147 results about "High field" patented technology

The invention belongs to the technical field of superconducting wires, and relates to a niobium-tin composite superconducting wire and a preparation method thereof. The invention provides a Nb3Sn composite superconducting wire. The Nb3Sn composite superconducting wire sequentially comprises an Nb3Sn superconducting wire core, a barrier layer, a stable layer, a transition layer, a substrate layer and a functional layer from inside to outside, the transition layer is formed by mixing copper and a dielectric polymer, and the copper content is continuously decreased in a gradient manner from inside to outside; the substrate layer is the dielectric polymer; the functional layer is a plurality of protruding metal microstructures. According to the invention, the functional layer with the broadband electromagnetic stealth function is integrated on the basis of the Nb3Sn superconducting wire rod, so that the radar cross section is obviously reduced while the Nb3Sn superconducting wire rod bears high-density superconducting current and generates a strong magnetic field, and the technical problem that a high-field superconducting magnet system is easy to detect in an electromagnetic environment is solved.

The invention provides an enhancement method and device for a low-field magnetic resonance image, electronic equipment and a storage medium, and the method comprises the steps: obtaining a to-be-enhanced low-field magnetic resonance image, and carrying out the partitioning of the to-be-enhanced low-field magnetic resonance image, and obtaining a plurality of image blocks; inputting the plurality of image blocks into an image enhancement model to obtain a plurality of enhanced image blocks output by the image enhancement model; splicing the plurality of enhanced image blocks to obtain an enhanced magnetic resonance image corresponding to the low-field magnetic resonance image; wherein the image enhancement model is obtained based on training of a high-field magnetic resonance image sample and a synthetic low-field magnetic resonance image corresponding to the high-field magnetic resonance image sample. By adopting the technical scheme, the problem that a high-field magnetic resonance image corresponding to a low-field magnetic resonance image is difficult to obtain in the prior art is solved.

The present invention provides an appealing, fast, and cost-effective alternative to conventional nuclear fusion reactors. An ultra-compact spherical tokamak that combines three key features aimed at accelerating fusion energy as a viable energy source, these features are spherical type tokamaks, negative triangularity plasma shape and high-temperature superconducting coils. More specifically, the tokamak includes a toroidal vacuum vessel and a magnetic field system configured to confine a high temperature plasma. The magnetic field system includes a solenoid having a sand-hourglass shape; toroidal field coils having an inverse D-shaped design and high temperature superconductor (HTS) material; and poloidal field coils, external to the vacuum vessel. The vacuum vessel has a cross-section with similar inverse D-shape as the toroidal field coils.

The invention discloses an internally-inserted water-cooled magnet device for a high-field hybrid magnet. The internally-inserted water-cooled magnet device comprises a container assembly and a magnet coil assembly arranged in the container assembly. The container assembly comprises an upper barrel assembly, a container end cover, a hydraulic machine assembly, a center pipe assembly, an inner supporting assembly, a middle barrel assembly, a lower barrel assembly and an electric connecting assembly. The hydraulic machine assembly comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column. The axial force application device has the advantages that axial force application can be performed on the magnet coil assembly, the pressing force on the magnet coil assembly is improved, and the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved.

The invention discloses a high-field water-cooling magnet device which comprises a container assembly and a magnet coil assembly, and the magnet coil assembly is located in the container assembly and communicated with the container assembly. The container assembly comprises a hydraulic machine assembly, and the hydraulic machine assembly comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column. The axial force application device has the advantages that axial force application can be performed on the magnet coil assembly, the pressing force on the magnet coil assembly is improved, and the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved.

The invention relates to the technical field of superconducting material processing, in particular to a preparation method of an Nb3Sn superconducting wire. The method mainly comprises the steps that Nb-Zr alloy is loaded into the exterior and / or the center of a Sn-Cu single-core rod, oxide powder is filled between the Nb-Zr alloy and the Sn-Cu single-core rod, then the Sn-Cu single-core rod and the Nb-Zr alloy are loaded into a copper substrate, and Nb3Sn subcomponents are obtained after multi-pass stretching, forming and fixed-length cutting; and uniformly arranging the Nb3Sn sub-components in the copper pipe along the circumferential direction to form a bundle, and after multi-pass stretching, carrying out heat treatment and cutting to obtain the Nb3Sn superconducting wire. By introducing the artificial point pinning array in density gradient distribution, the critical current density of the Nb3Sn superconducting wire in a high magnetic field of 8T-16T is enhanced, the problems that an existing uniform artificial point pinning center scheme generates a matching effect and limits the actual application of the superconducting wire are solved, and the decline degree of the critical current density of the Nb3Sn superconducting wire in the high field is relieved.

Disclosed is a system comprising a database storing a preoperative high-resolution image of an object of interest and a control circuit. The control circuit comprises a processor and a memory. The memory stores instructions executable by the processor to obtain a low-field strength magnetic resonance image of the object of interest. The memory stores further instructions executable by the processor to input the low-field strength MRI of the object of interest into a generator model of a pre-trained generative adversarial network. The generator model is pre-trained with low-field strength MRIs and paired high-resolution images to correct image distortions. The memory stores further instructions executable by the processor to output a distortion-corrected image of the object of interest from the generator model based on the low-field strength MRI and transmit the distortion-corrected image of the object of interest to a user interface.

The invention discloses a decoupling method based on high-field solid-state nuclear magnetic resonance T2 relaxation, and the method comprises the steps: carrying out the preprocessing of a collected T2 relaxation signal, including data conversion, chemical shift sorting, normalization processing and signal screening; converting the time domain signal into a frequency domain model by adopting inverse Laplacian transformation, and extracting pole features; on the basis of frequency domain pole information, automatic estimation and nonlinear fitting of signal parameters are achieved through radial basis function fitting in combination with a numerical optimization algorithm; and storing the processed time domain signal data. The method innovatively solves the technical problem of multi-atomic-nucleus relaxation signal analysis under the high-field condition, has the advantages of high signal-to-noise ratio, good analysis precision, wide application range and the like compared with a traditional low-field nuclear magnetic technology, and is particularly suitable for research and analysis in the fields of energy materials, catalysts and the like. And the processing capability and the decoupling effect of the high-field solid-state nuclear magnetic resonance relaxation signal are remarkably improved through technologies of system integration signal conversion, parameter optimization, regularization processing and the like.

Techniques are described for lowering strains applied to superconducting material in a superconducting magnet by arranging structural partitions between turns of the superconducting material that intercept and transfer strain to a mechanically stronger structure, such as the housing of the magnet. A structural partition may be formed with a feedthrough slit so that the superconducting material can easily pass through the partition. A number of structural partitions may be interspersed between groups of turns of superconducting material in a magnet so that forces can be sufficiently distributed by the partitions throughout the magnet. At the same time, the number of structural partitions may be selected to minimize the amount of space within the magnet occupied by the partitions that could otherwise be occupied by current-carrying superconducting material.

The invention provides a transcranial electrical stimulation device and method compatible with high-field and ultrahigh-field magnetic resonance imaging, and belongs to the technical field of medical equipment. The device comprises an electrical stimulation module, a multi-stage bidirectional filtering module and a multi-magnetic-conduction compatible electrode, the electrical stimulation module generates an electrical stimulation signal according to an electrical stimulation mode and parameters selected by a user, and sends the electrical stimulation signal to the multi-permeability compatible electrode; after the multi-permeability compatible electrode completes electrical stimulation, corresponding electroencephalogram signals are collected; the bidirectional filtering module carries out filtering processing on bidirectional communication signals in the multi-conductor shielding wire. The problem that high-field and ultrahigh-field nuclear magnetic resonance environments interfere with the electrical stimulation device is solved, the electrical stimulation device does not affect nuclear magnetic resonance imaging, compatibility of high-field and ultrahigh-field nuclear magnetic resonance imaging and the electrical stimulation device is truly achieved, meanwhile, multiple electrical stimulation modes are provided, the multi-channel electroencephalogram collection function and other functions are achieved, and the application range is wide. The newest requirements of clinical use and scientific research are met.

The invention belongs to the technical field of superconducting materials, and discloses an internal tin method Nb3Sn superconducting wire integrated with a piezoelectric sensing function and a preparation method of the internal tin method Nb3Sn superconducting wire. According to the method, a piezoelectric functional layer and a dielectric layer are prepared on the surface of a SnAl alloy rod, a CuAg alloy rod is installed after drilling to form a composite rod, the composite rod is inserted into an inner tin method Nb3Sn / CuNb composite pipe to be drawn into a subcomponent, then the subcomponent is bundled and installed into a Ta pipe and an oxygen-free copper pipe, and the wire is prepared through multiple times of stretching. The piezoelectric functional layer can convert micro strain into measurable electric signals, in-situ real-time monitoring of mechanical stress and the like in the wire rod is achieved, the CuAg alloy bar can stabilize the tensile strength of the wire rod and promote generation of an Nb3Sn phase, and on the premise that the superconducting performance is not affected, the operation reliability and safety of the high-field magnet under the extreme working condition are improved.

The invention provides a niobium rod for an Nb3Sn superconducting wire niobium material and a preparation method of the niobium rod, and the preparation method of the niobium rod comprises the following steps: a, upsetting and drawing forging: carrying out n times of upsetting and drawing forging on a niobium cast ingot, n is any integer in 2-5, and carrying out annealing heat treatment in a gap between two times of upsetting and drawing forging or after the last upsetting and drawing forging, the upsetting and drawing forged round bar is obtained; b, radial forging is conducted, specifically, the upsetting and drawing forging round bar is subjected to radial forging; and c, rotary forging: carrying out rotary forging on the rod blank subjected to radial forging. The niobium rod prepared by the method meets one or more of the following items: the grain size is 7-8 grades, the elongation at break is greater than or equal to 40%, and the hardness (HV / 2.9 N) is greater than or equal to 40 and less than or equal to 65. Namely, the niobium rod prepared by the preparation method has at least one of the characteristics of uniform and fine grains, low hardness and high plasticity, and the comprehensive performance of the niobium rod is improved, so that the strict requirements of the Nb3Sn superconducting wire on the base material in high-field magnet application are met.

The invention relates to the technical field of nuclear magnetic resonance, and provides a broadband tuning system for a high-field nuclear magnetic resonance coil. The system comprises a radio frequency coil, a radio frequency shielding layer and a driving mechanism, the radio frequency shielding layer and the radio frequency coil are coaxially arranged in the axial direction, and the radial size of the radio frequency shielding layer is larger than that of the coil. The driving mechanism drives the radio frequency shielding layer and the radio frequency coil to generate axial relative movement, so that the axial overlapping length between the radio frequency shielding layer and the radio frequency coil is continuously changed. According to the system, the electromagnetic coupling strength between the radio frequency shielding layer and the radio frequency coil can be adjusted through mechanical displacement, then the equivalent inductance of the coil is changed, and finally continuous and broadband tuning of the resonant frequency of the coil is achieved. According to the invention, traditional capacitance tuning is replaced by pure physical mechanical adjustment, so that the physical limitation and parasitic effect of micro capacitance in a high field are effectively avoided, the uniformity of a radio frequency magnetic field is maintained on the premise of not changing the structure of the coil, and the compatibility and stability of high-field and multi-core detection are effectively improved.

The present invention belongs to the field of medical image processing, and particularly relates to a semi-supervised automatic segmentation method for hippocampal subregions based on ultra-high field 7T magnetic resonance image synthesis. The method includes obtaining 3T magnetic resonance images and 7T magnetic resonance images and performing preprocessing; processing the 3T magnetic resonance images by using a trained image generation model to generate 7T magnetic resonance images; processing the 7T magnetic resonance images by using the first 3D U-Net network cascaded in a trained image segmentation model to extract multi-scale rough segmentation results of the 7T magnetic resonance images; and processing the multi-scale rough segmentation results of the 7T magnetic resonance images by using the second 3D U-Net network cascaded in a trained image segmentation model to extract fine segmentation results of the 7T magnetic resonance images. The present invention can improve the accuracy of the segmentation network and automatically segment 7T magnetic resonance images.

The application discloses a method for improving critical current of REBCO superconducting layer and relates to the technical field of superconducting materials.The method for improving critical current of REBCO superconducting layer comprises the following steps: REBCO superconducting tapes are annealed in a pure oxygen atmosphere, quenched to 20-25 DEG C, and then the surface silver layer is removed by a chemical method, after which the REBCO superconducting tapes are annealed in a mixed atmosphere of ozone and oxygen, and a protective layer is deposited, so that the critical current of the REBCO superconducting layer is finally improved.The carrier concentration of the REBCO superconducting tapes can be effectively controlled through the specific multi-step oxidation process, so that the REBCO superconducting tapes break through the under-doped state commonly existing in the prior art, reach the over-doped level, and then the critical current performance of the tapes is significantly improved.The method has simple process, high stability and high industrial feasibility, and can meet the demand of higher current-carrying capacity of REBCO tapes in key fields such as power transmission and high-field magnets.

The invention provides a superconducting magnet quench protection system and method, and relates to the technical field of superconducting magnets, the superconducting magnet quench protection system comprises: an energy release assembly comprising a first superconducting coil and a second superconducting coil connected in series with the first superconducting coil; the heating assembly is configured to release oscillation currents in opposite directions to the first superconducting coil and the second superconducting coil at the moment that the first superconducting coil and the second superconducting coil quench, and coupling loss is generated in the first superconducting coil and the second superconducting coil so as to heat the first superconducting coil and the second superconducting coil. And converting the first superconducting coil and the second superconducting coil from a superconducting state to a normal state. The superconducting magnet quench protection system can solve the problems of high field intensity, large energy storage and difficult quench protection of a wire slot type superconducting magnet.

The invention discloses a micro-needle tip annular array cathode electron gun and a preparation method of a cathode thereof, and belongs to the technical field of vacuum electronic devices, the electron gun comprises a cathode, a grid electrode, a double focusing electrode and an anode; specifically, the cathode is of an annular array structure and is divided into two parts by a cone along a symmetry axis, the tangent plane is a bottom surface, the tip end faces inwards, and the cathode is uniformly distributed in a cathode groove, is in a concave surface shape and has a pre-focusing effect; the micro needle tip design of the cathode significantly increases the field enhancement factor, thereby improving the electric field intensity of the tip, improving the emission current density, and reducing the turn-on voltage. The grid is a rhombic grid hole grid mesh, the side length of the rhombus is consistent with the radius of a cathode groove, electric field distribution is optimized by adjusting the acute angle of the rhombus, and the field emission efficiency is remarkably improved; the first focusing electrode is a hyperbolic focusing electrode, the inner wall of the first focusing electrode is in a hyperbolic curve shape, and the focusing effect is enhanced by guiding an electric field line to bend towards the anode along the central axis; the electron gun has high field emission performance and high beam compression ratio.

The invention relates to the technical field of ultra-low field magnetic resonance systems, in particular to a battery charge state detection method and system based on closed-loop adaptive ultra-low field MRI, and the method comprises the steps: collecting the phase change of a water molecule H signal caused by the magnetic field disturbance of a to-be-detected battery, and reconstructing a first signal phase image; extracting to obtain a high-information-content area mask, and then performing resampling to obtain a second signal phase image; and inputting the second signal phase image into a state-of-charge detection model to predict a state-of-charge value of the to-be-detected battery. In order to solve the problem that a battery magnetic resonance detection scheme in the prior art needs to adopt a high-field magnetic resonance system and is not beneficial to production line use, detection equipment is replaced with an ultralow-field magnetic resonance system, so that structures such as a shielding room in a traditional magnetic resonance system are omitted, and a high-information-content area is positioned firstly, so that the detection efficiency is improved; and resampling is carried out on the region, so that the imaging precision is improved, and the accuracy of state of charge estimation of the detection model is improved.

The invention discloses a radio frequency superconducting material performance testing system and a surface resistance measuring method.The radio frequency superconducting material performance testing system comprises a radio frequency cavity module, a low temperature module and a measuring module, the radio frequency cavity module comprises a mushroom-shaped superconducting cavity, the inner wall of the superconducting cavity is plated with a Ni3tin film, and the inner wall of the superconducting cavity is plated with a Ni3tin film; the low-temperature module is provided with a multi-stage cooling structure and a magnetic shielding shell. The measuring module is used for collecting the sample temperature, the magnetic field, the vacuum degree, the radio frequency power and the direct-current power of the heater. According to the radio frequency superconducting material performance testing system, by optimizing the design of the mushroom-shaped cavity and adopting the Nb3Sn coating technology and the efficient conduction cooling low-temperature module, the dependence of a traditional radio frequency material testing system on a liquid helium low-temperature system is eliminated, a compact testing platform is formed, and high-field and high-resolution measurement of the surface resistance of an SRF material is achieved.

The present invention belongs to the technical field related to refrigeration and cryogenic containers, and discloses a eddy-current-free liquid helium cryostat for use in a pulsed high-magnetic field environment. The cryostat comprises a sample rod, a helium chamber, a liquid nitrogen layer, a vacuum chamber, and a tail pipe. The tail pipe is composed of an inner epoxy tail pipe and an outer epoxy tail pipe, each of which is mounted via metal flanges. The epoxy tail pipe and the metal flanges are bonded together with epoxy sealant. The vacuum interlayer between the helium chamber and the vacuum chamber is interconnected with the vacuum interlayer between the inner epoxy tail pipe and the outer epoxy tail pipe. In addition, the metal flange of the inner tail pipe is precisely mounted concentrically from top to bottom, and a removable metal seal is achieved between the metal flange of the inner tail pipe and the bottom flange of the helium chamber. The present invention effectively solves the problem of liquid helium loss caused by Joule heat generated by induced eddy currents in a pulsed high-magnetic field environment in the prior art, while significantly improving the measurement accuracy of scientific experiments in a high-field pulsed high-magnetic field environment.

The invention discloses a method for enhancing the superconducting performance of a MgB2 block material by doping Fe-Ga alloy. The preparation method comprises the following steps: firstly, weighing, mixing, grinding and tabletting magnesium powder, boron powder and Fe-Ga alloy powder according to a certain mass ratio in a protective atmosphere to obtain a precursor block material; after vacuum sealing, putting the precursor block material into a heat treatment device for sintering; and after the temperature of the device is reduced to room temperature, taking out the block sample. When a magnetic field is applied externally, the Fe-Ga alloy with the magnetostrictive effect in the sample induces stress strain in the MgB2 superconductor under a strong field, and a strong pinning center with a wide action range and high pinning strength can be formed. According to the method, chemical doping is carried out on the MgB2 superconductor through the Fe-Ga alloy material with high magnetostriction performance, operation is convenient, cost is low, performance improvement is obvious, the current-carrying performance of MgB2 in a high field can be enhanced, and the superconducting performance and future application potential of MgB2 are greatly improved.

The invention discloses a preparation method of an in-situ Ag NWs fiber reinforced Cu-Ag alloy wire. The method comprises the following steps: 1, synthesizing Ag NWs in situ based on a liquid phase polyol method; 2, preparing a pre-dispersed Ag NWs fiber solution; 3, Cu powder is poured into the pre-dispersed Ag NWs fiber solution to be stirred and dried; 4, performing heat treatment to obtain Cu / Ag NWs composite powder; 5, performing spark plasma sintering to obtain a Cu / Ag NWs composite bar; and sixthly, cold drawing machining is conducted after tubing. Through in-situ synthesis of Ag NWs, mixing, sintering and drawing deformation processes, a microstructure of a large-length-diameter-ratio Ag NWs fiber reinforced submicron copper matrix is constructed from the angles of low Ag content, avoidance of grain growth and reduction of electron scattering, and a Cu-Ag alloy wire with good strength and conductivity matching is obtained under the low Ag content; the magnet is suitable for the fields of electronic communication, power transmission, high-field pulse magnets and the like.

This invention belongs to the field of superconducting materials technology and discloses an internal tin-based Nb3Sn superconducting wire with integrated piezoelectric sensing function and its preparation method. The method involves preparing a piezoelectric functional layer and a dielectric layer on the surface of a SnAl alloy rod, drilling a hole, inserting a CuAg alloy rod to form a composite rod, inserting it into an internal tin-based Nb3Sn / CuNb composite tube, drawing it into sub-components, and then bundling them into a Ta tube and an oxygen-free copper tube. The wire is then obtained through multiple stretching operations. The piezoelectric functional layer can convert minute strains into measurable electrical signals, enabling in-situ real-time monitoring of internal mechanical stresses within the wire. The CuAg alloy rod can stabilize the tensile strength of the wire and promote the formation of the Nb3Sn phase, improving the operational reliability and safety of high-field magnets under extreme conditions without affecting superconducting performance.

An optically controlled, multi-transmitter magnetic resonance imaging system for multi-nuclear, high field applications is disclosed. In one embodiment, the MRI system may include a dual-tuned radio-frequency (RF), on-coil power amplifier for amplifying RF power signals at two or more frequencies for the multi-nuclear excitations for use in a dual-tuned coil MRI device or a nested coil MRI device. In one particular implementation, the dual-tuned amplifier of the MRI system may receive optical carrier signals through the broadband optical interface to control the on-coil amplifiers. A variable effective inductor circuit for use in tuning the dual-tuned amplifier is also disclosed. The variable effective inductor circuit includes a gallium nitride (eGaN) field effect transistor (FET) device connected to an inductor. The inductance of the variable effective inductor circuit can be adjusted by modulating a drain-source voltage of the eGaN FET device controlled based on a pulse duration of an optical carrier signal.

The invention provides an ion irradiation method for improving the performance of a copper-based superconducting strip, and belongs to the technical field of ion irradiation. The ion irradiation method comprises the following steps: carrying out ion irradiation on the copper-based superconducting tape by adopting an ion beam under a vacuum condition; the ion beam comprises a light ion beam or a heavy ion beam. By accurately controlling the energy, dosage and current intensity of the ion beam, effective modification of the copper-based superconducting strip is realized, the current-carrying performance of the 2G-HTS strip under high temperature and high field is remarkably improved, and the critical current density Jc is improved by 2.1-5 times. In addition, modification can be carried out according to the specific requirements of the copper-based superconducting strip, and then the consistency and stability of the modification effect are improved.

The invention discloses a reconstruction method for breaking through a low-field magnetic resonance imaging quality limit. The method comprises the following steps: acquiring and constructing a low-field data set; acquiring and constructing a high field data set; respectively training a basic super-resolution model from a low-field low-resolution image excited by 1-N times to a low-field high-resolution image excited by N times; comparing the influence of different excitation times on the performance of the basic super-resolution model; training a cross-field super-resolution model from a low-field and N-time excited high-resolution image to a high-field and ultrahigh-resolution image; cascading the basic super-resolution model and the cross-field super-resolution model to construct an enhanced two-stage cross-field super-resolution model; a high-field and ultrahigh-resolution image is reconstructed from a low-field, low-excitation-frequency and low-resolution image through an enhanced two-stage cross-field super-resolution model. According to the invention, the low-field magnetic resonance scanner can realize high-quality imaging breaking through the magnetic field intensity constraint within a short scanning time.

The present invention discloses an axial reinforcement device for a high-field pulse magnet, which belongs to the field of pulsed high magnetic field technology; the reinforcement device includes an end assembly and an internal fixing assembly; wherein the end assembly includes two parallel end plates, which are parallel to the radial plane of the pulse magnet coil and are respectively arranged at both ends of the pulse magnet coil; the internal fixing assembly is perpendicular to the end plate of the end assembly, and its main body is arranged between the two end plates of the end assembly, and is located at an interface position inside the magnet coil where free separation between coil layers will occur. After the magnet coil is wound or assembled to a predetermined step, the internal fixing assembly is arranged to clamp the two end plates of the end assembly to provide additional axial pre-tightening force for the end plates; the present invention can effectively reduce the axial gap between the coil turns caused by the circumferential pre-tightening force on the coil during the winding or assembly process of the magnet coil, thereby reducing the axial gap between the magnet end coil and the end plate when the magnet is discharged, thereby improving the service life of the magnet.

The application relates to a field effect transistor and a power electronic system. The field effect transistor comprises a substrate, a channel layer formed on the substrate, a barrier layer formed on the channel layer, a two-dimensional electron gas channel formed between the barrier layer and the channel layer, a source electrode, a gate electrode and a drain electrode formed on the barrier layer and arranged in sequence at intervals along a first direction, a P-type compensation island at least partially higher than the barrier layer and located between the gate electrode and the drain electrode, the P-type compensation island being spaced apart from the drain electrode and the gate electrode, a shielding plate located above the P-type compensation island, a passivation layer arranged between the shielding plate and the P-type compensation island, and the shielding plate being arranged at intervals from the gate electrode and the drain electrode. Through the coupling effect of the P-type compensation island and the shielding plate, the potential distribution between the gate electrode and the drain electrode is more uniform, thereby reducing the peak value of the high field on the drain side, improving the breakdown margin, and effectively reducing the virtual gate effect caused by electron capture after high-voltage turn-off, thereby greatly reducing the increase of the dynamic on-resistance.

The invention relates to the technical field of magnetic resonance imaging, in particular to an intra-operative low-field magnetic resonance intelligent navigation method based on preoperative high-field data guidance, which comprises the following steps: acquiring a high-field MRI image of a patient before an operation and extracting a three-dimensional segmentation mask and clinical features of a focus; adjusting according to the clinical features to obtain an intraoperative scanning protocol; and performing low-field magnetic resonance examination during the operation to generate an intra-operation navigation image, and marking focus information. Aiming at the problem that the accuracy of a focus image provided by an ultra-low field system in the operation process in the prior art is not enough, a high-field MRI image collected before the operation is introduced as a reference, scanning sequence parameters of the ultra-low field system used in the operation are dynamically adjusted based on clinical features embodied in the high-field MRI image, a better imaging effect is achieved, and meanwhile, the accuracy of the focus image provided by the ultra-low field system in the operation process is improved. Focus information is marked on the intraoperative navigation image based on the three-dimensional segmentation mask as prior information, so that more refined segmentation of focuses on the intraoperative navigation image is realized, and the surgical requirements are met.

The application provides a radio frequency coil applied to a magnetic resonance imaging device, which comprises a plurality of loop-shaped coil units, the plurality of coil units are distributed in a circumferential direction around a preset axis and are sequentially connected; a plurality of feed ports corresponding to the coil units, the feed ports are arranged on the corresponding coil units; and a plurality of capacitors, at least one capacitor is coupled to each coil unit. Through the above configuration, the capacitors are arranged to adjust the circuit characteristics of the coil units; compared with the prior art, the plurality of coil units and the corresponding plurality of feed ports can increase the number of channels of the radio frequency coil to be greater than four, so that the radio frequency coil can be applied to a high-field or ultrahigh-field transmitting coil; in addition, the cooperation of the plurality of coil units and the plurality of feed ports can also improve the shimming of the radio frequency coil.