A wide-range neutron flux measurement system and calibration method for a fusion device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWESTERN INST OF PHYSICS
- Filing Date
- 2026-05-14
- Publication Date
- 2026-08-07
AI Technical Summary
然而，裂变室探测器还存在显著本底信号（α信号），导致标定方法精度低、可重复性差，亟需可在装置现场完成、且基于低本底探测器的原位标定技术
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Figure CN122525618A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of neutron flux measurement technology for nuclear fusion devices, specifically to a wide-range neutron flux measurement system and calibration method for fusion devices. Background Technology
[0002] In magnetically confined or inertial confinement fusion devices, the fusion neutron production rate is directly proportional to the fusion power and is a core parameter for evaluating the device's operational status and fusion performance. However, the fusion neutron production rate range is extremely wide (typically exceeding 1E+07), making it difficult for a single-stage detector to simultaneously meet the requirements of time resolution and effective counting. Therefore, designing multi-stage detectors to cover the entire neutron production rate range is one of the technical challenges. Furthermore, the ranges of each stage of the detectors must overlap appropriately to facilitate calibration and detection efficiency. However, fission chamber detectors still exhibit a significant background signal (alpha signal), leading to low accuracy and poor repeatability in calibration methods. Therefore, there is an urgent need for in-situ calibration techniques that can be performed on-site and are based on low-background detectors. Summary of the Invention
[0003] The purpose of this invention is to address the aforementioned shortcomings of neutron flux measurement technology in nuclear fusion devices by providing a wide-range neutron flux measurement system and calibration method for fusion devices. This system is composed of a cascaded three-stage detector consisting of a gas-filled proportional counter tube, a first fission chamber, and a second fission chamber. It has a wide single-channel measurement range and uses a low-background proportional counter tube as the first-stage calibration, which significantly reduces the background interference of traditional fission chambers and solves the problems of wide range and calibration.
[0004] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a wide-range neutron flux measurement system for a fusion device, comprising: a gas-filled proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector; wherein the gas-filled proportional counter tube detector has a detection efficiency of k for fast neutrons, the first fission chamber detector has a detection efficiency of k / 10 for fast neutrons, and the second fission chamber detector has a detection efficiency of k / 10000 for fast neutrons. The three detectors in the system operate in pulse counting mode or mean square voltage mode, respectively. The system achieves continuous coverage of neutron production rate by sequentially switching or parallelly acquiring the output signals of the three detectors in the same measurement channel according to the detection efficiency from high to low. This extends the total measurement range of the system from (5E+03 / k) / s to (1E+13 / k) / s, with a range greater than 1E+09.
[0005] As a further embodiment of the present invention, the value of k ranges from 1E-08 to 1E-06, and k can be calibrated by a fast neutron source of known intensity.
[0006] As a further embodiment of the present invention, the air-filled proportional counter tube detector operates in pulse counting mode, and its linear counting rate range is 5E+03 / s to 5E+04 / s. The linear count rate range of the first and second fission chamber detectors in pulse counting mode is 5E+03 / s to 5E+05 / s; the equivalent count rate range of the first and second fission chamber detectors in mean square voltage mode is 1E+05 / s to 1E+09 / s.
[0007] As a further aspect of the present invention, the pulse counting mode of the gas-filled proportional counter tube detector corresponds to a neutron generation rate range of (5E+03 / k) / s to (5E+04 / k) / s. The pulse counting mode of the first fission chamber detector corresponds to a neutron generation rate range of (5E+04 / k) / s to (5E+06 / k) / s; the mean square voltage mode of the first fission chamber detector corresponds to a neutron generation rate range of (1E+06 / k) / s to (1E+10 / k) / s.
[0008] As a further aspect of the present invention, the pulse counting mode of the second fission chamber detector corresponds to a neutron generation rate range of (5E+07 / k) / s to (5E+09 / k) / s; the mean square voltage mode of the second fission chamber detector corresponds to a neutron generation rate range of (1E+09 / k) / s to (1E+13 / k) / s.
[0009] As a further aspect of the present invention, the gas-filled proportional counter tube detector uses a helium-3 proportional counter tube or a boron trifluoride proportional counter tube as the detection element.
[0010] As a further aspect of the present invention, the first fission chamber detector and the second fission chamber detector use one or two of the following as detection elements: uranium-235 fission chamber, uranium-238 fission chamber, and thorium-232 fission chamber.
[0011] As a further embodiment of the present invention, for the helium-3 proportional counter tube, the boron trifluoride proportional counter tube, and the uranium-235 fission chamber, the detector comprises, from the outside to the inside: an outer shell, a cadmium layer, a moderator layer, a lead layer, and a detection element.
[0012] As a further aspect of the present invention, for the uranium-238 fission chamber and the thorium-232 fission chamber, the detector comprises, from the outside to the inside: an outer shell, a lead layer, and a detection element.
[0013] In a second aspect, the present invention provides a calibration method for a wide-range neutron flux measurement system for a fusion device as described in the first aspect, comprising the following steps: Step 1: Calibrate the counting mode of the gas-filled proportional counter tube detector using a fast neutron source with a known intensity greater than 1 / k. The calibration requires the cumulative count of the gas-filled proportional counter tube detector to be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the gas-filled proportional counter tube detector counting mode = cumulative count of the gas-filled proportional counter tube detector / cumulative number of neutrons produced by the neutron source. Step 2: Calibrate the counting mode of the first fission chamber detector using the neutron source of the fusion device. The calibration requires that the neutron production rate be in the range of (5E+03 / k) / s to (5E+04 / k) / s, the total neutron production be greater than 1E+05 / k, and the cumulative count of the first fission chamber detector be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the first fission chamber detector counting mode = cumulative count of the first fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the gas-filled proportional counter tube detector. Step 3: Calibrate the counting mode of the second fission chamber detector using the neutron source of the fusion device. The calibration requires that the neutron production rate be in the range of (5E+04 / k) / s to (5E+06 / k) / s, the total neutron production be greater than 1E+08 / k, and the cumulative count of the second fission chamber detector be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the second fission chamber detector counting mode = cumulative count of the second fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the counting mode of the first fission chamber detector. Step 4: Calibrate the mean square voltage mode of the first fission chamber detector using the neutron source of the fusion device. The calibration requires the neutron production rate to be in the range of (5E+06 / k) / s to (5E+09 / k) / s and the running time to be greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the first fission chamber detector with the neutron production rate result given by the counting mode of the second fission chamber detector. The intercept is set to the mean square voltage output value of the first fission chamber detector when the device produces no neutrons, so as to obtain the slope of the mean square voltage mode output of the first fission chamber detector with respect to the neutron production rate of the device. Step 5: Calibrate the mean square voltage mode of the second fission chamber detector using the neutron source of the fusion device. The calibration requires the neutron production rate to be between (1E+09 / k) / s and (1E+10 / k) / s, and the running time to be greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the second fission chamber detector with the neutron production rate result given by the mean square voltage mode of the first fission chamber detector. The intercept is set to the output value of the second fission chamber detector when the device produces no neutrons, and the slope of the mean square voltage mode output of the second fission chamber detector relative to the neutron production rate of the device is obtained.
[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: The measurement system of this invention consists of a gas-filled proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector cascaded together, with efficiencies k, k / 10, and k / 10000 respectively. The three detectors operate in pulse counting or mean square voltage mode respectively. The system achieves continuous coverage of neutron production rate by sequentially switching or parallelly acquiring the output signals of the three detectors in the same measurement channel according to their detection efficiencies from high to low. This allows the total measurement range of the system to cover (5E+03 / k) / s to (1E+13 / k) / s, with a range greater than 1E+09. At the same time, by using a low-background proportional counter tube as the first-stage calibration, this invention significantly reduces the background interference of traditional fission chambers, improves calibration accuracy, and has good repeatability. This system solves the two major problems of wide range and absolute efficiency calibration, and is suitable for online power monitoring of various fusion devices such as deuterium-deuterium and deuterium-tritium fusion devices. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 The working range diagram of the three detectors is shown for the measurement system of this invention, taking k=1E-07 as an example; Figure 2 This is a schematic diagram of the detector structure when using a helium-3 proportional counter tube, a boron trifluoride proportional counter tube, and a uranium-235 fission chamber as detection elements. Figure 3 This is a schematic diagram of the detector structure when uranium-238 fission chambers and thorium-232 fission chambers are used as detection elements.
[0016] The attached diagram shows the markings and corresponding component names: 01-Operating range and corresponding count rate of the gas-filled proportional counter tube detector; 02-Operating range and corresponding count rate of the first fission chamber detector in counting mode; 03-Operating range and corresponding count rate of the first fission chamber detector in mean square voltage mode; 04-Operating range and corresponding count rate of the second fission chamber detector in counting mode; 05-Operating range and corresponding count rate of the second fission chamber detector in mean square voltage mode; 11-Shell; 12-Cadmium layer; 13-Moderator layer; 14-Lead layer; 15-Detector element; 16-Cable; 21-Shell; 22-Lead layer; 23-Detector element; 24-Cable. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.
[0019] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.
[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0021] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.
[0022] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.
[0023] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.
[0024] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.
[0025] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.
[0026] In magnetically confined or inertial confinement fusion devices, the fusion neutron production rate is directly proportional to the fusion power and is a core parameter for evaluating the device's operational status and fusion performance. However, the fusion neutron production rate range is extremely wide (typically exceeding 1E+07), making it difficult for a single-stage detector to simultaneously meet the requirements of time resolution and effective counting. Therefore, designing multi-stage detectors to cover the entire neutron production rate range is one of the technical challenges. Furthermore, the ranges of each stage of the detectors must overlap appropriately to facilitate calibration and detection efficiency. However, fission chamber detectors still exhibit significant background signals, leading to low accuracy and poor repeatability in calibration methods. Therefore, there is an urgent need for in-situ calibration techniques that can be performed on-site and are based on low-background detectors.
[0027] In view of this, after in-depth research, the applicant proposed a neutron flux measurement system, which consists of a gas-filled proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector cascaded together, with efficiencies of k, k / 10, and k / 10000 respectively. They operate in pulse counting mode or mean square voltage mode respectively, and seamless connection is achieved through software switching. The system completes five-step in-situ calibration using a neutron source of known intensity and the neutron output of the fusion device itself, and achieves source tracing of absolute neutron production rate.
[0028] Please refer to Figures 1 to 3This application provides a wide-range neutron flux measurement system for a fusion device, comprising a gas-filled proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector. The gas-filled proportional counter tube detector has a detection efficiency of k for fast neutrons, the first fission chamber detector has a detection efficiency of k / 10 for fast neutrons, and the second fission chamber detector has a detection efficiency of k / 10000 for fast neutrons. The value of k ranges from 1E-08 to 1E-06, and k can be calibrated using a fast neutron source of known intensity. The gas-filled proportional counter tube detector operates in pulse counting mode, with a linear counting rate range of 5E+03 / s to 5E+04 / s; the linear counting rate range of the first fission chamber detector and the second fission chamber detector in pulse counting mode is both 5E+03 / s to 5E+05 / s; the equivalent counting rate range of the first fission chamber detector and the second fission chamber detector in mean square voltage mode is both 1E+05 / s to 1E+09 / s. The pulse counting mode of the gas-filled proportional counter tube detector corresponds to a neutron generation rate range of (5E+03 / k) / s to (5E+04 / k) / s; the pulse counting mode of the first fission chamber detector corresponds to a neutron generation rate range of (5E+04 / k) / s to (5E+06 / k) / s; the mean square voltage mode of the first fission chamber detector corresponds to a neutron generation rate range of (1E+06 / k) / s to (1E+10 / k) / s; the pulse counting mode of the second fission chamber detector corresponds to a neutron generation rate range of (5E+07 / k) / s to (5E+09 / k) / s; the mean square voltage mode of the second fission chamber detector corresponds to a neutron generation rate range of (1E+09 / k) / s to (1E+13 / k) / s. The three detectors in the system operate in either pulse counting mode or mean square voltage mode, and are seamlessly switched via software. The system achieves continuous coverage of neutron production rate by sequentially switching or acquiring the output signals of the three detectors in the same measurement channel according to their detection efficiency from high to low. This extends the total measurement range of the system from (5E+03 / k) / s to (1E+13 / k) / s, with a range greater than 1E+09.
[0029] According to some embodiments of this application, the gas-filled proportional counter tube detector uses a helium-3 proportional counter tube or a boron trifluoride proportional counter tube as the detection element; the first fission chamber detector and the second fission chamber detector use one or two of the following as the detection element: a uranium-235 fission chamber, a uranium-238 fission chamber, and a thorium-232 fission chamber.
[0030] According to some embodiments of this application, for a helium-3 proportional counter tube, a boron trifluoride proportional counter tube, and a uranium-235 fission chamber, the detector, from the outside in, comprises: a shell 11, a cadmium layer 12, a moderator layer 13, a lead layer 14, and a detection element 15, such as... Figure 2 As shown. The outer shell 11 serves as an overall enclosure and provides mechanical protection; the cadmium layer 12 is used to shield external thermal neutrons; the moderator layer 13 is used to reduce neutron energy and improve detection efficiency; the lead layer 14 is used to shield gamma rays and reduce background interference; the detection element 15 serves as a neutron-sensitive element for neutron counting; and the signal is led out to the outside of the outer shell through the cable 16 for signal transmission.
[0031] According to some embodiments of this application, for uranium-238 fission chambers and thorium-232 fission chambers, the detector, from the outside in, includes: a shell 21, a lead layer 22, and a detection element 23, such as... Figure 3 As shown. The outer shell 21 serves as an overall enclosure and provides mechanical protection; the lead layer 22 is used to shield gamma rays and reduce background interference; the detection element 23 serves as a neutron-sensitive element for neutron counting; and the signal is led out to the outside of the outer shell through the cable 24 for signal transmission.
[0032] The calibration method for a wide-range neutron flux measurement system for a fusion device as described above, provided in this application embodiment, includes the following steps: Step 1: Calibrate the counting mode of the gas-filled proportional counter tube detector using a fast neutron source with a known intensity greater than 1 / k. During calibration, the cumulative count of the gas-filled proportional counter tube detector should be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the gas-filled proportional counter tube detector counting mode = cumulative count of the gas-filled proportional counter tube detector / cumulative number of neutrons produced by the neutron source. Step 2: Calibrate the counting mode of the first fission chamber detector using the neutron source of the fusion device. During calibration, the neutron production rate of the device should be in the range of (5E+03 / k) / s to (5E+04 / k) / s, the total neutron production should be greater than 1E+05 / k, and the cumulative count of the first fission chamber detector should be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the first fission chamber detector counting mode = cumulative count of the first fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the gas proportional counter tube detector. Step 3: Calibrate the counting mode of the second fission chamber detector using the neutron source of the fusion device. During calibration, the neutron production rate of the device should be in the range of (5E+04 / k) / s to (5E+06 / k) / s, the total neutron production should be greater than 1E+08 / k, and the cumulative count of the second fission chamber detector should be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the second fission chamber detector counting mode = cumulative count of the second fission chamber detector / cumulative number of neutrons produced by the neutron source of the device given by the counting mode of the first fission chamber detector. Step 4: Calibrate the mean square voltage mode of the first fission chamber detector using the neutron source of the fusion device. During calibration, the neutron production rate of the device is required to be in the range of (5E+06 / k) / s to (5E+09 / k) / s, and the running time is greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the first fission chamber detector with the neutron production rate result given by the counting mode of the second fission chamber detector. The intercept is set to the mean square voltage output value of the first fission chamber detector when the device produces no neutrons, so as to obtain the slope of the mean square voltage mode output of the first fission chamber detector relative to the neutron production rate of the device. Step 5: Calibrate the mean square voltage mode of the second fission chamber detector using the neutron source of the fusion device. During calibration, the neutron production rate of the device should be between (1E+09 / k) / s and (1E+10 / k) / s, and the running time should be greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the second fission chamber detector with the neutron production rate result given by the mean square voltage mode of the first fission chamber detector. The intercept is set to the output value of the second fission chamber detector when the device produces no neutrons, so as to obtain the slope of the mean square voltage mode output of the second fission chamber detector relative to the neutron production rate of the device.
[0033] The neutron flux measurement system for the fusion device in this application consists of a gas-filled proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector cascaded together, with efficiencies of k, k / 10, and k / 10000, respectively. The three detectors operate in pulse counting or mean square voltage mode, respectively, and are seamlessly connected through software switching. The measurement range is wide and the measurement span is large. At the same time, this application completes a five-step in-situ calibration by using a neutron source of known intensity and the neutron output of the fusion device itself, realizing the traceability of absolute neutron production rate, with high calibration accuracy and good repeatability. Example
[0034] The following explanation uses k=1E-07 and a tokamak fusion device as an example. Other k values only need to be scaled proportionally.
[0035] The gas-filled proportional counter tube detector in the measurement system uses a helium-3 proportional counter tube with a sensitivity of 1 cm², while the detector in the first fission chamber uses a uranium-235 fission chamber with a sensitivity of 0.1 cm². 2 The second fission chamber detector uses a uranium-238 fission chamber with a sensitivity of 1E-4cm. 2 The three detectors were placed at the same location outside the tokamak, where the detection efficiency of the proportional counter tube detector was approximately 1E-07.
[0036] In the pulse counting link, the signals from the three detectors are fed into the counting circuit after passing through the preamplifier, main amplifier, and discriminator; in the mean square voltage link, the main amplifier signals from the first fission chamber detector and the second fission chamber detector are fed into the analog-to-digital converter after passing through a low-pass filter.
[0037] Figure 1 Taking k=1E-07 as an example, the operating ranges of three detectors in the measurement system are shown. Considering a time resolution of 10ms and a statistical error of less than 15%, the operating count rate of the three detectors should be greater than 5E+03 / s. The maximum count rate of the gas-filled proportional counter tube detector can reach 5E+04 / s, and its operating range is... Figure 1 The maximum count rate of the first and second fission chamber detectors can reach 5E+05 / s, and their operating range is... Figure 1 02 and 04. The equivalent count rate of the mean square voltage mode of the first and second fission chamber detectors is 1E+05 / s to 1E+09 / s, and their operating range is... Figure 1 03 and 05.
[0038] The in-situ calibration of this measurement system is performed according to the following steps: Step 1 Calibration target: Counting mode of the air-filled proportional counter tube detector. Neutron source used: Californium neutron source with known intensity and intensity greater than 1E+07. Calibration requirement: The cumulative count of the gas-filled proportional counter tube detector should be greater than 1E+4. Calibration result calculation method: Detection efficiency of gas-filled proportional counter tube detector in counting mode = cumulative count of gas-filled proportional counter tube detector / cumulative number of neutrons produced by neutron source.
[0039] Step 2 Target calibration: Counting mode of the first fission chamber detector. Neutron source used: Neutron source for fusion device Calibration requirements: neutron production rate approximately 1E+11 / s, total neutron production greater than 1E+12, and cumulative count of the first fission chamber detector greater than 1E+4. Calibration result calculation method: Detection efficiency of the first fission chamber detector in counting mode = cumulative count of the first fission chamber detector / cumulative number of neutrons generated by the device neutron source given by the gas proportional counter tube detector.
[0040] Step 3 Calibration target: Second fission chamber detector counting mode. Neutron source used: Neutron source for fusion device Calibration requirements: neutron production rate approximately 1E+13 / s, total neutron production greater than 1E+15, and cumulative count of the second fission chamber detector greater than 1E+4. Calibration result calculation method: Detection efficiency of the second fission chamber detector counting mode = cumulative count of the second fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the first fission chamber detector counting mode.
[0041] Step 4 Calibration target: Mean square voltage mode of the first fission chamber detector. Neutron source used: Neutron source for fusion device Calibration requirements: Neutron production rate in the range of 5E+13 / s to 5E+15 / s, running time greater than 1E+02 s. Calibration result calculation method: Linear fitting of the mean square voltage output value of the first fission chamber detector with the neutron production rate of the device given by the counting mode of the second fission chamber detector. The intercept is set to the mean square voltage output value of the first fission chamber detector when no neutrons are produced in the device, so as to obtain the slope of the mean square voltage mode output of the first fission chamber detector with respect to the neutron production rate of the device.
[0042] Step 5 Calibration target: Mean square voltage mode of the second fission chamber detector. Neutron source used: Neutron source for fusion device Calibration requirements: Neutron production rate between 1E+16 / s and 1E+17 / s, running time greater than 1E+02 s. Calibration result calculation method: Linear fitting of the mean square voltage output value of the second fission chamber detector with the neutron production rate of the device given by the mean square voltage mode of the first fission chamber detector. The intercept is set to the output value of the second fission chamber detector when no neutrons are produced in the device, so as to obtain the slope of the mean square voltage mode output of the second fission chamber detector with respect to the neutron production rate of the device.
[0043] After calibration, the real-time software automatically selects the corresponding detector channel based on the current count rate or mean square voltage, outputs the fusion neutron production rate, with a time resolution of 10 ms and a statistical error of less than 15%. For other k values, only proportional scaling is required.
[0044] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A wide-range neutron flux measurement system for a fusion device, characterized in that, It includes an inflatable proportional counter tube detector, a first fission chamber detector, and a second fission chamber detector; the detection efficiency of the inflatable proportional counter tube detector for fast neutrons is k, the detection efficiency of the first fission chamber detector for fast neutrons is k / 10, and the detection efficiency of the second fission chamber detector for fast neutrons is k / 10000. The three detectors in the system operate in pulse counting mode or mean square voltage mode, respectively. The system achieves continuous coverage of neutron production rate by sequentially switching or parallelly acquiring the output signals of the three detectors in the same measurement channel according to the detection efficiency from high to low. This extends the total measurement range of the system from (5E+03 / k) / s to (1E+13 / k) / s, with a range greater than 1E+09.
2. The wide-range neutron flux measurement system for fusion devices according to claim 1, characterized in that, in, The value of k ranges from 1E-08 to 1E-06, and k can be calibrated using a fast neutron source of known intensity.
3. The wide-range neutron flux measurement system for fusion devices according to claim 1, characterized in that, The gas-filled proportional counter tube detector operates in pulse counting mode, and its linear counting rate ranges from 5E+03 / s to 5E+04 / s. The linear count rate range of the first and second fission chamber detectors in pulse counting mode is 5E+03 / s to 5E+05 / s; the equivalent count rate range of the first and second fission chamber detectors in mean square voltage mode is 1E+05 / s to 1E+09 / s.
4. The wide-range neutron flux measurement system for fusion devices according to claim 1, characterized in that, The pulse counting mode of the gas-filled proportional counter tube detector corresponds to a neutron generation rate range of (5E+03 / k) / s to (5E+04 / k) / s. The pulse counting mode of the first fission chamber detector corresponds to a neutron generation rate range of (5E+04 / k) / s to (5E+06 / k) / s; the mean square voltage mode of the first fission chamber detector corresponds to a neutron generation rate range of (1E+06 / k) / s to (1E+10 / k) / s.
5. The wide-range neutron flux measurement system for fusion devices according to claim 1, characterized in that, The pulse counting mode of the second fission chamber detector corresponds to a neutron generation rate range of (5E+07 / k) / s to (5E+09 / k) / s; the mean square voltage mode of the second fission chamber detector corresponds to a neutron generation rate range of (1E+09 / k) / s to (1E+13 / k) / s.
6. The wide-range neutron flux measurement system for fusion devices according to claim 1, characterized in that, The gas-filled proportional counter tube detector uses a helium-3 proportional counter tube or a boron trifluoride proportional counter tube as the detection element.
7. The wide-range neutron flux measurement system for fusion devices according to claim 6, characterized in that, The first fission chamber detector and the second fission chamber detector use one or two of the following as detection elements: uranium-235 fission chamber, uranium-238 fission chamber, and thorium-232 fission chamber.
8. The wide-range neutron flux measurement system for fusion devices according to claim 7, characterized in that, For helium-3 proportional counters, boron trifluoride proportional counters, and uranium-235 fission chambers, the detectors, from the outside in, consist of: an outer shell, a cadmium layer, a moderator layer, a lead layer, and a detection element.
9. The wide-range neutron flux measurement system for fusion devices according to claim 7, characterized in that, For the uranium-238 fission chamber and the thorium-232 fission chamber, the detector consists of, from the outside in, the outer shell, the lead layer, and the detection element.
10. A calibration method for a wide-range neutron flux measurement system for a fusion device as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Calibrate the counting mode of the gas-filled proportional counter tube detector using a fast neutron source with a known intensity greater than 1 / k. The calibration requires the cumulative count of the gas-filled proportional counter tube detector to be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the gas-filled proportional counter tube detector counting mode = cumulative count of the gas-filled proportional counter tube detector / cumulative number of neutrons produced by the neutron source. Step 2: Calibrate the counting mode of the first fission chamber detector using the neutron source of the fusion device. The calibration requires that the neutron production rate be in the range of (5E+03 / k) / s to (5E+04 / k) / s, the total neutron production be greater than 1E+05 / k, and the cumulative count of the first fission chamber detector be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the first fission chamber detector counting mode = cumulative count of the first fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the gas-filled proportional counter tube detector. Step 3: Calibrate the counting mode of the second fission chamber detector using the neutron source of the fusion device. The calibration requires that the neutron production rate be in the range of (5E+04 / k) / s to (5E+06 / k) / s, the total neutron production be greater than 1E+08 / k, and the cumulative count of the second fission chamber detector be greater than 1E+4. The calibration result is calculated as follows: Detection efficiency of the second fission chamber detector counting mode = cumulative count of the second fission chamber detector / cumulative number of neutrons produced by the device neutron source given by the counting mode of the first fission chamber detector. Step 4: Calibrate the mean square voltage mode of the first fission chamber detector using the neutron source of the fusion device. The calibration requires the neutron production rate to be in the range of (5E+06 / k) / s to (5E+09 / k) / s and the running time to be greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the first fission chamber detector with the neutron production rate result given by the counting mode of the second fission chamber detector. The intercept is set to the mean square voltage output value of the first fission chamber detector when the device produces no neutrons, so as to obtain the slope of the mean square voltage mode output of the first fission chamber detector with respect to the neutron production rate of the device. Step 5: Calibrate the mean square voltage mode of the second fission chamber detector using the neutron source of the fusion device. The calibration requires the neutron production rate to be between (1E+09 / k) / s and (1E+10 / k) / s, and the running time to be greater than 1E+02 s. The calibration result is calculated by linearly fitting the mean square voltage output value of the second fission chamber detector with the neutron production rate result given by the mean square voltage mode of the first fission chamber detector. The intercept is set to the output value of the second fission chamber detector when the device produces no neutrons, and the slope of the mean square voltage mode output of the second fission chamber detector relative to the neutron production rate of the device is obtained.