the high-temperature filament surface to the cooler beam channel wall (Tr) through electromagnetic waves, the core of which is the Stefan-Boltzmann law.
[0020] Energy conservation relationship: A basic law of physics, which in this model is expressed as: Joule heat power (Pf) - thermal radiation heat dissipation power (Prad) = rate of change of internal energy of the filament. In the steady state, the rate of change of internal energy is zero, i.e. Pf=Prad.
[0021] Embodiment 1 It should be noted that the one or more processors and / or other data processing circuits described above can be referred to herein generally as "data processing circuitry". The data processing circuitry can be embodied in whole or in part as software, hardware, firmware, or any combination thereof. In addition, the data processing circuitry can be a single independent processing module, or incorporated in whole or in part into any of the other elements of the computing device. As referred to in the embodiments of the present disclosure, the data processing circuitry serves as a processor to control, for example, the selection of the variable resistance terminal path connected to the interface.
[0022] The memory can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the air quality prediction in the embodiments of the present disclosure. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory, i.e. implements the air quality prediction method of the application program described above. The memory can include a high-speed random access memory, and can also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory can further include a memory remotely arranged with respect to the processor, which can be connected to the computing device through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.
[0023] The transmission device is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by the computing device's communication provider. In one example, the transmission device includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device may be a Radio Frequency (RF) module used for wireless communication with the Internet.
[0024] The display can be, for example, a touchscreen liquid crystal display (LCD), which allows users to interact with the user interface of the computing device.
[0025] It should be noted here that, in some optional embodiments, the above... Figure 1 The computing device shown may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements. It should be noted that... Figure 1 This is only one instance of a specific particular instance, and is intended to illustrate the types of components that may exist in the aforementioned computing devices.
[0026] The embodiments provided in this specification are applied to scenarios involving the prediction of the emission capability of a flat filament. The X-ray tube typically consists of a cathode, an anode, and a tube shell. The cathode includes different types of thermal emission sources (spiral filaments or flat filaments). Heating generates heat particles around the emission source, which are then accelerated by high voltage to bombard the anode target disk, generating bremsstrahlung radiation and producing X-rays.
[0027] For ease of understanding, this instruction manual is based on Figure 2 The schematic diagram of the three-dimensional simulation model shown illustrates the method for predicting the emission capability of a flat filament in an X-ray tube.
[0028] Figure 2 A schematic diagram of a three-dimensional simulation model is shown for implementing the method for predicting the emission capability of an X-ray tube flat filament as described in this embodiment. (Reference) Figure 2 As shown, the schematic diagram of the three-dimensional simulation model includes: filament leads, flat filament, focusing structure components, electron beam channel, and anode target disk.
[0029] The filament lead is the input channel and electrical connection component for the applied current (If). It connects the external power supply to the flat filament and forms the physical basis for establishing the electrothermal conversion relationship.
[0030] Flat filament, in simulation, generates Joule heat after being loaded with current (If), and the temperature rises to the required range for thermionic emission. Its structural shape, mesh properties, and temperature distribution are used for subsequent coupling model solving, and its surface temperature field is the input of the emission current calculation model. The embodiments provided in the specification are used to predict the emission capacity (It) of the flat filament.
[0031] Focusing structure assembly, used for electrostatic focusing or shaping of the thermionic electrons emitted from the flat filament, affecting the initial trajectory and shape of the electron beam.
[0032] Electron beam channel, providing a vacuum passage and acceleration area for the thermionic electrons to fly from the cathode (filament) to the anode (target disc). In addition, it is a component of the thermal radiation heat dissipation relationship in the coupling model. Its inner wall has a preset or calculable temperature (Tr) as the target of the flat filament surface thermal radiation heat dissipation (i.e., the radiation boundary temperature). The radiation heat exchange between the filament and the channel wall is used to determine the heat dissipation condition of the filament steady-state temperature (Tfi).
[0033] Anode target disc, in simulation, is the endpoint and target of electron beam bombardment. When bombarded by high-speed electrons, X-rays are generated through bremsstrahlung.
[0034] Based on the above structure, as Figure 2 indicated, the three-dimensional simulation model of the X-ray tube including the flat filament whose emission capacity is to be predicted contains geometric entities. Together they constitute the carrier of the multi-physical field coupling simulation. Among them, the filament lead and the flat filament are the bodies where electrothermal conversion occurs. The flat filament surface and the inner wall of the electron beam channel constitute a pair of thermal radiation heat dissipation relationship. The focusing structure assembly and the electron beam channel are used to define the electron motion environment. After all the structures are meshed, their geometric properties and material properties are defined, which jointly act on the solution of the coupling model and the emission current calculation model, so as to realize the quantitative prediction from the loaded current (If) to the predicted emission current (It). For example, when the X-ray tube is working, the filament needs to be loaded with appropriate current, which generates heat after passing through the flat filament, and a hot spot is generated around the flat filament. Then, through the high-voltage acceleration under the vacuum condition of the X-ray tube, the electron beam flow bombards the anode target disc, and finally forms bremsstrahlung to generate X-rays.
[0035] Further, in order to facilitate the understanding of the flow path of the current in the flat filament, the schematic diagram as Figure 3A indicated is used in the specification to schematically illustrate the structure of the flat filament.
[0036] Figure 3A The structural schematic diagram of the flat filament used to implement the embodiment described in the specification is shown. As Figure 3A indicated, the flat filament involved in the embodiment is obtained, and Figure 3AOn the basis of the flat filament, grid processing is performed to obtain a plurality of grid units.
[0037] The flat filament obtained after the grid processing is as shown in Figure 3B . Figure 3B A structure diagram for implementing the flat filament containing a plurality of grid units is shown. According to the plurality of grid units divided in the flat filament, when the current is loaded, the current flows along the texture of the structure of the plurality of grid units, enters from the entrance and flows out from the exit in the diagram.
[0038] In Figure 3B , the current flows along the path with the minimum resistance, that is, the texture defined direction, which causes the non-uniform distribution of the current density on the surface of the filament. In addition, due to the different lengths and cross-sectional areas of the current path, the resistance values (Ri) of different regions are different. According to the Joule law, the Joule heat power (Pf) is non-uniformly generated in space, which further causes the non-uniform distribution of the subsequent temperature field (Tfi).
[0039] The Joule heat power can be represented as: Where i represents the i-th grid unit, and the value range is 1, 2, 3…N, is the filament current; is the resistance value of the grid, is the temperature of the grid, represents the resistance value of the filament as a temperature-dependent relationship.
[0040] When the flat filament works, heat is generated by loading the current, and then the flat filament and the annular edge of the electron channel perform heat radiation to dissipate heat, and the radiation heat dissipation power Prad is calculated as follows: σ Where is the thermal emissivity of the filament surface, σ is the Boltzmann constant, and the value is 5.67x10-8 W / (m2K4), is the area of the grid of the filament, is the temperature of the grid of the filament, is the temperature of the annular edge of the electron channel.
[0041] Further, when the flat filament works, the power generated by loading the current, but due to the temperature difference between the electron beam channel and the surface of the filament, heat radiation is formed, so the power Pem accumulated on the surface of the filament for heat emission can be calculated using the following formula: Pem=Pf–Prad Using the thermodynamic calculation formula, we get: wherein, is the heat of each grid unit of the flat filament, is the specific heat capacity of the flat filament grid unit, is the mass of the grid unit.
[0042] Based on the above, the relationship between the filament loading current If and the filament temperature It is obtained: σ On this basis, by heating a hot electron around the emission source, an electron beam current is generated by accelerating the hot electron around the emission source to bombard the target disc of the prototype. The emission current It can be calculated by the following formula: According to the above obtained steady-state temperature field distribution between the loading current and the temperature, and the relationship between the emission current It and the temperature, the relationship between the loading current and the emission current is obtained: Under the above operating premise, in order to facilitate the calculation of the relationship between the loading current and the emission current, according to a first aspect of the embodiment, a prediction method for the emission capacity of an X-ray tube flat filament is provided, which is realized based on Figure 2 the three-dimensional simulation model shown in Figure 4A A flow chart for realizing a prediction method for the emission capacity of an X-ray tube flat filament is shown, referring to Figure 4A the method comprises: S402: Establish a three-dimensional simulation model of an X-ray tube including a flat filament whose emission capacity is to be predicted, and perform grid division on the three-dimensional simulation model.
[0043] Wherein, the emission capacity: refers to the ability of the filament to generate an electron beam current through thermionic emission under specific working conditions, and the quantitative index is the emission current (It).
[0044] Grid division: the process of discretizing a continuous three-dimensional model into a finite number of small units (grids) with regular shapes (such as tetrahedrons, hexahedrons).
[0045] Specifically, first, a three-dimensional geometric model of an X-ray tube containing the target filament is constructed, then it is meshed, the continuous geometry is converted into a discrete set of grid units, and each grid unit is given material properties such as resistivity, thermal conductivity, specific heat capacity, and surface emissivity.
[0046] The flat filament is meshed to obtain multiple mesh elements, and the geometric and material properties of each mesh element are determined.
[0047] Among them, geometric properties refer to quantitative parameters describing the spatial shape and size of each mesh cell. For example, these include: Volume: used to calculate the cell's mass and internal energy storage; Surface area: the effective emission surface area exposed on the surface participating in thermal radiation and electron emission, which is a direct input for calculating radiative heat dissipation power (Prad) and emission current contribution (It); Centroid coordinates, normal vector, etc.: used to determine the cell's spatial position and orientation.
[0048] Material properties: These are parameters assigned to each mesh element that characterize its physical properties. Examples include: Electrical properties such as resistivity (or conductivity), which is fundamental for calculating the element resistance (Ri) and thus determining Joule heat (Pf). Thermal properties such as specific heat capacity (used to calculate changes in internal energy), thermal conductivity (affecting internal heat conduction, especially in transient analysis), and surface thermal emissivity (ε) (key to determining radiative heat dissipation capacity). Mass density: Combined with element volume, it allows calculation of element mass (mi), and is part of the inertia term. Emission properties such as work function (W) and Richardson's constant (A0), while typically global material properties, are also associated with mesh elements as key parameters.
[0049] In one specific embodiment provided in this specification, the flat filament is spatially discretized. For example, using professional CAE software, the user sets the mesh type (e.g., tetrahedron), size, and accuracy requirements. The software automatically divides the three-dimensional CAD model of the flat filament into an assembly composed of thousands of mesh units. Each spatially discretized abstract geometric unit is given a real physical meaning, making it an entity that carries specific physical processes, thus obtaining the mesh unit.
[0050] The flat filament structure obtained by meshing is as described above. Figure 3B The contents shown will not be repeated here.
[0051] According to the embodiments provided in this specification, the structure of the flat filament leads to non-uniformity in current, heat generation, and temperature. Meshing, by decomposing the filament into a large number of small cells, allows the software to independently calculate the local current density, resistance, heating power, and temperature of each cell. Binding material properties to each mesh cell means that physical laws (Joule's law, radiation law) are applied to every point in space during the calculation. This ensures the physical fidelity of the subsequent coupled model solution, enabling the predicted temperature field (Tfi) to reflect the true spatial impact of material properties, thereby significantly improving the prediction accuracy and reliability of the subsequent current relationship model.
[0052] S404: For a plurality of different values of the preset loading current, based on the three-dimensional simulation model after meshing, the coupling model and the emission current calculation model are used to determine the predicted emission current of the flat filament under different values of the loading current.
[0053] wherein the loading current (If): the working current flowing in for heating the filament, is a controllable input variable, used to determine the heating power of the filament.
[0054] Coupling model: a multi-physics mathematical model integrating the two mutually influencing physical processes of electro-thermal conversion and thermal radiation heat dissipation. It needs to be understood that the two processes of electro-thermal conversion and thermal radiation heat dissipation are strongly coupled due to the sharing of temperature variables, and therefore need to be solved simultaneously.
[0055] Emission current calculation model: a mathematical model based on the theory of thermionic emission (e.g. Richardson-Dushman law), which quantifies the spatial distribution of the temperature field as the total emission current.
[0056] Predicted emission current (It): the filament emission current value corresponding to a certain specific loading current (If), which is the output result of the simulation.
[0057] S406: According to the loading current of each value and the corresponding predicted emission current, an electric current relationship model for evaluating the emission capacity of the flat filament is established.
[0058] Current relationship model: a mathematical expression form based on multiple sets of (If, It) data, used to describe the quantitative correspondence between the two, such as fitting curve, empirical formula or data table.
[0059] wherein the coupling model is used to couple the electro-thermal conversion relationship of the flat filament and the thermal radiation heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube to determine the steady-state temperature field distribution of the flat filament under each value of the loading current; the emission current calculation model is based on the theory of thermionic emission and takes the steady-state temperature field distribution as the input parameter.
[0060] Steady-state temperature field distribution: when the heat generated by Joule heating inside the filament and the heat dissipated to the environment through radiation reach a dynamic balance, the temperature spatial distribution state (Tfi) formed throughout the filament volume and surface that does not change with time.
[0061] Specifically, when the flat filament is loaded with current, Joule heat is generated. Based on the loading current and the resistance value of each grid element, the filament Joule heat power Pf is obtained as: wherein i represents the i-th grid element, the value range is 1, 2, 3…N, is the loading current of the flat filament; is the resistance value of the filament at the grid unit, is the temperature of the filament at the grid unit, indicates that the resistance value of the filament has a relationship related to temperature.
[0062] Furthermore, based on the temperature, surface area of each grid unit, and the preset radiation boundary temperature of the electron beam channel, the thermal radiation heat dissipation power is determined. That is, when the flat filament is working, heat is generated by the loading current, and then the flat filament and the annular edge of the electron channel perform thermal radiation heat dissipation. The calculation method of the radiation heat dissipation power Prad is as follows: σ Among them, is the thermal emissivity of the filament surface, σ is the Boltzmann constant, and its value is 5.67x10-8 W / (m2K4), is the area of the filament grid, is the temperature of the filament at the grid, is the temperature of the annular edge of the electron channel.
[0063] When the flat filament is working, the loading current generates power Pf. However, due to the temperature difference between the electron beam channel and the filament surface, thermal radiation heat dissipation is formed. Therefore, the power Pem accumulated on the filament surface for thermal emission can be calculated using the following formula: Pem = Pf – Prad Furthermore, the rate of change of the internal energy of the flat filament with time can be characterized as: Among them, is the heat of each grid point of the filament, is the specific heat capacity of the filament grid point, is the mass of the grid unit.
[0064] It should be understood that in this specification, by setting the density of the flat filament, the size of each grid unit is obtained after grid division, and the mass of the grid unit is obtained by multiplying the density of the flat filament by the size of each grid unit.
[0065] On this basis, based on the relationship that the difference between the Joule heat power and the thermal radiation heat dissipation power is equal to the rate of change of the internal energy of the flat filament with time, the energy conservation relationship is determined, and we get: σ Based on the above, a coupled model is constructed. It is important to understand that the coupled model is used to solve the electrothermal conversion relationship of the flat filament and the thermal radiation dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, in order to determine the steady-state temperature field distribution of the flat filament under various applied current values.
[0066] Specifically, to facilitate understanding of the steady-state temperature field, this specification uses the following... Figure 4B The method shown is illustrated as an example.
[0067] Figure 4B A temperature distribution diagram of the flat filament of the X-ray tube according to this embodiment is shown.
[0068] like Figure 4B The image shows the flat filament described above in this specification. In this flat filament, the perforated portions on the left and right sides are filament leads for carrying current; the comb-shaped area in the middle is the thermal emission body of the flat filament. Figure 4B In the middle, on the right side, there is also a region representing a temperature range (1800K~2600K is used as an example in this manual). The central part of the comb-shaped region is the lightest color, indicating that this part has the highest temperature according to the temperature range representation. The color gradually darkens as you move closer to the leads on both sides, indicating that the temperature gradually decreases according to the temperature range representation. Based on this, it can be seen that because the central region is farther from the leads and has more heat accumulation, while the edge regions are closer to the leads and dissipate heat faster, there is an uneven temperature distribution in the flat filament.
[0069] According to the embodiments provided in this specification, the electrothermal heat generation and radiative heat dissipation are modeled, reflecting the physical essence. This allows the model to simulate the complete dynamic process from the initial temperature rise (Pf > Prad) after energization to the final attainment of thermal equilibrium (Pf = Prad). Heat generation and dissipation are coupled based on the energy conservation principle, ensuring the physical plausibility of the solved temperature field. Furthermore, by building the model on a grid and specifying the parameters in the relationships, a structured framework is provided for accurately handling physical nonlinearities and spatial distribution characteristics. This enables the model to predict localized overheating (hot spots) or cooling phenomena caused by irregular filament shapes and complex current paths.
[0070] In one specific embodiment provided in this specification, thermal particles are generated around the emission source by heating, and an electron beam is generated by accelerating the thermal particles around the emission source using high voltage to bombard the prototype target disk. The emission current It can be calculated using the following formula: in, For the area of the grid cell, These are constants related to the material. This is the work function of the cathode material. is the Boltzmann constant.
[0071] According to the above manner, the emission current calculation model is obtained.
[0072] Further, based on the Richardson-Dushman thermal emission law, the thermal electron emission current density of each grid element is calculated according to the temperature of each grid element in the steady-state temperature field distribution, the work function and the emission constant of the flat filament cathode material. The thermal electron emission current density of all grid elements is integrated along the surface area of each grid element, and the sum is obtained to obtain the predicted emission current.
[0073] The Richardson-Dushman thermal emission law is a basic physical law for describing the phenomenon of thermal electron emission of metal materials at high temperatures.
[0074] The work function (W) of the flat filament cathode material refers to the minimum energy required to move an electron from the interior of the filament cathode material to the vacuum. It is an intrinsic property of the material, and the greater the value, the smaller the emission current at the same temperature.
[0075] The emission constant (A0) is also known as the Richardson constant, which is a physical constant related to the surface properties of the cathode material, and is used to quantify the thermal electron emission capability of the material.
[0076] Thermal electron emission current density refers to the emission current size per unit area on the filament surface generated by thermal excitation effect, which is an intensity quantity. Each grid element has its own independent current density value, which is determined by the temperature (Tfi) and material properties (W, A0) of the element itself.
[0077] Surface integration is a mathematical operation used to calculate the total amount of a non-uniform field (such as current density) on a curved surface (such as the filament emission surface). In a discretized grid model, the integration is realized by summation.
[0078] Predicted emission current (It): the total current value emitted from the entire filament surface calculated by the above integration and summation.
[0079] Specifically, the steady-state temperature field distribution of the flat filament under the loading current of each numerical value obtained in the above content is input into the emission current calculation model to obtain the following relationship: Further, the current relationship model for evaluating the emission capability of the flat filament is obtained.
[0080] The emission current calculation model refers to the conversion process from the steady-state temperature field distribution (Tfi) to the predicted emission current (It).
[0081] Specifically, for ease of understanding, the current relationship model is described in the form of a fitting curve in the specification.
[0082] Figure 4C The correlation curve representing the current relationship in the X-ray tube flat filament according to the present embodiment is shown.
[0083] As Figure 4C shown, the horizontal axis represents the flat filament temperature (Tfi), which is represented in the graph as Temperature / K, and the results obtained by electrothermal coupling and thermal radiation simulation. The left vertical axis represents the emission current (It), which is represented in the graph as Emission Current / mA, and the results calculated by substituting the temperature into the thermal emission formula. The right vertical axis is the filament loading current (If), which is represented in the graph as 4.8A / 6.7A, used to represent the change of the loading current from 4.8A to 6.7A.
[0084] As Figure 4C shown, as the temperature rises, the emission current shows a rapid upward trend. That is, as the temperature is higher, the probability of thermal electron escape increases faster, so the emission current will increase exponentially with the temperature.
[0085] According to Figure 4C , for a specific emission current, the required filament temperature can be quickly determined by the curve, and the corresponding loading current (If) is then deduced. This intuitively reflects the regulatory effect of the loading current on the emission capacity.
[0086] According to the above embodiments provided in the specification, the prediction method is ensured to be correct and reliable in terms of theoretical origin according to the basic physical law of thermal emission. The discrete non-uniform temperature field (Tfi) is taken as input, and the total emission current is accurately calculated. The real contribution of hot spots or cold zones caused by filament structure and uneven current distribution to the overall performance is accurately reflected.
[0087] Specifically, for a plurality of different numerical values of the loading current, based on the three-dimensional simulation model after grid division, the coupling model and the emission current calculation model are used to determine the predicted emission current of the flat filament under different numerical values of the loading current, including: For each current value in the plurality of different numerical values of the loading current, the following steps are performed: The current value of the loading current is applied to the flat filament in the three-dimensional simulation model after grid division as an excitation condition; Based on the excitation condition, the three-dimensional simulation model is numerically solved by the coupling model to determine the steady-state temperature field distribution of the flat filament when thermal equilibrium is reached; Based on the steady-state temperature field distribution, the predicted emission current of the flat filament under the current loading value is calculated by the emission current calculation model.
[0088] The preset multiple different current loading values are a set of discrete current values preset according to the actual working conditions of the X-ray tube flat filament before simulation calculation, which are used to cover the conventional working current range of the filament, and the core purpose is to establish the corresponding relationship between the loading current and the emission current through multiple sets of data.
[0089] The predicted emission current refers to the theoretical value of the thermionic emission current of the flat filament under a specific loading current obtained by the coupling model and the emission current calculation model simulation, which is used to represent the emission capacity of the filament, and the deviation from the actual test value is small.
[0090] The current loading value refers to a single current value selected from the preset multiple different current loading values, which is the input excitation of single simulation and is used to calculate the temperature field and emission current of the filament under the current.
[0091] The excitation condition refers to the electric load applied to the flat filament in the three-dimensional simulation model, that is, the current loading value, which functions to simulate the actual working state of the flat filament.
[0092] Thermal equilibrium refers to the state in which the Joule heat power (Pf) and the thermal radiation heat dissipation power (Prad) of the flat filament reach dynamic balance, at which time the temperature of the filament no longer fluctuates with time, forming a stable temperature distribution.
[0093] In a specific embodiment provided in the specification, the input known parameters are the Boltzmann constant σ, the surface thermal emissivity ε of the filament, and the temperature Tr of the annular edge of the electron beam channel. The material library function is called to obtain the temperature-related properties of each grid element. The simulation software iteratively calculates the integrated equation of the coupling model until the temperature of the filament no longer changes, and outputs the temperature value of each grid element, forming a steady-state temperature field distribution.
[0094] Based on the above, the temperature Tfi of each grid element is extracted and substituted into the emission current calculation model, where A0 is a material constant, W is the cathode escape work, and k is the Boltzmann constant. The surface integral of the emission current contribution density of all grid elements is performed, and the sum is obtained to get the total emission current It (i.e., the predicted emission current).
[0095] According to the embodiments provided in the specification, the steady-state temperature field distribution when thermal equilibrium is reached avoids the calculation deviation of the emission current caused by the non-steady-state temperature. In addition, the coupling model integrates the three core relationships of electro-thermal, thermal radiation and energy conservation, covers all key factors of the filament temperature change, and ensures that the temperature field calculation is close to the actual situation. The deviation between the predicted emission current and the actual test value is small, which can provide reliable quantitative basis for the research and development of the X-ray tube and avoid product design defects caused by estimated emission capacity. By presetting multiple different loading currents and designing each solution, the conventional working current range of the filament can be covered at one time without making multiple physical samples for testing one by one; at the same time, the efficiency of numerical solution after grid division is much higher than that of physical testing. The development cycle of the X-ray tube flat filament is shortened, and the development cost is reduced.
[0096] It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the action sequence described, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily necessary for the present application.
[0097] From the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be realized by means of software and the necessary general hardware platform, and of course it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product in essence or in the form of a part that contributes to the prior art. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a plurality of instructions for making a terminal device (which can be a mobile phone, computer, server, or network device, etc.) execute the method described in each embodiment of the present application.
[0098] Embodiment 2 Figure 5 The prediction device of the X-ray tube flat filament emission capacity according to the present embodiment is shown, which corresponds to the method according to the first aspect of embodiment 1. Referring to Figure 5As shown, the device comprises: a processing module 510, configured to establish a three-dimensional simulation model of an X-ray tube including a flat filament to be predicted for emission capacity, and perform meshing on the three-dimensional simulation model; a determination module 520, configured to, for a plurality of different values of a preset loading current, determine a predicted emission current of the flat filament under different values of the loading current based on the three-dimensional simulation model after meshing, by using a pre-constructed coupling model and an emission current calculation model; and a construction module 530, configured to establish a current relationship model for evaluating the emission capacity of the flat filament according to each value of the loading current and the corresponding predicted emission current; wherein the coupling model is used to couple the solution of the electro-thermal conversion relationship of the flat filament, and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, to determine the steady-state temperature field distribution of the flat filament under each value of the loading current; and the emission current calculation model is established based on the thermionic emission theory and takes the steady-state temperature field distribution as an input parameter.
[0099] It should be noted that the X-ray tube flat filament emission capacity prediction device provided in the embodiment can realize all functions and steps in the method embodiment, solve the same technical problem, and achieve the same technical effect. The same parts will not be described again.
[0100] Thus, in the present embodiment, firstly, a three-dimensional simulation model containing the flat filament to be predicted is established and meshed, providing an accurate geometric structure and spatial discrete basis for subsequent high-precision multi-physical field coupling analysis, ensuring that key attributes such as the specific structure shape and size of the filament can be completely incorporated into the calculation system. Then, for multiple load current values, based on the meshed model, the filament's electro-thermal conversion and heat radiation between the filament and the electron beam channel are simultaneously solved using the coupling model to accurately determine the steady-state temperature field distribution of the filament under different currents, breaking through the limitation of only considering the filament's own heating, realizing the real simulation of the key thermal behavior in the actual working environment, and inputting the obtained steady-state temperature field distribution into the emission current calculation model based on the thermal electron emission theory to realize the direct and theoretical quantitative calculation of the filament's emission current, making the prediction of the emission capacity have a solid physical theory basis. Finally, a current relationship model is established according to the correspondence between the load current and the predicted emission current, providing a clear and quantifiable mapping relationship between the input and output for evaluating the emission capacity of the flat filament. Thus, it is realized that during the design stage of the X-ray tube, the emission capacity of the flat filament in the real thermal environment can be accurately predicted through the electrical parameters (i.e., the load current), and the structure design, thermal boundary conditions, and final emission performance are systematically and reliably related, providing a reliable quantitative basis for research and development design. Moreover, through batch simulation of multiple load currents and establishment of the current relationship model, researchers can quickly query the emission capacity under different working conditions without repeated simulation, thereby improving design efficiency and shortening the research and development cycle. Further, the technical problem of being difficult to predict the emission capacity of the flat filament of the X-ray tube in the prior art is solved.
[0101] Embodiment 3 Figure 6 A device for predicting the emission capacity of the flat filament of the X-ray tube according to the present embodiment is shown, which corresponds to the method according to the first aspect of embodiment 1. Reference is made to Figure 6As shown, the device comprises: a processor 610; and a memory 620 connected with the processor 610, used to provide the processor 610 with instructions to process the following processing steps: establishing a three-dimensional simulation model of an X-ray tube including a flat filament to be predicted for emission capacity, and performing meshing on the three-dimensional simulation model; for a plurality of different values of a preset loading current, based on the three-dimensional simulation model after meshing, using a pre-constructed coupling model and an emission current calculation model to determine the predicted emission current of the flat filament under different values of the loading current; according to each value of the loading current and the corresponding predicted emission current, establishing a current relationship model for evaluating the emission capacity of the flat filament; wherein the coupling model is used to couple the solution of the electro-thermal conversion relationship of the flat filament, and the thermal radiation heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, to determine the steady-state temperature field distribution of the flat filament under each value of the loading current; the emission current calculation model is established based on the thermionic emission theory, and the steady-state temperature field distribution is taken as an input parameter.
[0102] It should be noted that the X-ray tube flat filament emission capacity prediction device provided in the embodiment can realize all functions and steps in the method embodiment, solve the same technical problem, and achieve the same technical effect. The same parts will not be described again.
[0103] In the embodiments of the present disclosure, firstly, a three-dimensional simulation model containing the flat filament to be predicted is established and meshed, thereby providing an accurate geometric structure and spatial discrete basis for subsequent high-precision multi-physical field coupling analysis, and ensuring that the key attributes such as the specific structure shape and size of the filament can be completely included in the calculation system. Then, for multiple loaded current values, based on the meshed model, the filament's electric-thermal conversion and the heat radiation between the filament and the electron beam channel are simultaneously solved by using the coupling model, so as to accurately determine the steady-state temperature field distribution of the filament under different currents, break through the limitation of only considering the filament's own heating, realize the real simulation of the key thermal behavior under the actual working environment, and input the obtained steady-state temperature field distribution into the emission current calculation model established based on the thermal electron emission theory, so as to realize the direct and theoretical quantitative calculation of the filament emission current, so that the prediction of the emission capacity has a solid physical theory basis. Finally, a current relationship model is established according to the corresponding relationship between the loaded current and the predicted emission current, thereby providing a clear and quantifiable mapping relationship between the input and output for evaluating the emission capacity of the flat filament. Thus, the emission capacity of the flat filament under the real thermal environment can be accurately predicted through the electrical parameter (i.e., the loaded current) in the design stage of the X-ray tube, the structure design, the thermal boundary condition and the final emission performance are systematically and reliably associated, and a reliable quantitative basis is provided for the research and development design. Moreover, through batch simulation of multiple loaded currents and establishment of the current relationship model, the research and development personnel can quickly query the emission capacity under different working conditions without repeated simulation, thereby improving the design efficiency and shortening the research and development cycle. Further, the technical problem that the emission capacity of the flat filament of the X-ray tube is difficult to predict in the prior art is solved.
[0104] The above-mentioned serial numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.
[0105] In the above-mentioned embodiments of the present application, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.
[0106] In several embodiments provided in the present application, it should be understood that the disclosed technical content can be implemented by other ways. Among them, the above-mentioned device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division way, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed each other can be through some interface, indirect coupling or communication connection between units or modules, which can be electrical or other forms.
[0107] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.
[0108] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present alone, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.
[0109] The integrated unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the present application or the part of the prior art that essentially contributes or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The foregoing storage medium includes: a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, and various program code storage media.
[0110] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.
Claims
1. A method of predicting the emission capability of a flat filament of an X-ray tube, characterized in that, The method comprises the steps of: establishing a three-dimensional simulation model of an X-ray tube including a flat filament to be predicted emission capacity, and performing meshing on the three-dimensional simulation model; for a plurality of preset different values of loading current, based on the three-dimensional simulation model after meshing, using a pre-constructed coupling model and an emission current calculation model, determining the predicted emission current of the flat filament under different values of loading current; according to each value of loading current and the corresponding predicted emission current, establishing a current relationship model for evaluating the emission capacity of the flat filament; wherein the coupling model is used to couple the solution of the electro-thermal conversion relationship of the flat filament, and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube, to determine the steady-state temperature field distribution of the flat filament under each value of loading current; the emission current calculation model is established based on the thermionic emission theory, and the steady-state temperature field distribution is used as an input parameter.
2. The method of claim 1, wherein, The operation of determining the predicted emission current of the flat filament under different values of loading current based on the three-dimensional simulation model after meshing, using a pre-constructed coupling model and an emission current calculation model, for a plurality of preset different values of loading current, comprises: for each current value in the plurality of different values of loading current, performing the following steps: applying the current value of loading current as an excitation condition to the flat filament in the three-dimensional simulation model after meshing; based on the excitation condition, performing numerical solution on the three-dimensional simulation model through the coupling model to determine the steady-state temperature field distribution of the flat filament when reaching thermal equilibrium; based on the steady-state temperature field distribution, calculating the predicted emission current of the flat filament under the current value of loading current through the emission current calculation model.
3. The method of claim 1, wherein, The flat filament in the three-dimensional simulation model after meshing comprises at least one grid unit; the coupling model is constructed by the following method: establishing an electro-thermal relationship for determining Joule heat power based on the loading current and the resistance value corresponding to each grid unit; establishing a heat radiation and heat dissipation relationship for determining heat radiation and heat dissipation power based on the temperature, surface area of each grid unit and the preset radiation boundary temperature of the electron beam channel; establishing an energy conservation relationship, and coupling the Joule heat power and the heat radiation and heat dissipation power based on the energy conservation relationship.
4. The method of claim 3, wherein, The energy conservation relationship satisfies the following relationship: the difference between the Joule heat power and the heat radiation and heat dissipation power is equal to the rate of change of the internal energy of the flat filament with respect to time.
5. The method of claim 3, wherein, The calculation of the heat radiation and heat dissipation power is proportional to the difference between the fourth power of the temperature of each grid unit and the fourth power of the preset radiation boundary temperature of the electron beam channel.
6. The method of claim 3, wherein, The resistance value corresponding to each grid unit is determined based on the temperature of each grid unit.
7. The method according to claim 1 or 2, characterized in that, The emission current calculation model is constructed by the following method: based on the Richardson-Dushman thermionic emission law, calculating the thermionic emission current density of each grid unit according to the temperature of each grid unit in the steady-state temperature field distribution, the work function and the emission constant of the cathode material of the flat filament; The thermal electron emission current density of all the grid cells is integrated along the surface area of each grid cell, and summed to obtain the predicted emission current.
8. The method of claim 1, wherein, The meshing of the three-dimensional simulation model comprises: The flat filament is meshed to obtain a plurality of grid cells, and geometric properties and material properties of each grid cell are determined.
9. An apparatus for predicting the emission capability of a flat filament of an X-ray tube, characterized by Comprise: A processing module is configured to establish a three-dimensional simulation model of an X-ray tube including a flat filament whose emission capability is to be predicted, and mesh the three-dimensional simulation model; A first determining module is configured to, for a plurality of different values of loading current preset, determine predicted emission currents of the flat filament under different values of loading current based on the three-dimensional simulation model after meshing, by using a coupling model and an emission current calculation model constructed in advance; A constructing module is configured to establish a current relationship model for evaluating the emission capability of the flat filament according to each value of loading current and the corresponding predicted emission current. The coupling model is used to couple the solution of the electro-thermal conversion relationship of the flat filament and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube to determine the steady-state temperature field distribution of the flat filament under each value of loading current; and the emission current calculation model is established based on the theory of thermal electron emission and takes the steady-state temperature field distribution as an input parameter.
10. An apparatus for predicting the emission capability of a flat filament of an X-ray tube, characterized by Comprise: A processor; And A memory connected with the processor, configured to provide the processor with instructions for processing the following processing steps: Establish a three-dimensional simulation model of an X-ray tube including a flat filament whose emission capability is to be predicted, and mesh the three-dimensional simulation model; For a plurality of different values of loading current preset, determine predicted emission currents of the flat filament under different values of loading current based on the three-dimensional simulation model after meshing, by using a coupling model and an emission current calculation model constructed in advance; According to each value of loading current and the corresponding predicted emission current, establish a current relationship model for evaluating the emission capability of the flat filament; The coupling model is used to couple the solution of the electro-thermal conversion relationship of the flat filament and the heat radiation and heat dissipation relationship between the flat filament and the electron beam channel of the X-ray tube to determine the steady-state temperature field distribution of the flat filament under each value of loading current; and the emission current calculation model is established based on the theory of thermal electron emission and takes the steady-state temperature field distribution as an input parameter.