阅读说明：本技术 一种复合涂层测磁光纤及其制备方法 (Composite coating magnetic measurement optical fiber and preparation method thereof ) 是由 戴少涛 方埼磊 张腾 莫思铭 蔡渊 袁文 马韬 王邦柱 胡磊 于 2020-03-27 设计创作，主要内容包括：本发明涉及一种复合涂层测磁光纤,包括裸光纤和涂覆层,所述涂覆层为丙烯酸树酯、铁镓合金和铟铋合金组成的复合涂覆层。本发明的复合涂层测磁光纤的制备方法,包括：1、采用浸渍涂敷-紫外光固化工艺将丙烯酸树脂涂敷于裸光纤表面,在裸光纤表面形成丙烯酸树脂涂层；2、将气体雾化法制备的铁镓合金粉末和铟铋合金混合均匀,在80℃熔融后放入涂敷杯中；3、将涂敷了丙烯酸树脂涂层的光纤经过步骤2制备的涂敷杯,在丙烯酸树脂涂层表面涂敷金属合金熔体,然后进行冷却,制备成复合涂层测磁光纤。本发明解决了低温下传统材料应变较低、光纤磁场传感器灵敏度低的问题,显著提高了测磁光纤在低温下的测量精度和灵敏度。(The invention relates to a composite coating magneto-optical fiber, which comprises a bare fiber and a coating layer, wherein the coating layer is a composite coating layer consisting of acrylic resin, iron-gallium alloy and indium-bismuth alloy. The preparation method of the composite coating magnetic measurement optical fiber comprises the following steps: 1. coating acrylic resin on the surface of the bare fiber by adopting a dip coating-ultraviolet light curing process to form an acrylic resin coating on the surface of the bare fiber; 2. uniformly mixing iron-gallium alloy powder prepared by a gas atomization method and an indium-bismuth alloy, melting at 80 ℃, and putting into a coating cup; 3. and (3) passing the optical fiber coated with the acrylic resin coating through the coating cup prepared in the step (2), coating the metal alloy melt on the surface of the acrylic resin coating, and then cooling to prepare the composite coating magnetic measuring optical fiber. The invention solves the problems of lower strain of the traditional material and low sensitivity of the optical fiber magnetic field sensor at low temperature, and obviously improves the measurement precision and sensitivity of the magnetic measurement optical fiber at low temperature.)

1. The composite coating magnetic measurement optical fiber is characterized by comprising a bare optical fiber and a coating layer, wherein the coating layer is as follows: the inner layer is an acrylic resin coating, and the outer layer is a composite coating of a metal alloy coating; the metal alloy coating is an iron-gallium alloy coating and an indium-bismuth alloy coating.

2. The composite coated magnetic fiber of claim 1, wherein: the bare fiber is a quartz core single-mode fiber only containing a fiber core.

3. The composite coated magnetic fiber of claim 1, wherein: the mass ratio of the iron-gallium alloy to the indium-bismuth alloy is 85-95: 15 to 5.

4. The composite coated magnetic fiber of claim 3, wherein: the mass ratio of iron to gallium in the iron-gallium alloy is 5: 1.

5. the composite coated magnetic fiber of claim 3, wherein: the mass ratio of indium to bismuth in the indium-bismuth alloy is 2: 1.

6. the method for preparing the composite coating magnetic measuring optical fiber according to claim 1, which comprises the following steps:

step 1, coating acrylic resin on the surface of a bare fiber by adopting a dip coating-ultraviolet curing process to form an acrylic resin coating on the surface of the bare fiber;

step 2, mixing the iron-gallium alloy powder and the indium-bismuth alloy powder prepared by a gas atomization method according to a mass ratio of 85-95: 15-5, uniformly mixing, melting at 80 ℃, and putting into a coating cup;

and 3, passing the optical fiber coated with the acrylic resin coating through the coating cup prepared in the step 2, coating the metal alloy melt on the surface of the acrylic resin coating, and then cooling.

And 4, finally, preparing the composite coating magnetism measuring optical fiber with the inner layer of the acrylic resin coating and the outer layer of the metal alloy coating.

7. The method for preparing a composite coating magnetic measuring optical fiber according to claim 6, wherein: in the step 1, the thickness of the acrylic resin coating is 10-200 μm.

8. The method for preparing a composite coating magnetic measuring optical fiber according to claim 6, wherein: in the step 2, the grain sizes of the iron-gallium alloy and the indium-bismuth alloy are 5-80 μm.

9. The method for preparing a composite coating magnetic measuring optical fiber according to claim 6, wherein: in the step 2, the mass ratio of iron to gallium in the iron-gallium alloy is 5: 1, the mass ratio of indium to bismuth in the indium-bismuth alloy is 2: 1.

10. the method for preparing a composite coating magnetic measuring optical fiber according to claim 6, wherein: in step 3, the thickness of the cooled metal alloy coating is 10-200 μm.

Technical Field

The invention belongs to the technical field of optical fiber magnetic field sensors for superconducting magnets, and particularly relates to a magnetic measurement optical fiber for measuring the magnetic field change of a superconducting magnet at low temperature and a preparation method thereof.

Background

The magnetic field is an important parameter reflecting the operating state of the superconducting magnet in the operation of the superconducting equipment, and the quench fault of the superconducting magnet can be timely found through the real-time monitoring of the magnetic field, so that the normal operation of the superconducting magnet is facilitated. However, the superconducting magnet is in a complex electromagnetic environment with a strong magnetic field and a large current, and although the traditional electric magnetic field sensors (flux gate magnetometers, hall sensors, induction coil magnetometers, giant magneto-impedance magnetic sensors, and the like) have mature application modes in many occasions, due to the influence of the magneto-resistance effect, the conventional electric magnetic field sensors are difficult to apply to the superconducting magnet with the complex electromagnetic environment, and the measurement requirement for monitoring the whole magnetic field of the superconducting magnet in a low-temperature environment is difficult to meet.

The optical fiber sensing technology takes optical fibers as sensing media and light waves as carriers, and can detect changes of external environments (magnetic fields, electric fields, temperature, humidity and the like) by demodulating changes of wavelengths, phases, amplitudes and the like of the light waves in the optical fibers; under the action of an external magnetic field, the length and the volume of the magnetostrictive material can change along the direction of the magnetic field. The magnetostrictive material is used as a coating layer and attached to the optical fiber, when an external magnetic field changes, the distributed optical fiber can generate tensile strain in the axial direction, so that the central wavelength of the optical fiber is shifted, and the magnetic field intensity can be monitored by constructing a functional relation between the central wavelength of the optical fiber and the magnetic field intensity. The optical fiber magnetic field sensor has strong anti-electromagnetic interference capability, is very suitable for monitoring precise instruments such as a superconducting magnet and the like, can realize distributed multiplexing, can effectively overcome the defects of the traditional electrical magnetic field sensing system in the aspects of long-term stability, durability and distribution range, and realizes high-precision, long-distance, distributed and long-term magnetic field environment monitoring.

The optical fiber magnetic field sensor is applied to monitoring of the superconducting magnet at low temperature, and the sensor can not avoid irreversible damage to superconducting equipment caused by quench fault to the maximum extent only by responding in time when the magnetic field of the magnet is abnormal, but the accurate measurement of the magnetic field at low temperature and the monitoring application in the superconducting magnet are not realized at present.

Disclosure of Invention

The invention overcomes the defect that the existing optical fiber magnetic field sensor can only carry out point-mode measurement, and adopts the distributed optical fiber sensor based on magnetostrictive materials to realize the magnetic field sensing demodulation of the whole optical fiber link. Meanwhile, the optical frequency domain reflection method is combined with the low-temperature sensitive magnetostrictive iron gallium alloy (Fe-Ga) coated optical fiber, so that high spatial resolution and high sensitivity monitoring of a weak magnetic field at low temperature is realized.

In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:

the utility model provides a compound coating surveys magnetic fiber, includes bare fiber and coating, the coating is: the inner layer is an acrylic resin coating, and the outer layer is a composite coating of a metal alloy coating; the metal alloy coating is an iron-gallium alloy coating and an indium-bismuth alloy coating.

The bare fiber is a quartz core single-mode fiber only containing a fiber core.

The mass ratio of the iron-gallium alloy to the indium-bismuth alloy is 85-95: 15 to 5.

The mass ratio of iron to gallium in the iron-gallium alloy is 5: 1.

the mass ratio of indium to bismuth in the indium-bismuth alloy is 2: 1.

the preparation method of the composite coating magnetic measurement optical fiber comprises the following steps:

step 1, coating acrylic resin on the surface of a bare fiber by adopting a dip coating-ultraviolet curing process to form an acrylic resin coating on the surface of the bare fiber;

step 2, mixing the iron-gallium alloy powder and the indium-bismuth alloy powder prepared by a gas atomization method according to a mass ratio of 85-95: 15-5, uniformly mixing, melting at 80 ℃, and putting into a coating cup;

and 3, passing the optical fiber coated with the acrylic resin coating through the coating cup prepared in the step 2, coating the metal alloy melt on the surface of the acrylic resin coating, and then cooling.

And 4, finally, preparing the composite coating magnetism measuring optical fiber with the inner layer of the acrylic resin coating and the outer layer of the metal alloy coating.

In the step 1, the thickness of the acrylic resin coating is 10-200 μm.

In the step 2, the grain sizes of the iron-gallium alloy and the indium-bismuth alloy are 5-80 μm.

In the step 2, the mass ratio of iron to gallium in the iron-gallium alloy is 5: 1, the mass ratio of indium to bismuth in the indium-bismuth alloy is 2: 1.

in step 3, the thickness of the cooled metal alloy coating is 10-200 μm.

The invention has the beneficial effects that:

1. the magnetostrictive material adopted by the invention is the iron-gallium alloy, has the advantages of high strain, small hysteresis, high stress sensitivity and the like under a low magnetic field, and solves the problems of low strain of the traditional material and low sensitivity of the optical fiber magnetic field sensor at a low temperature.

2. The invention adopts a composite coating magnetism-measuring optical fiber with an inner layer of acrylic resin coating and an outer layer of magnetostrictive metal coating. When the external magnetic field changes, the outer magnetostrictive metal coating deforms, and the strain is amplified through the inner high-elasticity acrylic resin coating; and further, the measurement precision and sensitivity of the magnetic measurement optical fiber at low temperature are obviously improved.

3. The optical fiber adopted by the invention is a fully distributed optical fiber, is not limited to the traditional point measurement, can realize the full-line monitoring of the optical fiber through Rayleigh scattering, realizes the overall magnetic field detection of the superconducting magnet, and can timely feed back the magnetic field mutation of the superconducting magnet.

Drawings

The invention has the following drawings:

FIG. 1 is a composite coated magnetic sensing fiber of the present invention;

wherein, 1 is a bare optical fiber, and 2 is a coating layer containing acrylic resin, iron-gallium alloy and indium-bismuth alloy.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1, the composite coating magnetic measurement fiber of the present invention includes a bare fiber 1 and a coating layer 2, wherein the coating layer 2 is: the inner layer is a composite coating layer of an acrylic resin coating and the outer layer is a metal alloy coating; the metal alloy coating is an iron-gallium alloy coating and an indium-bismuth alloy coating.

The bare fiber is a quartz core single-mode fiber only containing a fiber core.

The mass ratio of the iron-gallium alloy to the indium-bismuth alloy is 85-95: 15 to 5.

The mass ratio of iron to gallium in the iron-gallium alloy is 5: 1.

the mass ratio of indium to bismuth in the indium-bismuth alloy is 2: 1.

the preparation method of the composite coating magnetic measurement optical fiber comprises the following steps:

1. coating acrylic resin on the surface of the bare fiber by adopting a dip coating-ultraviolet light curing process to form an acrylic resin coating with the thickness of 10-200 mu m on the surface of the bare fiber;

2. mixing iron-gallium alloy powder (Fe-Ga, the mass ratio of Fe to Ga is 5: 1) and indium-bismuth alloy powder (In, Bi is 2: 1) with the particle size of 5-80 mu m prepared by a gas atomization method according to the mass ratio of 85-95: 15-5, uniformly mixing, melting at 80 ℃, and putting into a coating cup;

3. and (3) coating the optical fiber coated with the acrylic resin coating with a metal alloy melt on the surface of the acrylic resin coating by using the coating cup containing the molten metal alloy (Fe-Ga and InBi) prepared in the step (2), and cooling to obtain the metal alloy coating with the thickness of 10-200 mu m.

4. Finally, the composite coating magnetism-measuring optical fiber with the inner layer of the acrylic resin coating and the outer layer of the magnetostrictive metal alloy coating is prepared.