A magnetic field scanning device and a magnetic mass spectrometer

Abstract

The application discloses a magnetic field scanning device and a magnetic mass spectrometer. The magnetic field scanning device comprises a magnetic assembly and a control assembly. The number of turns of a main coil in the magnetic assembly is less than the number of turns of an auxiliary coil. A first main coil and a second main coil in a magnetic core unit are connected in series, which are a main magnetic unit. A first auxiliary coil and a second auxiliary coil are connected in series, which are an auxiliary magnetic unit. The control assembly is electrically connected with the main magnetic unit and the auxiliary magnetic unit respectively. The control assembly is used for adjusting the current of the main magnetic unit and adjusting the current in the auxiliary magnetic unit, so as to adjust the magnetic field intensity of the electromagnetic field between the first end and the second end, and then realize the magnetic field scanning. When the magnetic field is rapidly scanned, the combination control of the main magnetic unit and the auxiliary magnetic unit can make the magnetic field intensity rapidly and stably reach the required setting value.

Description

TECHNICAL FIELD

[0001] The present application relates to a magnetic field scanning device and a magnetic mass spectrometer comprising the same. BACKGROUND

[0002] The magnetic mass spectrometer has the advantages of simple structure, good stability, high resolution, wide dynamic range, high abundance sensitivity, etc., and is widely used in quantitative analysis of isotopic abundance and abundance ratio.

[0003] The mass analyzer is one of the most critical parts of the magnetic mass spectrometer, and generally comprises a magnetic field scanning device. The magnetic field scanning device is used for magnetic field scanning, i.e. changing the magnetic field strength to separate the charged ions passing through the magnetic field, so as to perform accurate mass spectrum analysis.

[0004] However, the existing magnetic field scanning device has the problem of slow scanning speed, which seriously slows down the analysis speed of the traditional magnetic mass spectrometer. SUMMARY

[0005] The present application aims to solve the above problems in the prior art, and provides a magnetic field scanning device and a magnetic mass spectrometer comprising the same, which has high scanning speed.

[0006] According to an embodiment of the first aspect of the present application, a magnetic field scanning device is provided, comprising: a magnetic assembly and a control assembly; the magnetic assembly comprises a magnetic yoke, the magnetic yoke comprises a first end portion and a second end portion, the first end portion is arranged opposite to the second end portion; the magnetic assembly further comprises a first coil unit and a second coil unit, the first coil unit and the second coil unit are arranged opposite to each other, the first coil unit is sleeved on the first end portion, and the second coil unit is sleeved on the second end portion; the first coil unit comprises a first main coil and a first auxiliary coil, the second coil unit comprises a second main coil and a second auxiliary coil, the number of turns of the first main coil is equal to that of the second main coil, the number of turns of the first auxiliary coil is equal to that of the second auxiliary coil, and the number of turns of the main coil is less than that of the auxiliary coil; the first main coil and the second main coil are connected in series, the series circuit of the first main coil and the second main coil is set as a main magnetic unit, the first auxiliary coil and the second auxiliary coil are connected in series, and the series circuit of the first auxiliary coil and the second auxiliary coil is set as an auxiliary magnetic unit; the control assembly is electrically connected with the main magnetic unit and the auxiliary magnetic unit respectively, the control assembly is used for adjusting the current of the main magnetic unit and adjusting the current in the auxiliary magnetic unit, so as to adjust the magnetic field strength of the electromagnetic field between the first end portion and the second end portion, and further realize magnetic field scanning.

[0007] Preferably, the control assembly comprises a controller, the controller is electrically connected with the main magnetic unit and the auxiliary magnetic unit respectively, the controller is used to obtain a set magnetic field intensity value, and obtain a corresponding magnetic field coarse adjustment threshold value according to the set magnetic field intensity value; the controller is also used to adjust the current of the main magnetic unit, so that the magnetic field intensity of the electromagnetic field between the first end and the second end reaches the magnetic field coarse adjustment threshold value, to complete the fast coarse adjustment of the magnetic field, and the current of the auxiliary magnetic unit is adjusted, so that the magnetic field intensity of the electromagnetic field between the first end and the second end reaches the set magnetic field intensity value, to complete the fine adjustment of the magnetic field intensity.

[0008] Preferably, the control assembly further comprises a magnetic induction sensor, the magnetic induction sensor is used to detect the magnetic field intensity of the electromagnetic field between the first end and the second end and feed back a magnetic field induction signal; the controller is electrically connected with the magnetic induction sensor, used to receive the magnetic field induction signal fed back by the magnetic induction sensor, and obtain the current magnetic field intensity of the electromagnetic field according to the magnetic field induction signal, the controller is also used to adjust the current in the main magnetic unit and the auxiliary unit according to the current magnetic field intensity of the electromagnetic field, until the magnetic field intensity of the electromagnetic field reaches the set magnetic field intensity value.

[0009] Preferably, the control assembly further comprises a first adjusting circuit and a second adjusting circuit; the controller is used to obtain corresponding first current value and second current value according to the set magnetic field intensity value, the first current value is the current value in the main magnetic unit when the magnetic field intensity reaches the magnetic field coarse adjustment threshold value, the second current value is the current value in the auxiliary magnetic unit when the magnetic field intensity reaches the set magnetic field intensity value, the first current value is greater than the second current value; the controller is electrically connected with the main magnetic unit through the first adjusting circuit, used to adjust the current of the main magnetic unit through the first adjusting circuit, so that the current in the main magnetic unit reaches the first current value, and then the magnetic field intensity of the main magnetic unit reaches the magnetic field coarse adjustment threshold value; the controller is electrically connected with the auxiliary magnetic unit through the second adjusting circuit, used to adjust the current of the auxiliary magnetic unit through the second adjusting circuit, so that the current in the auxiliary magnetic unit reaches the second current value, and then the magnetic field intensity of the main magnetic unit and the auxiliary magnetic unit as a whole reaches the set magnetic field intensity value.

[0010] Preferably, the first adjusting circuit comprises a first current detecting unit and a first current adjusting unit; the first current adjusting unit is electrically connected with the main magnetic unit, for adjusting the current value in the main magnetic unit; the first current detecting unit is electrically connected with the main magnetic unit, for detecting the current in the main magnetic unit and outputting a first feedback signal; the controller is electrically connected with the first current adjusting unit and the first current detecting unit respectively, for obtaining the actual current value in the main magnetic unit according to the first feedback signal, and for controlling the first current adjusting unit to adjust the current in the main magnetic unit according to the actual current value in the main magnetic unit and the first current value, so that the current in the main magnetic unit reaches the first current value.

[0011] Preferably, the second adjusting circuit comprises a second current detecting unit and a second current adjusting unit; the second current adjusting unit is electrically connected with the auxiliary magnetic unit, for adjusting the current value in the auxiliary magnetic unit; the second current detecting unit is electrically connected with the auxiliary magnetic unit, for detecting the current in the auxiliary magnetic unit and outputting a second feedback signal; the controller is electrically connected with the second current adjusting unit and the second current detecting unit respectively, for obtaining the actual current value in the auxiliary magnetic unit according to the second feedback signal, and for controlling the second current adjusting unit to adjust the current in the auxiliary magnetic unit according to the actual current value in the auxiliary magnetic unit and the second current value, so that the current in the first auxiliary coil and the second auxiliary coil reaches the second current value.

[0012] Preferably, the magnetic yoke further comprises a connecting portion, one end of the connecting portion is connected with the first end portion, and the other end of the connecting portion is connected with the second end portion; the magnetic yoke is formed by stacking a plurality of first magnetic conductive sheets, the first magnetic conductive sheets are vertically arranged, a plurality of the first magnetic conductive sheets are arranged along the width direction of the magnetic yoke, and adjacent two first magnetic conductive sheets are bonded by an adhesive layer, and each of the first magnetic conductive sheets is in a C shape.

[0013] Preferably, the first end portion is directly above the second end portion, the magnetic assembly further comprises magnetic pole heads, the number of the magnetic pole heads is two, and the two magnetic pole heads are oppositely arranged, one of the magnetic pole heads is installed on the lower end face of the first end portion and located below the first coil unit, and the other magnetic pole head is installed on the upper end face of the second end portion and located above the second coil.

[0014] Preferably, the cross section of the magnetic pole head is in a fan shape, the magnetic pole head is formed by stacking a plurality of second magnetic conductive sheets, a plurality of the second magnetic conductive sheets are arranged along the central arc direction of the magnetic pole head, and adjacent two second magnetic conductive sheets are bonded by an adhesive layer.

[0015] Preferably, the magnetic assembly further comprises a support column, the support column is located between the two magnetic pole heads, and the support column extends in the opposite direction of the two magnetic pole heads, and the two ends of the support column are connected with the two magnetic pole heads respectively, for limiting the moving direction of the two magnetic pole heads.

[0016] Preferably, the first magnetic conducting sheet and the second magnetic conducting sheet are both made of silicon steel sheet.

[0017] Preferably, the first main coil and the first auxiliary coil are both sleeved on the side wall of the first end portion, and the first main coil is wrapped outside the first auxiliary coil, and the second main coil and the second auxiliary coil are both sleeved on the side wall of the second end portion, and the second main coil is wrapped outside the second auxiliary coil.

[0018] According to the embodiment of the second aspect of the present application, a magnetic mass spectrometer is provided, comprising a mass analysis tube and the above-mentioned magnetic field scanning device, the mass analysis tube is located between the first end portion and the second end portion of the magnetic field scanning device, and the magnetic field scanning device is used for scanning the magnetic field of the mass analysis tube.

[0019] The magnetic field scanning device in the present application sets a main magnetic unit (i.e. the first main coil and the second main coil) with less turns, which is used for fast coarse adjustment of the magnetic field, and sets an auxiliary magnetic unit (i.e. the first auxiliary coil and the second auxiliary coil) with more turns, which is used for fine adjustment of the magnetic field. The current change amount of each adjustment of the main magnetic unit is large (for example: 1 ampere), which further leads to a large change range of the magnetic field intensity of each adjustment. The adjustment accuracy of the auxiliary magnetic unit is high, and the minimum current change amount of each adjustment is small (for example: 0.1 ampere), so the change range of the magnetic field intensity of each adjustment of the auxiliary magnetic unit is small, which can realize accurate adjustment of the magnetic field intensity. The control assembly measures the current magnetic field intensity according to the magnetic induction sensor, and if the current magnetic field intensity is lower than the set value, then the magnetic field intensity is increased by gradually increasing the current of the main coil, and when the set value of the magnetic field intensity is about to be reached or has not been reached, the coarse adjustment is stopped, and the fine adjustment is started until the set value of the magnetic field intensity is reached, and then the fine adjustment is completed. Therefore, the combination of the main magnetic unit and the auxiliary magnetic unit in the magnetic field scanning device can quickly and stably adjust the magnetic field intensity to the required set value during the fast scanning of the magnetic field. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the magnetic field scanning device in some embodiments of the present application;

[0021] Figure 2 is a circuit structural schematic diagram of the control assembly in some embodiments of the present application;

[0022] Figure 3is a characteristic curve comparison diagram of silicon steel sheet and DT4 pure iron in some embodiments of the present application;

[0023] Figure 4 is a curve diagram of magnet scanning speed under different materials in some embodiments of the present application;

[0024] Figure 5 is a structural schematic diagram of a magnetic yoke in some embodiments of the present application;

[0025] Figure 6 is a top view of a magnetic pole head in some embodiments of the present application.

[0026] In the figure: fixed top plate 1, magnetic yoke 2, first end part 21, second end part 22, first magnetic conducting sheet 23, main magnetic unit 3, auxiliary magnetic unit 4, adjusting base 5, coil connection terminal 6, cooling water pipe 7, magnetic pole head 8, second magnetic conducting sheet 81, magnetic induction sensor 9, support column 10, fixed rod 11. DETAILED DESCRIPTION

[0027] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0028] In the description of the present application, it should be noted that the terms "upper", "lower", "upstream", "downstream" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the devices or elements referred to must be provided with a particular orientation, constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0029] The structures, proportions, sizes and the like shown in the drawings attached to the present specification are only used to cooperate with the content disclosed in the present specification, to be understood and read by those skilled in the art, and do not have technical substantive significance, and any modification of structure, change of proportion relationship or adjustment of size, without affecting the effects that can be produced by the present application and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present application.

[0030] In the description of the present application, the terms "first", "second", "third" are only for description purposes, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "connection", "arrangement", "installation", "fixation" and the like should be understood in a broad sense, for example, they can be fixed connection or detachable connection, or integral connection; they can be directly connected or indirectly connected through an intermediate medium, or they can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] First of all, it should be noted that magnetic mass spectrometry has been widely used in quantitative analysis of isotopic abundance and abundance ratio due to its simple structure, good stability, high resolution, wide dynamic range, high abundance sensitivity and other advantages, forming dozens of types of mass spectrometers such as thermal ionization mass spectrometry (TIMS), high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), glow discharge mass spectrometry (GD-MS), multi-receiver plasma mass spectrometry (MC-ICP-MS), noble gas isotope mass spectrometry, and stable isotope mass spectrometry. One of the most important components of a magnetic mass spectrometer is its mass analyzer (electromagnet).

[0033] However, the traditional magnetic mass spectrometer has the disadvantages of large size, high energy consumption, and slow analysis speed, which poses a great challenge in its application field. The fundamental reason for its significant disadvantage of slow analysis speed is that the scanning speed of the magnet cannot reach the expected design level due to the magnetic hysteresis effect.

[0034] In a magnetic mass spectrometer, in order to separate ions of different masses, the magnetic field strength needs to be changed. This process of changing the magnetic field is called magnetic field scanning. The scanning speed refers to the amount of change in the magnetic field strength per unit time.

[0035] The working principle of the mass analyzer is described as follows: the mass analyzer includes an electromagnet (magnetic field scanning device) and a mass analysis tube. The two ends of the mass analysis tube are respectively connected to the ion source and the detector. Charged particles from the ion source pass through the mass analysis tube. The ions are separated according to their mass-to-charge ratio (m / z) under the action of the magnetic field. During the magnetic field scanning process, by changing the magnetic field strength, different mass-to-charge ratio ions can be selectively passed through the analysis tube, thereby realizing the detection and analysis of ions.

[0036] Magnetic field scanning is an essential process in mass spectrometry, because the core function of a mass spectrometer is to separate different ions in a complex mixture for subsequent qualitative and quantitative analysis. By changing the magnetic field strength, magnetic field scanning allows ions of different mass-to-charge ratios to experience different degrees of Lorentz force in the magnetic field, thereby moving along different trajectories and achieving effective separation of the ions. Moreover, this helps to improve the resolution of the mass spectrometer, thereby improving the accuracy and reliability of the analysis.

[0037] It is also necessary to explain that the hysteresis effect refers to the hysteresis effect of the magnetic induction intensity (or magnetization intensity) of a magnetic material under the action of a magnetic field. In other words, when a magnetic field acts on a magnetic material, the magnetic induction intensity of the material will change with the change of the magnetic field intensity, but the change of the magnetic field of the material will not immediately respond to the change of the external magnetic field, but will have a delayed response time, that is, the so-called "hysteresis". In a magnetic mass spectrometer, the magnet (i.e. the magnetic field scanning device) used needs to adjust its magnetic field intensity to achieve the separation and analysis of ions. Because the change and stability of the magnetic field need to consume time, if the magnet has a significant hysteresis effect, it will seriously affect the analysis speed of the magnetic mass spectrometer.

[0038] The magnet (magnetic field scanning device) for a magnetic mass spectrometer is usually composed of a magnetic yoke, a magnetic pole head, a coil and a fixed support mechanism. The coil is used to provide a stable current to form a stable magnet; the magnetic yoke is used to guide the magnetic field and support the magnetic pole head and the coil; a uniform magnetic field is formed between the upper and lower magnetic pole heads, and the structure of the magnetic pole head directly affects the ion transmission light path of the mass spectrometer. In order to ensure the stability of the magnetic field and the fastest response speed, the magnetic yoke and the magnetic pole head are usually made of DT4 or DT4C brand of pure iron with good magnetic conductivity at present, but due to the existence of coercive force, the scanning speed of such magnets is usually in the range of several seconds to tens of seconds. At the same time, the response speed of a single coil is also a key factor limiting the scanning speed when a rapid change of the magnetic field is required.

[0039] Therefore, the present application provides a fast scanning magnet structure and device which can be widely used in various magnetic mass spectrometers, and can shorten the magnetic field scanning time from tens of seconds to 100-200 ms, greatly improving the analysis speed and use efficiency of the mass spectrometer.

[0040] Example 1

[0041] Please refer to Figure 1 The application discloses a magnetic field scanning device, which comprises a magnetic component and a control component.

[0042] The magnetic assembly comprises a magnetic yoke 2, the magnetic yoke 2 comprising a first end portion 21 and a second end portion 22, the first end portion 21 being oppositely arranged with the second end portion 22. The magnetic assembly further comprises a first coil unit and a second coil unit, the first coil unit being oppositely arranged with the second coil unit, the first coil unit being sleeved on the first end portion 21, and the second coil unit being sleeved on the second end portion 22. The first coil unit comprises a first main coil and a first auxiliary coil, and the second coil unit comprises a second main coil and a second auxiliary coil, the number of turns of the first main coil being equal to the number of turns of the second main coil, the number of turns of the first auxiliary coil being equal to the number of turns of the second auxiliary coil, and the number of turns of the main coil being less than the number of turns of the auxiliary coil. The first main coil and the second main coil are connected in series, and the series circuit of the first main coil and the second main coil is set as a main magnetic unit 3. The first auxiliary coil and the second auxiliary coil are connected in series, and the series circuit of the first auxiliary coil and the second auxiliary coil is set as an auxiliary magnetic unit 4. The control assembly is electrically connected with the main magnetic unit 3 and the auxiliary magnetic unit 4 respectively, and is used for adjusting the current of the main magnetic unit 3 and adjusting the current in the auxiliary magnetic unit 4, so as to adjust the magnetic field intensity of the electromagnetic field between the first end portion 21 and the second end portion 22, and further realize magnetic field scanning.

[0043] It should be noted that the magnetic field scanning device is provided with a main magnetic unit (i.e., the first main coil and the second main coil) with a small number of turns, which is used for rapid coarse adjustment of the magnetic field; and an auxiliary magnetic unit (i.e., the first auxiliary coil and the second auxiliary coil) with a large number of turns, which is used for fine adjustment of the magnetic field. The current change amount of each adjustment of the main magnetic unit is large (for example: 1 ampere), thereby causing the change range of the magnetic field intensity of each adjustment to be large. The adjustment accuracy of the auxiliary magnetic unit is high, and the minimum current change amount of each adjustment is small (for example: 0.1 ampere), so the change range of the magnetic field intensity of each adjustment of the auxiliary magnetic unit is small, and the magnetic field intensity can be accurately adjusted. The control assembly measures the current magnetic field intensity according to the magnetic induction sensor, and if the current magnetic field intensity is lower than the set value, the magnetic field intensity is increased by gradually increasing the current of the main coil. When the magnetic field intensity is close to or reaches the set value, the coarse adjustment is stopped, and the fine adjustment is started until the set magnetic field intensity is reached, and then the fine adjustment is completed. Therefore, the magnetic field scanning device can quickly and stably adjust the magnetic field intensity to the set value by combining the control of the main magnetic unit and the auxiliary magnetic unit.

[0044] The existing magnetic field scanning device mostly adopts a single coil. If the adjustment accuracy of the current of the coil is required to meet the accuracy requirement of the magnetic field intensity, the adjustment accuracy of the current of the coil needs to be high, for example, the current of the coil is adjusted by 1 / 100 ampere each time. When the span of the magnetic field intensity is large, the target magnetic field intensity needs to be reached by many times of adjustment. This will cause the magnetic field scanning speed to be very low. If the adjustment accuracy of the current of the coil is low, for example, the current of the coil is adjusted by 1 ampere each time, the accuracy requirement of the magnetic field intensity may not be met.

[0045] Compared with the prior art single-coil magnetic field scanning device, the magnetic field scanning device does not need to be adjusted for multiple times, but only needs to adjust the current in the main magnetic unit 3 to quickly coarsely adjust the magnetic field strength, and when the magnetic field strength is about to reach or has reached the set value, the coarse adjustment is stopped and fine adjustment is started until the set magnetic field strength is reached, so that a higher scanning speed is achieved.

[0046] The magnetic field scanning device in the embodiment can shorten the magnetic field scanning time from tens of seconds to 100-200 ms, greatly improving the analysis speed and use efficiency of the mass spectrometer.

[0047] Please refer to Figure 1 and Figure 5 , the magnetic yoke 2 further comprises a connecting portion, one end of the connecting portion is connected with the first end portion 21, and the other end is connected with the second end portion 22. The magnetic yoke 2 is formed by laminating a plurality of first magnetic conductive sheets 23, the first magnetic conductive sheets 23 are vertically arranged, the plurality of first magnetic conductive sheets 23 are arranged along the width direction of the magnetic yoke, and adjacent two first magnetic conductive sheets 23 are bonded by an adhesive layer. Each first magnetic conductive sheet 23 is in a C shape.

[0048] Specifically, as shown in Figure 5 , the silicon steel sheets are bonded by epoxy resin adhesive varnish with a viscosity coefficient of DIN4, the punched sheets are stacked along the tangential direction of the particle center track, and the stacking coefficient is not less than 98%. The thickness of each first silicon steel sheet is the same, wherein the thickness of any first silicon steel sheet is between 0.2-0.5mm, for example: the thickness of the first silicon steel sheet is 0.2mm, 0.3mm or 0.5mm. Using the silicon steel sheet stacking method can effectively reduce the eddy current effect of the magnet. On the one hand, the silicon steel sheet has a large resistivity, which can reduce the size of the eddy current. On the other hand, the insulating adhesive layer between the silicon steel sheets blocks the eddy current, reducing the induced electromotive force in the silicon steel sheet. In addition, when designing the magnet, the model of the silicon steel sheet is also considered. The silicon steel sheet and the magnetic field saturation characteristic are as close as possible to the DT4 electrical pure iron performance to ensure that the magnetic field of the magnet has good stability.

[0049] The first end portion 21 is located directly above the second end portion 22, and the magnetic assembly further comprises two magnetic pole heads 8. The two magnetic pole heads 8 are oppositely arranged, one of the two magnetic pole heads 8 is installed on the lower end face of the first end portion 21 and located below the first coil unit, and the other magnetic pole head 8 is installed on the upper end face of the second end portion 22 and located above the second coil.

[0050] Specifically, as shown in Figure 6As shown, the shape of the horizontal projection of the magnetic pole head 8 is adapted to the shape of the mass analysis tube. Exemplarily, the mass analysis tube is an arc-shaped tube, and the cross section of the magnetic pole head 8 is fan-shaped, and the arc-shaped mass analysis tube is between the two magnetic pole heads 8. The magnetic pole head 8 is shaped by a plurality of second magnetic conductive sheets 81, which are arranged along the central arc direction of the magnetic pole head, and adjacent two second magnetic conductive sheets 81 are bonded by an adhesive layer.

[0051] Similarly to the magnetic yoke, the adjacent two second magnetic conductive sheets 81 are bonded by stamping bonding of the epoxy resin bonding varnish with a viscosity coefficient DIN4, and the stamping pieces are stacked along the tangential direction of the particle central orbit, and the stacking coefficient is not less than 98%. The thickness of each second silicon steel sheet is between 0.2-0.5mm, for example, the thickness of the first silicon steel sheet is 0.2mm, 0.3mm or 0.5mm.

[0052] The first magnetic conductive sheet 23 and the second magnetic conductive sheet 81 both adopt silicon steel sheets. Specifically, the silicon steel sheet is a kind of soft magnetic material, which presents small hysteresis loss, and the use of the silicon steel sheet in the present magnetic field scanning device can effectively weaken the hysteresis effect and further improve the magnetic field scanning speed.

[0053] The first main coil and the first auxiliary coil are both sleeved on the side wall of the first end portion 21, and the first main coil is wrapped outside the first auxiliary coil, and the second main coil and the second auxiliary coil are both sleeved on the side wall of the second end portion 22, and the second main coil is wrapped outside the second auxiliary coil.

[0054] In other words, the main coil and the auxiliary coil are respectively composed of a series of upper and lower symmetrical coils, and the coils are wound by flat enameled wire "racetrack-shaped" structure, and sufficient tension is applied to the wire during winding to minimize the distortion at the turning point and ensure the tightness of the coil. After the main coil and the auxiliary coil are wound, the whole vacuum casting resin is formed, and the resin main system is composed of radiation-resistant insulating materials such as epoxy resin, plastic resin, acid anhydride curing agent and accelerator.

[0055] The main coil is responsible for the coarse adjustment of the magnetic field strength, and the coarse adjustment control loop (i.e. the first adjusting circuit) uses the DSP controller to control the 16-bit DA converter to set the current value, and the change of the current size is reflected in the voltage change of the current sampling resistor. If it is lower than the set value, the amplifier U1B will increase the output voltage to increase the current to reach the set value. The auxiliary coil is responsible for the fine adjustment of the magnetic field strength, and the principle of the fine adjustment control circuit (i.e. the second adjusting circuit) is the same as that of the main coil, but the current range of the auxiliary coil is 10 times that of the main coil, so the adjustment accuracy of the auxiliary coil is 10 times that of the main coil. The combination of the main coil and the auxiliary coil can make the magnetic field strength quickly and stably reach the setting value required by the adjustment during the fast scanning of the magnetic field. The magnetic main coil and auxiliary coil circuit control diagram is shown in Figure 2 .

[0056] In order to keep the temperature of the coil constant, after the coil is wound, the outer layer of the coil is wound around the cooling water pipe 7 of the outer square inner circle, and the heat is taken away from the outside.

[0057] Further, the magnetic assembly further comprises a support column 10, the support column 10 is located between the two magnetic pole heads 8, and the support column 10 extends in the opposite direction of the two magnetic pole heads 8, and the two ends of the support column 10 are connected with the two magnetic pole heads 8 respectively, for limiting the moving of the two magnetic pole heads 8 towards each other.

[0058] Since the magnetic attraction between the upper and lower magnetic pole heads 8 will cause the gap between the magnetic pole heads 8 to change when the magnet is in use, a plurality of equal-height support columns 10 are provided to ensure the stability of the working gap size between the two magnetic pole heads 8 during the operation of the magnet.

[0059] The structure and control principle of the control assembly in the embodiment will be described below.

[0060] Please refer to Figure 2 In the embodiment, the control assembly comprises a controller, the controller is electrically connected with the main magnetic unit 3 and the auxiliary magnetic unit 4 respectively, and the controller is used to obtain a set magnetic field strength value, and obtain a corresponding magnetic field coarse adjustment threshold value according to the set magnetic field strength value. The controller is also used to adjust the current of the main magnetic unit 3, so that the magnetic field strength of the electromagnetic field between the first end portion 21 and the second end portion 22 reaches the magnetic field coarse adjustment threshold value, to complete the rapid coarse adjustment of the magnetic field, and by adjusting the current of the auxiliary magnetic unit 4, the magnetic field strength of the electromagnetic field between the first end portion 21 and the second end portion 22 reaches the set magnetic field strength value, to complete the fine adjustment of the magnetic field strength.

[0061] Specifically, the corresponding magnetic field coarse adjustment threshold value obtained according to the set magnetic field strength value is that the set magnetic field strength value is converted according to a preset proportion value. In the embodiment, the preset proportion value is 95%-99%. For example: the set magnetic field strength is 5000Gs; the preset proportion value is 95%, and the magnetic field coarse adjustment threshold value is 4750Gs. The specific magnetic field adjustment process is as follows: first, the magnetic field strength of the electromagnetic field is rapidly adjusted to the magnetic field coarse adjustment threshold value 4750Gs by the main magnetic unit 3, and then the magnetic field is precisely adjusted by adjusting the auxiliary magnetic unit 4, so that the magnetic field strength of the magnetic field gradually increases to 5000Gs. In this way, both the rapid scanning of the magnetic field and the accuracy requirement of the magnetic field strength adjustment can be met.

[0062] In the embodiment, the controller can be implemented by using an existing DSP controller. The DSP controller is used for processing digital signals. The DSP controller receives the set magnetic field strength value (digital signal) through the CAN bus and processes the digital signal.

[0063] It should be noted that the set magnetic field strength value can be manually input into the DSP controller by the staff through the CAN bus. Alternatively, the set magnetic field strength value can be pre-stored in a database, and the DSP controller can directly call the set magnetic field strength value from the database when the magnetic field scanning is needed. When the magnetic field scanning is performed, a plurality of target values of different magnetic field strengths can be set, i.e., the number of set magnetic field strength values is multiple. The plurality of set magnetic field strength values can be input into the DSP controller at one time, and the DSP controller arranges the plurality of set magnetic field strength values in order from low to high.

[0064] Further, in order to realize the closed-loop control of the magnetic field strength, the current magnetic field strength of the electromagnetic field needs to be detected in real time, and the magnetic field strength is fed back to the controller, so that the controller determines whether the real-time magnetic field strength reaches the first current value. The control assembly further comprises a magnetic induction sensor for detecting the magnetic field strength of the electromagnetic field between the first end portion 21 and the second end portion 22 and feeding back a magnetic field induction signal. The controller is electrically connected with the magnetic induction sensor, for receiving the magnetic field induction signal fed back by the magnetic induction sensor, and obtaining the current magnetic field strength of the electromagnetic field according to the magnetic field induction signal. The controller is further configured to adjust the current in the main magnetic unit 3 and the auxiliary unit 4 according to the current magnetic field strength of the electromagnetic field, until the magnetic field strength of the electromagnetic field reaches the set magnetic field strength value.

[0065] Specifically, if the feedback link is not set, the error will accumulate, and the accuracy requirement of the magnetic field scanning cannot be met. In the coarse adjustment stage, i.e., the process of quickly adjusting the magnetic field strength of the electromagnetic field to the magnetic field coarse adjustment threshold by adjusting the current of the main magnetic unit 3, the controller determines whether the magnetic field strength in the electromagnetic field reaches the magnetic field coarse adjustment threshold by receiving the magnetic field induction signal fed back by the magnetic induction sensor 9. If yes, the coarse adjustment stage is ended, and the fine adjustment stage is entered, i.e., the process of accurately adjusting the magnetic field strength of the electromagnetic field to the set magnetic field strength value by adjusting the current of the auxiliary magnetic unit 4. At this time, the controller determines whether the magnetic field strength in the electromagnetic field reaches the set magnetic field strength value by receiving the magnetic field induction signal fed back by the magnetic induction sensor 9. If yes, the magnetic field scanning process is ended.

[0066] In other words, the magnetic field strength control method adopts closed-loop control. The magnetic field strength value is set by receiving instructions through the CAN bus. The controller measures the current magnetic field strength according to the magnetic induction sensor 9. If it is lower than the set value, the magnetic field strength is increased by gradually increasing the main coil current. When it is about to reach the set magnetic field strength value but has not yet reached it, the coarse adjustment stops and the fine adjustment begins until the set magnetic field strength is reached. The magnetic induction sensor 9 can be any existing gaussmeter, Hall sensor or magnetic sensor, as long as it has a fast response time.

[0067] like Figure 2 As shown, in this embodiment, the control component further includes a first adjustment circuit and a second adjustment circuit. The controller controls the main magnetic unit 3 (i.e., ...) through the first adjustment circuit and the second adjustment circuit, respectively. Figure 2 The main magnet) and auxiliary magnetic unit 4 (i.e. Figure 2 The controller determines the current in the auxiliary magnet (of the main magnetic unit 3). Specifically, based on the set magnetic field strength value, the controller obtains a corresponding first current value and a second current value, where the first current value is greater than the second current value. The first current value is the current value in the main magnetic unit 3 when the magnetic field strength reaches the magnetic field coarse adjustment threshold, and the second current value is the current value in the auxiliary magnetic unit 4 when the magnetic field strength reaches the set magnetic field strength value. The controller is electrically connected to the main magnetic unit 3 through a first adjustment circuit, which is used to adjust the current in the main magnetic unit 3 so that the current in the main magnetic unit 3 reaches the first current value, thereby making the magnetic field strength of the main magnetic unit 3 reach the magnetic field coarse adjustment threshold. The controller is electrically connected to the auxiliary magnetic unit 4 through a second adjustment circuit, which is used to adjust the current in the auxiliary magnetic unit 4 so that the current in the auxiliary magnetic unit 4 reaches the second current value, thereby making the overall magnetic field strength of the main magnetic unit 3 and the auxiliary magnetic unit 4 reach the set magnetic field strength value.

[0068] The first adjustment circuit includes a first current detection unit and a first current adjustment unit. The first current adjustment unit is electrically connected to the main magnetic unit 3 and is used to adjust the current value in the main magnetic unit 3. The first current detection unit is also electrically connected to the main magnetic unit 3 and is used to detect the current in the main magnetic unit 3 and output a first feedback signal. The controller is electrically connected to both the first current adjustment unit and the first current detection unit, and is used to obtain the actual current value in the main magnetic unit 3 based on the first feedback signal. The controller is also used to control the first current adjustment unit to adjust the current in the main magnetic unit 3 based on the actual current value and the first current value, so that the current in the main magnetic unit 3 reaches the first current value.

[0069] In this embodiment, the first current detection unit can use an existing current sampling resistor, such as... Figure 2 R1 is shown in the diagram. The first current regulation unit can use an existing field-effect transistor, such as... Figure 2The second current detection unit is electrically connected with the main magnetic unit 3 and is configured to detect the current in the main magnetic unit 3 and output a second feedback signal. The controller is electrically connected with the second current detection unit and the second current regulation unit, respectively, and is configured to obtain the actual current value in the main magnetic unit 3 according to the second feedback signal. The controller is further configured to control the second current regulation unit to regulate the current in the main magnetic unit 3 according to the actual current value in the main magnetic unit 3 and the second current value, so that the current in the main coil reaches the second current value.

[0070] Similarly, the second regulation circuit includes a second current detection unit and a second current regulation unit. The second current regulation unit is electrically connected with the auxiliary magnetic unit 4 and is configured to regulate the current value in the auxiliary magnetic unit 4. The second current detection unit is electrically connected with the auxiliary magnetic unit 4 and is configured to detect the current in the auxiliary magnetic unit 4 and output a second feedback signal. The controller is electrically connected with the second current regulation unit and the second current detection unit, respectively, and is configured to obtain the actual current value in the auxiliary magnetic unit 4 according to the second feedback signal. The controller is further configured to control the second current regulation unit to regulate the current in the auxiliary magnetic unit 4 according to the actual current value in the auxiliary magnetic unit 4 and the second current value, so that the current in the first auxiliary coil and the second auxiliary coil reaches the second current value.

[0071] In the embodiment, the second current detection unit adopts an existing current sampling resistor, as shown by R2 in Figure 2 The second current regulation unit adopts an existing field effect transistor, as shown by Q2 (MOSFET-N) in Figure 2 The voltage of the input field effect transistor Q2 is increased to prolong the on time of the field effect transistor Q2, so as to increase the current value in the main magnetic unit 3.

[0072] As shown in Figure 2 The controller is further integrated with a DA converter and an ADC converter. The DA converter (Digital-to-Analog Converter, DAC) is configured to convert an analog signal into a digital signal. Specifically, the DSP controller receives a set magnetic field strength value (digital signal) through the CAN bus and processes the digital signal. The DSP controller is responsible for converting the set value into a corresponding current value and outputting a control signal through the 16-bit DA converter. The controller sets the required current value of the main coil by controlling the 16-bit DA converter. The DA converter outputs an analog signal, which is amplified by the amplifier U1B, and then controls the switch of the MOSFET-N, so as to regulate the current through the main coil. The current in the main coil generates a voltage drop through the current sampling resistor R1, and the voltage drop reflects the size of the current. The 16-bit ADC converter converts the voltage signal into a digital signal and feeds back to the DSP controller. If the detected current is lower than the set current value, the DSP controller adjusts the output of the DA converter, increases the output voltage through the amplifier U1B, and thus increases the on time of the MOSFET-N, increases the current of the main coil, until the current reaches the set value. The current control principle of the auxiliary magnetic unit 4 is the same as that of the main magnetic unit 3, which will not be described here.

[0073] The following describes the overall working process of this magnetic field scanning device:

[0074] The magnetic field scanning device in this embodiment provides a stable and uniform magnetic field for the magnetic mass spectrometer, while greatly improving the scanning speed when the magnetic field changes rapidly, thus enhancing the performance of the magnetic mass spectrometer. This magnetic field scanning device is a Faraday cup moving device for a surface thermal ionization mass spectrometer, comprising: a fixed top plate 1, a magnetic yoke 2, a main coil, an auxiliary coil, an adjusting base 5, coil terminals 6, a cooling water pipe 7, a magnetic pole head 8, a magnetic induction sensor 9, a height-equalizing support column 10, a fixing rod 11, and control components.

[0075] The fixed top plate 1 is used to fix and connect components such as the magnetic yoke 2, coil, adjusting base 5 and height support column 10. Lifting rings can also be installed on the fixed top plate 1 for moving and installing magnets.

[0076] like Figure 3 As shown, the yoke 2 and the pole head 8 are made of 0.5mm B50A600 grade silicon steel sheets (or other grades with similar magnetic field saturation characteristics) with magnetic field saturation characteristics closest to electrical pure iron DT4. The silicon steel sheets are bonded together by stamping with epoxy resin adhesive varnish with a viscosity coefficient of DI N4. The sheets are stacked tangentially along the particle center track, with a stacking coefficient of not less than 98%. The stacked silicon steel sheets have good insulation between each other. At the same time, the yoke 2 and the pole head 8 have the same good processing characteristics as DT4 pure iron, and can be processed by CNC machine tools to the shape and structure required by the magnet design.

[0077] The main coil and auxiliary coil are each composed of a set of symmetrical coils connected in series. The coils are wound with flat enameled wire in a "racetrack-shaped" structure. Sufficient tension is applied to the wire during winding to minimize distortion at bends and ensure the coil's tightness. After the main coil and auxiliary coil are wound, they are integrally vacuum-cast with resin. The resin body system consists of a radiation-resistant insulating material composed of epoxy resin, plastic resin, acid anhydride curing agent, and accelerator.

[0078] To maintain a constant coil temperature, after the coil is wound, a cooling water pipe 7 with an outer square and inner circle is wound around the outer layer of the coil, with water entering from the top and exiting from the bottom, to remove heat from the outside.

[0079] The adjusting base 5 is composed of an adjusting base plate and adjusting bolts, and can realize the overall posture adjustment of the magnet in front and back, left and right, and up and down. Since a large magnetic attraction force is generated between the two magnetic pole heads 8 when the magnet is in use, causing the gap between the two magnetic pole heads 8 to change, an equal-height support column 10 is arranged to ensure the stability of the working gap size between the two magnetic pole heads 8 during the operation of the magnet. The fixed rod 11 is used for the fixing, positioning and supporting of the magnet fixed top plate 1, the magnetic yoke 2, the main coil, the auxiliary coil, the adjusting base 5, the magnetic pole head 8 and other single components.

[0080] As shown in Figure 2 The control assembly includes a DSP controller, a magnet power supply, a first adjusting circuit and a second adjusting circuit. The first adjusting circuit is electrically connected with the main coil (i.e. the main magnetic unit 3), and the second adjusting circuit is electrically connected with the auxiliary coil (i.e. the auxiliary magnetic unit 4). The magnet power supply is electrically connected with the first adjusting circuit and the second adjusting circuit, and is used for supplying power to the first adjusting circuit and the second adjusting circuit. The magnet power supply provides a voltage of +60V as the power supply of the main coil and the auxiliary coil.

[0081] Specifically, the DSP controller is also integrated with a DA converter and an ADC converter. The first adjusting circuit includes an amplifier U1B, a field effect transistor Q1 and a current sampling resistor R1. The second adjusting circuit includes an amplifier U2B, a field effect transistor Q2 and a current sampling resistor R2. The DSP controller is the core of the circuit, and is responsible for receiving and processing instructions from the CAN bus, which set the required magnetic field strength value. The DSP controller sets the required current value of the main coil by controlling the 16-bit DA converter. The DA converter outputs an analog signal, which is amplified by the amplifier U1B to control the switching of the MOSFET-N, thereby adjusting the current through the main coil.

[0082] The current in the main coil generates a voltage drop through the current sampling resistor R1, and this voltage drop reflects the size of the current. The 16-bit ADC converter converts this voltage signal into a digital signal and feeds it back to the DSP controller. If the detected current is lower than the set current value, the DSP controller will adjust the output of the DA converter, increase the output voltage through the amplifier U1B, and thus increase the on-time of the MOSFET-N, increase the current of the main coil, until the current reaches the set value.

[0083] Fine adjustment of the auxiliary coil: the current control principle of the auxiliary coil is the same as that of the main coil, but the current range of the auxiliary coil is 10 times that of the main coil, so more precise magnetic field strength adjustment can be achieved. When the main coil current approaches but does not reach the set magnetic field strength, the DSP controller will start the fine adjustment circuit of the auxiliary coil, and through a similar current feedback and adjustment mechanism, the magnetic field strength is accurately adjusted to the set value.

[0084] When the magnetic field is rapidly scanned, the DSP controller controls the main coil and the auxiliary coil at the same time. The main coil is responsible for the coarse adjustment of the magnetic field strength to quickly approach the set value; the auxiliary coil is responsible for fine adjustment to ensure that the magnetic field strength accurately reaches the set value.

[0085] As shown in Figure 4 , the scanning speeds of magnets of different materials and different structures are then compared. The magnet of pure DT4 material has a magnetic field of only 76.26% of the rated value within 100 ms, and the response time constant of the magnet at this time is approximately 33.74 ms; under the condition that the whole block of DT4 pure iron is cut into 9 blocks, the magnetic field rises to 94.7% of the rated value within 100 ms, and the time constant of the two-pole magnet is about 5.3 ms; under the condition of using a silicon steel sheet, the magnetic field rises to 98.06% of the rated value within 100 ms, and the time constant of the two-pole magnet is about 1.94 ms.

[0086] In summary, the device can improve the scanning speed of the existing magnet under the premise of ensuring the stability of the magnetic field, shorten the instrument acquisition time, improve the working efficiency of the mass spectrometer, and expand the application field and application scenario of the magnetic mass spectrometer.

[0087] Embodiment 2

[0088] The application further discloses a magnetic mass spectrometer, which comprises a mass analysis tube and the magnetic field scanning device in embodiment 1, and the mass analysis tube is located between the first end portion 21 and the second end portion 22 of the magnetic field scanning device, and the magnetic field scanning device is used for performing magnetic field scanning on the mass analysis tube.

[0089] Specifically, the fast scanning magnet in the magnetic mass spectrometer (i.e. the magnetic field scanning device in embodiment 1) supplies power to the main coil and the auxiliary coil through the coil connection terminal 6, the current in the main coil and the auxiliary coil generates a stable and uniform magnetic field between the magnetic yoke 2 and the magnetic pole head 8, the magnetic induction sensor 9 detects the real-time magnetic field strength and feeds back to the magnetic field control system (i.e. the control assembly in embodiment 1).

[0090] Wherein, in order to reduce the hysteresis effect and improve the scanning speed of the magnet, the material of the magnetic yoke 2 and the magnetic pole head 8 is selected to be amorphous silicon steel sheet material stacking. The main coil and the auxiliary coil are multi-layer spiral conductors, and after winding, the whole is vacuum cast resin forming, and the outside of the coil is a single-layer spiral air-copper cooling water pipe 7 for controlling the temperature stability of the coil. The fixed top plate 1 is used for fixing and connecting the magnetic yoke 2, the coil, the adjusting base 5 and the equal-height support column 10 and the like. The adjusting base 5 is used for adjusting the attitude of the magnet in X, Y and Z directions. The equal-height support column 10 is used for ensuring the stability of the working gap size between the two magnetic pole heads 8 during the operation of the magnet. The fixed rod 11 is used for fixing the single components of the magnet.

[0091] The magnetic mass spectrometer can shorten the magnetic field scanning time from tens of seconds to 100-200 ms by using the magnetic field scanning device in the embodiment 1, greatly improving the analysis speed and use efficiency of the mass spectrometer.

[0092] It can be understood that the above embodiments are only exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A magnetic field scanning device for use in a magnetic mass spectrometer, characterized in that The magnetic assembly comprises a magnetic yoke (2) and a control assembly. The magnetic yoke (2) comprises a first end (21) and a second end (22), and the first end (21) is opposite to the second end (22). The magnetic yoke (2) is formed by a plurality of first magnetic conductive sheets (23) stacked together, the first magnetic conductive sheets (23) are vertically arranged, a plurality of the first magnetic conductive sheets are arranged along the width direction of the magnetic yoke, and two adjacent first magnetic conductive sheets (23) are bonded by an adhesive layer, and each of the first magnetic conductive sheets (23) is in a C shape. The first end is located directly above the second end, and the magnetic assembly further comprises a magnetic pole head (8), the number of the magnetic pole head (8) is two, and the two magnetic pole heads (8) are opposite to each other, and the cross section of the magnetic pole head (8) is in a fan shape. The magnetic assembly further comprises a first coil unit and a second coil unit, the first coil unit and the second coil unit are opposite to each other, the first coil unit is sleeved on the first end, and the second coil unit is sleeved on the second end. The first coil unit comprises a first main coil and a first auxiliary coil, the second coil unit comprises a second main coil and a second auxiliary coil, the number of turns of the first main coil is equal to that of the second main coil, the number of turns of the first auxiliary coil is equal to that of the second auxiliary coil, and the number of turns of the main coil is less than that of the auxiliary coil. The first main coil and the second main coil are connected in series, the series circuit of the first main coil and the second main coil is set as a main magnetic unit (3), the first auxiliary coil and the second auxiliary coil are connected in series, the series circuit of the first auxiliary coil and the second auxiliary coil is set as an auxiliary magnetic unit (4), the first main coil and the first auxiliary coil are sleeved on the side wall of the first end, and the first main coil is located outside the first auxiliary coil, and the second main coil and the second auxiliary coil are sleeved on the side wall of the second end, and the second main coil is located outside the second auxiliary coil. The control assembly comprises a controller, the controller is electrically connected with the main magnetic unit (3) and the auxiliary magnetic unit (4), respectively, the controller is used for obtaining a set magnetic field intensity value, and obtaining a corresponding magnetic field coarse adjustment threshold value according to the set magnetic field intensity value, the controller is also used for adjusting the current of the main magnetic unit (3), so that the magnetic field intensity of the electromagnetic field between the first end and the second end reaches the magnetic field coarse adjustment threshold value, to complete the rapid coarse adjustment of the magnetic field, and the current of the auxiliary magnetic unit (4) is adjusted, so that the magnetic field intensity of the electromagnetic field between the first end and the second end reaches the set magnetic field intensity value, to complete the fine adjustment of the magnetic field intensity.

2. The magnetic field scanning device of claim 1, wherein, The control assembly further comprises a magnetic induction sensor, and the magnetic induction sensor is used for detecting the magnetic field intensity of the electromagnetic field between the first end and the second end and feeding back a magnetic field induction signal. The controller is electrically connected with the magnetic induction sensor, is used for receiving the magnetic field induction signal fed back by the magnetic induction sensor, and obtains the current magnetic field intensity of the electromagnetic field according to the magnetic field induction signal, The controller is further configured to adjust the current in the main magnetic unit (3) and the auxiliary unit (4) according to the current magnetic field strength of the electromagnetic field until the magnetic field strength of the electromagnetic field reaches the set magnetic field strength value.

3. The magnetic field scanning device of claim 2, wherein, The control assembly further comprises a first adjusting circuit and a second adjusting circuit; The controller is configured to obtain a corresponding first current value and a second current value according to the set magnetic field strength value, the first current value being the current value in the main magnetic unit (3) when the magnetic field strength reaches the magnetic field coarse adjustment threshold, and the second current value being the current value in the auxiliary magnetic unit (4) when the magnetic field strength reaches the set magnetic field strength value, the first current value being greater than the second current value; The controller is electrically connected to the main magnetic unit (3) through the first adjusting circuit, and is configured to adjust the current of the main magnetic unit (3) through the first adjusting circuit, so that the current in the main magnetic unit (3) reaches the first current value, and then the magnetic field strength of the main magnetic unit (3) reaches the magnetic field coarse adjustment threshold; The controller is electrically connected to the auxiliary magnetic unit (4) through the second adjusting circuit, and is configured to adjust the current of the auxiliary magnetic unit (4) through the second adjusting circuit, so that the current in the auxiliary magnetic unit (4) reaches the second current value, and then the magnetic field strength of the main magnetic unit (3) and the auxiliary magnetic unit (4) as a whole reaches the set magnetic field strength value.

4. The magnetic field scanning device of claim 3, wherein, The first adjusting circuit comprises a first current detection unit and a first current adjusting unit; The first current adjusting unit is electrically connected to the main magnetic unit (3) and is configured to adjust the current value in the main magnetic unit (3); The first current detection unit is electrically connected to the main magnetic unit (3) and is configured to detect the current in the main magnetic unit (3) and output a first feedback signal; The controller is electrically connected to the first current adjusting unit and the first current detection unit respectively, is configured to obtain the actual current value in the main magnetic unit (3) according to the first feedback signal, and is further configured to control the first current adjusting unit to adjust the current in the main magnetic unit (3) according to the actual current value in the main magnetic unit (3) and the first current value, so that the current in the main magnetic unit (3) reaches the first current value.

5. The magnetic field scanning device of claim 4, wherein, The second adjusting circuit comprises a second current detection unit and a second current adjusting unit; The second current adjusting unit is electrically connected to the auxiliary magnetic unit (4) and is configured to adjust the current value in the auxiliary magnetic unit (4); The second current detection unit is electrically connected to the auxiliary magnetic unit (4) and is configured to detect the current in the auxiliary magnetic unit (4) and output a second feedback signal; The controller is electrically connected to the second current adjusting unit and the second current detection unit respectively, is configured to obtain the actual current value in the auxiliary magnetic unit (4) according to the second feedback signal, and is further configured to control the second current adjusting unit to adjust the current in the auxiliary magnetic unit (4) according to the actual current value in the auxiliary magnetic unit (4) and the second current value, so that the current in the first auxiliary coil and the second auxiliary coil reaches the second current value.

6. The magnetic field scanning device according to any one of claims 1 to 5, characterized in that The magnetic yoke (2) further comprises a connecting part, one end of the connecting part is connected with the first end part (21), and the other end is connected with the second end part (22).

7. The magnetic field scanning device of claim 6, wherein, One of the two magnetic pole heads (8) is installed on the lower end surface of the first end part and is located below the first coil unit, and the other magnetic pole head (8) is installed on the upper end surface of the second end part and is located above the second coil.

8. The magnetic field scanning device of claim 7, wherein, The magnetic pole head (8) is formed by laminating a plurality of second magnetic conductive sheets (81), and the plurality of second magnetic conductive sheets (81) are arranged along the central arc direction of the magnetic pole head, and adjacent two second magnetic conductive sheets (81) are bonded by an adhesive layer.

9. The magnetic field scanning device of claim 7, wherein, The magnetic assembly further comprises a support column (10), the support column (10) is located between the two magnetic pole heads (8), and the support column (10) extends in the opposite direction of the two magnetic pole heads (8), and the two ends of the support column (10) are respectively connected with the two magnetic pole heads (8), for limiting the movement of the two magnetic pole heads (8) towards each other.

10. The magnetic field scanning device of claim 8, wherein, The first magnetic conductive sheet and the second magnetic conductive sheet are both made of silicon steel sheet.

11. A magnetic mass spectrometer, characterized by, The magnetic field scanning device according to any one of claims 1 to 10, wherein the mass analysis tube is located between the first end part and the second end part of the magnetic field scanning device, and the magnetic field scanning device is used for performing magnetic field scanning on the mass analysis tube.

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