Showing papers on "Magnetic core published in 1999"

Hall effect sensor of displacement of magnetic core

Abstract: A sensor for measuring linear displacement has a core of magnetic material disposed for movement within a bobbin about which a coil of insulated, electrically conductive wire is wound. At least one Hall effect device is disposed about the coil. The sensor is contained with a magnetic housing. When the coil is excited by a DC power source, the direction of magnetic flux flowing through the Hall effect device is dependent upon the position of the core.

Calculation of losses in ferro- and ferrimagnetic materials based on the modified Steinmetz equation

Abstract: This paper discusses the influence of nonsinusoidal flux-waveforms on the remagnetization losses in ferro- and ferrimagnetic materials of inductors, transformers and electrical machines used in power electronic applications. The nonsinusoidal changes of flux originate from driving these devices by nonsinusoidal voltages and currents at different switching frequencies. A detailed examination of a dynamic hysteresis model shows that the physical origin of losses in magnetic material is the average remagnetization velocity rather than the remagnetization frequency. This principle leads to a modification of the most common calculation rule for magnetic core losses, i.e., to the "modified Steinmetz equation" (MSE). In the MSE the remagnetization frequency is replaced by an equivalent frequency which is calculated from the average remagnetization velocity. This approach allows, for the first time, to calculate the losses in the time domain for arbitrary waveforms of flux while using the available set of parameters of the classical Steinmetz equation, DC premagnetization of the material, having a substantial influence on the losses, can also be included. Extensive measurements verify the modified Steinmetz equation presented in this paper.

Handbook of Modern Ferromagnetic Materials

Abstract: Foreword Takeshi Takei. Preface. Acknowledgements. 1. Applications and Functions of Ferromagnetic Material. 2. Basics of Magnetism - Source of Magnetic Effect. 3. The Magnetization in Domains and Bulk Materials. 4. AC Properties of Magnetic Materials. 5. Materials for Permanent Magnet Applications. 6. DC and Low Frequency Applications. 7. Soft Cobalt-Iron Alloys. 8. Metallic Materials for Magnetic Shielding Applications. 9. High Permeability-High Frequency Metal Strip. 10. Metal Powder Cores for Telecommunications. 11. Crystal Structure of Ferrites. 12. Chemical Aspects of Ferrites. 13. Microstructural Aspects of Ferrites. 14. Ferrite Processing. 15. Ferrite Inductors and Transformers for Low Power. 16. Soft Magnetic Materials for EMI Suppression. 17. Ferrites for Entertainment Applications. 18. Ferrite Transformers and Inductors at High Power. 19. Materials for Magnetic Recording. 20. Ferrites for Microwave Applications. 21. Miscellaneous Magnetic Material Applications. 22. Physical-Thermal Aspects of Magnetic Materials. 23. Magnetic Measurements-Materials and Components. Bibliography. Appendix 1: Abbreviations and Symbols. Appendix 2: List of World's Major Ferrite Suppliers. Appendix 3: Units Conversion from CGS to MKS(SI) System. Index.

A micro-fluxgate magnetic sensor using micromachined planar solenoid coils

Abstract: This paper presents a new micro-fluxgate magnetic sensor based on micromachined 3-dimensional toroidal type planar coils used as excitation and sensing elements. A rectangular-ring shaped magnetic core and the `second harmonic' operation principle are adopted in this fluxgate sensor. With the use of a newly developed UV-LIGA thick photoresist process and electroplating techniques, excitation and sensing coils as well as permalloy magnetic cores were fabricated to realize a planar three-dimensional magnetic fluxgate sensor on silicon wafers. Excellent linear response over the range of −500 μT to +500 μT, with a system sensitivity of 8360 V T−1 and a resolution of 60 nT was achieved from the sensor realized in this work. The total response range of the sensor is −1.3 to +1.3 mT. The electroplated thick, Cu coil windings result in low coil resistance and a low power consumption of ∼100 mW for an operational frequency range of 1–100 kHz. The small size, the high sensitivity and resolution, and lower power consumption, make this integratable magnetic fluxgate sensor suitable for various applications such as: portable navigation systems, space research, and proximity sensors and detectors.

Integrated inductive components and method of fabricating such components

Abstract: An inductive component includes a substrate (12) on the surface of which is a lower insulation layer (32) having a shallow concavity (34) or trench, a first plurality of conductive elements (16) formed in the trench, a magnetic core (14) formed over the first plurality of conductive elements, and a second plurality of conductive elements (18) formed over the core. The first and second pluralities of conductive elements are connected to each other so as to form an inductive coil around the core. First and second core insulation layers (28, 30) are disposed between the core and the first and second pluralities of conductive elements, respectively. The component is fabricated by a method in which it is built up in the trench using thin film techniques. A first array of conductors (16) is patterned over the lower insulation layer (34), and a first core insulation layer (28) is applied over the first conductor array. A magnetic core (14) is formed on top of the first core insulation layer, and a second core insulation layer (30) is applied over the core. A second array of conductors (18) is patterned on top of the second core insulation layer so that the ends of the conductors in the first and second arrays contact each other to form an inductive coil around the core. The formation of either the first or second plurality of conductors may coincide with the formation of the metal conductor layer in the manufacture of a semiconductor integrated circuit, whereby the inductive component can be manufactured as part of the integrated circuit.

High-frequency small-signal model of ferrite core inductors

Abstract: A circuit model of ferrite core inductors is presented. The behavior of the model parameters versus frequency is considered. The total power loss in inductors consisting of the winding resistance loss and the core loss, is modeled by a frequency-dependent equivalent series resistance. The total inductance given by the sum of the main inductance and the leakage inductance is obtained as a function of frequency. In order to study the core equivalent resistance and main inductance versus frequency, the magnetic field distribution in the core is derived from Maxwell's equations for a long solenoid. The complex permeability and permittivity of the ferrite core are introduced in the electromagnetic field equations. Experimental results are also given.

Coreless printed circuit board (PCB) transformers for power MOSFET/IGBT gate drive circuits

Abstract: Gate drive circuits for modern power electronic switches, such as MOSFET and insulated gate bipolar transistor (IGBT), often require electrical isolation. This paper describes the modeling and experimental results of some coreless printed circuit board (PCB)-based transformers that can be used for MOSFET and IGBT devices at high-frequency (500 kHz to 2 MHz) operation. PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. With no core loss, coreless transformers are found to have favorable characteristics at high-frequency operations. This project demonstrates an important point that the size of the magnetic core can approach zero and become zero when the frequency is sufficiently high.

Optimal operation of coreless PCB transformer-isolated gate drive circuits with wide switching frequency range

Abstract: Gate drive circuits for power MOSFETs and insulated gate bipolar transistors (IGBTs) often require electrical isolation. Coreless printed circuit board (PCB) transformers have been shown to have desirable characteristics from a few hundreds of hertz to a few megahertz and can be used for both power and signal transfer at low-power level. At low operating frequency, the magnetizing inductance has such low impedance that the driving power requirement could become excessive. This paper describes the use of a coreless PCB transformer for isolated gate drive circuits over a wide-frequency range. Based on a resonance concept, the optimal operating condition that minimizes the power consumption of the gate drive circuits is developed and verified with experiments. The coreless PCB transformer demonstrated here confirms a fundamental concept that the size and volume of a magnetic core could approach zero and become zero if the operating frequency is sufficiently high. Coreless PCB transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits and low-power converters. Their sizes can be much smaller than those of typical core-based pulse transformers. The electrical isolation of a PCB is much higher than that of an optocoupler.

Batch-fabricated microinductors with electroplated magnetically anisotropic and laminated alloy cores

Abstract: Although many integrated inductors have been made by integrated circuit and electronic packaging batch-fabrication techniques, their magnetic characteristics are inferior to their discrete counterparts, in part because of the relatively poor magnetic properties of integrated magnetic cores. If the permeability of an integrated magnetic core can be increased, the magnetic characteristics of microinductors based on these cores will improve. To address this issue, batch-fabricated, integrated magnetic devices incorporating electroplated magnetically anisotropic cores and electroplated copper coils are investigated. These devices are made by micromachining and electroplating techniques at low temperature. Three different geometries of inductors, each possessing two different core materials [permalloy (NiFe) and supermalloy (NiFeMo)] are presented. The cores have been rendered magnetically anisotropic by application of a magnetic field during electrodeposition, resulting in easy and hard axis orientations. In addition, some cores consist of a two-layer electrodeposit separated by a polyimide thin-film lamination. At low frequencies (less than several hundred kHz), the easy-axis devices have higher inductance than the hard-axis devices. However, the hard-axis devices have better performance at higher frequencies because of a far less steep falloff of material permeability as a function of frequency in the hard axis direction.

Iron core device and its manufacture

Abstract: PROBLEM TO BE SOLVED: To provide a mass-producible iron core device whose magnetic performance and mechanical strength can be improved. SOLUTION: In this method of manufacturing an iron core device, a plurality of plate core pieces 3 are arrayed continuously to form a first core member 4 and a plurality of other plate core pieces 3 are done in the same manner to form a second core member 5. The first and second core members 4, 5 are stacked in the stacking direction alternately in such a way that each position between the core pieces of the first core member 4 and each position between the core pieces of the second core member 5 are dislocated in the longitudinal direction and that edge parts neighboring each other in the stacking direction of each core piece 3 are on top of the other. A connecting means is provided which connects at least a pair of edge parts of neighboring core pieces 3. An annular or rectangular iron core device is formed by rotating each core piece 3 with the connecting means.

Low noise full integrated multilayers magnetic for power converters

Abstract: A multilayer structure in which all the magnetic elements have the windings edged in the inner layers and the magnetic core which surrounds the winding has the legs penetrating through the multilayer structure. The interconnection between the magnetic elements and the rest of electronic components is done through the layers of the multilayer board, horizontally and vertically through via. For higher power components special cuts are performed in the multilayer board to accommodate the body of the components which may be connected to an external heatsink. The winding arrangement in the transformer is done in a such way to minimize and even eliminate the common mode noise injected through the capacitance between primary and secondary winding. The input filter is constructed to exhibit a differential and a common mode impedance. Supplementary capacitors are incorporated in the multilayers structure to offer a low impedance to the noise to short it to the source, or for injecting currents of opposite polarity to cancel the common mode current transferred through the transformer's inter winding capacitance and through the parasitic capacitance of the switching elements to the secondary. The insulation between winding can be in accordance with the safety agency requirements, allowing much shorter creapage distances inside of the multilayer PCB structure than in the air due to the compliance with coating environment.

Magnetism of nanometer-scale iron particles arrays (invited)

Abstract: The magnetization behavior in arrays of small ferromagnetic iron particles is investigated. Arrays were fabricated by a combination of chemical vapor deposition and scanning tunneling microscopy. This method allows a variety of particle arrays to be grown differing in particle height, diameter, or arrangement. Moreover, the arrays can be grown directly onto different materials such as Au or permalloy. Magnetic measurements were conducted by Hall magnetometery up to 100 K and compared to switching field measurements by means of magnetic force microscopy at room temperature. The magnetization reversal mechanisms were studied from magnetization curves measured for an arbitrary angle ϑ of the applied field with respect to the long axis of the particles. By analyzing the reversible rotation, the particles’ magnetic core diameter and the shape anisotropy could be determined. A phenomenological model based on thermally activated magnetization reversal was introduced and compared to experimental switching field d...

Permanent-magnet rotor of permanent-magnet mounted motor

Abstract: PROBLEM TO BE SOLVED: To see that the rotor can lessen the cogging torque, lessen the vibration and noise, and further lessen the unevenness of rotation without incurring the cost up. SOLUTION: This rotor is provided with rectangular magnet mounting holes 22 at equal intervals by the number of poles of a rotor in the circumferential direction of a rotor iron core 21, and a permanent magnet 23 is mounted in each of the magnet mounting hole 22 so that the adjacent magnetic poles may vary from each other, with their magnetic pole facing in the radial direction of the iron core. In this case, the peripheral shape of the iron core magnetic pole 24 made at each peripheral magnetic pole face of the permanent magnet 23 is made in such circular form in every iron core magnetic pole that the distance from the center of the iron core becomes the largest at the center Pa in circumferential direction, and that the distance from the center of the iron core may be the smallest at the point Pb between poles.

Inclusion of interbar currents in a network-field coupled time-stepping finite-element model of skewed-rotor induction motors

Abstract: In order to include the interbar currents of skewed-rotor inductor motors in finite-element analysis, a three-dimensional (3-D) model is usually necessary. In this paper a two-dimensional multislice time-stepping finite element method of skewed-rotor induction motors is presented to solve such complicated 3-D problems. It is shown that the network of the rotor cage is coupled to finite-element equations so that the interbar currents in the rotor can be taken into account. By arranging the unknowns and mesh-current equations ingeniously, the resultant coefficient matrix of the global system equations are made symmetrical. Compared with 3-D finite-element methods, the computation time for solving field equations with the proposed method is significantly shorter. The model can be used to estimate the high-order harmonic stray losses in induction motors. A comparison between computed and tested results is also given.

Rotary electric machine and electric vehicle using the same

Abstract: An rotary electric machine 1 comprises stator 2 having a stator core 4 wounded with stator windings 5 and a rotor 3 having a rotor core 7 rotatable and opposite to the stator core 4 through a gap. The rotor core 4 of the roraty electric machine 1 is composed of a plurality of projecting pole magnetic core portions 73 arranged in a side of the gap and along the circumferential direction and a plurality of rotor yoke portions 76 for forming a magnetic path conducting magnetic fluxes of each of the projecting pole magnetic core portions 73 , and the rotor core is divided in the circumferential direction on a unit of each of the projecting pole magnetic core portions 73 and each of the rotor yokes 76 opposite to each of the projecting pole magnetic core portions 73 . It is possible to provide a rotary electric machine which is high in material use factor at manufacturing a rotor core and small in size and light in weight, and to provide an electric vehicle using the rotary electric machine.

Development of passive fault current limiter in parallel biasing mode

Abstract: So far literature reports on the magnetic fault current limiter (FCL) are based on the series biasing mode in which the flux due to line current flows through the permanent magnet. As a result there is a high possibility of demagnetization of the permanent magnet. A passive fault current limiter is a combination of passive elements such as permanent magnet and saturable core. The permanent magnet is used to bias the core. In order to avoid severe demagnetization of the permanent magnet, we have investigated the performance of passive fault current limiters based on permanent magnet and saturable core in parallel biasing mode. The functional characteristics have been analyzed by Tableau approach and the simulation results are presented, The experimental results for a small scale prototype model are also presented for verification.

Magnetic core that is suitable for use in a current transformer, method for the production of a magnetic core and current transformer with a magnetic core

Abstract: The magnetic core (M) consists of a coiled ferromagnetic alloy strip whereby at least 50 % of the volume contains fine crystalline particles with an average particle size of 100 nm or less (nanocrystalline alloy). Its permeability is greater than 12 000 and lower than 350 000. The saturation-magnetostriction of the magnetic core (M) is less than 1 ppm.The core (M) is substantially free from mechanical stress. The magnetic core (M) has an anisotropic axis (A) along which the magnetization of the magnetic core (M) can be oriented in a particularly easy manner and which is perpendicular to a plane in which the center line of the strip (B) runs. The composition of the alloy essentially corresponds to the formula FeaCobCucSidBeMf, whereby M is at least one of the elements V, Nb, Ta, Ti, Mo, W, Zr and Hf, a, b, c, d, e, f are indicated in atom %, and a, b, c, d, e and f meet the following conditions:0,5 ≤ c ≤ 2; 6,5 ≤ d ≤ 18; 5 ≤ e ≤ 14; 1 ≤ f ≤ 6; with d + e > 18 and 0 ≤ b ≤ 15, whereby a + b + c + d + e + f = 100.

New hybrid technology for planar fluxgate sensor fabrication

Abstract: We have adapted a new printed circuit board (PCB) technology to the fabrication of ultraflat and sensitive fluxgate magnetic field sensors. The two outer layers of the PCB stack compose the electrical windings of fluxgates, while the inner layer is made of a micro-patterned amorphous magnetic ribbon with extremely high relative magnetic permeability (/spl mu//sub r//spl ap/100 000). Two basic configurations were considered: one based on a toroidal magnetic core and the other on a rectangular core with and without an air gap. The field response and sensitivity of the fluxgate devices have been studied as a function of the gap length, the excitation current, and excitation frequency. Compared to fluxgate sensors of similar size, a relatively high sensitivity of 60 V/T was found at 30 kHz for a five-winding detection coil wound around a rectangular E-shaped magnetic core. This high performance is primarily attributable to the high-permeability magnetic core. The results clearly show the potential of this fluxgate device for application as a magnetic sensor.

A DC/DC boost converter toward fully on-chip integration using new micromachined planar inductors

Abstract: A surface mounted DC/DC boost converter using new micromachined planar inductors has been designed, implemented and characterized for complete on-chip integration. Microfabricated inductors without an air gap in the magnetic core and with an air gap of 100 /spl mu/m in the magnetic core have been realized and used in the boost converter. The converter using the inductor with the air gap shows better performance than that using the inductor with no air gap in the core. This can be attributed to the better quality factor and suppression of the DC current saturation for large loads for the inductor with air gap in its core. The converter shows the best performance in the driving frequency range of 3 MHz to 10 MHz for a load of 100 k/spl Omega/. An input of 3 V was boosted up to 6.55 V in the above switching frequency range and load condition. A maximum achievable voltage conversion factor of 2.2 was obtained from the converter employing the inductor with an air gap of 100 /spl mu/m in its magnetic core.

Electromagnetic induction heating device and image recording device using the same

Abstract: The electromagnetic induction heating device has a simple construction, holds an object to be heated in a favorable heating condition while effectively suppressing the irregularities of heat generation of the object to be heated, and reduces an energy consumption. The electromagnetic induction heating device which heats the object to be heated provided with at least an electromagnetic induction heat generating layer includes a magnetic core made of magnetic material which is disposed in such a manner that it faces the electromagnetic induction heat generating layer of the object to be heated in an opposed manner, and an exciting coil which is wound around the magnetic core and generates a fluctuation magnetic field which penetrates the electromagnetic induction heat generating layer. A movable core which is capable of moving relative to the object to be heated so as to change the intensity of the fluctuation magnetic field which penetrates the electromagnetic induction heat generating layer is provided to at least a portion of the magnetic core. Furthermore, an image recording device is constructed such that the electromagnetic induction heating device is provided for an image carrying body which corresponds to the object to be heated and fixing unit or a pressure device is disposed at the downstream of the electromagnetic induction heating device.

Combined sensor system for rail vehicle wheels

Abstract: Each vehicle wheel (3) is checked by means of an eddy current and magnetic field sensor for mechanical defects of the wheel rim (4) and each set of wheels or each rotary frame (2) is investigated by a radar-doppler sensor (8) for correct wheel running. Each wheel bearing (5) is monitored by a body noise sensor (16) for bearing defects, unacceptable running noise and vibrations. A three-dimensional acceleration sensor installed in each rail vehicle detects vibrations, longitudinal and cross accelerations to which the vehicle structure is subjected. The eddy current/magnetic field sensor (7) comprises a U-shaped iron core, on which two separate wire windings are installed. The first winding has a direct current flowing through it to produce a magnetic field, which acts on the wheel rim. The second winding represents the sensor winding, which detects the magnetic flow alterations caused by wheel defects (cracks and brakes in the wheel rim). The sensor winding is connected to a signal evaluation electronic apparatus.

Differential solenoidal magnetic field sensing device and method for manufacturing the same

Abstract: A differential solenoidal magnetic field sensing device is a magnetic field sensor fabricated on a microscopic scale and is constructed by two soft magnetic film cores laminated on a semiconductor substrate, an excitation of the soft magnetic film cores, and a magnetic flux variation detecting coil formed of a spirally wound metal film pattern. Since two soft magnetic film cores constitutes closed magnetic paths, leakage of magnetic flux can be minimized. Also, the magnetic sensing device is a differential type sensor, the combination of driving signals can be offset. That is to say, the magnetic field sensing device is constructed such that two soft magnetic film cores are laminated and are formed lengthwise in the direction of a detection axis to reduce anti-magnetic field components, and the excitation coil wound around the two soft magnetic film cores and the magnetic flux variation detecting coil for obtaining the sum of magnetic flux variations generated in the soft magnetic film cores are alternately wound turn by turn around the soft magnetic film cores.

Permanent magnet type dynamo electric machine and electric vehicle using the same

Abstract: A permanent magnet type dynamoelectric machine for driving a motor vehicle has a stator with a stator iron core and a rotor with a rotor iron core facing the stator iron core through an air gap permitting rotation of the rotor. A plurality of permanent magnets are embedded along the circumference of the rotor iron core. The mechanical angle θ formed about an axial center by the outer circumferential width of a side of each of the permanent magnets which face the stator is set to, θ=n×τ.sub.s +16/P wherein τ s is the slot pitch of the stator 1 in mechanical angle, P is number of poles of the dynamoelectric machine and n is an integer.

New method for integration of resonant inductor and transformer-design, realisation, measurements

Abstract: For the miniaturisation of resonant converters the resonant inductor has been integrated into the transformer by using the leakage inductance as the inductor. A new method of adjusting the leakage inductance for planar transformers with integrated windings by using an additional layer of low permeable magnetic material is introduced. The leakage inductance of planar transformers with integrated windings can be adjusted very precisely and reproducibly.

3-D microfabricated toroidal planar inductors with different magnetic core schemes for MEMS and power electronic applications

Abstract: Micromachined toroidal planar inductors that have three different magnetic core structures have been designed, fabricated, and characterized for MEMS and power electronic applications. A plain ring core shows a high inductance value of 10 /spl mu/H in a low frequency range below 2 kHz, whereas both a ring core with an air gap and a spiral type core show higher inductance values in a high frequency range of 2 kHz-1 MHz. The inductors have a low resistance value of /spl sim/1.5 /spl Omega/ with total dimensions 4 mm/spl times/1.5 mm/spl times/120 /spl mu/m.

Analysis of current distribution in magnetic film inductors

Abstract: We have extended our electromagnetic model for high-frequency magnetic film inductors [A. Gromov, V. Korenivski, K. V. Rao, R. B. van Dover, and P. M. Mankiewich, IEEE Trans. Magn. 34, 1246 (1998)] to account for driving current redistribution in structures where the conductor and the magnetic film are in direct electrical contact. We consider a stripe conductor of a rectangular cross section enclosed in a magnetic film. A potential difference of fixed amplitude is applied to both the conductor and the magnetic film. Maxwell’s equations for this geometry are solved analytically, and a simple expression for the impedance is obtained. The inductance at low frequencies is practically unchanged compared to the case where the magnetic film is insulated from the conductor. However, the maximum achievable quality factor is found to be higher than that for the insulated case, even when a significant portion of the driving current flows through the magnetic film. Magnetic film inductors without insulation layers a...

Magnetic device and manufacuring method thereof

Abstract: PROBLEM TO BE SOLVED: To provide a magnetic device such as inductor, choke coil, and transformer which are suitable for high-current use of various kinds of electronic equipment. SOLUTION: The magnetic device comprises a composite magnetic member 1 including 50 to 70 volume % of metal magnetic powder and 50 to 30 volume % of a thermosetting resin, magnetic member 2 which is a ferrite sintered body or a compact magnetic body of the metal magnetic powder, and coils 3, wherein the magnetic path determined by the arrangement of the coils 3 passes through the composite magnetic member 1 and the magnetic member 2 in series and the coils 3 are embedded in the composite magnetic member 1.

Magnetic component and manufacture thereof

Abstract: PROBLEM TO BE SOLVED: To provide a magnetic component of a thin and effective structure, which is strong against mechanical stresses, and also to provide a method for manufacturing the component. SOLUTION: In place of a ferrite substrate, a soft magnetic thin strip and an organic insulating thin film are alternately stacked by a plurality of sheets, on an uppermost of which a wiring sheet is provided to thereby form a multi- layered magnetic substrate 1, a magnetic core 4 is inserted and bonded into and to the air cores of coils 2 and 3, and the ends of the coils are connected to a wiring pattern 5. The structure may also include a structure, wherein the coil and core are embedded into a part of the multilayered magnetic substrate, and a structure where the core is tapered.

Differential spiral magnetic field sensing device and magnetic field detection module using the same

Abstract: A differential spiral magnetic field sensing device is constructed such that two soft magnetic film cores are arranged parallel to each other, each soft magnetic film core is divided into several parts in a detection axial direction to reduce anti-magnetic field components, the differential excitation coil, the magnetic flux variation detecting coil and the zero magnetic field detecting coil are laminated and wound turn by turn around the soft magnetic film cores, and there is no induced voltage waveform to the magnetic flux variation detecting coil without external magnetic field. Also, in order to minimize the leaked magnetic field components of the soft magnetic film cores, the soft magnetic film cores are sandwiched to form closed magnetic paths, and the differential excitation coil, the magnetic flux variation detecting coil and the zero magnetic field detecting coil are spirally laminated around the sandwiched soft magnetic film cores. Further, in the magnetic field detection module, a differential spiral magnetic field sensing device and a signal process for driving the same are integrated on the substrate of a monolithic semiconductor device.

New line of high voltage high current pulse generators for plasma-based ion implantation

Abstract: The two general specifications required for plasma-based ion implantation are low pressure, large size plasmas and high voltage high current pulse generators. In addition, pulses with rise and fall times of the order of the inverse ion plasma frequency and with much longer durations than those of the inverse ion plasma frequency are most often required. To fulfill these requirements, a new type of high voltage generator using a pulse transformer has been developed. A “mettglass”® magnetic core is used as step-up pulse transformer. Voltage at the primary is provided by transistor switches which can achieve rise and fall times of less than 1 μs and maximum pulse currents of 100 A. The primary of the transformer consists of 96 turns wired in parallel and the secondary of 96 turns wired in series. The performances reported with this pulse generator were obtained on a test resistor and then on a substrate immersed in a plasma.