CN115628826A - Fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage charged component - Google Patents
Fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage charged component Download PDFInfo
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- CN115628826A CN115628826A CN202211287590.1A CN202211287590A CN115628826A CN 115628826 A CN115628826 A CN 115628826A CN 202211287590 A CN202211287590 A CN 202211287590A CN 115628826 A CN115628826 A CN 115628826A
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- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
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Abstract
The invention discloses a Fiber Bragg Grating temperature sensor suitable for a vacuum high-temperature high-voltage electrified component, which comprises a quartz capillary tube, a metal capillary tube, a corundum tube, a Fiber jumper head and a Fiber Bragg Grating (FBG); FBG encapsulation is in the quartz capillary, the quartz capillary encapsulation is in the metal capillary, realizes the insulating intercommunication between the metal capillary through the corundum pipe, the one end at the metal capillary is installed to the optic fibre jumper head to link to each other with the FBG tail fiber. The FBG temperature sensor does not contain electronic components, has the advantages of long-term stable measurement performance and capability of being directly installed on a live component, and can package FBG strings to realize multipoint quasi-distributed temperature sensing; the optical signal obtained by the FBG temperature sensor is led out of the vacuum environment through the vacuum flange and then transmitted to the demodulator.
Description
Technical Field
The invention relates to the technical field of high-temperature measurement, in particular to an optical fiber Bragg grating temperature sensor suitable for a vacuum high-temperature high-voltage charged component.
Background
Traditional electronic sensors, such as thermocouples and resistance thermometers, have the disadvantages that a metal probe is easily oxidized in a high-temperature environment, so that the working stability of the traditional electronic sensor is reduced, the measurement error is increased, the traditional electronic sensor cannot be used for a long time, and the traditional electronic sensor cannot tolerate the action of high-energy charged particles. Therefore, most sensors cannot work normally under the conditions of high temperature, high vacuum degree and high-energy charged particles, while the fiber sensor based on the Fiber Bragg Grating (FBG) has the advantages of electromagnetic interference resistance, radiation resistance, corrosion resistance, small size, light weight, easiness in multiplexing and the like, can measure parameters such as temperature, strain, humidity and the like, is widely applied to structural health monitoring in the aspects of aviation, aerospace, navigation, dams, bridges and the like at present, is generally packaged in a quartz capillary tube during packaging, and is directly wound with a protective layer outside.
For the optical fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage electrified components, the sensor integrally needs to have certain flexibility, so that an FBG temperature measuring point is conveniently fixed on a component to be measured without damaging an optical fiber, and a material used for packaging the FBG temperature sensor needs to be resistant to high temperature (20-800 ℃); the whole sensor needs insulation, so that safety accidents caused by electric conduction are avoided. In addition, the FBG temperature sensor also needs to have good air tightness, and the used optical fiber cannot be provided with a polymer coating layer, so that the polymer coating layer is prevented from decomposing at high temperature to generate gas to pollute the vacuum environment.
Most of the current commercial FBG temperature sensors cannot meet the conditions, and particularly, optical fibers without coating layers are very fragile, so that great inconvenience is caused to the packaging and the use of the FBG temperature sensors.
Disclosure of Invention
The invention aims to solve the defects of the technology and provides the optical fiber Bragg grating temperature sensor suitable for a vacuum high-temperature high-voltage charged component.
The invention is realized by the following technical scheme:
the fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage electrified components comprises a quartz capillary tube, a metal capillary tube, a corundum tube, a fiber jumper and FBGs (fiber Bragg gratings).
The fiber bragg grating packaged in the FBG temperature sensor is a II-type FBG prepared in an anti-radiation single-mode fiber by adopting femtosecond laser, and has good high temperature resistance and anti-radiation capability. Under the condition of no radiation, the radiation-resistant single-mode fiber can be replaced by a common single-mode fiber, and the type II FBG can also be replaced by a regeneration grating or other high-temperature-resistant gratings. Considering that the FBG temperature sensor still needs to have good elasticity after being heated and cooled for multiple times so as to be repeatedly installed and used, the adopted metal capillary tube is made of GH3030 nickel-based alloy, the diameter is 1mm, and the wall thickness is 0.2mm.
In order to not pollute the high-temperature vacuum environment of a component to be measured, the optical fiber engraved with the FBG is completely removed of the coating layer and is very fragile, in order to prevent the coating layer removed optical fiber from being broken in the using process, a quartz capillary tube without a coating layer is adopted as a protective sleeve of the optical fiber, the inner diameter of the quartz capillary tube is 130-320 mu m, the wall thickness is 65-100 mu m, the optical fiber engraved with the FBG is firstly packaged in the quartz capillary tube, the quartz capillary tube and the optical fiber are fixed by using high-temperature resistant glue at one end of the quartz capillary tube, and then the quartz capillary tube is penetrated into a metal capillary tube.
The FBG is characterized in that when broadband light passes through the FBG, it reflects a light wave carrying a grating structure characteristic and refractive index information, the light wave having a corresponding characteristic wavelength.
The reflection condition of the fiber Bragg grating is as the formula (1)
λ B ＝2n eff Λ (1)
Temperature influences the effective refractive index n of the optical fiber mode through thermo-optic effect and thermal expansion effect eff And grating period Λ, resulting in λ B Drift occurs, as in formula (2)
The metal capillary tube has two sections, and the two sections of metal capillary tubes are in insulated connection through the corundum tube or the ceramic tube, because compared with a quartz tube, the corundum tube has good rapid cooling and heat resistance and is not easy to crack, and the corundum tube and the metal capillary tube are bonded and fixed by high-temperature-resistant glue which does not volatilize at high temperature.
The optical fiber jumper head is made of stainless steel and ceramic ferrules, the stainless steel can be replaced by other radiation-resistant metal materials, the optical fiber jumper head is installed at one end of the metal capillary tube in a high-temperature-resistant glue bonding mode, and the packaged jumper head is circularly heated on the heating table for multiple times so as to ensure that the high-temperature-resistant glue is firmly bonded.
The FBG temperature sensor can package FBG strings according to the measurement requirement, and quasi-distributed sensing is realized.
In conclusion, the FBG temperature sensor does not contain electronic components, the quartz capillary tube, the metal capillary tube, the corundum tube and the optical fiber jumper wire head are all resistant to high temperature, the optical fiber and the quartz capillary tube are not provided with coating layers, the relevant connection part and the through hole of the FBG temperature sensor are sealed by adopting high-temperature-resistant glue, the whole structure is good in air tightness, the temperature can be within the range of 20-800 ℃, and the vacuum degree is 10 -4 ～10 -3 pa. The FBG temperature sensor is integrally insulated, can be directly arranged on a component to be detected in an electrified state and connected with a demodulator, and the FBG temperature sensor can be packaged with FBG strings to form the same path of signal to realize quasi-distributed sensing.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the invention, are incorporated in and constitute a part of this specification:
FIG. 1 is a schematic structural diagram of an FBG temperature sensor of the present invention;
FIG. 2 is a schematic view of the internal structure of the joint of the corundum tube of the FBG temperature sensor of the invention;
FIG. 3 is a reflection spectrum of an FBG temperature sensor in example 1 of the present invention, wherein the FBG is fabricated by femtosecond laser point-by-point writing;
FIG. 4 is a reflection spectrum of an FBG temperature sensor in example 2 of the present invention, wherein the FBG is prepared by femtosecond laser combined with a phase mask;
fig. 5 is a graph showing the relationship between the grating center wavelength and the temperature of the FBG temperature sensors in the embodiments 1 and 2 of the present invention;
FIG. 6 is the transmission spectrum and temperature response curve of the FBG temperature sensor in example 3 of the present invention, wherein the FBG is a regeneration grating;
FIG. 7 is a schematic view of a test charging member according to an embodiment of the present invention;
FIG. 8 is a graph showing the real-time temperature change during the temperature rise of the test charging member according to example 1 of the present invention;
reference numbers and corresponding part names in the drawings:
1-optical fiber jumper wire head, 2-metal capillary sensing section, FBG carved on the optical fiber packaged in the metal capillary, 3-metal capillary light transmission section, wherein the optical fiber packaged in the metal capillary does not contain FBG, 4-corundum tube, 5-FBG temperature measuring point, 6-optical fiber, 7-quartz capillary, 8-FBG temperature sensor, 9-live part, 10-armored transmission optical fiber, 11-vacuum flange, 12-demodulator and 13-FBG temperature sensor clamp.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Referring to fig. 1 and 2, the overall structure of the FBG temperature sensors in the embodiments 1, 2 and 3 of the present invention is the same as follows: the metal capillary sensing section (2) and the metal capillary light-transmitting section (3) are respectively inserted from two ends of the corundum tube (4), keep a certain distance and are fixed by high-temperature-resistant glue to be used as an integral protective shell of the FBG temperature sensor. The optical fiber etched with the FBG (6) is packaged in a quartz capillary tube (7), the position of the FBG (6) in the quartz capillary tube (7) is adjusted according to a preset grating temperature measuring point, the tail fiber of the FBG (6) exceeds 2cm from one end of the quartz capillary tube (7) so as to facilitate the packaging treatment of a subsequent optical fiber jumper head (1), and then the quartz capillary tube and the optical fiber are fixed by using high-temperature-resistant glue at the other end of the quartz capillary tube. The polymer coating layers of the optical fiber carved with the FBG (6) and the quartz capillary tube (7) are stripped before packaging, so that the optical fiber is not decomposed under a high-temperature environment to generate gas to pollute a vacuum environment.
The quartz capillary tube (7) is packaged in the fixed metal capillary tube sensing section (2), the corundum tube (4) and the metal capillary tube light transmitting section (3), the optical fiber jumper head (1) is packaged at the tail end of the metal capillary tube light transmitting section (3), and the quartz capillary tube and the metal capillary tube are fixed and sealed by high-temperature-resistant glue at the tail end of the metal capillary tube sensing section (2).
Referring to fig. 3 to 5, compared to the phase mask method, FBGs with different periods prepared by the femtosecond laser dot-by-dot writing method have smaller variation in reflection intensity. However, since the optical fibers used for the FBG temperature sensor packages in the embodiments 1 and 2 of the present invention are the same type of optical fiber, the temperature sensitivities of the FBGs are almost the same.
Fig. 6 is a transmission spectrum and a temperature response curve thereof of the FBG temperature sensor in embodiment 3 of the present invention, where the FBG is a regenerated grating, before the regenerated grating is prepared, the optical fiber needs to be subjected to hydrogen loading treatment to increase the photosensitivity of the optical fiber, so as to obtain an initial grating with high transmission intensity, the quality of the initial grating will have a great influence on the regenerated grating, after the initial grating is inscribed, the initial grating is placed in a tube furnace, the temperature is raised to 1000 ℃, and thermal regeneration treatment is performed, that is, the transmission intensity of the initial grating is reduced to be enhanced, and finally the whole process tends to be stable. Compared with the preparation of common FBG, although the preparation of the regenerated grating is more difficult, the heat resistance of the regenerated grating is obviously improved.
Referring to fig. 7, the FBG temperature sensor is fixed on a temperature measuring point arranged on an electrified component by a corresponding clamp (13), grating reflection information is led out of a vacuum environment through an armored transmission optical fiber (5) and a vacuum flange (11) and is transmitted into a demodulator (12), when the temperature of the environment where the FBG temperature sensor is located rises, the bragg reflection wavelength of the FBG can drift due to a thermal expansion effect and a thermo-optic effect, the wavelength drift amount delta lambda and the temperature variation delta T are approximately linearly related, and the influence on the temperature response speed of the FBG is small because the used metal capillary and quartz capillary have thin tube walls. The wavelength information of the FBG temperature sensor is transmitted to a fiber grating demodulator through a vacuum flange, and the measured external environment temperature is obtained through demodulating delta lambda.
FIG. 8 shows the FBG temperature sensor of this example 1 with the test charged component (12 kv voltage) at a vacuum of 10 -4 ～10 -3 pa, the initial temperature is room temperature, and the temperature real-time change curve obtained in coating processing in the environment of the clothWhen the temperature sensor is arranged, the FBG-1 is closer to the heating source, the FBG-2 is separated from the FBG-1 by about 5cm, and finally, after the system is stabilized, the temperature measured at the FBG-1 is 462.4 ℃ and the temperature measured at the FBG-2 is 423.3 ℃.
Claims (6)
1. The fiber Bragg grating temperature sensor is suitable for vacuum high-temperature high-voltage electrified components and is characterized by comprising a quartz capillary tube, a metal capillary tube, a corundum tube, an optical fiber jumper wire head and an optical fiber carved with FBG (fiber Bragg Grating);
the optical fiber package is in the quartz capillary, and the coating has all been got rid of on the two surfaces, and the quartz capillary of the optic fibre that has FBG and the quartz capillary of the optic fibre that does not have FBG package are in two independent metal capillary, metal capillary passes through the corundum pipe and realizes insulating connection, the one end at metal capillary is installed to the optic fibre jumper wire head.
2. The fiber bragg grating temperature sensor suitable for the vacuum high-temperature high-voltage charged component as claimed in claim 1, wherein the metal capillary is divided into two sections and made of an alloy material GH3030 with good elasticity and high temperature resistance, the diameter of the metal capillary is 1mm, and the wall thickness is 0.2mm.
3. The fiber bragg grating temperature sensor suitable for vacuum high-temperature high-voltage live parts as claimed in claim 1, wherein the fiber jumper head is made of an electroless metal material except for the ferrule.
4. The fiber bragg grating temperature sensor suitable for the vacuum high-temperature high-voltage charged component as claimed in claim 1, wherein the fiber jumper head is mounted at one end of the metal capillary tube by high temperature resistant glue bonding.
5. The fiber bragg grating temperature sensor suitable for the vacuum high-temperature high-voltage charged component as claimed in claim 1, wherein the metal capillary tube has two sections, the two sections of metal capillary tubes are connected through a corundum tube, the length of the corundum tube is 70-80 mm, the diameter of the corundum tube is 2mm, the wall thickness of the corundum tube is 0.4-0.5 mm, and the metal capillary tube and the corundum tube are fixed through high-temperature resistant glue.
6. A fiber bragg grating temperature sensor suitable for vacuum high-temperature high-voltage live parts according to claim 1, wherein the FBG temperature sensor can package FBG strings, i.e. a plurality of FBGs with different central wavelengths are connected in series to the same optical fiber.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211287590.1A CN115628826A (en) | 2022-10-20 | 2022-10-20 | Fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage charged component |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211287590.1A CN115628826A (en) | 2022-10-20 | 2022-10-20 | Fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage charged component |
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| CN115628826A true CN115628826A (en) | 2023-01-20 |
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| CN202211287590.1A Pending CN115628826A (en) | 2022-10-20 | 2022-10-20 | Fiber Bragg grating temperature sensor suitable for vacuum high-temperature high-voltage charged component |
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- 2022-10-20 CN CN202211287590.1A patent/CN115628826A/en active Pending
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