A high-temperature fast-response optical fiber temperature sensor

Abstract

This invention provides a high-temperature, fast-response fiber optic temperature sensor, comprising a single-mode fiber and a sensor encapsulation structure. The single-mode fiber includes a head end, a body, and a pigtail connected sequentially along its extension direction, and a temperature grating is disposed on the single-mode fiber. The sensor encapsulation structure includes an encapsulation shell and a front connector and a pigtail structure respectively connected to both ends of the encapsulation shell. The encapsulation shell is fitted onto the body, and a connecting plate is disposed inside the encapsulation shell; the encapsulation shell and the connecting plate are an integrated structure. A pressure balancing hole is provided on the front connector, and the pigtail structure is fitted onto the pigtail. This application integrates the encapsulation shell and the connecting plate into a single structure, allowing the encapsulation shell to quickly transfer ambient temperature to the grating fiber through the integrated structure, thus improving the sensor's response speed. The pressure balancing hole on the front connector ensures pressure balance and effective detection under vacuum conditions.

Description

Technical Field

[0001] This invention belongs to the field of temperature detection equipment technology, specifically relating to a high-temperature fast-response fiber optic temperature sensor. Background Technology

[0002] A neutral beam injector (NBI) is a device that generates a beam of high-energy neutral particles and delivers it to a Tokamak plasma to complete a nuclear fusion reaction.

[0003] During experimental operation of the neutral beam injector, the internal temperature approaches 200°C, and the vacuum level is less than 0.1 Pa. Simultaneously, due to the electrode structure and spatial effects of the ion source, the diverging beam collidees with various limiters along the beam channel, causing the limiters and related components to overheat rapidly, exacerbating component damage and affecting the service life of the neutral beam injector. Therefore, it is necessary to effectively and accurately monitor the internal temperature of the neutral beam injector. This is crucial for preventing rapid temperature increases that could damage heat-flow components and ensuring the stable operation of the nuclear fusion device.

[0004] Currently, thermocouple temperature sensors are commonly used to monitor the temperature during the neutral beam ion implantation heating process. However, due to the strong magnetic and high-voltage environment at the neutral beam injector experimental site, thermocouple temperature sensors are easily affected by electromagnetic noise and cannot effectively and accurately monitor the internal temperature of the neutral beam injector. Summary of the Invention

[0005] This application provides a high-temperature fast-response fiber optic temperature sensor that is suitable for the strong magnetic and high-temperature environment of the neutral beam injector test site, is not easily affected by electromagnetic noise, and can effectively and accurately monitor the internal temperature of the neutral beam injector.

[0006] This embodiment provides a high-temperature fast-response fiber optic temperature sensor, including a single-mode fiber and a sensor packaging structure;

[0007] The single-mode optical fiber includes a head end, a body part and a pigtail part connected sequentially along the extension direction, and a temperature grating is provided on the single-mode optical fiber.

[0008] The sensor packaging structure includes a packaging shell and a front connector and a pigtail structure respectively connected to both ends of the packaging shell;

[0009] The encapsulation shell is sleeved on the main body, and a connecting plate is provided inside the encapsulation shell. The single-mode optical fiber is fixed on the connecting plate, and the connecting plate is used to conduct temperature to the temperature grating. The encapsulation shell and the connecting plate are an integrated structure.

[0010] The front-end connector is sleeved on the first end, and the front-end connector is provided with an air pressure balance hole. The air pressure balance hole is used to balance the air pressure inside and outside the sensor packaging structure. The pigtail structure is sleeved on the pigtail.

[0011] In one feasible implementation, a first groove is formed along the length direction on the connecting plate, and at least a portion of the single-mode optical fiber is embedded in the first groove.

[0012] In one feasible implementation, a first optical fiber fixing point is provided at one end of the first groove near the front-end connector, and a second optical fiber fixing point is provided at one end of the first groove near the pigtail structure. The single-mode optical fiber is fixed inside the first groove at the first optical fiber fixing point and the second optical fiber fixing point.

[0013] In one feasible implementation, a filter screen is provided inside the front-end connector, and the filter screen is located on the side of the air pressure balance hole near the encapsulation shell.

[0014] In one feasible implementation, the outer layer of the pigtail is provided with a Teflon sleeve along its length. The Teflon sleeve includes a first part and a second part. The first part is located between the front end connector and the second part. The outer layer of the second part is provided with a glass fiber sleeve. The connecting plate extends into the pigtail structure. The connecting plate is also provided with a second groove and a third groove. The second groove and the third groove are located on the side of the second optical fiber fixing point on the connecting plate away from the first optical fiber fixing point. The second groove is used to place the Teflon sleeve, and the third groove is used to place the glass fiber sleeve.

[0015] In one feasible implementation, the end of the pigtail structure away from the encapsulation shell has a mounting through hole, which is used to install the single-mode optical fiber, Teflon sleeve and glass fiber sleeve into the sensor encapsulation structure.

[0016] In one feasible implementation, one end of the encapsulation shell is provided with a first connecting portion, the front end connector is sleeved on the first connecting portion, and the first connecting portion has a first external insertion hole communicating between the encapsulation shell and the front end connector. The other end of the encapsulation shell is provided with a second connecting portion, the pigtail structure is sleeved on the second connecting portion, and the second connecting portion has a second insertion hole communicating between the encapsulation shell and the pigtail structure.

[0017] In one feasible implementation, the single-mode fiber is a pure silicon fiber or an F-doped radiation-resistant single-mode fiber, and the outer surface of the single-mode fiber is coated with a polyimide coating.

[0018] In one feasible implementation, the temperature grating is characterized by being a C-band or L-band fiber Bragg grating, and the length of the temperature grating is between 10 mm and 12 mm.

[0019] In one feasible implementation, the encapsulation shell and the connecting plate are made of copper, silver, or aluminum alloy.

[0020] This application provides a high-temperature fast-response fiber optic temperature sensor. Since the fiber optic temperature sensor uses light as the medium for signal sensing and transmission, it is immune to electromagnetic interference. This application fully utilizes the electromagnetic interference resistance advantage of the fiber optic temperature sensor by improving the sensor's packaging structure. The packaging shell and connecting plate are integrated into a single structure, with the grating fiber mounted on the connecting plate. The packaging shell can quickly transmit the ambient temperature to the grating fiber through the integrated structure with the connecting plate, improving the sensor's response speed. Furthermore, a pressure balancing hole is provided on the front connector to balance the air pressure inside and outside the fiber optic temperature sensor, thereby preventing the sensor from exploding due to excessive air pressure in a vacuum environment. This ensures pressure balance in a vacuum environment and effective temperature detection. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a high-temperature fast-response fiber optic temperature sensor provided in one embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the packaging shell of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the radial cross-section of the packaging shell of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of the front-end connector of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application;

[0025] Figure 5 This is a side view of the pigtail structure of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application.

[0026] Figure 6 This is a schematic diagram of the structure of a single optical fiber of a high-temperature fast-response optical fiber temperature sensor provided in one embodiment of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100 - Single-mode optical fiber; 200 - Sensor packaging structure; 300 - Temperature grating; 400 - Pressure balance hole; 500 - First groove; 600 - First optical fiber fixing point; 700 - Second optical fiber fixing point; 800 - Filter screen; 900 - Teflon sleeve; 1000 - Glass fiber sleeve; 1100 - Second groove; 1200 - Third groove; 1300 - Mounting through hole;

[0029] 110 - Head end; 120 - Main body; 130 - Tail fiber section;

[0030] 210 - Encapsulation housing; 220 - Front connector; 230 - Pigtail structure; 240 - Connecting plate;

[0031] 211 - First external socket; 212 - Second external socket;

[0032] 910 - Part 1; 920 - Part 2. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0034] In related technologies, temperature monitoring of the neutral beam ion implantation heating process generally adopts thermocouple temperature sensors.

[0035] However, due to the strong magnetic and high-pressure environment at the neutral beam injector test site, the thermocouple temperature sensor is easily interfered with by electromagnetic noise, making it impossible to effectively and accurately monitor the internal temperature of the neutral beam injector.

[0036] Therefore, there is a need for an optical fiber temperature sensor that is suitable for the strong magnetic and high temperature environment of the neutral beam injector test site, and has a fast response speed, high monitoring sensitivity, and can perform temperature detection in a vacuum environment.

[0037] Figure 1 This is a schematic diagram of the overall structure of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application. See also... Figure 1As shown, this application provides a high-temperature fast-response fiber optic temperature sensor, including a single-mode fiber 100 and a sensor packaging structure 200. For ease of description, the single-mode fiber 100 includes a head end 110, a body portion 120, and a pigtail portion 130 connected sequentially along the extension direction, and a temperature grating 300 is provided on the single-mode fiber 100; the sensor packaging structure 200 includes a packaging shell 210 and a front connector 220 and a pigtail structure 230 respectively connected to both ends of the packaging shell 210.

[0038] The encapsulation shell 210 is fitted onto the main body 120, and a connecting plate 240 is provided inside the encapsulation shell 210. The single-mode optical fiber 100 is fixed on the connecting plate 240, and the connecting plate 240 is used to conduct temperature to the temperature grating 300 of the optical fiber main body 120. The encapsulation shell 210 and the connecting plate 240 are an integrated structure. The front end connector 220 is fitted onto the front end 110, and the pigtail structure 230 is fitted onto the pigtail part 130.

[0039] Figure 4 This is a schematic diagram of the front-end connector of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application. See also... Figure 4 As shown, the front connector 220 is provided with a pressure balancing hole 400, which is used to balance the air pressure inside and outside the sensor packaging structure 200.

[0040] In this embodiment, the encapsulation shell 210 and the connecting plate 240 are integrated into a single structure. The fiber grating is disposed on the connecting plate 240. The fiber grating has photosensitive properties; when a broadband light wave passes through the grating region, light satisfying a specific wavelength is reflected back by the grating, with the reflected wavelength λ = 2n. eff Λ, where n eff Λ represents the effective refractive index of the optical fiber and Λ represents the grating period. When the ambient temperature changes, the temperature is rapidly transferred to the single-mode optical fiber 100 through the thermally conductive metal of the sensor encapsulation structure 200. The grating on the single-mode optical fiber 100 is affected by both the thermo-optical effect and the axial thermal expansion of the connecting plate 240 due to the increased sensor temperature. This causes axial strain in the pre-tightened grating itself. Under the combined effects of temperature and stress, the effective refractive index and period of the grating change, causing a shift in the grating reflection center wavelength. Therefore, the ambient temperature can be monitored based on the pre-calibrated relationship between the grating reflection wavelength shift and temperature.

[0041] The encapsulation shell 210 can quickly transmit the ambient temperature to the fiber optic grating through the integrated structure formed with the connecting plate 240, thereby improving the sensor's response speed. Furthermore, a pressure balancing hole 400 is provided on the front connector 220. The pressure balancing hole 400 is used to balance the air pressure inside and outside the fiber optic temperature sensor, thereby preventing the fiber optic temperature sensor from "exploding" due to excessive air pressure in a vacuum environment, ensuring the air pressure balance of the ambient temperature in a vacuum environment and the effective detection of temperature.

[0042] Figure 2 This is a schematic diagram of the packaging shell of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application. See also... Figure 2 As shown, in some examples, a first groove 500 may be formed on the connecting plate 240 along the length direction, and at least a portion of the single-mode optical fiber 100 is embedded in the first groove 500.

[0043] For example, the diameter of the first groove 500 is 1 mm.

[0044] For example, the diameter of the first groove 500 is 1.1 mm.

[0045] The first groove 500 has a first optical fiber fixing point 600 at one end near the front connector 220, and a second optical fiber fixing point 700 at one end near the pigtail structure 230. The single-mode optical fiber 100 is fixed inside the first groove 500 by glass welding at the first optical fiber fixing point 600 and the second optical fiber fixing point 700.

[0046] In this embodiment, a pre-tightening operation is performed before the fiber Bragg grating is encapsulated. The pre-tightening wavelength range can be selected from 1 to 3 nm depending on the specific temperature monitoring range. For example, the pre-tightening wavelength can be 1 nm, 2 nm, or 3 nm. After pre-tightening, the first fiber fixing point 600 and the second fiber fixing point 700 at both ends of the first groove 500 are fixed by glass welding and cured at high temperature, effectively avoiding wavelength shift caused by high-temperature aging of the adhesive. As the temperature rises, the connecting plate 240 will undergo axial strain, which causes a change in the grating wavelength. This superimposes the temperature effect and strain effect of the grating, effectively improving the temperature detection sensitivity of the sensor. Through the tight contact between the grating and the first groove 500, the ambient temperature can be quickly transmitted to the fiber Bragg grating through the integrated sensor structure, improving the sensor's response speed.

[0047] Figure 4 This is a schematic diagram of the front-end connector of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application. See also... Figure 4As shown, in some examples, a filter 800 is provided inside the front connector 220, and the filter 800 is located on the side of the pressure balance hole 400 near the package housing 210.

[0048] For example, the air pressure filter hole 400 is provided on the side wall of the front connector 220.

[0049] For example, the air pressure balancing hole 400 is provided on the end face of the front connector 220.

[0050] For example, the sensor front-end connector 220 is shaped as a cylinder with one end closed.

[0051] In this embodiment, the filter 800 is mainly used to ensure the balance between the fiber optic grating inside the fiber optic temperature sensor and the external air pressure of the environment to be measured, while filtering out the influence of dust and other particles on the grating, thereby enabling temperature monitoring in a vacuum environment.

[0052] Figure 6 This is a schematic diagram of the structure of a single optical fiber in a high-temperature fast-response optical fiber temperature sensor according to an embodiment of this application. See also... Figure 6 As shown, in some examples, the outer layer of the pigtail 130 is provided with a Teflon sleeve 900 along the length direction. The Teflon sleeve 900 includes a first part 910 and a second part 920. The first part 910 is located between the front connector 220 and the second part 920. The outer layer of the second part 920 is provided with a glass fiber sleeve 1000. The connecting plate 240 extends into the pigtail structure 230.

[0053] See Figure 2 As shown, the connecting plate 240 is also provided with a second groove 1100 and a third groove 1200. The second groove 1100 and the third groove 1200 are located on the side of the second optical fiber fixing point 700 on the connecting plate 240 away from the first optical fiber fixing point 600. The second groove 1100 is used to place the Teflon sleeve 900, and the third groove 1200 is used to place the glass fiber sleeve 1000.

[0054] Figure 5 This is a side view schematic diagram of the pigtail structure of a high-temperature fast-response fiber optic temperature sensor according to an embodiment of this application. See also... Figure 5 As shown, the end of the pigtail structure 230 away from the packaging shell 210 has a mounting through hole 1300, which is used to install the single-mode optical fiber 100, the Teflon sleeve 900 and the glass fiber sleeve 1000 into the sensor packaging structure 200.

[0055] In some examples, the diameter of the Teflon sleeve 900 is 1mm-1.3mm, the diameter of the fiberglass sleeve 1000 is 1.5mm-1.8mm, the diameter of the second groove 1100 is 1.1mm-1.4mm, the diameter of the third groove 1200 is 1.6mm-1.9mm, and the diameter of the mounting through hole 1300 is 1.9mm-2.1mm.

[0056] In practice, the diameter of the Teflon sleeve 900 is 1.2mm, the diameter of the fiberglass sleeve 1000 is 1.7mm, the diameter of the second groove 1100 is 1.3mm, the diameter of the third groove 1200 is 1.8mm, and the diameter of the mounting through hole 1300 is 2mm.

[0057] For example, the Teflon sleeve 900 has a diameter of 1 mm, the glass fiber sleeve 1000 has a diameter of 1.5 mm, the second groove 1100 has a diameter of 1.1 mm, the third groove 1200 has a diameter of 1.6 mm, and the mounting through hole 1300 has a diameter of 1.9 mm.

[0058] For example, the diameter of the Teflon sleeve 900 is 1.3 mm, the diameter of the glass fiber sleeve 1000 is 1.8 mm, the diameter of the second groove 1100 is 1.4 mm, the diameter of the third groove 1200 is 1.9 mm, and the diameter of the mounting through hole 1300 is 2.1 mm.

[0059] In this embodiment, both Teflon and glass fiber materials have extremely strong high temperature resistance and corrosion resistance. By setting a Teflon sleeve 900 and a glass fiber sleeve 1000 on the outer layer of the tail fiber 130, the high temperature resistance and radiation resistance of the tail fiber 130 can be improved, effectively avoiding the gas emitted by the high temperature aging of the tail fiber material during sensor measurement from affecting the vacuum degree inside the neutral beam injector device.

[0060] See in some examples Figure 1 As shown, one end of the encapsulation shell 210 is provided with a first connecting part, and the front end connector 220 is sleeved on the first connecting part. The first connecting part has a first external insertion hole 211 that connects the encapsulation shell 210 and the front end connector 220. The other end of the encapsulation shell 210 is provided with a second connecting part, and the pigtail structure 230 is sleeved on the second connecting part. The second connecting part has a second external insertion hole 212 that connects the encapsulation shell 210 and the pigtail structure 230.

[0061] For example, the first connecting part is a threaded structure, and correspondingly, the inner sidewall of the front connector 220 near the end of the encapsulation shell 210 is provided with a thread that mates with the threaded structure on the first connecting part.

[0062] For example, the second connection part is a threaded structure, and correspondingly, the inner sidewall of the pigtail structure 230 near the end of the packaging shell 210 is provided with threads that cooperate with the threaded structure on the second connection part.

[0063] For example, the front connector 220 is connected to the package housing 210 by applying epoxy resin adhesive to the outer surface of the first external socket 211.

[0064] For example, the pigtail structure 230 is connected to the package housing 210 by applying epoxy resin adhesive to the outer surface of the second external socket 212.

[0065] In this embodiment of the application, by setting the first connecting part and the second connecting part, the three parts of the sensor packaging structure 200, namely the packaging shell 210, the front connector 220 and the pigtail structure 230, can be connected to achieve overall packaging.

[0066] In some examples, the outer surface of the single-mode fiber 100 is coated with a polyimide coating.

[0067] For example, single-mode fiber 100 is pure silicon fiber.

[0068] For example, single-mode fiber 100 is an F-doped radiation-resistant single-mode fiber.

[0069] The embodiments of this application can effectively reduce the impact of irradiation on the performance of fiber Bragg gratings. By coating the outer surface of the single-mode fiber 100 with a polyimide coating, monitoring of high-temperature environments can be achieved.

[0070] In some examples, the length of the temperature grating 300 is between 10 mm and 12 mm.

[0071] For example, the temperature grating 300 is a C-band fiber Bragg grating with a length of 10 mm.

[0072] For example, the temperature grating 300 is a C-band fiber Bragg grating with a length of 11 mm.

[0073] For example, the temperature grating 300 is an L-band fiber Bragg grating with a length of 12 mm.

[0074] In this embodiment, temperature measurement is achieved based on the grating wavelength shift.

[0075] In some examples, the housing 210 and the connecting plate 240 are made of a metal with excellent thermal conductivity.

[0076] For example, the materials of the encapsulation shell 210 and the connecting plate 240 can be copper, silver or aluminum alloy, etc.

[0077] In the embodiment of the present application, a metal with excellent thermal conductivity is used as the sensor packaging material for the fiber optic temperature sensor. The sensor packaging structure 200 is an integrated structure. By the close contact between the grating and the integrated structure, it is ensured that the ambient temperature can be quickly transferred to the grating through the integrated structure of the sensor, improving the response speed of the sensor.

[0078] During actual use, Figure 3 It is a schematic structural diagram of the radial cross-section of the packaging shell of a high-temperature and fast-response fiber optic temperature sensor provided by an embodiment of the present application. Refer to Figure 3 As described, the packaging shell 210 is a copper integrated cylindrical structure, and its radial cross-section is a "day" - shaped structure. A first groove 500 for fixing the single-mode optical fiber 100 is provided inside the cylindrical structure. The first groove 500 and the second groove 1100 are respectively used to fix the optical fiber and the Teflon sleeve 900. The cross-section of the first groove 500 is a semi-circular U-shaped structure, where the diameter of the first groove 500 is 1 mm and the diameter of the second groove 1100 is 1.3 mm, ensuring the close contact between the fiber grating and the packaging shell 210 and improving the response speed of the sensor. [

[0079] During the manufacturing process, first, the bonding part of the Teflon sleeve 900 is immersed in the naphthalene sodium treatment solution for about 1 minute. After taking out the Teflon sleeve 900 and rinsing it with clean water, the single-mode optical fiber 100 and the Teflon sleeve 900 are passed through the installation through-hole 1300 and then laid flat inside the first groove 500 and the second groove 1100 respectively. The single-mode optical fiber 100 is fixed by glass welding, and the Teflon sleeve 900 is fixed by epoxy resin glue. Finally, the glass fiber sleeve 1000 is passed through the installation through-hole 1300 and fixed in the third groove 1200 with epoxy resin glue, where the diameter of the installation through-hole 1300 is about 2 mm.

[0080] Before the fiber grating is packaged, a pre-tightening operation is first performed. The pre-tightening wavelength range can be selected from 1 to 3 nm according to the specific temperature monitoring range. After the pre-tightening is completed, high-temperature curing is performed by glass welding at the first optical fiber fixing point 600 and the second optical fiber fixing point 700 respectively. Assume that the temperature sensitivity coefficient kt of the grating in the normal state is 10 pm / °C, the grating strain coefficient ε is 1.2 pm / με, and the thermal expansion coefficient α of copper is 18×10 -6(That is, when the temperature of 1000 m of copper increases by 1 °C, the linear expansion is approximately 18 mm). Therefore, when the temperature of the copper tube increases by 1 °C, approximately 18 με (microstrain) is generated. It can be obtained that when the temperature of copper increases by 1 °C, the change in the grating wavelength caused by the axial strain is 21.6 pm. The copper "day"-shaped integrated cylinder structure fiber optic temperature sensor superimposes the temperature effect and the strain effect of the grating, and the temperature sensitivity coefficient of the superimposed fiber optic temperature sensor is 31.6 pm / °C, thereby greatly improving the sensitivity of the sensor. Expressed by the formula: K = kt + α·ε. The fiber grating is pre-tightened and encapsulated on the connecting plate 240. On the one hand, the encapsulation shell 210 can quickly transfer the ambient temperature to the fiber grating through the integrated structure formed with the connecting plate 240, improving the response speed of the sensor. On the other hand, it superimposes the temperature effect and the strain effect of the grating, effectively improving the monitoring sensitivity of the sensor.

[0081] The front end joint 220 is provided with a pneumatic balance hole filter structure, which is mainly used to ensure the balance of the internal fiber grating of the sensor and the external air pressure of the measured environment, and at the same time filter out the possible influence of dust, etc. on the fiber grating, so as to realize the temperature monitoring of the vacuum environment.

[0082] The outer layer of the fiber optic tail section 130 of the temperature sensor is a Teflon sleeve 900 with a sleeve diameter of 1.2 mm. The outer layer of the part of the Teflon sleeve 900 far from the front end joint 220 is provided with a fiberglass sleeve 1000 with a fiberglass sleeve 1000 diameter of 1.7 mm. Both the Teflon and fiberglass materials have extremely strong high temperature resistance and corrosion resistance. By improving the high temperature resistance and radiation resistance of the tail section 130, it effectively avoids the influence of the gas emitted by the high temperature aging of the tail fiber material during the measurement process of the sensor on the vacuum degree inside the neutral beam injector device.

[0083] The three parts of the front end joint 220, the encapsulation shell 210, and the tail fiber structural member 230 of the sensor encapsulation structure 200 are integrally encapsulated by applying epoxy resin glue on the outer surfaces of the first outer socket 211 and the second outer socket, and waiting for the glue to cure.

[0084] The method for the fiber optic temperature sensor to monitor the internal temperature of the neutral beam injector. In practical applications, the parameters such as the shape, length, wall thickness, and thread of the encapsulation shell 21 can be appropriately adjusted according to needs.

[0085] The temperature sensor can achieve self - compensation for the irradiation wavelength drift. The grating wavelength / temperature coefficient is \(k_t\). The functional relationship among the grating wavelength change \(\lambda\), the irradiation dose \(r\), and the irradiation duration \(t\) is \(\lambda=f(r,t)\), and all these three functional relationships are obtained through experimental tests. \(\lambda_0\) is the reference wavelength of the grating at temperature \(T_0\). Specifically, the wavelength / temperature coefficient \(k_t\) is the ratio between the change in the center wavelength of the grating and the change in the ambient temperature when the irradiation intensity is zero; the functional relationship \(f(r,t)\) is the functional mapping relationship between the change in the center wavelength \(\Delta\lambda\) of the grating and the irradiation intensity \(r\) and the irradiation duration \(t\) when the ambient temperature is constant. The functional relationship specifically depends on the corresponding relationship between the irradiation type, irradiation intensity, irradiation duration, and the grating wavelength, and can be expressed as: r The functional mapping relationship between the irradiation intensity \(r\) and the irradiation duration \(t\). The functional relationship specifically depends on the corresponding relationship between the irradiation type, irradiation intensity, irradiation duration, and the grating wavelength, and can be expressed as:

[0086] \(\Delta\lambda\) r =f(r,t)

[0087] After compensating for the change in the wavelength of the fiber grating caused by irradiation, the temperature to be measured obtained by the sensor is:

[0088]

[0089] The sensor in this embodiment adopts a copper "day" - shaped integrated fiber encapsulation structure and an internal and external air pressure balance hole filter structure, which ensures the internal and external air pressure balance of the sensor in different environments and effectively realizes the rapid response and high - precision monitoring of the temperature in the vacuum environment inside the nuclear fusion neutral beam injector device; by establishing the functional relationship between the irradiation intensity and the wavelength shift to compensate and calibrate the wavelength drift of the grating fiber caused by irradiation, the long - term reliability of the fiber optic temperature sensor is improved; and in this embodiment, the materials and structures of the sensor pigtail are optimized to avoid the influence of the aging of the pigtail material on the internal vacuum degree of the equipment under the long - term high - temperature radiation state.

[0090] It is easy to understand that those skilled in the art can combine, split, recombine, etc. the embodiments of the present application based on several embodiments provided in the present application to obtain other embodiments, and these embodiments do not exceed the protection scope of the present application.

[0091] The above - mentioned specific implementation manners further elaborate on the purpose, technical solutions, and beneficial effects of the embodiments of the present application. It should be understood that the above is only the specific implementation manners of the embodiments of the present application and is not used to limit the protection scope of the embodiments of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A high-temperature fast-response fiber optic temperature sensor, characterized in that, Including single-mode optical fiber and sensor packaging structure; The single-mode fiber includes a head end, a body part and a tail fiber part connected sequentially along the extension direction. A temperature grating is provided on the single-mode fiber. After a pre-tightening operation, the temperature grating of the single-mode fiber is encapsulated into the sensor encapsulation structure. The single-mode fiber is a pure silicon fiber or an F-doped radiation-resistant single-mode fiber. The sensor packaging structure includes a packaging shell and a front connector and a pigtail structure respectively connected to both ends of the packaging shell; The encapsulation shell is fitted onto the main body, and a connecting plate is provided inside the encapsulation shell. The single-mode optical fiber is fixed on the connecting plate, and the connecting plate is used to conduct temperature to the temperature grating. The encapsulation shell and the connecting plate are an integrated structure. The encapsulation shell is an integrated cylindrical structure, and the radial cross-section of the encapsulation shell is a H-shaped structure. The front end connector is sleeved on the first end, and the front end connector is provided with an air pressure balance hole. The air pressure balance hole is used to balance the air pressure inside and outside the sensor packaging structure. The pigtail structure is sleeved on the pigtail part. The connecting plate has a first groove along its length, and the head end and the main body are both embedded in the first groove; A first optical fiber fixing point is provided at one end of the first groove near the front end connector, and a second optical fiber fixing point is provided at one end of the first groove near the pigtail structure. The single-mode optical fiber is fixed inside the first groove at the first optical fiber fixing point and the second optical fiber fixing point. The outer layer of the pigtail is provided with a Teflon sleeve along its length. The Teflon sleeve includes a first part and a second part. The first part is located between the front end connector and the second part. The outer layer of the second part is provided with a glass fiber sleeve. The connecting plate extends into the pigtail structure. The connecting plate is also provided with a second groove and a third groove. The second groove and the third groove are located on the side of the second optical fiber fixing point on the connecting plate away from the first optical fiber fixing point. The second groove is used to place the Teflon sleeve, and the third groove is used to place the glass fiber sleeve. The adhesive part of the Teflon sleeve is treated with sodium naphthalene treatment solution and then fixed with epoxy resin glue. The temperature T to be measured obtained by the fiber optic temperature sensor is calculated using the following formula: ； ； Where T is the temperature to be measured, λ is the grating wavelength change, T0 is the temperature, λ0 is the reference wavelength of the grating at temperature T0, and Δλ r Let r be the irradiation dose, t be the irradiation duration, and f(r,t) be the irradiation center wavelength variation Δλ when the ambient temperature is constant. r The functional mapping relationship between k and irradiation intensity r and irradiation duration t t This represents the grating wavelength / temperature coefficient.

2. The high-temperature fast-response fiber optic temperature sensor according to claim 1, characterized in that, A filter screen is provided inside the front-end connector, and the filter screen is located on the side of the air pressure balance hole near the encapsulation shell.

3. The high-temperature fast-response fiber optic temperature sensor according to claim 1, characterized in that, The pigtail structure has a mounting through hole at one end away from the encapsulation shell. The mounting through hole is used to install the single-mode optical fiber, Teflon sleeve and glass fiber sleeve into the sensor encapsulation structure.

4. A high-temperature fast-response fiber optic temperature sensor according to any one of claims 1-3, characterized in that, One end of the encapsulation shell is provided with a first connecting part, the front end connector is sleeved on the first connecting part, and the first connecting part has a first external insertion hole communicating between the encapsulation shell and the front end connector. The other end of the encapsulation shell is provided with a second connecting part, the pigtail structure is sleeved on the second connecting part, and the second connecting part has a second insertion hole communicating between the encapsulation shell and the pigtail structure.

5. A high-temperature fast-response fiber optic temperature sensor according to any one of claims 1-3, characterized in that, The outer surface of the single-mode optical fiber is coated with a polyimide coating.

6. A high-temperature fast-response fiber optic temperature sensor according to any one of claims 1-3, characterized in that, The temperature grating is a C-band or L-band fiber Bragg grating, and the length of the temperature grating is between 10mm and 12mm.

7. A high-temperature fast-response fiber optic temperature sensor according to claim 1, characterized in that, The encapsulation shell and the connecting plate are made of copper, silver or aluminum alloy.

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