阅读说明：本技术 一种具有连续空间分辨能力的磁场测量装置及方法 (Magnetic field measuring device and method with continuous spatial resolution capability ) 是由 吴坚 姜志远 张道源 陈紫维 石桓通 李兴文 于 2020-12-25 设计创作，主要内容包括：本发明公开了一种具有连续空间分辨能力的磁场测量装置及方法,属于磁场测量领域,包括：激光诱导装置与分裂光谱线收集装置；在待测空间中引入氯化钠晶体作为示踪剂；用纳秒激光聚焦并烧蚀氯化钠晶体从而在氯化钠晶体表面诱导等离子体；诱导等离子体在真空中向周围扩散；通过4-f成像系统用光谱仪收集连续分布的钠离子分裂光线的分裂谱线；对收集的谱线进行拟合,得到磁感应强度的分布。本发明通过引入氯化钠诱导等离子体作为示踪剂,不依赖于空间中原有的离子,从而可以测量各种情况下的真空磁场分布；同时诱导等离子体的运动具有连续性,加强了磁场测量的连续空间分辨能力。(The invention discloses a magnetic field measuring device with continuous spatial resolution capability and a method thereof, belonging to the field of magnetic field measurement and comprising the following steps: a laser induction device and a split spectral line collection device; introducing sodium chloride crystals as a tracer into a space to be detected; focusing and ablating sodium chloride crystals by nanosecond laser so as to induce plasmas on the surfaces of the sodium chloride crystals; inducing plasma to diffuse to the periphery in vacuum; collecting the splitting spectral lines of the sodium ion splitting rays which are continuously distributed by a spectrometer through a 4-f imaging system; and fitting the collected spectral lines to obtain the distribution of the magnetic induction intensity. According to the invention, sodium chloride induced plasma is introduced as a tracer, and the tracer does not depend on original ions in space, so that the distribution of a vacuum magnetic field under various conditions can be measured; meanwhile, the motion of the induced plasma has continuity, and the continuous spatial resolution capability of magnetic field measurement is enhanced.)

1. A magnetic field measurement device having continuous spatial resolution, comprising:

the device comprises a vacuum working cavity (1), wherein a nanosecond laser inlet, a continuous laser inlet and a split light outlet are formed in the cavity of the vacuum working cavity (1), and quartz glass (2) is respectively arranged on the nanosecond laser inlet, the continuous laser inlet and the split light outlet; an attachment rod (5) is arranged in the cavity, and a tracer is attached to the attachment rod (5);

the nanosecond laser (7) is used for generating a nanosecond laser beam (8), the nanosecond laser beam (8) enters the cavity from the nanosecond laser inlet, is focused on the tracer, and generates an induced plasma (10);

the continuous laser (15), continuous laser (15) are used for producing continuous laser beam (16), continuous laser beam (16) get into the cavity by continuous laser entry, focus on to be surveyed the space in order to simulate sodium ion split light (3), split light (3) are jetted out by the split light export to image on spectrum appearance slit (14).

2. The magnetic field measurement device with continuous spatial resolution according to claim 1, characterized in that a first plano-convex lens (9) is disposed on the optical path between the nanosecond laser (7) and the quartz glass (2) of the nanosecond laser entrance; a lens (17) is arranged on a light path between the continuous laser (15) and the quartz glass (2) at the continuous laser inlet; a second plano-convex lens (12) and a third plano-convex lens (13) are sequentially arranged on a light path between the quartz glass (2) of the split light ray outlet and a spectrometer slit (14).

3. The magnetic field measurement device with continuous spatial resolution according to claim 1, characterized in that the attachment rod (5) is an insulating rod, an insulating rope, a copper rod or an aluminum rod, and the tracer is a sodium chloride crystal (6).

4. A magnetic field measurement device having continuous spatial resolution, comprising:

the device comprises a vacuum working cavity (1), wherein a nanosecond laser inlet, a continuous laser inlet and a split light outlet are formed in the cavity of the vacuum working cavity (1), and quartz glass (2) is respectively arranged on the nanosecond laser inlet, the continuous laser inlet and the split light outlet; an anode (11), a cathode (18) and an attachment rod (5) are arranged in the cavity, and a sodium chloride crystal (6) is attached to the attachment rod (5); the attachment rod (5) is fixed between the cathode (18) and the anode (11); the cathode (18) is positioned at the continuous laser inlet, the side surface of the anode (11) is open, and the opening is opposite to the splitting light ray outlet; a reflector (4) is arranged inside the anode, and the reflector (4) is used for reflecting the split light (3) to the split optical fiber outlet;

the nanosecond laser (7) is used for generating a nanosecond laser beam (8), the nanosecond laser beam (8) enters the cavity from the nanosecond laser inlet and is focused on the sodium chloride crystal (6) to generate an induced plasma (10);

the continuous laser (15), continuous laser (15) are used for producing continuous laser beam (16), continuous laser beam (16) get into the cavity by continuous laser entry, focus on to be surveyed the space in order to simulate sodium ion split light (3), split light (3) are jetted out by the split light export to image on spectrum appearance slit (14).

5. The magnetic field measurement device with continuous spatial resolution according to claim 4, characterized in that a first plano-convex lens (9) is arranged in the optical path between the nanosecond laser (7) and the quartz glass (2) of the nanosecond laser entrance; a lens (17) is arranged on the light path between the continuous laser (15) and the quartz glass (2); a second plano-convex lens (12) and a third plano-convex lens (13) are sequentially arranged on a light path between the quartz glass (2) of the split light ray outlet and a spectrometer slit (14).

6. The magnetic field measuring device with continuous spatial resolution according to claim 4, characterized in that the attachment rod (5) is a copper or aluminum rod with a diameter of 2 mm.

7. A method for measuring a magnetic field with continuous spatial resolution using the apparatus according to any one of claims 1 to 6, comprising the steps of:

an attachment rod (5) is fixed in the space to be measured;

uniformly coating a saturated sodium chloride solution on the surface of the attachment rod (5);

naturally drying the sodium chloride solution or drying the sodium chloride solution by using a heat source until the water in the solution is completely evaporated so as to form a layer of fine sodium chloride crystals (6) on the surface of a solid object;

turning on a nanosecond laser (7), and aligning the emitting direction of the nanosecond laser to the coated sodium chloride crystal (6);

a lens (17) is added between the nanosecond laser (7) and the attachment rod (5), so that the nanosecond laser is focused on the surface of the sodium chloride crystal (6), and the position of the lens (17) is adjusted to minimize the focusing point of the nanosecond laser;

focusing a continuous laser (15) in a space to be measured to simulate split rays (3) of sodium ions, and imaging light spots generated by focusing to a slit (14) of a spectrometer by using a 4-f optical system;

linearly moving a focus point of a continuous laser (15) along the radial direction of an attachment rod (5), keeping the focus point always positioned in a region to be measured, and calibrating a 4-f optical system to keep an image formed by a light spot so that the light spot is always positioned on a spectrometer slit (14) in the movement process;

after calibration, the area to be measured is evacuated to a vacuum pressure of less than 7 × 10 by a vacuum pump^-2Pa；

Turning on a nanosecond laser (7), and ablating and exciting the sodium chloride crystal (6) by focused laser in a measured magnetic field to generate induced plasma (10);

inducing the plasma (10) to perform diffusion movement in the space to be measured;

simultaneously collecting the split rays (3) at all spatial positions along the diffusion direction using a spectrometer;

and fitting the experimental spectral line to obtain the magnitude of the magnetic induction intensity in the continuous space.

Technical Field

The invention belongs to the technical field of magnetic field measurement, and particularly relates to a magnetic field measurement device with continuous spatial resolution and a magnetic field measurement method.

Background

The magnetic field measurement technology is mainly used for solving important scientific research and physical problems, and is widely applied to the fields of military affairs, astronomy, resource exploration, scientific research and the like.

The Z-pinch refers to a process of inducing plasma generated under the action of pulse current to reach a high-temperature and high-density state and simultaneously generating strong X radiation under the action of a magnetic field, and is mainly applied to an X-ray source or inertial confinement fusion and the like. The space-time distribution of the induced plasma and the magnetic field and the coupling effect between the induced plasma and the magnetic field are the core problems of Z-pinch dynamics and are the basis for further improving the Z-pinch implosion quality and the X-ray radiation power. However, in terms of magnetic field distribution, this makes the measurement more challenging due to the high magnetic field strength in the induced plasma, large variation range (10T-104T), short duration (-100 ns), fast variation speed, and in extreme environments of high voltage (-MV), large current (-MA), and strong radiation.

The measurement of the magnetic field in vacuum is mainly performed by magnetic induction coils. Magnetic induction coils have the characteristics of simple principle, low cost and easy operation, and are widely used for measuring time-varying magnetic fields. The main body of the magnetic induction coil is one or more small coils, the number of turns of the coil is generally 3-5, and when the magnetic induction coil is used, the magnetic induction coil is placed in a certain region to be measured in the induced plasma, so that induced electromotive force is generated in a coil loop due to the change of a magnetic field in a space where the magnetic induction coil is located. Because the size of the electromotive force is in direct proportion to the change rate of the magnetic field intensity along with the time, the size of the magnetic field at the position of the magnetic induction coil can be obtained after the induced electromotive force is integrated with the time. However, the influence of the probe of the magnetic probe directly penetrating into the induced plasma on the induced plasma mainly has the following two aspects: firstly, the induced plasma is cooled and generates disturbance to the motion process; secondly, the induced current generated by the plasma induction device can interfere with the magnetic field of the induced plasma. Meanwhile, when the external temperature is too high, the coating covered by the magnetic probe is ablated, and a measuring signal may suddenly exceed a measurable threshold value to damage a measuring instrument, which is one of the limitations of the magnetic probe.

Another non-contact measurement method is faraday rotation, which is suitable for use in the presence of plasma in a vacuum. When a beam of linearly polarized light passes through the plasma, the plasma is taken as a magneto-optical medium, and the linearly polarized light can be regarded as the superposition of two beams of equal-amplitude left-handed circularly polarized light and right-handed circularly polarized light. The two beams of light have different refractive indexes and propagation speeds due to the magneto-optical effect, so that the two beams of light have different phase lags after passing through the same distance, and the linearly polarized light passing through the plasma is deflected, wherein the calculation formula of the deflection angle is as follows:

where λ is the wavelength of the incident light, n_eFor electron density, B is the component of the magnetic field vector on the experimental optical path, and dl is the element of the incident optical path. However, this method requires the plasma distribution in space to be symmetrical, and the electron density at all positions in the optical path is known, which is environmentally demanding.

In summary, it can be seen from the analysis that, in the background art disclosed in the prior art, it is a technical problem to be solved to develop a vacuum magnetic field measurement method which is simple in principle, convenient to operate, wide in range, efficient and reliable.

Disclosure of Invention

The invention aims to solve the problems existing in the measurement of the magnetic field distribution in vacuum at present and provides a magnetic field measurement device with continuous spatial resolution capability and a method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a magnetic field measurement device with continuous spatial resolution comprising:

the device comprises a vacuum working cavity, a laser processing cavity and a laser processing cavity, wherein a nanosecond laser inlet, a continuous laser inlet and a split light outlet are formed in the cavity of the vacuum working cavity, and quartz glass is respectively arranged on the nanosecond laser inlet, the continuous laser inlet and the split light outlet; an attachment rod is arranged in the cavity, and a tracer is attached to the attachment rod;

the nanosecond laser is used for generating a nanosecond laser beam, the nanosecond laser beam enters the cavity from the nanosecond laser inlet, is focused on the tracer, and generates induced plasma;

the continuous laser device is used for generating a continuous laser beam, the continuous laser beam enters the cavity from the continuous laser inlet, is focused in the space to be measured to simulate the splitting light of sodium ions, and the splitting light is emitted from the splitting light outlet and is imaged on the slit of the spectrometer.

The invention further improves the following steps:

a first plano-convex lens is arranged on a light path between the nanosecond laser and the quartz glass at the nanosecond laser inlet; a lens is arranged on a light path between the continuous laser and the quartz glass at the continuous laser inlet; and a second plano-convex lens and a third plano-convex lens are sequentially arranged on a light path between the quartz glass of the split light ray outlet and the slit of the spectrometer.

The attaching rod is an insulating rod, an insulating rope, a copper bar or an aluminum bar, and the tracer is a sodium chloride crystal.

A magnetic field measurement device with continuous spatial resolution comprising:

the device comprises a vacuum working cavity, a laser processing cavity and a laser processing cavity, wherein a nanosecond laser inlet, a continuous laser inlet and a split light outlet are formed in the cavity of the vacuum working cavity, and quartz glass is respectively arranged on the nanosecond laser inlet, the continuous laser inlet and the split light outlet; an anode, a cathode and an attachment rod are arranged in the cavity, and sodium chloride crystals are attached to the attachment rod; the attachment rod is fixed between the cathode and the anode; the cathode is positioned at the continuous laser inlet, the side surface of the anode is provided with an opening, and the opening is opposite to the split light ray outlet; a reflector is arranged inside the anode and used for reflecting the split light to the split optical fiber outlet;

the nanosecond laser is used for generating a nanosecond laser beam, the nanosecond laser beam enters the cavity from the nanosecond laser inlet, is focused on the sodium chloride crystal, and generates an induction plasma;

the continuous laser device is used for generating a continuous laser beam, the continuous laser beam enters the cavity from the continuous laser inlet, is focused in the space to be measured to simulate the splitting light of sodium ions, and the splitting light is emitted from the splitting light outlet and is imaged on the slit of the spectrometer.

The device is further improved in that:

a first plano-convex lens is arranged on a light path between the nanosecond laser and the quartz glass at the nanosecond laser inlet; a lens is arranged on a light path between the continuous laser and the quartz glass; and a second plano-convex lens and a third plano-convex lens are sequentially arranged on a light path between the quartz glass of the split light ray outlet and the slit of the spectrometer.

The attachment rod is a copper bar or an aluminum bar, and the diameter of the attachment rod is 2 mm.

A method of measuring a magnetic field with continuous spatial resolution, comprising the steps of:

fixing an attachment rod in a space to be measured;

uniformly coating a saturated sodium chloride solution on the surface of the attachment rod;

naturally drying the sodium chloride solution or drying the sodium chloride solution by using a heat source until the water in the solution is completely evaporated so as to form a layer of fine sodium chloride crystals on the surface of a solid object;

turning on a nanosecond laser, and aligning the emitting direction of the nanosecond laser to the coated sodium chloride crystal;

adding a lens between the nanosecond laser and the attachment rod to focus the nanosecond laser on the surface of the sodium chloride crystal, and adjusting the position of the lens to minimize the focus point of the nanosecond laser;

focusing the space to be measured by using a continuous laser to simulate split rays of sodium ions, and imaging light spots generated by focusing to a slit of a spectrometer by using a 4-f optical system;

linearly moving a focus point of the continuous laser along the radial direction of the attachment rod, keeping the focus point always positioned in a region to be measured, and calibrating a 4-f optical system to keep an image formed by a light spot so that the light spot is always positioned on a slit of a spectrometer in the movement process;

after calibration, the area to be measured is evacuated to a vacuum pressure of less than 7 × 10 by a vacuum pump^-2Pa；

Turning on a nanosecond laser, and ablating and exciting the sodium chloride crystal by focused laser in a detected magnetic field to generate induced plasma;

inducing the plasma to perform diffusion motion in the space to be measured;

collecting the split light rays at all spatial positions along the diffusion direction simultaneously by using a spectrometer;

and fitting the experimental spectral line to obtain the magnitude of the magnetic induction intensity in the continuous space.

Compared with the prior art, the invention has the following beneficial effects:

the invention obtains the magnitude of the magnetic induction intensity by measuring the splitting condition of the induced plasma generated in the magnetic field, the measurement precision mainly depends on the observation duration and the resolution of a spectrometer, but is not related to the strength of the measurement magnetic field, the measurement range depends on the diffusion range of the induced plasma, and the magnetic field of the area where all laser induced plasmas are positioned can be measured simultaneously, the locality is good, thereby realizing the high-efficiency and reliable measurement of the magnetic induction intensity.

The method is based on the laser-induced plasma and the Zeeman effect, and the magnetic field intensity of the space position where the induced plasma is located is determined by measuring the splitting spectral line of the splitting light of the laser-induced plasma in the magnetic field and performing data fitting. The space range for measuring the magnetic field is large, the precision can not be changed along with the strength of the magnetic field, and meanwhile, the device does not depend on the inherent plasma in vacuum, and can realize the high-efficiency, reliable and quick measurement of the magnetic induction intensity.

Drawings

In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic structural view of example 1 of the present invention;

FIG. 2 is a schematic structural diagram of a spatial resolution implementation method of the present invention;

fig. 3 is a schematic structural diagram of embodiment 2 of the present invention.

In the figure: 1-vacuum working chamber 1, 2-quartz glass, 3-splitting light, 4-reflector, 5-attaching rod, 6-sodium chloride crystal, 7-nanosecond laser, 8-nanosecond laser beam, 9-first plano-convex lens, 10-induced plasma, 11-anode, 12-second plano-convex lens, 13-third plano-convex lens, 14-spectrometer slit, 15-continuous laser, 16-continuous laser beam, 17-lens and 18-cathode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, the embodiment of the invention discloses a magnetic field measuring device with continuous spatial resolution capability, which comprises a vacuum working chamber 1, a nanosecond laser 7 and a continuous laser 15.

A nanosecond laser inlet, a continuous laser inlet and a split light outlet are formed in the cavity of the vacuum working cavity 1, and quartz glass 2 is respectively arranged on the nanosecond laser inlet, the continuous laser inlet and the split light outlet; an attachment rod 5 is arranged in the cavity, and a sodium chloride crystal 6 is attached to the attachment rod 5; the attaching rod 5 is an insulating rod, an insulating rope, a copper bar or an aluminum bar and is used for attaching a tracer.

The nanosecond laser 7 is used for generating a nanosecond laser beam 8, the nanosecond laser beam 8 enters the cavity from the nanosecond laser inlet and is focused on the sodium chloride crystal 6 to generate an induced plasma 10; a first plano-convex lens 9 is arranged on a light path between the nanosecond laser 7 and the quartz glass 2 at the nanosecond laser inlet; a lens 17 is arranged on the optical path between the continuous laser 15 and the quartz glass 2; a second plano-convex lens 12 and a third plano-convex lens 13 are sequentially disposed on the light path between the quartz glass 2 of the split light exit and the spectrometer slit 14, as shown in fig. 2.

The continuous laser 15 is used for generating a continuous laser beam 16, the continuous laser beam 16 enters the cavity from the continuous laser inlet, focuses on the space to be measured to simulate the splitting light 3 of sodium ions, and the splitting light 3 is emitted from the splitting light outlet and imaged on the slit 14 of the spectrometer.

According to the embodiment of the invention, a space magnetic field is provided by using pulse current, a copper rod with the diameter of 2mm and the height of 20mm is used as a load, and the surface of the copper rod is coated with sodium chloride crystals 6. The sodium chloride crystal 6 coated by nanosecond laser focusing ablation is combined with a Zeeman splitting spectral line of a laser-induced plasma 10 splitting light 3 in a magnetic field to measure continuous spatial distribution magnetic induction intensity in vacuum, and the magnetic field measurement method with continuous spatial resolution capability comprises the following steps:

polishing the surface of the copper rod by using sand paper, and uniformly coating a small amount of saturated sodium chloride solution on the surface of the copper rod;

naturally drying or drying the sodium chloride solution by using a heat source until the water in the solution is completely evaporated to form a layer of fine sodium chloride crystals 6 on the surface of the copper rod;

fixing a copper bar between the cathode 18 and the anode 11 and ensuring good electrical contact on both sides;

turning on a nanosecond laser 7, and directly aligning the emitting direction of nanosecond laser to the coated sodium chloride crystal 6 by using a low-energy continuous triggering mode;

a lens 9 is added between the nanosecond laser 7 and the quartz glass 2, so that the nanosecond laser is focused on the surface of the sodium chloride crystal, and the position of the lens is continuously adjusted to minimize the focusing point of the nanosecond laser;

focusing on a space to be measured by using a continuous laser 15 to simulate split rays 3 of sodium ions, and imaging light spots generated by focusing to a spectrometer slit 14 by using a 4-f optical system;

linearly moving a focus point of a continuous laser 15 along the radial direction of the copper cylinder, keeping the focus point always positioned in a region to be measured, and calibrating a 4-f optical system to keep an image formed by a light spot always positioned on a spectrometer slit 14 in the movement process;

after calibration, the area to be measured is evacuated to a vacuum pressure of less than 7 × 10 by a vacuum pump^-2Pa；

Turning on a nanosecond laser 7, and using a high-energy single-trigger mode, ablating and exciting the sodium chloride crystal 6 by focused laser in a detected magnetic field to generate an induced plasma 10, and inducing the plasma 10 to perform diffusion motion in a space to be detected;

after 300ns, electrifying the load, and applying pulse current with the leading edge of 450ns and the peak value of 400 kA;

after the interval of 300ns again, the split light rays 3 at all spatial positions along the diffusion direction are collected simultaneously by using the spectrometer;

and fitting the experimental spectral line to obtain the magnitude of the continuously distributed magnetic induction intensity.

Example (b):

as shown in fig. 3, the embodiment of the invention discloses a magnetic field measuring device with continuous spatial resolution, which comprises a vacuum working chamber 1, wherein the surface of the vacuum working chamber 1 is provided with three pieces of quartz glass 2, the interior of the vacuum working chamber comprises a cathode 18, an anode 11 and a copper bar, and the surface of the copper bar is coated with sodium chloride crystals 6; a nanosecond laser 7 is arranged outside the cavity, a nanosecond laser beam 8 generated by the nanosecond laser 7 is focused on the surface of the sodium chloride crystal 6 through a lens 9 to generate an induced plasma 10, and the generated free light generates Zeeman splitting in a magnetic field to generate split light 3; the reflector 4 is positioned right below the copper rod and used for reflecting the split light 3 to pass through the quartz glass 2 to a 4-f optical system consisting of a second plano-convex lens 12 and a third plano-convex lens 13 so as to form an image on a spectrometer slit 14; the 4-f optical system is calibrated by generating a continuous laser 19 from a continuous laser 15 focused through quartz glass 2 and lens 20 to form a spot simulating the emission of induced plasma 10.

The vacuum working cavity 1 is sealed by a steel plate and is pumped to be vacuum by a vacuum pump; the copper rod is a cylinder with the diameter of 2mm and the length of 20mm and is made of pure copper materials; the 4-f optical system consists of two plano-convex lenses with the focal length of 500 mm; the surface of the copper bar is evenly coated with sodium chloride crystals 6, and the optical path direction of the nanosecond laser beam 8 is set to be vertical to the surface of the copper bar.

The specific operation method of the invention is as follows:

the light collection system is calibrated by focusing the continuous laser at different radial positions to simulate the split rays 3 being imaged onto the spectrometer slit 14 prior to the actual measurement. Turning on the nanosecond laser 7, ablating the sodium chloride crystal 6 to generate an induced plasma 10 in the magnetic field; the interval is 300ns, so that the induced plasma 10 is diffused to a more distant position; switching on pulse current to generate a magnetic field around the copper rod; collecting the splitting spectral lines at different diffusion positions by using a 4-f optical system; and fitting the collected spectral lines to obtain the magnitude of the magnetic induction intensity.

The principle of the invention is as follows:

when the atoms or ions absorb energy, the atoms or ions are excited to a high energy level, and the atoms or ions at the high energy level jump to a low energy level, and simultaneously emit photons to generate a spectrum. When the external magnetic field or electric field acts, the coupling mode of the internal angular momentum of atoms is affected, spectral lines are split, and the influence of the magnetic field on the spectrum or the energy level is called the Zeeman effect. Sodium is considered by far to be one of the most readily observed elements of the zeeman-split spectrum. To accurately calculate the effect of the zeeman effect, consider a representation that introduces a hamiltonian of atomic states when the applied magnetic field and the LS-coupled internal magnetic field are comparable. Taking the 2P state of a sodium atom as an example, the hamilton can be written as:

H＝μ_B(L+gS)B+ξLS

in the formula, ξ is 11.5cm as the 3P energy level of sodium^-1Term μ to represent coupling strength_BIs 0.4669cm^-1T^-1. The theoretical energy level can be obtained by standard calculation according to the Hamiltonian in the formula, and the energy between the energy levels can be obtained according to the energyAnd (4) obtaining the splitting condition of the spectral line by changing.

Meanwhile, according to theory and experiment, the observed splitting spectral line is not an independent geometric line, but has a certain width and contour, and is generally represented by a linear function.

In this experiment, the linear function is expressed as the distribution function g (λ) of energy in terms of wavelength, i.e. the ratio of the energy distributed in a unit wavelength interval around λ to the total energy, as the line intensity I₀Full width at half maximum of the spectral line Δ λ and center wavelength λ₀To quantify, the center wavelength has been calculated as described above.

In the induced plasma 10, the quadratic stark effect, which is the main factor causing line broadening, is of the lorentzian type,is a function of electron density and temperature:

in the formula, N_eDenotes the electron density, alpha is the ion broadening parameter, omega denotes the electron collision full width at half maximum, their temperature T with the electrons_eIt is related.

The spectral lines in the experiment are also affected by instrument broadening, which can be measured by mercury lamps. But is negligible because the broadening is too small compared to the stark.

When both the center wavelength and the broadening of the split line are determined, the shape of the line can be determined accordingly. Therefore, by fitting the experimental spectral line, the central wavelength and the broadening of the spectral line can be obtained. According to the splitting condition of the central wavelength, the magnitude of the magnetic induction intensity in the region to be measured can be obtained.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.