331 results about "Ferromagnetic resonance" patented technology

Provided is a thin-film magnetic head capable of writing data with high accuracy on a magnetic recording medium having high coercive force without heating. The head comprises an electromagnetic coil element comprising: a main magnetic pole; an auxiliary magnetic pole; and a write coil formed so as to pass through at least between the main magnetic pole and the auxiliary magnetic pole, for generating the write magnetic field. In this head, a part of the write coil has a layered structure of: a resonance coil layer for generating a resonance magnetic field having ferromagnetic resonance frequency of a magnetic recording layer of a magnetic recording medium or having a frequency in the vicinity thereof; and a write coil layer. And further, the resonance coil layer and the write coil layer sandwich an insulating layer therebetween.

The invention discloses a unipolar current-voltage integration sensor, relating to an electronic sensor in the field of intelligent power grids. The sensor comprises a current sensor, a voltage measurement sensor, a voltage correction sensor, a signal modulation circuit, an A/D (Analog to Digital) conversion circuit, an FPGA (Field Programmable Gate Array) unit, a wireless transmission extension unit and a high-voltage electricity getting device. A current signal of a power transmission line is collected by the three sensors and the signal is processed. After a voltage value of tested current is calculated, detection information is transmitted through a wireless communication network. The high-voltage electricity getting device can be used for supplying electric energy to online monitoring equipment for a long time by getting energy through a current transformer and cooperatively supplying power with a lithium cell. According to the unipolar current-voltage integration sensor disclosed by the invention, current and voltage information can be transmitted to the computer to be subjected to data processing rapidly, integrally and accurately; high voltage, large current and ferromagnetic resonance cannot be generated; the sensor can be conveniently connected with an electronic instrument and micro-computer measurement and control protection equipment; the system structure is simplified; the space is saved; the energy consumption is very low; and the stability and the accuracy of the whole system are improved.

The invention discloses an all-fiber current transformer and a method thereof, aiming to overcome the defects that a traditional electromagnetic current transformer is easily subjected to electromagnetic interference and has complicated insulation structure, magnetic saturation existence and the like. The technical scheme of the invention comprises the following steps of: demodulating light output by a light source into X-axis polarized light and Y-axis polarized light by a Y-branch integrated optical phase modulator; converting into sinistral circular polarized light and dextral circular polarized light in a lambda/4 retarder; generating a magnetic field by a current in a lead due to the faraday effect; returning the two beams carrying faraday effect phase information to the Y-branch integrated optical phase modulator to intervene when beams in optical fiber is transmitted around the lead; and enabling an interference result to enter a subsequent treatment system from the optical fiber coupler to acquire the faraday effect phase information at the measuring point. The invention avoids the hidden danger of ferromagnetic resonance and magnetic saturation by adopting the optical fiber as a sensing medium and has a series of advantages of high detection accuracy, good environmental suitability, and the like.

To realize an electric field-driven type ferromagnetic resonance excitation method of low power consumption using an electric field as drive power, and provide a spin wave signal generation element and a spin current signal generation element using the method, a logic element using the elements, and a magnetic function element such as a high-frequency detection element and a magnetic recording device using the method. A magnetic field having a specific magnetic field application angle and magnetic field strength is applied to a laminate structure in which an ultrathin ferromagnetic layer sufficiently thin so that an electric field shield effect by conduction electrons does not occur and a magnetic anisotropy control layer are directly stacked on each other and an insulation barrier layer and an electrode layer are arranged in order on an ultrathin ferromagnetic layer side. An electric field having a high-frequency component of a magnetic resonance frequency is then applied between the magnetic anisotropy control layer and the electrode layer, thereby efficiently exciting ferromagnetic resonance in the ultrathin ferromagnetic layer.

A high sensitivity magnetic anomaly detector for geomagnetic exploration comprises a shorted coaxial transmission line having as central conductor an amorphous magnetic wire. A static magnetic field is applied along the transmission line. A transverse electromagnetic wave also propagates along the transmission line and excites a ferromagnetic resonance of the magnetic ions located within the depth of penetration of the circumferential microwave magnetic field into the magnetic wire. The microwave giant magnetoimpedance effect occurring in the magnetic wire changes the magnetic wire impedance as follows: the real part of the impedance peaks and the imaginary part passes through zero at a given frequency (the ferromagnetic resonance frequency). This frequency depends on the saturation magnetization of the magnetic wire and the strength of the static magnetic field. A slight variation of the Earth's magnetic field (a magnetic anomaly) changes this frequency, thus providing information about large metallic masses hidden under the Earth's surface or underwater.

The invention provides a quick diagnostic and processing method of power distribution network ferromagnetic resonance and one-phase earth faults. When a power grid operation mode changes, firstly, excitation reactance Xp of an electromagnetic type voltage transformer of a transformer substation bus system is typed in a computer measure and control unit, then a power grid tracking measurement branch circuit is used for carrying out tracking measurement on the system capacitive reactance value of the power grid operation mode, if the system capacitive reactance value meets a power grid ferromagnetic resonance condition is judged, and resonance condition dynamic early-warning is carried out. When power grid neutral point displacement voltages are abnormal, an earth current compensation and detection branch circuit is adopted to detect zero sequence currents of a loop, and according to the magnitude of the zero sequence currents, ferromagnetic resonance and one-phase earth judgement is carried out. When it is judged that ferromagnetic resonance faults happen, a resonance eliminating branch circuit is switched for eliminating resonance, and when it is judged that one-phase earth faults happen, the zero sequence current method is used for selecting a fault line.

The invention discloses a method of eliminating ferromagnetic resonances. A sine fitting algorithm is utilized to identify ferromagnetic resonances and one-phase grounding faults, according to the method, zero sequence voltage sampling data are subjected to fitting, whether zero sequence voltages are in fundamental frequency quantity can be judged according to the amplitude of a fitting function, wave distortion characteristics of the zero sequence voltages in the fundamental resonances are utilized to construct a wave distortion degree function, and degrees of wave distortion are calculated to distinguish the fundamental resonances and the one-phase grounding. The method has the advantages of being simple in principle, small in calculation amount, and high in sensitivity, the fundamental resonances and the one-phase grounding are accurately distinguished, and moreover ferromagnetic resonance faults are eliminated.

The invention discloses a high-power yttrium-gadolinium garnet ferrite having the composition chemical formula specifically expressed as Sm[x]Y[3-x-y-2z-p-q-q']Gd[y]Ca[2z+p+q+q']V[z]Ge[p]Sn[q]Ti[q']In[q'']Al[w]Mn[w']Fe[5-z-p-q-q'-q''-w-w'-[delta]]O[12], wherein 0<=x<=0.20, 0<=y<=3.0, 0<=z<=1.3, 0<=p<=0.9, 0<=q<=0.7, 0<=q'<=0.7, 0<=q''<=0.70, 0<=w<=1.3, 0<=w'<=0.10, 0<=delta<=0.8, and delta represents iron deficient quantity. The high-power garnet ferrite material having high spin wave line width [delta]Hk, low ferromagnetic resonance line width [delta]H and high dielectric constant epsilon' can be obtained.

The invention discloses a hexagonal ferrite material with high anisotropy and low ferromagnetic resonance line width and a preparation method and belongs to the technical field of preparation of ferrite materials. The material is prepared from a main component and a dopant and is characterized in that the main component comprises 67.0mol%-75.0mol% of Fe2O3, 0.5mol%-7.5mol% of SrCO3, 0.5mol%-7.5mol% of BaCO3, 3.5mol%-6.5mol% of Co2O3, 3.5mol%-11.5mol% of La2O3 and 8.5mol%-13.5mol% of CuO; the dopant comprises, in percentage by weight of the main component in terms of oxide, 0.5wt%-2.0wt% of Bi2O3, 0.15wt%-1.0wt% of B2O3, 0.02wt%-0.32wt% of CaCO3, 0.02wt%-0.32wt% of SiO2 and 0.05wt%-0.50wt% of ISOBAM. The ferrite material has the characteristics of high density d larger than 5.20 g/cm<3>, high remanence 4 phi Mr larger than 4.3 kGs, high anisotropic field Ha larger than 15.0 kOe and low ferromagnetic resonance line width delta H smaller than 3,700 e (@44 GHz and Zero field).

The present invention relates to a resonance elimination apparatus and method of ferromagnetic resonance, wherein the apparatus is electrically connected to an electromagnetic voltage transformer in a power distribution network, and comprises: a power source module, a resonance judging module, a resonance elimination module, and a current transformer, wherein the power source module is electrically connected to the resonance judging module and the resonance elimination module; the current transformer is electrically connected to a connecting wire between a neutral point of the electromagnetic voltage transformer and the earth, and the current transformer is electrically connected to the resonance judging module; the resonance elimination module comprises a resonance elimination resistor and a first control switch, both ends of the resonance elimination resistor are connected to both ends of an open triangular loop of the electromagnetic voltage transformer in series, the first control switch is connected between the resonance elimination resistor and the open triangular loop in series; and the resonance judging module is electrically connected to the first control switch. The apparatus provided in this embodiment can accurately and fast eliminate ferromagnetic resonance and improve resonance elimination efficiency of ferromagnetic resonance.

The invention belongs to the technical field of magnetic materials, and discloses a high-stability garnet microwave ferrite magnetic sheet and a preparation method thereof. The material composition ofthe high-stability garnet microwave ferrite magnetic sheet is Y<3-f-2d-a>Gd<f>Ca<2d+a>Bi<e>Fe<5-a-b-c-d-sigma>SnInMn<c>V<d>O<12>, wherein a is more than 0 and no more than 0.7; b is more than 0and no more than 0.7; c is more than 0 and no more than 0.6; d is more than 0 and no more than 1.5; e is more than 0 and no more than 0.6; f is more than 0 and no more than 0.8; and sigma is more than 0 and no more than 0.4. According to the high-stability garnet microwave ferrite magnetic sheet, Bi<3+> ions are added into the material, so the dielectric constant of the material is improved, anda Curie temperature is increased; and in addition, SnO<2>, In<2>O<3>, SnO<2> and In<2>O<3> are added into the material, so the anisotropy coefficient K of the material can be reduced, and the ferromagnetic resonance linewidth Delta(H) of the material is reduced. In terms of the process, high-pressure sintering is adopted to replace normal-pressure sintering, so sintering density is improved, the porosity of the material is reduced, and the ferromagnetic resonance linewidth Delta(H) of the material is reduced. Thus, the problem that the temperature coefficient of the material is poor is solved,and the material is guaranteed to have low ferromagnetic resonance linewidth Delta(H), high dielectric constant and high Curie temperature.