CN108401409A - A kind of magnetic field shielding device that open full frequency band is adjusted - Google Patents
A kind of magnetic field shielding device that open full frequency band is adjusted Download PDFInfo
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Abstract
本发明公开了属于电磁兼容技术领域的涉及一种开放式全频段调节的磁场屏蔽装置，该磁场屏蔽装置由磁场探测线圈、磁场检测线圈、驱动电路，磁场调节线圈和相应配套的样品台构成；磁场探测线圈负责监测环境磁场变化，经过驱动电路功率放大后驱动磁场调节线圈对外磁场进行抵消，其中磁场探测线圈放在正上方，样品台置于磁场调节线圈中心，磁场检测线圈和磁场检测探头连接，并放在样品台面上，驱动电路放在磁场调节线圈外侧，被屏蔽磁场在驱动电路上方。本发明提供的全频段调节的磁场屏蔽装置更有利于工程实践。
The invention discloses an open-type full-frequency adjustable magnetic field shielding device belonging to the technical field of electromagnetic compatibility. The magnetic field shielding device is composed of a magnetic field detection coil, a magnetic field detection coil, a drive circuit, a magnetic field adjustment coil and a corresponding supporting sample stage; The magnetic field detection coil is responsible for monitoring the change of the environmental magnetic field. After the power of the drive circuit is amplified, the magnetic field adjustment coil is driven to offset the external magnetic field. The magnetic field detection coil is placed directly above, the sample stage is placed in the center of the magnetic field adjustment coil, and the magnetic field detection coil is connected to the magnetic field detection probe. , and placed on the sample table, the driving circuit is placed outside the magnetic field adjustment coil, and the shielded magnetic field is above the driving circuit. The full-frequency adjustable magnetic field shielding device provided by the invention is more beneficial to engineering practice.
Description
技术领域technical field
本发明涉及电磁兼容领域，特别涉及一种开放式全频段调节的磁场屏蔽装置，具体涉及一种开放式交、直流全频段调节的磁场屏蔽装置。The invention relates to the field of electromagnetic compatibility, in particular to an open magnetic field shielding device for full-frequency regulation, in particular to an open magnetic field shielding device for AC and DC full-frequency regulation.
背景技术Background technique
随着人类文明的不断发展，电磁环境也日益恶化。在高压线，大型用电器，大型钢结构建筑周围，电磁噪音尤其严重，磁场抵消是许多精密科学的通用保障性技术，在一些极端测量环境：如高精密原子钟电子束成像装置，质谱仪，中微子探测中得到广泛引用。在某些生物磁测量中，待测信号多处于10pT(1×10-11)量级甚至更低。而环境噪音磁场要大3-6个数量级。去除噪音信号成为这类测量必不可少的环节。With the continuous development of human civilization, the electromagnetic environment is deteriorating day by day. Electromagnetic noise is especially serious around high-voltage lines, large electrical appliances, and large steel structures. Magnetic field cancellation is a common support technology for many precision sciences. In some extreme measurement environments: such as high-precision atomic clock electron beam imaging devices, mass spectrometers, medium and micro Widely referenced in subprobing. In some biomagnetic measurements, the signal to be measured is mostly in the order of 10pT (1×10 -11 ) or even lower. The ambient noise magnetic field is 3-6 orders of magnitude larger. Removing noisy signals becomes an essential part of this type of measurement.
目前普遍采用的磁场屏蔽方式有两种：被动屏蔽式和主动抵消式。其中被动屏蔽式应用历史最为悠久，屏蔽系统采用高磁导率材料构建封闭腔体将被保护对象封闭其内，搭建屏蔽腔的材料的磁导率愈高，腔壁愈厚，屏蔽效果就愈显著。常用高磁导率材料如软铁、硅钢、坡莫合金等。这种屏蔽质量大，重量沉，屏蔽磁场方向光学不透明。其次，就是一些抵消式的屏蔽系统，比如，现有技术提供了一种基于闭合超导线圈组结构的屏蔽装置，其基本结构是由特定半径比和匝数比的超导线圈组电连接形成。如专利200910237483.6，201310318660.X，201310318686.4，201510128739.5。但这些专利设计的磁场调节器无法对直流磁场进行调节；其次，由于至少需要两个线圈，造成体积比大，不利于工程实践。There are two commonly used magnetic field shielding methods: passive shielding and active cancellation. Among them, passive shielding has the longest application history. The shielding system uses high magnetic permeability materials to construct a closed cavity to seal the protected object. The higher the magnetic permeability of the material used to build the shielding cavity, the thicker the cavity wall, and the greater the shielding effect. significantly. Commonly used high magnetic permeability materials such as soft iron, silicon steel, permalloy, etc. This kind of shielding has high mass and heavy weight, and is optically opaque in the direction of the shielding magnetic field. Secondly, there are some offset shielding systems. For example, the prior art provides a shielding device based on a closed superconducting coil structure. The basic structure is formed by electrical connection of superconducting coils with a specific radius ratio and turns ratio. . Such as patents 200910237483.6, 201310318660.X, 201310318686.4, 201510128739.5. However, these patented magnetic field regulators cannot adjust the DC magnetic field; secondly, because at least two coils are required, the volume ratio is large, which is not conducive to engineering practice.
发明内容Contents of the invention
本发明的目的是提供一种开放式全频段调节的磁场屏蔽装置，其特征在于，该磁场屏蔽装置由磁场探测线圈、磁场检测线圈、驱动电路，磁场调节线圈和相应配套的样品台构成；磁场探测线圈负责监测环境磁场变化，经过驱动电路功率放大后驱动磁场调节线圈对外磁场进行抵消，但是，磁场调节线圈必须由超导线圈构成；其中磁场探测线圈1放在磁场调节线圈5的正上方，样品台6置于磁场调节线圈5中心，磁场检测线圈2放在样品台6面上，磁场检测探头3位于磁场检测线圈2附近，磁场探测线圈1接收磁场检测探头3的信号；驱动电路4放在磁场调节线圈5外侧，被屏蔽磁场7在驱动电路4上方。The purpose of the present invention is to provide an open-type full-band adjustable magnetic field shielding device, which is characterized in that the magnetic field shielding device is composed of a magnetic field detection coil, a magnetic field detection coil, a drive circuit, a magnetic field adjustment coil and a corresponding supporting sample stage; the magnetic field The detection coil is responsible for monitoring the change of the environmental magnetic field. After the power of the drive circuit is amplified, the magnetic field adjustment coil is driven to offset the external magnetic field. However, the magnetic field adjustment coil must be composed of a superconducting coil; the magnetic field detection coil 1 is placed directly above the magnetic field adjustment coil 5, The sample stage 6 is placed in the center of the magnetic field adjustment coil 5, the magnetic field detection coil 2 is placed on the surface of the sample stage 6, the magnetic field detection probe 3 is located near the magnetic field detection coil 2, and the magnetic field detection coil 1 receives the signal of the magnetic field detection probe 3; Outside the magnetic field adjusting coil 5 , the shielded magnetic field 7 is above the drive circuit 4 .
所述驱动电路由直流放大偏置模块8、功率放大模块9构成。The drive circuit is composed of a DC amplifier bias module 8 and a power amplifier module 9 .
所述磁场调节线圈为亥姆霍兹(Helmholtz)线圈，采用三组5X、5Y、5Z线圈正交的方式构成磁场调节线圈组；该磁场调节线圈组形成一个能够屏蔽三个方向磁场的开放式全频段磁场屏蔽装置。The magnetic field adjustment coil is a Helmholtz (Helmholtz) coil, and three groups of 5X, 5Y, and 5Z coils are used to form a magnetic field adjustment coil group in an orthogonal manner; Full-band magnetic field shielding device.
该开放式全频段调节的磁场屏蔽装置的基本原理是利用磁场探测线圈监测环境磁场变化，根据电磁感应定律，磁场检测线圈接收到磁场检测探头探测的信号，探磁场探测线圈会产生U＝dΦ/dt的电压信号,其中Φ是磁场探测线圈包含面积内的磁通；假设空间磁场是正弦磁场，由50Hz传输线产生的磁场，那么磁场探测线圈的电压信号U经过微分与空间磁场呈90°，磁场探测线圈产生的电压信号U输入驱动电路，由于驱动电路是由直流放大偏置模块、功率放大模块构成的，并且驱动电路设计成输入电压与输出电压无相位差；经过驱动电路放大之后的电压驱动磁场调节线圈工作；磁场调节线圈是采用超导线圈，磁场超导线圈电阻可视为0，呈现出纯电感性，则纯电感电路电流满足i＝-kdU/L,其中k为放大系数，是可调节的参量，发现当磁场调节线圈电流i与磁场探测线圈电压U信号相位呈90°时，与空间磁场恰好呈180°，相当于反相位，因此由磁场调节线圈产生的磁场与空间磁场可相互抵消；调节磁场调节线圈的放大系数k来实现对外界磁场同时减小，抵消或者放大；此处需要特别说明是，磁场调节线圈需要采用超导线圈，如果利用常规线圈搭建，因为有电阻，磁场调节线圈电流一定会产生相移，无法与空间磁场相位形成反相位；磁场检测线圈放置在磁场调节线圈5的正上方，磁场检测探头位于磁场检测线圈附近，通过观测磁场检测线圈电压值，调节磁场调节线圈的放大系数k，使磁场检测线圈无电压信号输出时，即达到最佳屏蔽效果；由此说明了这种开放式全频段磁场屏蔽装置对于动态特别是谐态外磁场的屏蔽能力。The basic principle of the open-type full-band adjustable magnetic field shielding device is to use the magnetic field detection coil to monitor the change of the environmental magnetic field. According to the law of electromagnetic induction, the magnetic field detection coil receives the signal detected by the magnetic field detection probe, and the magnetic field detection coil will generate U=dΦ/ The voltage signal of dt, where Φ is the magnetic flux within the area contained in the magnetic field detection coil; assuming that the space magnetic field is a sinusoidal magnetic field, the magnetic field generated by a 50Hz transmission line, then the voltage signal U of the magnetic field detection coil is 90° from the space magnetic field after differentiation, and the magnetic field The voltage signal U generated by the detection coil is input to the drive circuit, because the drive circuit is composed of a DC amplifier bias module and a power amplifier module, and the drive circuit is designed so that there is no phase difference between the input voltage and the output voltage; the voltage drive after the drive circuit is amplified The magnetic field adjustment coil works; the magnetic field adjustment coil is a superconducting coil, and the resistance of the magnetic field superconducting coil can be regarded as 0, showing pure inductance, then the pure inductance circuit current satisfies i=-kdU/L, where k is the amplification factor, is Adjustable parameters, it is found that when the phase of the magnetic field adjustment coil current i and the magnetic field detection coil voltage U signal is 90°, it is exactly 180° with the space magnetic field, which is equivalent to the opposite phase, so the magnetic field generated by the magnetic field adjustment coil and the space magnetic field Can cancel each other; adjust the amplification factor k of the magnetic field adjustment coil to realize the simultaneous reduction, offset or amplification of the external magnetic field; here it needs to be specially explained that the magnetic field adjustment coil needs to use a superconducting coil, if it is built with a conventional coil, because there is resistance , the current of the magnetic field adjustment coil will definitely produce a phase shift, and cannot form an antiphase with the phase of the space magnetic field; the magnetic field detection coil is placed directly above the magnetic field adjustment coil 5, and the magnetic field detection probe is located near the magnetic field detection coil, and the voltage value of the coil is detected by observing the magnetic field , adjust the amplification factor k of the magnetic field adjustment coil, so that when the magnetic field detection coil has no voltage signal output, the best shielding effect is achieved; thus it shows that this open full-band magnetic field shielding device can shield the dynamic, especially harmonic, external magnetic field ability.
其次，对于直流型外磁场调节能力主要依靠驱动电路的直流偏置功能完成；首先通过磁场检测线圈探测直流磁场，再通过直流放大偏置模块加载直流偏置，经功率放大模块放大后驱动磁场调节线圈调节其放大系数k，使磁场检测线圈无电压信号输出，形成对直流磁场的抵消能力。Secondly, the adjustment ability of the DC external magnetic field mainly depends on the DC bias function of the drive circuit; firstly, the DC magnetic field is detected through the magnetic field detection coil, and then the DC bias is loaded through the DC amplifier bias module, and the magnetic field is adjusted after being amplified by the power amplifier module. The coil adjusts its amplification factor k, so that the magnetic field detection coil has no voltage signal output, forming the ability to offset the DC magnetic field.
本发明的有益效果是相对于现有技术，本发明提供的全频段调节的磁场屏蔽装置更有利于工程实践。The beneficial effect of the invention is that compared with the prior art, the magnetic field shielding device with full frequency band adjustment provided by the invention is more conducive to engineering practice.
附图说明Description of drawings
图1为磁场屏蔽装置的结构示意图。Fig. 1 is a schematic structural diagram of a magnetic field shielding device.
图2为驱动电路结构示意图。Figure 2 is a schematic diagram of the drive circuit structure.
图3为磁场屏蔽装置对噪音磁场屏蔽效果图。Fig. 3 is a diagram showing the shielding effect of the magnetic field shielding device on the noise magnetic field.
具体实施方式Detailed ways
本发明提供一种开放式全频段调节的磁场屏蔽装置，下面结合附图和实施例予以说明。The present invention provides an open-type full-frequency adjustable magnetic field shielding device, which will be described below in conjunction with the accompanying drawings and embodiments.
图1所示为磁场屏蔽装置的结构示意图；该磁场屏蔽装置由磁场探测线圈、磁场检测线圈、驱动电路，磁场调节线圈和相应配套的样品台构成；磁场探测线圈负责监测环境磁场变化，经过驱动电路功率放大后驱动磁场调节线圈对外磁场进行抵消，但是，磁场调节线圈必须由超导线圈构成，超导线圈采用YBCO超导体绕制或采用Bi2223高温超导绕制。其中磁场探测线圈1放在磁场调节线圈5的正上方，样品台6置于磁场调节线圈5中心，磁场检测线圈2放在样品台6面上，磁场检测探头3位于磁场检测线圈2附近，驱动电路4放在磁场调节线圈5外侧，被屏蔽磁场7在驱动电路4上方。Figure 1 shows the structural schematic diagram of the magnetic field shielding device; the magnetic field shielding device is composed of a magnetic field detection coil, a magnetic field detection coil, a drive circuit, a magnetic field adjustment coil and a corresponding supporting sample stage; the magnetic field detection coil is responsible for monitoring changes in the environmental magnetic field. After the power of the circuit is amplified, the magnetic field adjustment coil is driven to offset the external magnetic field. However, the magnetic field adjustment coil must be composed of a superconducting coil, and the superconducting coil is wound with YBCO superconductor or Bi2223 high temperature superconductor. Wherein the magnetic field detection coil 1 is placed directly above the magnetic field adjustment coil 5, the sample stage 6 is placed at the center of the magnetic field adjustment coil 5, the magnetic field detection coil 2 is placed on the surface of the sample stage 6, the magnetic field detection probe 3 is located near the magnetic field detection coil 2, and the driving The circuit 4 is placed outside the magnetic field adjusting coil 5 , and the shielded magnetic field 7 is above the drive circuit 4 .
所述驱动电路由直流放大偏置模块8、功率放大模块9构成(如图2所示)；所述磁场调节线圈为亥姆霍兹(Helmholtz)线圈，采用三组5X、5Y、5Z线圈正交的方式构成磁场调节线圈组(如图3所示)；磁场调节线圈组形成一个可屏蔽三个方向磁场的开放式全频段磁场屏蔽装置。The driving circuit is composed of a DC amplifier bias module 8 and a power amplifier module 9 (as shown in Figure 2); The magnetic field adjustment coil group is formed in an alternating manner (as shown in Figure 3); the magnetic field adjustment coil group forms an open full-band magnetic field shielding device that can shield the magnetic field in three directions.
该开放式全频段调节的磁场屏蔽装置的基本原理是利用磁场探测线圈监测环境磁场变化，根据电磁感应定律，磁场检测线圈接收到磁场检测探头探测的信号，磁场探测线圈会产生U＝dΦ/dt的电压信号,其中Φ是磁场探测线圈包含面积内的磁通；假设空间磁场是正弦磁场，由50Hz传输线产生的磁场，那么磁场探测线圈的电压信号U经过微分与空间磁场呈90°，磁场探测线圈产生的电压信号U输入驱动电路，由于驱动电路是由直流放大偏置模块、功率放大模块构成的，并且驱动电路设计成输入电压与输出电压无相位差；经过驱动电路放大之后的电压驱动磁场调节线圈工作；磁场调节线圈是采用超导线圈，磁场超导线圈电阻可视为0，呈现出纯电感性，则纯电感电路电流满足i＝-kdU/L,其中k为放大系数，是可调节的参量，发现当磁场调节线圈电流i与磁场探测线圈电压U信号相位呈90°时，与空间磁场恰好呈180°，相当于反相位，因此由磁场调节线圈产生的磁场与空间磁场可相互抵消；调节磁场调节线圈的放大系数k来实现对外界磁场同时减小，抵消或者放大；此处需要特别说明是，磁场调节线圈需要采用超导线圈，如果利用常规线圈搭建，因为有电阻，磁场调节线圈电流一定会产生相移，无法与空间磁场相位形成反相位；磁场检测线圈放置在磁场调节线圈的正上方；通过观测磁场检测线圈电压值，调节磁场调节线圈的放大系数k，使磁场检测线圈无电压信号输出时，即达到最佳屏蔽效果；由此说明了这种开放式全频段磁场屏蔽装置对于动态特别是谐态外磁场的屏蔽能力。The basic principle of the open-type full-band adjustable magnetic field shielding device is to use the magnetic field detection coil to monitor the change of the environmental magnetic field. According to the law of electromagnetic induction, the magnetic field detection coil receives the signal detected by the magnetic field detection probe, and the magnetic field detection coil will generate U=dΦ/dt The voltage signal, where Φ is the magnetic flux within the area contained in the magnetic field detection coil; assuming that the space magnetic field is a sinusoidal magnetic field, a magnetic field generated by a 50Hz transmission line, then the voltage signal U of the magnetic field detection coil is 90° from the space magnetic field after differentiation, and the magnetic field detection The voltage signal U generated by the coil is input to the drive circuit. Since the drive circuit is composed of a DC amplifier bias module and a power amplifier module, and the drive circuit is designed so that there is no phase difference between the input voltage and the output voltage; the voltage amplified by the drive circuit drives the magnetic field The adjustment coil works; the magnetic field adjustment coil is a superconducting coil, and the resistance of the magnetic field superconducting coil can be regarded as 0, showing pure inductance, then the pure inductance circuit current satisfies i=-kdU/L, where k is the amplification factor, which can be Adjusting parameters, it is found that when the phase of the magnetic field adjustment coil current i and the magnetic field detection coil voltage U signal are 90°, they are exactly 180° with the space magnetic field, which is equivalent to the opposite phase. Therefore, the magnetic field generated by the magnetic field adjustment coil and the space magnetic field can be Mutual cancellation; adjust the amplification factor k of the magnetic field adjustment coil to realize the reduction, offset or amplification of the external magnetic field at the same time; here it needs to be specially explained that the magnetic field adjustment coil needs to use a superconducting coil. If a conventional coil is used to build, because there is resistance, The current of the magnetic field adjustment coil will definitely produce a phase shift, and cannot form an antiphase with the phase of the space magnetic field; the magnetic field detection coil is placed directly above the magnetic field adjustment coil; by observing the voltage value of the magnetic field detection coil, the amplification factor k of the magnetic field adjustment coil is adjusted, so that When there is no voltage signal output from the magnetic field detection coil, the best shielding effect is achieved; thus, the shielding ability of this open full-band magnetic field shielding device for dynamic, especially harmonic, external magnetic fields is explained.
其次，对于直流型外磁场调节能力主要依靠驱动电路的直流偏置功能完成；首先通过磁场检测线圈探测直流磁场，再通过直流放大偏置模块加载直流偏置，经功率放大模块放大后驱动磁场调节线圈调节其放大系数k，使磁场检测线圈无电压信号输出，形成对直流磁场的抵消能力。Secondly, the adjustment ability of the DC external magnetic field mainly depends on the DC bias function of the drive circuit; firstly, the DC magnetic field is detected through the magnetic field detection coil, and then the DC bias is loaded through the DC amplifier bias module, and the magnetic field is adjusted after being amplified by the power amplifier module. The coil adjusts its amplification factor k, so that the magnetic field detection coil has no voltage signal output, forming the ability to offset the DC magnetic field.
实施例1Example 1
如图1所示，本实施例公开一种磁场屏蔽装置，包括：磁场探测线圈1，磁场检测线圈2，磁场检测探头3，驱动电路4，磁场调节线圈5，除此之外还有样品台6，被屏蔽磁场7。As shown in Figure 1, this embodiment discloses a magnetic field shielding device, including: a magnetic field detection coil 1, a magnetic field detection coil 2, a magnetic field detection probe 3, a drive circuit 4, a magnetic field adjustment coil 5, and a sample stage in addition 6. Shielded by magnetic field7.
磁场探测线圈1负责监测环境磁场变化，磁场探测线圈1接收到磁场检测探头3探测的信号，磁场探测线圈会产生U＝dΦ/dt的电压信号，探测线圈的电压信号经过驱动电路功率放大后驱动磁场调节线圈5对外磁场7进行抵消。在实施例1中，为了获得尽可能大的匀场区，采用亥姆霍兹(Helmholtz)结构线圈的磁场调节线圈5是一种分离式线圈组结构，在中心可产生比较均匀的磁场。实施例1中亥姆霍兹线圈采用边长1米结构。在Helmholtz线圈中心区域放置样品台6。实施例1中磁场检测线圈2放置在样品台之6上，磁场探测线圈1放置在亥姆霍兹线圈5之外，磁场探测线圈和磁场检测线圈均采用表面带有绝缘层的铜导线绕制。实施例1中磁场探测线圈采用半径1cm，匝数100匝扁平状线圈结构。The magnetic field detection coil 1 is responsible for monitoring the change of the environmental magnetic field. The magnetic field detection coil 1 receives the signal detected by the magnetic field detection probe 3. The magnetic field detection coil will generate a voltage signal of U=dΦ/dt. The voltage signal of the detection coil is amplified by the drive circuit and then driven The magnetic field adjusting coil 5 cancels the external magnetic field 7 . In Embodiment 1, in order to obtain a shimming area as large as possible, the magnetic field adjustment coil 5 adopting a Helmholtz structure coil is a separate coil group structure, which can generate a relatively uniform magnetic field in the center. In Example 1, the Helmholtz coil adopts a structure with a side length of 1 meter. Place the sample stage 6 in the central area of the Helmholtz coil. In Embodiment 1, the magnetic field detection coil 2 is placed on the sample stage 6, the magnetic field detection coil 1 is placed outside the Helmholtz coil 5, and the magnetic field detection coil and the magnetic field detection coil are both wound with copper wires with an insulating layer on the surface . In Embodiment 1, the magnetic field detection coil adopts a flat coil structure with a radius of 1 cm and a number of turns of 100 turns.
根据电磁感应定律，磁场探测线圈产生会产生U＝dΦ/dt的电压信号。其中Φ是探测线圈包含面积内的磁通。假设空间磁场是正弦磁场，比如是由50Hz传输线产生的磁场，那么探测线圈的电压信号经过微分后，与空间磁场呈90°，探测线圈产生的电压信号输入驱动电路。驱动电路由直流放大模块8、功率放大模块9构成的。其中驱动电路基本要求输入电压与输出电压无相位差。According to the law of electromagnetic induction, the magnetic field detection coil will generate a voltage signal of U=dΦ/dt. where Φ is the magnetic flux within the area contained by the search coil. Assuming that the spatial magnetic field is a sinusoidal magnetic field, such as the magnetic field generated by a 50Hz transmission line, then the voltage signal of the detection coil is differentiated to form a 90° angle with the spatial magnetic field, and the voltage signal generated by the detection coil is input to the drive circuit. The drive circuit is composed of a DC amplifier module 8 and a power amplifier module 9 . The drive circuit basically requires no phase difference between the input voltage and the output voltage.
经过驱动电路4放大之后的电压驱动磁场调节线圈5工作。磁场调节线圈最为重要的是采用超导线圈，超导线圈电阻可视为0，体现为一个纯电感性质。纯电感电路电流满足i＝-kdU/L,其中k为放大系数是可以人为调节的参量，L是线圈电感。可发现调节线圈电流i与探测线圈电压信号相位呈90°与空间磁场恰好呈180°相当于反相位。因此由调节线圈产生的磁场与空间磁场可相互抵消。仔细调节系数k可实现对外界磁场同相位的减小，抵消或者放大。此处需要特别说明是，调节线圈需要采用超导线圈，如果利用常规线圈搭建，因为有电阻，调节线圈电流一定会产生相移，无法与空间磁场相位形成反相位。在实施例1中，超导线圈采用YBCO超导体绕制而成。还可以采用Bi2223等高温超导绕制而成，系数k通过动态调整驱动电路功放放大系数获得最佳值。具体调节方式如下The voltage amplified by the drive circuit 4 drives the magnetic field adjustment coil 5 to work. The most important thing for the magnetic field adjustment coil is to use a superconducting coil. The resistance of the superconducting coil can be regarded as 0, which is reflected as a purely inductive property. The pure inductance circuit current satisfies i=-kdU/L, where k is the amplification factor and can be adjusted manually, and L is the coil inductance. It can be found that the phase of the adjustment coil current i and the voltage signal of the detection coil is 90°, and the space magnetic field is exactly 180°, which is equivalent to the opposite phase. Therefore, the magnetic field generated by the adjustment coil and the spatial magnetic field can cancel each other out. Carefully adjusting the coefficient k can reduce, cancel or amplify the same phase of the external magnetic field. What needs to be specially explained here is that the adjustment coil needs to use a superconducting coil. If a conventional coil is used to build it, because of the resistance, the adjustment coil current will definitely produce a phase shift, which cannot form an antiphase with the space magnetic field phase. In Embodiment 1, the superconducting coil is wound with a YBCO superconductor. It can also be made of high-temperature superconductors such as Bi2223, and the coefficient k can obtain the best value by dynamically adjusting the amplification factor of the power amplifier of the driving circuit. The specific adjustment method is as follows
将磁场检测线圈2放置在样品台6处，通过观测磁场检测线圈电压值，调节系数k，当磁场检测线圈无电压信号时达到最佳屏蔽效果。Place the magnetic field detection coil 2 on the sample stage 6, adjust the coefficient k by observing the voltage value of the magnetic field detection coil, and achieve the best shielding effect when the magnetic field detection coil has no voltage signal.
以上介绍了这种开放式全频段磁场调节器对于动态特别是谐态外磁场的调节能力。对于直流型外磁场调节能力主要依靠驱动电路的直流偏置功能完成。首先通过放置在样品台6上的磁场检测探头3探测直流磁场，再通过加载直流偏置，经过放大电路驱动调节线圈产生一个可以抵消环境磁场的磁场，从而对直流磁场形成抵消能力。在实施例1中磁场检测探头采用基于磁通门原理的磁场探头。The above describes the ability of this open full-band magnetic field regulator to adjust the dynamic, especially harmonic, external magnetic field. The ability to adjust the DC external magnetic field mainly depends on the DC bias function of the drive circuit. Firstly, the DC magnetic field is detected by the magnetic field detection probe 3 placed on the sample stage 6, and then by applying a DC bias, the amplifying circuit drives the adjusting coil to generate a magnetic field that can offset the ambient magnetic field, thereby forming a counteracting capability for the DC magnetic field. In Embodiment 1, the magnetic field detection probe adopts a magnetic field probe based on the fluxgate principle.
实施例2Example 2
在实施例1中，提供了一种对单方向磁场屏蔽结构，实施例2中提供了一种可屏蔽三个方向磁场的开放式全频段磁场屏蔽装置。它是采用三组正交方式的Helmholtz线圈构成磁场调节线圈组，如图3所示。相应的磁场探测线圈，磁场检测线圈也需匹配，在此不再赘述。In embodiment 1, a single-directional magnetic field shielding structure is provided, and in embodiment 2, an open full-band magnetic field shielding device capable of shielding three-directional magnetic fields is provided. It uses three sets of Helmholtz coils in an orthogonal manner to form a magnetic field adjustment coil group, as shown in Figure 3. Corresponding magnetic field detection coils, the magnetic field detection coils also need to be matched, which will not be repeated here.
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