34 results about "Zero field" patented technology

The invention provides a high-sensitivity magnetic field measurement method based on a quantum measurement principle and a related device, and belongs to the technical field of magnetic field measurement. The method comprises the following steps: correcting a zero field splitting parameter by using an initial magnetic field to enhance the stability of compression strength, and driving an NV cluster to generate a spinning compression state through microwaves to obtain a compression state probe; taking the compressed-state probe as an initial state of the quantum probe, and performing space-time polarization modulation decoupling on the target magnetic field and the environment magnetic field to obtain a decoupling signal; performing quantum phase-locked interference processing on the decoupling signal and a given reference microwave frequency to obtain a frequency shift signal; and performing magnetic field integral reconstruction and sensitivity calibration by using the frequency shift signal and combining the compression parameter of the compressed probe to obtain a final target magnetic field at the detection moment. Based on the quantum measurement principle, in combination with quantum coherent regulation, space-time modulation decoupling and the like, accurate extraction of the target magnetic field can be realized in a high electromagnetic interference environment, and the measurement sensitivity and accuracy are improved.

The magnetorheological fluid comprises an ionic liquid, a basic liquid, magnetic particles and an additive, and is characterized in that the magnetorheological fluid contains imidazole cations, the general formula of the imidazole cations is [R1R2N +] C3H4, R1 is selected from substituted or unsubstituted alkyl with the carbon atom number of 1-10, and R2 is selected from substituted or unsubstituted alkyl with the carbon atom number of 1-10. The magnetorheological fluid disclosed by the invention has excellent sedimentation stability, relatively low zero-field viscosity and relatively high shear yield stress.

The invention provides an input current optimization method based on MPI orthogonal model constant-speed rotary scanning, which aims at a rotary scanning device formed by combining two zero field line devices constructed by two groups of coils, and comprises the following steps of: controlling the input current of the two groups of coils which generate mutually vertical zero field lines to be periodic current; therefore, the fusion null field line generated by the rotary scanning device is controlled to perform periodic constant-speed rotation so as to determine the position of the fusion null field line at any moment. According to the method, the problem that the FFL of an existing selected model rotates irregularly can be solved, the effect of uniform-speed scanning is achieved, the position of the FFL is controllably observed, and the controllability of MPI is improved.

The invention discloses a multi-core J coupling constant-based pH measurement method, which comprises the following steps of: 1, preparing a series of compound samples with different pH values, and measuring J coupling constants of compounds in the samples; 2, drawing a coupling constant and pH relation curve of the compound J, and deducing a pH calculation formula; and 3, measuring the J coupling constant of the compound-containing sample to be measured, and determining the pH value of the sample to be measured. According to the method, the J coupling constant is measured through a nuclear magnetic resonance spectrum method or a zero field-near zero field J coupling spectrum method, and the pH value of the surrounding environment of the compound can be measured.

The application relates to the technical field of simulation calculation and discloses a hysteresis loop simulation method based on mumax3, which comprises the following steps: obtaining the parameters of a magnetic material, and establishing a simulation model according to the parameters of the magnetic material; applying a field strength to the simulation model to obtain a fully saturated state of the magnetic material; applying a cosine-type field strength gradually decreasing with time in a peak value to the simulation model in the saturated state, and simultaneously performing LLG equation solving until the field strength peak value is reduced to below a preset threshold value, and taking the corresponding magnetic moment state as a zero field strength state; applying an alternating field strength to the simulation model in the zero field strength state, and simultaneously performing LLG equation solving calculation to complete loop simulation, so that a hysteresis loop is obtained. The magnetic material in the saturated state is demagnetized, the magnetic moment distribution of a demagnetized state under the zero field strength which is in line with the actual physical situation is obtained, and the state is taken as the basis of Mumax3 micromagnetic simulation calculation, so that a hysteresis loop with higher precision can be obtained.

The invention belongs to the technical field of condensed state physics and material research, and particularly relates to a heavy rare earth transition metal oxide magnetocaloric material screening method which comprises the following steps: obtaining zero field cooling of a test sample and a magnetization intensity-temperature curve of the field cooling, and deriving the magnetization intensity-temperature curve of the field cooling to obtain a magnetic field temperature curve of the field cooling; then the absolute value of the derivative of the field cooling magnetization intensity-temperature curve is obtained, and an absolute value curve is obtained; calculating an average magnetic phase transition temperature based on the absolute value curve; calculating the variance of the absolute value curve at the average magnetic phase transition temperature; calculating the dimensionless variance of the absolute value curve based on the variance of the absolute value curve at the average magnetic phase transition temperature; obtaining an isothermal magnetization curve of the test sample and calculating a magnetic entropy change value; and based on the dimensionless variance value, establishing a quantitative relationship between the magnetic phase change interaction intensity and the magnetic entropy change value, and further screening out a target sample. And theoretical support is provided for development and physical mechanism analysis of the low-temperature heavy rare earth based giant magnetocaloric material.

The present application relates to a kind of cobalt-based spinel ferrite nanoparticles with zero-field magnetic quantum tunneling properties and its application, the inside of the nanoparticle has the topological structure of broken spatial symmetry;The topological structure includes the first topological domain and the second topological domain distributed staggeredly in space, so that the cobalt-based spinel ferrite nanoparticle produces intrinsic transverse tunneling energy level splitting under zero applied magnetic field.The sharp stepwise magnetization jump of the cobalt-based spinel ferrite nanoparticle of the present application at zero field can realize the high sensitivity nonlinear response to weak magnetic field, and can be applied to the preparation and development of low-temperature quantum sensing probe or multi-level nonvolatile logic memory.

A spin-orbit torque (SOT) magnetic device with synthetic antiferromagnetic (SAF) structure, including a SOT layer for providing a spin current, a SAF structure composed of a first ferromagnetic layer, a nickel oxide (NiO) exchange coupling layer and a second ferromagnetic layer, and a capping layer on the SAF structure. This magnetoelectric device of oxide SAF structure can achieve zero-field switching through current-induced SOT, and can be used as the free layer of a magnetoresistive random access memory (MRAM).

The invention discloses a zero-field spin-orbit moment memory with a ferromagnetic layer component gradient structure and a preparation method thereof, the core structure of the memory comprises a CoFeB ferromagnetic layer with a vertical component gradient, and magnetic moments at two sides of a domain wall generate asymmetry in amplitude or orientation by regulating and controlling gradient distribution of Co, Fe and B elements and inducing non-uniform Dzyaloshiski-Moriya interaction (DMI); furthermore, domain wall chiral characteristics are weakened, a net effective field is formed, and deterministic magnetization overturning without assistance of an external magnetic field is finally realized. In the preparation process, a magnetron sputtering technology is adopted, a heavy metal strong spin orbit coupling layer, a vertical magnetic anisotropy magnetic free layer with component gradient, a tunnel barrier layer, a magnetic vertical reference layer, an artificial antiferromagnetic pinning layer and a covering layer are stacked in sequence, and a magnetic tunnel junction (MTJ) unit is prepared through annealing and micro-nano processing technologies. The invention provides an efficient solution for the research and development of controllable magnetic memories and logic devices, and has a wide application prospect in the field of high-density magnetic memories.

The invention discloses a vertical magnetic anisotropy GaN-based spin polarized light emitting diode and a preparation method thereof, and the core of the preparation method is as follows: firstly, converting 1-3 layers of graphene into a circular ring shape on n-GaN through dry transfer and laser direct writing; and secondly, in an ultrahigh vacuum environment, continuously and sequentially sputtering and depositing an MgO tunneling layer, a single-layer CoFeB ferromagnetic layer with vertical magnetic anisotropy and an ITO transparent conductive layer in the same sputtering cavity without breaking vacuum. According to the invention, an inverted structure is utilized to enhance heat dissipation and optimize a spin injection interface, and polarized light observation easy to observe is realized. Meanwhile, graphene is used for blocking the defect of MgO, conductance mismatch is solved, spin injection efficiency is enhanced, zero-field perpendicular magnetic anisotropy is achieved through single-layer CoFeB, ITO serves as a conducting layer and also serves as a light window, a full-vacuum magnetron sputtering process is combined to guarantee atomic-scale interface cleanness, and finally the device obtains high-spin-polarization polarized light at the room temperature under the zero external magnetic field; and meanwhile, the spin injection efficiency is high, the spin service life is long, the operation is stable under high current density, the process is simplified, the cost is low, and the observation is easy.

The application relates to a mouse heart magnetocardiography and magnetoencephalography testing device and method based on a zero-field atomic magnetometer, and relates to the field of heart magnetocardiography and magnetoencephalography testing. The application solves the problems that the existing mouse heart magnetocardiography and magnetoencephalography testing device has a large volume, and the magnetic field signal is distorted due to the movement or struggle of the mouse, and motion artifacts are generated. A plurality of groups of tool fixing hole positions (1-1) are formed in pairs on the upper end face of a platform (1), a plurality of heart magnetometer mounting holes (1-2) are formed in the middle of the length direction of the lower end face of the platform (1), a heart magnetometer is mounted in the heart magnetometer mounting hole (1-2), one insert (2) is inserted in each group of tool fixing hole positions (1-1), the insert (2) is provided with a magnetoencephalography mounting hole (2-1) and a head mounting hole (2-2). The mouse heart magnetic signal and the magnetoencephalography signal are tested at the same time, and the error introduced by the environmental magnetic field change in the experiment process is reduced to the maximum extent. The application is used for mouse heart magnetocardiography and magnetoencephalography testing.

The present invention relates to a method, device, and medium for calculating AC loss in a superconducting cable. The method comprises obtaining superconducting cable operating data and structural parameters; calculating the horizontal and vertical components of the external magnetic field of each layer of strip at a constant critical current density using the operating data and structural parameters based on the Kim extended magnetic field effect; calculating the critical current density of the corresponding layer of strip and updating the zero-field region width parameter of the corresponding layer; obtaining the current density distribution; updating the vertical component of the strip's external magnetic field; and calculating the AC loss of the superconducting cable based on the updated zero-field region width parameter and the vertical component of the strip's external magnetic field. The device and medium are used to implement the above method. Compared with the prior art, the present invention simplifies the calculation of AC loss into a single item, making the calculation more accurate.

The invention discloses a Fe2O3 buffer layer-based magnetic random access memory capable of realizing directional overturning of a magnetization layer without an external magnetic field and driven by a vertical magnetic layer current, and belongs to the field of spintronics. The structure of the device sequentially comprises an antiferromagnetic layer Fe2O3, a spin current generation layer Pt, a magnetic layer Co with vertical anisotropy and a protective layer TaOx for preventing a thin film from being oxidized from bottom to top. Due to the addition of the antiferromagnetic layer Fe2O3, magnetization overturning can be induced to be free of external field. According to the invention, the insulated Fe2O3 is used as the buffer layer to be inserted into the Pt / Co system, so that not only can zero field flip be realized, but also the problem of increase of critical flip current of the device caused by a shunting effect due to introduction of the functional layer can be avoided. The invention provides a structure and a preparation process of a current-driven magnetization turnover device based on an insulating antiferromagnetic layer.

The application discloses a method for precisely compensating three-dimensional residual magnetism of a single-beam SERF atomic magnetometer, which is based on the principle of high-frequency magnetic field modulation and comprises the following steps: after rough compensation of three-dimensional residual magnetism of a single-beam SERF magnetometer based on a quasi-static magnetic field, performing precise compensation of three-dimensional residual magnetism, wherein the precise compensation of three-dimensional residual magnetism comprises the following steps: applying a high-frequency modulation magnetic field, respectively scanning XYZ three-axis magnetic fields, and making the zero-crossing point of a dispersion curve corresponding to a demodulated first-order harmonic coincide with a zero-field point, so as to realize precise magnetic field compensation of a single-beam SERF magnetometer system. The method effectively improves the precision of magnetic compensation, solves the problems that a traditional magnetic compensation mode is not applicable to a single-beam SERF atomic magnetometer or the precision of magnetic field compensation in the direction of pumping light is too low, and is reasonable and simple to operate, thus playing a great promoting role in the development of atomic magnetometers.

A device for guiding TEM waves using dielectric nanowires is disclosed, relating to the fields of nanotechnology and microwave technology. The device structure includes a substrate, a zinc oxide seed layer, a ground signal electrode, a transmission signal electrode, and zinc oxide nanowires, forming a coplanar waveguide structure. The dielectric nanowires replace the signal lines in traditional coplanar waveguide structures. The TEM signal fed to one electrode is guided by the nanowires to the other signal electrode, ensuring that the electric field is along the normal direction of the nanowire surface and the magnetic field is along the tangential direction. Under the influence of the external electric field and the Lorentz force, the space charge region of the nanowire undergoes dynamic polarization, achieving internal zero field and surface electromagnetic shielding, thereby guiding the TEM wave. This coplanar waveguide structure design ensures good guidance performance at frequencies above 10 GHz.

The application provides a method and system for improving the receiving bandwidth of a very low frequency atomic magnetometer, which polarizes alkali metal atoms in an atomic cell along the direction of a driving laser by using the driving laser; an external magnetic field at the cell is compensated by a three-axis magnetic coil and a three-axis magnetic sensor to provide a zero-field environment, and a main magnetic field B is applied to the coil in the direction of the driving light; the precession of the spin projection signal of the polarized atoms in the x direction is detected by using a detection laser in the x direction; an external very low frequency signal interacts with the atoms polarized in the z direction to make the atoms produce a precession signal in the xOy plane, so that the detection light is detected. After the detection light signal is collected, the control system feeds back a damping magnetic field to the atomic ensemble through the coil, and the bandwidth of the system is expanded by adjusting the feedback parameters while keeping the sensitivity unchanged. The technical scheme of the application solves the technical problem that high sensitivity and high bandwidth cannot be achieved simultaneously in the prior art.

The present invention relates to a method of detecting a zero-field resonance (ZFR), comprising the steps of i) directing a pump light beam in a first direction x through a vapor cell comprising gaseous atoms, ii) applying a magnetic field component to the vapor cell parallel or antiparallel to the first direction x with different magnitudes: formula (I), iii) detecting light of the pump light beam directed through the vapor cell for the different magnitudes: formula (I) of the magnetic field component applied parallel or antiparallel to the first direction x, iv) determining the maximum optical transmission Tmax and the minimum optical transmission Tmin based on the detected light, v) determining the difference between the maximum optical transmission and the minimum optical transmission D = Tmax - Tmin, vi) determining the magnitude of the x-component of an ambient magnetic field: formula (II) by determining the particular magnitude: formula (III) of the x-component of the applied magnetic field for which the minimum optical transmission Tmin is determined, vii) repeating at least steps i) to v) while applying magnetic field components to the vapor cell in second and third directions y and z perpendicular to the first direction x with different magnitudes: formula (IV) and formula (V) and viii) determining the magnitudes: formula (VI) and formula (VII) of the ambient magnetic field components in the second and third directions y and z by determining the particular magnitudes of the y- and z-components of the applied magnetic field: formula (VIII) and formula (IX) for which the difference between the maximum optical transmission and the minimum optical transmission D is minimized.

The application relates to the technical field of quantum materials, in particular to a van der Waals heterojunction type high-efficiency superconducting diode and a preparation method and application thereof. The superconducting diode comprises a substrate layer, an electrode layer, an Ising superconducting layer, a magnetic material layer and a packaging layer which are sequentially stacked from bottom to top; or, the superconducting diode comprises a substrate layer, a magnetic material layer, an Ising superconducting layer, an electrode layer and a packaging layer which are sequentially stacked from bottom to top. A heterojunction is formed by the Ising superconducting layer and the magnetic material layer to realize double symmetry cooperative breaking, and a system capable of realizing high-efficiency superconducting diode effect (SDE) is constructed by combining a vertical magnetic field training technology; wherein, the magnetic material layer breaks time reversal symmetry, and the Ising superconducting layer and the magnetic material layer form a heterojunction to break spatial inversion symmetry. The superconducting diode can maintain super-high SDE efficiency under zero field and has strong zero-field stability.

The application discloses a spin terahertz emitter with adjustable polarization without an external magnetic field and a manufacturing method thereof. A metal thin film layer heterostructure is deposited on a surface of a glass substrate. A ferromagnetic layer is a FeNi thin film layer, an anti-ferromagnetic layer is an IrMn3 thin film layer, and an interface between the FeNi thin film layer and the IrMn3 thin film layer is an exchange coupling interface subjected to directional magnetic field induction treatment. A surface of the metal thin film layer heterostructure is a periodic stripe array structure. The manufacturing method comprises the following steps: a magnetron sputtering process is used to sequentially deposit a ferromagnetic layer, an anti-ferromagnetic layer and a protective layer; the exchange coupling interface is formed through directional magnetic field induction treatment; and a micro-nano processing process is used for patterning treatment. Beneficial effects are as follows: under the condition of no external magnetic field, reliable spin current generation, spin-charge conversion and terahertz radiation can be realized. The stripe patterning structure realizes linear polarization, elliptical polarization and near-circular polarization output. The 'zero-field emission function' and the 'polarization control function' are integrated in the same thin film device system, and the system complexity is reduced.

The invention provides a solid-state spin zero-field magnetic resonance temperature measurement method and system. The method comprises the following steps: an IQ modulator modulates an intrinsic signal vt according to a baseband low-frequency I (t) signal and a baseband low-frequency Q (t) signal, generates a composite dual-frequency microwave containing two resonant frequencies, and applies the composite dual-frequency microwave to a diamond sample; the diamond sample outputs a fluorescence signal and acts on the lock-in amplifier, the waveform generator outputs a reference signal to the lock-in amplifier, and the pulse transmitter performs sequential control on the microwave signal source and the lock-in amplifier; the lock-in amplifier outputs a lock-in amplifier output signal according to the fluorescence signal and the reference signal; performing data processing on the output signal of the lock-in amplifier to obtain a temperature field variation; and according to a reference temperature and the temperature field variable quantity, calculating and obtaining a solid-state spin zero field magnetic resonance temperature measurement result. By applying the technical scheme of the invention, the technical problem that the quantum precision measurement sensitivity based on solid-state spin magnetic resonance is limited by multi-physics field coupling in the prior art is solved.

This invention provides an electromagnetic force-variable gap magnetorheological damper, comprising a rotating shaft mounted through a cylinder via bearings; a rotating disk fixed on the rotating shaft; a floating disk mounted on the rotating shaft via end-face bearings, with a return spring between the end-face bearings and the rotating disk, resulting in an adjustable working gap between the floating disk and the rotating disk; and an excitation coil assembly mounted inside the cylinder, fixedly connected to the upper and lower ends of the cylinder, surrounding the floating disk and the rotating disk. When the current in the excitation coil assembly decreases, the floating disk moves away from the rotating disk, the working gap gradually increases, and the damping force decreases; conversely, when the current in the excitation coil assembly increases, the floating disk moves closer to the rotating disk, the working gap gradually decreases, and the damping force increases. Based on the magnetic effect principle of charged coils, this invention achieves real-time dynamic adjustment of the effective working flow channel width. It exhibits a smaller zero-field damping force, a larger maximum damping force, and a wider adjustable range, thus adapting to more complex application scenarios.

The invention discloses low-zero-field-viscosity magnetorheological fluid as well as a preparation method and application thereof, and belongs to the technical field of intelligent materials and vehicle braking. The magnetorheological fluid is prepared from, by weight, 20%-30% of carbonyl iron powder, 1%-3% of a composite additive and the balance dimethyl silicone oil. The density is 3.0-3.2 g / ml, the working temperature is-40 DEG C to 150 DEG C, the zero magnetic field viscosity is smaller than or equal to 0.25 Pa.s at the shearing rate of 1000 / s, and the shearing yield stress is larger than or equal to 43 kPa under the magnetic field of 0.5 T. The preparation method comprises the steps of raw material preparation, preliminary mixing, vacuum stirring at the vacuum degree of not lower than-0.09 MPa and the temperature of 20-30 DEG C, post-treatment detection and the like. The magnetorheological fluid balances low zero field viscosity and high shear yield stress, has excellent sedimentation stability and wide temperature adaptability, and can remarkably reduce no-load loss and improve braking response speed, torque output precision and system reliability when being used for the vehicle magnetorheological fluid retarder.

The invention relates to a device for authenticity checking of a planar data carrier (10) having zero-field nuclear magnetic resonance (NMR) features (12, 14), having one or more excitation coils (30) for generating excitation pulses for the zero-field NMR features (12; 14), an array (40) of a plurality of receiving coils (42) which are independent of the excitation coils (30) and are arranged at least partially adjacent to one another for position-resolved detection of the signal response of the zero-field NMR features (12; 14), wherein the number (N) of the receiving coils (42) of the array (40) of receiving coils is greater than the number (M) of the excitation coils (30) and the area (F A ) covered by the excitation coils (30) at least partially covers the area (F E ) covered by the receiving coils (42) of the array (40) of receiving coils and exceeds the size of the area (F E ).

An ellipsometric atomic magnetometer-based magnetic field in-situ monitoring and automatic compensation device and method enable the magnetometer to automatically trigger an online magnetic field compensation program in a timely manner according to the monitoring result of the environmental magnetic field, and then restore the environmental magnetic field to zero field, thereby improving the ability of the magnetometer to resist changes in the environmental interference magnetic field, enabling the magnetometer to work stably for a long time without the need for manual zeroing of the magnetic field. The present application additionally collects the previously unused second harmonic component on the basis of the original magnetometer collecting the first harmonic component for magnetic field measurement, and realizes real-time monitoring of the three-axis magnetic field by comparing the difference between the value of the current second harmonic component and the value of the second harmonic component in a zero-field environment; the intelligent optimization algorithm is combined with the second harmonic component to realize online high-precision magnetic field compensation of three axes simultaneously with a low sampling point number, improve the compensation efficiency, and ultimately improve the long-term stability and magnetic field interference resistance of the magnetometer without affecting the original measurement sensitivity.

The invention relates to the technical field of magnetorheological fluids, and discloses a double-dispersion magnetorheological fluid and a preparation method thereof.The double-dispersion magnetorheological fluid comprises a dispersion phase and a dispersion medium, and the dispersion phase is evenly dispersed in the dispersion medium; the dispersion phase is formed by compounding FeCo alloy nanoparticles and NiXFe1-XFe2O4 micron particles, and the dispersion medium is a mixed base solution formed by mixing dimethyl silicone oil and poly-alpha olefin synthetic oil. According to the magnetorheological fluid, collaborative innovation is achieved in the three aspects of materials, structures and systems, comprehensive improvement of sedimentation stability, magnetic saturation strength, yield stress and redispersibility is synchronously achieved, meanwhile, the zero-field viscosity is reduced, and the magnetorheological fluid with excellent comprehensive performance is obtained. The prepared magnetorheological fluid can stand for a long time without hard block deposition, is fast in magnetic response and high in working stability, can better adapt to the actual working condition of the magnetorheological damper, and has outstanding application value.

The application provides a semi-metal compensation ferrimagnetic material, the chemical formula of the semi-metal compensation ferrimagnetic material is CrFeS2, the semi-metal compensation ferrimagnetic material has a hexagonal NiAs type crystal structure and belongs to the 194th space group, and a preparation method thereof comprises the following steps: sealing Cr powder, Fe powder and sulfur blocks and a transmission medium iodine in a vacuum quartz tube; placing the vacuum quartz tube in a heating furnace and heating at 780-920 DEG C for 4-30 days, and then quenching to a warm house. The semi-metal compensation ferrimagnetic material provided by the application has the characteristics of great perpendicular magnetic anisotropy and magnetic compensation characteristics, so that the material can realize zero-field cold exchange bias, and a unidirectional magnetic field with different sizes can control the direction of the exchange bias, and thus the material has a wide application prospect in the field of spintronics.

The invention provides a high-field and near-zero-field combined magnetic resonance system, which comprises a sample tube for placing a sample, a high-field measurement module for pre-polarization of the sample and high-field chemical shift spectrum measurement, and a near-zero-field magnetic resonance module for J coupling signal measurement of the sample in the near-zero field, the sample transmission module is used for driving a sample to move between a high field and a near-zero field and maintaining nuclear spin polarization of the sample in the moving process; the digital control and signal processing module is used for automatic control and synchronous signal acquisition of the high field measurement module and the near-zero field magnetic resonance module; the invention also provides a high field and near zero field combined magnetic resonance detection method and a measurement method. According to the invention, a high-field spectrogram and a near-zero-field spectrogram are obtained in one measurement cycle, and unified correspondence of chemical shift and J coupling is realized. Through combination of high-field pre-polarization and rapid shuttling, the signal-to-noise ratio of near-zero field measurement is improved by about one order of magnitude, and the spectral line width is significantly reduced.

This invention relates to the field of zero-field detection technology, specifically disclosing a measuring device for measuring the zero field within a tokamak device, and the tokamak device itself. It includes a magnetic probe fixing plate, within which several magnetic probes are disposed. The magnetic probe fixing plate is movably connected to a square frame, which is fixedly connected to a support frame. The support frame is movably connected to an annular support guide rail, and a limiting element is fixedly connected to the square frame. Through motor control, the zero field formed by the magnetic probe fixing plate at different circumferential positions within the tokamak device can be measured, solving the problems of fixed magnetic probe positions and high cost due to the large number of magnetic probes used. Simultaneously, the increased number of measurement points makes the measurement data more accurate. Because it can automatically measure the zero field at different circumferential positions of the device, the number of times the device needs to enter and exit the tokamak vacuum chamber and disassemble the array is reduced, ensuring the cleanliness of the vacuum chamber and reducing measurement errors and difficulty caused by human error.

The magnetorheological fluid comprises ionic liquid, basic liquid, magnetic particles and an additive, the particle density of the magnetic particles is smaller than 3 g / cm < 3 >, and the magnetic particles comprise one or more of polymer coated iron particles, iron oxide coated polymer particles, amorphous alloy particles, composite magnetic particles and porous magnetic particles; based on the total weight of the magnetorheological fluid, the content of the magnetic particles is 50-85% by weight, the content of the basic fluid is 10-30% by weight, the content of the additive is 0.5-10% by weight, and the content of the ionic liquid is 3-20% by weight. The magnetorheological fluid disclosed by the invention still has lower zero-field viscosity and better yield stress under the condition of excellent sedimentation stability, and is lower in density.

A magnetometer includes a first substrate, a bare semiconductor die, a first conductive trace, a second conductive trace, a second substrate, and a planar magnetic-field coil. The first substrate is composed of a high-temperature electrically insulating material. The bare semiconductor die is affixed to the first substrate and includes a p-n junction that contains paramagnetic recombination centers. The first and second conductive traces are on the first substrate. The first conductive trace is electrically connected to an anode of the p-n junction. The second conductive trace is electrically connected to a cathode of the p-n junction. The second substrate is composed of a high-temperature electrically insulating material and is affixed to the first substrate. The planar magnetic-field coil is composed of a metal trace formed on the second substrate.