Radiation-resistant protection structure of sapphire optical fiber high-temperature sensor

Abstract

The invention relates to the technical field of radiation protection of optical fiber sensors, in particular to a radiation-resistant protection structure of a sapphire optical fiber high-temperature sensor, which comprises a sapphire optical fiber high-temperature sensor and a radiation-resistant protection cladding arranged outside the sapphire optical fiber high-temperature sensor in a sleeving manner, the radiation-resistant protective cladding sequentially comprises a protective gas filling chamber, a radiation-resistant protective material filling chamber and a high-temperature cladding on the outermost layer from inside to outside; the high-temperature cladding is made of an alloy or ceramic material capable of resisting the high temperature of 800-1600 DEG C, and one end of the high-temperature cladding is closed; the protective gas filling chamber is an annular cavity and is filled with protective gas; the radiation-resistant protective material filling chamber is an annular cavity, a protective layer formed by mixing and curing a radiation-resistant protective material and high-temperature glue is filled in the radiation-resistant protective material filling chamber, the mixed radiation-resistant protective layer effectively prevents fracture and embrittlement under the extremely high-temperature condition, and thermal tension borne by the radiation-resistant protective material filling chamber is borne by the firm high-temperature cladding. The device is reliable in structure and excellent in protection effect, and can stably work in an extremely high-temperature and large-radiation-dose environment.

Description

Technical Field

[0001] This invention relates to the field of radiation protection technology for fiber optic sensors, and specifically to a radiation-resistant protection structure for a sapphire fiber optic high-temperature sensor. Background Technology

[0002] Sapphire optical fiber (primarily composed of Al2O3 single crystal) can withstand temperatures of 800-1600℃ and is widely used in sensing measurements under extreme high-temperature environments. However, in applications such as nuclear power plants, sensors not only face extreme high temperatures (≥800℃) but also need to withstand high-dose radiation (≥10). 6 High-energy radiation (such as gamma rays, X-rays, and neutrons) interacts with optical fiber materials, causing atomic ionization and the generation of color centers (point defects), resulting in attenuation of optical signals, changes in refractive index, and degradation of material structure, and even causing irreversible permanent damage.

[0003] Currently, conventional radiation protection methods mostly employ thin-film coatings. However, this type of protection is prone to failure under extreme temperatures due to peeling or cracking, and cannot meet the long-term stable operation requirements of high-temperature, high-radiation applications such as nuclear power. Therefore, there is an urgent need for a new radiation-resistant protection structure to protect the performance and lifespan of sapphire fiber optic sensors in harsh environments. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a radiation-resistant protection structure for a sapphire fiber optic high-temperature sensor. The structure is reliable and provides excellent protection, enabling stable operation under extreme high-temperature and high-radiation-dose environments.

[0005] This invention is achieved through the following technical solution: A radiation-resistant protection structure for a sapphire fiber optic high-temperature sensor is provided, comprising a sapphire fiber optic high-temperature sensor and a radiation-resistant protective shell fitted over the sapphire fiber optic high-temperature sensor; the radiation-resistant protective shell comprises, from the inside out: The protective gas filling chamber, the radiation-resistant protective material filling chamber, and the outermost high-temperature cladding; The high-temperature cladding is made of alloy or ceramic materials that can withstand temperatures of 800~1600℃, and one end of it is sealed; the protective gas filling chamber is an annular cavity filled with protective gas. The radiation-resistant protective material filling chamber is an annular cavity, which is filled with a protective layer made of radiation-resistant protective material mixed with high-temperature adhesive and cured.

[0006] In this invention, the radiation-resistant protective material is encapsulated within a rigid structure consisting of a high-temperature shell. The high-temperature adhesive primarily serves to bond and fix the material, while simultaneously preventing it from cracking and becoming brittle under high-temperature conditions. The thermal stress it bears is borne by the robust high-temperature shell, rather than acting directly on the fiber optic sensor itself. This structural design allows radiation-resistant materials sensitive to high temperatures (such as polymers) to maintain structural integrity and shielding functionality even in environments far exceeding their own temperature limits.

[0007] The structure of this invention is a standardized sandwich module. For environments dominated by neutron radiation, neutron-absorbing materials such as boron-containing polymers can be selected as filling materials; for higher temperatures, more heat-resistant ceramics can be used as cladding. This design allows a single core solution to be widely adaptable to different application scenarios such as nuclear reactors and spent fuel pools by adjusting the component materials.

[0008] The outermost high-temperature cladding serves as the primary load-bearing structure, withstanding mechanical stress and thermal shock, while the inner filling layer focuses on functional protection. Connecting components ensure a tight seal at the fiber optic exit point. This clearly defined modular design guarantees the long-term stability of the sensor's overall operation after insertion into the high-temperature, high-radiation heat chamber.

[0009] Furthermore, a radiation-resistant protective material injection port is provided on the high-temperature cladding, which is connected to the radiation-resistant protective material filling chamber.

[0010] Preferably, the protective gas is an inert gas or other protective gas.

[0011] Furthermore, the radiation-resistant protective material is a polymer-based coating material.

[0012] Preferably, the protective layer formed by mixing and curing with high-temperature adhesive has a thickness of not less than 1 mm.

[0013] Furthermore, the open end of the high-temperature cladding is also equipped with a connecting package, through which the pigtail of the sapphire fiber optic high-temperature sensor passes to connect to the transmission optical cable and fiber optic connector.

[0014] A sensor system, comprising: Radiation-resistant protective structure; A fiber optic sensor signal demodulator connected to a radiation-resistant protective structure via a fiber optic connector. The radiation-resistant protective structure is configured to be inserted into a high-temperature, high-radiation hot chamber.

[0015] The beneficial effects of this invention are: This invention solves the problem of sapphire fiber optic sensors operating under extreme high temperatures (≥800℃) and strong radiation (≥10℃) through an innovative synergistic protection mechanism of physical isolation and chemical passivation. 6The challenge of long-term stable operation in a Gy environment due to radiation damage and failure of traditional protection.

[0016] Specifically, its beneficial effects are mainly reflected in the following three aspects: 1. Structural Innovation: Fundamentally solves the problem of radiation-resistant protective layer peeling off at high temperatures, achieving reliable physical shielding. By designing a double-layer filling chamber cladding structure (protective gas filling chamber + radiation-resistant protective material filling chamber), the radiation-resistant material is mixed with high-temperature adhesive and cured in the cavity. At the same time, the high-temperature cladding is used to withstand thermal stress. Instead of being directly coated on the surface of the optical fiber or the surface of the high-temperature cladding, the risk of cracking and peeling caused by the mismatch between the thermal expansion coefficient of the protective coating and the optical fiber (or thermal stress under oxygen conditions) is completely eliminated, thus achieving long-term stable physical radiation protection.

[0017] 2. Gas protection: Inhibits damage and promotes repair at the chemical level, enhancing the intrinsic radiation resistance of optical fibers. A protective gas filling chamber is set between the optical fiber and the protective material layer. By filling it with inert gases and other protective gases, the corrosion and additional loss of the optical fiber caused by oxygen, water vapor (hydroxyl ions) at high temperatures are effectively reduced, and point defects caused by radiation can be passivated, thus delaying the degradation of optical fiber performance from a chemical mechanism.

[0018] The protective gas-filled chamber provides a dry, inert local environment. The inert gas (such as argon) isolates the fiber from oxygen and moisture, protecting the fiber surface and bulk material from corrosion at high temperatures and maintaining the fiber's intrinsic optical properties. Inert gas molecules can diffuse to regions with lattice defects (such as dangling bonds) caused by radiation, filling these defect sites or reacting with active defects, causing them to lose their ability to trap photons. This achieves a degree of self-repair and significantly reduces radiation-induced attenuation.

[0019] 3. Flexibility and Reliability: Modular design adapts to diverse and extreme environments. This structure is highly modular, allowing for flexible selection of cladding materials, radiation-resistant material composition and thickness, and protective gas composition based on different radiation types, dose rates, and temperature ranges, achieving customized optimal protection. The overall structure is robust, easy to assemble, and highly reliable.

[0020] In summary, this invention, through a multi-level, multi-mechanism collaborative protection structure, and by addressing the challenges that existing technologies cannot overcome from three dimensions—physical shielding, chemical protection, and decoupling design—systematically solves the problems that existing technologies cannot overcome, ultimately enabling sapphire fiber optic high-temperature sensors to perform long-term, stable, and accurate measurements in extremely harsh environments. Attached Figure Description

[0021] Figure 1 This is a schematic axial cross-sectional view of the present invention.

[0022] Figure 2 This is the overall three-dimensional assembly diagram of the present invention.

[0023] Figure 3 This is a schematic diagram illustrating the application of the present invention in a high-temperature, high-radiation environment.

[0024] Figure 4 This is a comparative test results table for the present invention.

[0025] As shown in the figure: 1. Sapphire fiber optic high-temperature sensor; 2. Radiation-resistant protective casing; 21. High-temperature casing; 22. Radiation-resistant protective material filling chamber; 221. Radiation-resistant protective material injection port; 22. Radiation-resistant protective material; 23. Protective gas filling chamber; 231. Protective gas; 24. High-temperature adhesive; 25. Connecting encapsulation component; 26. Transmission optical cable; 27. Fiber optic connector. 3. Fiber optic sensor signal demodulator; 4. High-temperature, high-radiation hot chamber. Detailed Implementation

[0026] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution. Example

[0027] A radiation-resistant protection structure for a sapphire fiber optic high-temperature sensor includes a sapphire fiber optic high-temperature sensor 1 and a radiation-resistant protective shell 2 fitted over the sapphire fiber optic high-temperature sensor 1; the radiation-resistant protective shell 2 comprises, from the inside out: The protective gas filling chamber 23, the radiation-resistant protective material filling chamber 22, and the outermost high-temperature shell 21; The high-temperature shell 21 is made of alloy or ceramic material that can withstand high temperatures of 800~1600℃, and one end of it is sealed; the protective gas filling chamber 23 is an annular cavity filled with protective gas 231. The radiation-resistant protective material filling chamber 22 is an annular cavity, which is filled with a protective layer made by mixing and curing radiation-resistant protective material 222 and high-temperature adhesive 24.

[0028] The high-temperature shell 21 has a radiation-resistant protective material injection port 221, which is connected to the radiation-resistant protective material filling chamber 22.

[0029] Protective gas 231 is an inert gas or a protective gas.

[0030] Radiation-resistant protective material 222 is a polymer-based coating material.

[0031] The thickness of the protective layer formed by mixing and curing is not less than 1 mm.

[0032] The open end of the high-temperature cladding 21 is also provided with a connecting package 25. The pigtail of the sapphire fiber high-temperature sensor 1 passes through the connecting package 25 and connects to the transmission optical cable 26 and the optical fiber connector 27.

[0033] like Figure 1 As shown, the core of the radiation-resistant protection structure of the present invention includes a sapphire fiber high-temperature sensor 1 and a radiation-resistant protective shell 2. The radiation-resistant protective shell 2 consists of three layers from the inside out: the innermost layer is a protective gas filling chamber 23 surrounding the sensor, which is filled with a high-purity protective gas 231 (such as argon); the middle layer is a radiation-resistant material filling chamber 22, which is filled with a mixed cured layer of radiation-resistant material 222 (such as a polymer-based coating) and high-temperature adhesive 24 through an injection port 221; the outermost layer is a high-temperature shell 21 that provides support and protection, and is made of high-temperature resistant alloy or ceramic.

[0034] The fabrication process for this structure is as follows: In the protective gas environment of a cleanroom glove box, the fabricated sapphire fiber optic high-temperature sensor 1 is inserted into the protective gas filling chamber 23 through the open end of the high-temperature cladding 21, and then the open end is sealed with high-temperature adhesive 24. Subsequently, liquid radiation-resistant protective material 222 and high-temperature adhesive 24 are injected into the radiation-resistant protective material filling chamber 22 through the radiation-resistant protective material injection port 221 on the high-temperature cladding 21, allowing them to mix evenly. After high-temperature curing, a solid protective layer tightly encapsulating the sensor is formed. Finally, the transmission optical cable 26 and the fiber optic connector 27 are connected to the open end of the high-temperature cladding 21 through the connecting package 25, completing the fabrication of the entire sensor.

[0035] In this invention, depending on the radiation scenario, radiation dose, and temperature range requirements, the shell material, high-density radiation shielding material, and protective gas can be flexibly selected. The advantage of the technical solution of this application lies in its modularity and customizability.

[0036] Application Scenario 1: Inside the core of a nuclear reactor, there is an extremely high flux of neutrons and gamma rays, and the temperature is above 800℃.

[0037] Material and gas selection: High-temperature cladding 21: Silicon carbide ceramic is selected due to its extremely high neutron absorption cross section and excellent high-temperature stability.

[0038] Radiation-resistant protective material 222: A composite material doped with boron compounds (such as boron carbide) into a polymer matrix. Boron has an extremely high absorption cross-section for thermal neutrons, effectively shielding neutron radiation.

[0039] Protective gas 231: Filled with high-purity helium. Helium has good thermal conductivity, which helps with local heat dissipation of the sensor, and it is an inert gas with stable chemical properties.

[0040] Protection principle: The boron carbide-doped protective layer is specifically designed to absorb neutrons, while the silicon carbide cladding and helium work together to cope with high temperature and gamma radiation, achieving synergistic protection.

[0041] Application Scenario 2: Nuclear waste (spent fuel) storage pools or processing facilities, dominated by strong gamma radiation, with a potentially corrosive atmosphere and a temperature range of 200~600℃.

[0042] Material and gas selection: High-temperature cladding 21: Hastelloy or Inconel series high-temperature alloys are selected. These alloys provide sufficient high-temperature strength while exhibiting excellent corrosion resistance.

[0043] Radiation-resistant protective material 222: High-density, high-atomic-number polymer-based composite materials (such as epoxy resin doped with lead oxide or tungsten powder) are selected. High-atomic-number materials have good shielding effects against gamma rays.

[0044] Protective Gas 231: Filled with high-purity nitrogen. Nitrogen is relatively inexpensive and effectively removes oxygen and moisture, preventing oxidation of internal components.

[0045] Protection principle: High-density filling material effectively attenuates gamma rays, corrosion-resistant alloy shell resists external corrosive atmosphere, and nitrogen provides an internal dry and inert environment.

[0046] Application Scenario 3: Temperature monitoring of aero-engine combustion chambers, facing instantaneous extremely high temperatures (up to 1600℃) and possible transient radiation fields.

[0047] Material and gas selection: High-temperature cladding 21: Yttrium oxide stabilized zirconia ceramic is selected. This is one of the ceramic materials with the highest temperature resistance limit and excellent thermal shock resistance currently available.

[0048] Radiation protection material 222: Given the extremely high temperature, high-temperature resistant glass-ceramic materials can be selected as fillers, which are mixed with high-temperature adhesives to form a robust protective body.

[0049] Protective gas 231: Argon filling gas. Argon is a common inert gas that reliably protects the sensor's optical fiber from oxidation at extreme temperatures.

[0050] Protection principle: The ultra-high temperature resistant ceramic shell and glass-ceramic filling layer work together to resist extreme high temperatures, while argon gas prevents internal high-temperature oxidation. This structure primarily ensures physical stability and basic radiation protection at temperature limits.

[0051] The above application scenarios demonstrate the powerful flexibility and adaptability of the protective structure of this invention. Those skilled in the art can select and combine high-temperature cladding materials, radiation-resistant protective filling materials, and protective gases based on specific conditions such as the main radiation type (neutron / gamma rays), dose rate, operating temperature range, and the presence of chemical corrosion in the target application scenario, thereby achieving optimized and customized protection for sapphire fiber optic high-temperature sensors. The specific assembly process of the structure of this invention provides a general framework for the selection of these materials. Example

[0052] A sensor system, comprising: Radiation-resistant protective structure; A fiber optic sensor signal demodulator connected to a radiation-resistant protective structure via a fiber optic connector. The radiation-resistant protective structure is configured to be inserted into a high-temperature, high-radiation hot chamber.

[0053] like Figure 3 As shown, in application, the prepared sensor is connected to the fiber optic sensor signal demodulator 3 through the fiber optic connector 27, and its sensing end is inserted into the high-temperature, high-radiation hot chamber 4 (such as the core of a nuclear reactor), so that the accurate measurement of physical quantities such as temperature can be achieved.

[0054] After completing the fabrication of the sapphire fiber high-temperature radiation-resistant sensor, we designed and conducted a series of comparative tests to verify its protective effect. The tests mainly evaluated two key performance indicators of the sensor: the degree of optical signal attenuation and the temperature measurement accuracy under high temperature and high radiation environments.

[0055] Test conditions: Radiation source: Cobalt-60 gamma-ray source, capable of providing up to 10 6 Dose rate of Gy / h.

[0056] High temperature environment: High temperature furnace, temperature controllable range 20℃~1200℃.

[0057] Test sample: Experimental group: Sapphire fiber optic high-temperature sensor using the protective structure of this invention (e.g., Figure 1 and Figure 2 (Structure shown).

[0058] Control group A: Bare sapphire fiber optic high-temperature sensor without any protection.

[0059] Control group B: High-temperature sapphire fiber optic sensor with direct coating of traditional radiation-resistant polymer film.

[0060] Test parameters: At a specific radiation dose point, measure the optical power attenuation (dB) of the sensor at a wavelength of 1550nm and its temperature measurement error (°C) at a constant temperature of 800°C.

[0061] Test result data as follows Figure 4 As shown. Result analysis: Up to 10 6 Under a radiation dose of Gy and a high temperature of 800°C, the optical power attenuation of the sensor with the protective structure of this invention is controlled within 2.1dB, and the temperature measurement error can still be kept within the industrially usable range of ±5°C. In contrast, the unprotected sensor at 5×10 5 Severe signal attenuation and measurement drift were observed at Gy, while traditional coated sensors failed prematurely at high temperatures due to coating peeling. This fully demonstrates the effectiveness of the double-layer protective shell structure of this invention in suppressing radiation damage.

[0062] The sensor of this invention can still function normally at extreme high temperatures of 1000℃. This indicates that the supporting and sealing system composed of the high-temperature shell 21 and the high-temperature adhesive 24, as well as the inert environment created by the protective gas 231, jointly ensure the long-term structural integrity and functional stability of the sensor at high temperatures, solving the core problem of high-temperature coating peeling in traditional systems.

[0063] Test data verified the effectiveness of the synergistic protection mechanism of "physical isolation (cladding + filling layer) + chemical passivation (protective gas)" in this invention. This mechanism successfully resisted the dual damage of high temperature and radiation, enabling the sapphire fiber optic sensor to withstand high temperatures and radiation. Figure 3 Reliable measurements were achieved in extreme environments such as the high-temperature, high-radiation hot chamber (4) shown.

[0064] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A radiation-resistant structure for a sapphire fiber optic high-temperature sensor, comprising a sapphire fiber optic high-temperature sensor (1), characterized in that: It also includes a radiation-resistant protective casing (2) fitted over the sapphire fiber high-temperature sensor (1); the radiation-resistant protective casing (2) includes, from the inside out: The protective gas filling chamber (23), the radiation-resistant protective material filling chamber (22), and the outermost high-temperature shell (21); The high-temperature shell (21) is made of alloy or ceramic material that can withstand high temperatures of 800~1600℃, and one end of it is sealed; the protective gas filling chamber (23) is an annular cavity filled with protective gas (231). The radiation protection material filling chamber (22) is an annular cavity, which is filled with a protective layer made of radiation protection material (222) and high-temperature adhesive (24) mixed and cured.

2. The radiation-resistant protection structure of the sapphire fiber high-temperature sensor according to claim 1, characterized in that: The high-temperature shell (21) has a radiation-resistant protective material injection port (221) which is connected to the radiation-resistant protective material filling chamber (22).

3. The radiation-resistant protection structure of the sapphire fiber high-temperature sensor according to claim 1, characterized in that: The protective gas (231) is an inert gas or a protective gas.

4. The radiation-resistant protection structure of the sapphire fiber high-temperature sensor according to claim 1, characterized in that: The radiation-resistant protective material (222) is a polymer-based coating material.

5. The radiation-resistant protection structure of the sapphire fiber high-temperature sensor according to claim 1, characterized in that: The protective layer formed by mixing and curing with high-temperature adhesive has a thickness of not less than 1 mm.

6. The radiation-resistant protection structure of the sapphire fiber high-temperature sensor according to claim 1, characterized in that: The open end of the high-temperature cladding (21) is also provided with a connecting package (25). The pigtail of the sapphire fiber high-temperature sensor (1) passes through the connecting package (25) and is connected to the transmission optical cable (26) and the optical fiber connector (27).

7. A sensor system, characterized in that, include: Radiation-resistant protective structure as described in any one of claims 1 to 6; A fiber optic sensor signal demodulator (3) is connected to the radiation-resistant protective structure via a fiber optic connector (27). Among them, the radiation-resistant protective structure is configured to be inserted into the high-temperature, high-radiation hot chamber (4).

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