Showing papers on "Solenoid published in 2009"

Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices

Abstract: This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially.

Beam-focused shear-horizontal wave generation in a plate by a circular magnetostrictive patch transducer employing a planar solenoid array

Abstract: In recent studies, the radiation patterns of the Lamb and shear-horizontal (SH) waves in a plate generated by a circular magnetostrictive patch transducer were investigated experimentally and theoretically. As a follow-up to this research, a method of focusing SH wave beams is suggested by using a specially-configured planar solenoid array (PSA) instead of the figure-of-eight coil used in the earlier work. An SH wave is preferred in nondestructive evaluation because the first SH mode is non-dispersive. In the suggested configuration, the actuating dynamic magnetic field is produced by the solenoid that is superimposed on a static magnetic field in the perpendicular direction. Because the PSA configuration is similar to a meander coil, it is expected to better focus wave energy along a target direction. Furthermore, PSA is also expected to generate higher-power waves than a meander coil because its configuration is similar to that of the figure-of-eight coil. This paper presents the experimental results obtained with PSA, such as the wave radiation pattern. The radiation patterns obtained from the experiments are analyzed by a theory based on a two-dimensional distributed line source model.

Induced current and Aharonov-Bohm effect in graphene

Abstract: The effect of vacuum polarization in the field of an infinitesimally thin solenoid at distances much larger than the radius of solenoid is investigated. The induced charge density and induced current are calculated. Though the induced charge density turned out to be zero, the induced current is a finite periodical function of the magnetic flux . The expression for this function is found exactly in a value of the flux. The induced current is equal to zero at the integer values of /0 as well as at half-integer values of this ratio, where 0=2c /e is the elementary magnetic flux. The latter is a consequence of the Furry theorem and periodicity of the induced current with respect to magnetic flux. As an example we consider the graphene in the field of solenoid perpendicular to the plane of a sample.

Effect of current sweep reversal on the magnetic field stability for a Bi-2223 superconducting solenoid

Abstract: The effect of current sweep reversal on the temporal drift in magnetic field intensity for a Bi-2223 solenoid was investigated by experiment and using numerical simulation. Current sweep reversal, by as small as 1% of the peak current, was found to stabilize the drift in magnetic field intensity for a Bi-2223 tape solenoid. The field drift was due to flux creep in the Bi-2223 tape and the current sweep reversal formed a barrier for flux entrance at the upper and lower surface of the conductor, preventing flux creep. With a current reversal of several% of the peak current, the barrier formation extended over half of the solenoid and the magnetic field intensity became constant with time. The current sweep reversal technique should prove useful to stabilize an ultra-high field low/high-temperature superconducting nuclear magnetic resonance magnet operated at frequencies (field intensities) beyond 1 GHz (23.5 T).

Focused RF hyperthermia using magnetic fluids

Abstract: Heat therapies such as hyperthermia and thermoablation are very promising approaches in the treatment of cancer. Compared with available hyperthermia modalities, magnetic fluid hyperthermia (MFH) yields better results in uniform heating of the deeply situated tumors. In this approach, fluid consisting of superparamagnetic particles (magnetic fluid) is delivered to the tumor. An alternating (ac) magnetic field is then used to heat the particles and the corresponding tumor, thereby ablating it. However, one of the most serious shortcomings of this technique is the unwanted heating of the healthy tissues. This results from the magnetic fluid diffusion from the tumor to the surrounding tissues or from incorrect localization of the fluids in the target tumor area. In this study, the authors demonstrated that by depositing appropriate static (dc) magnetic field gradients on the alternating (ac) magnetic fields, focused heating of the magnetic particles can be achieved. A focused hyperthermia system was implemented by using two types of coils: dc and ac coils. The ac coil generated the alternating magnetic field responsible for the heating of the magnetic particles; the dc coil was used to superimpose a static magnetic field gradient on the alternating magnetic field. In this way, focused heating of the particles was obtained in the regions where the static field was dominated by the alternating magnetic field. In vitro experiments showed that as the magnitude of the dc solenoid currents was increased from 0 to 1.8 A, the specific absorption rate (SAR) of the superparamagnetic particles 2 cm apart from the ac solenoid center decreased by a factor of 4.5, while the SAR of the particles at the center was unchanged. This demonstrates that the hyperthermia system is capable of precisely focusing the heat at the center. Additionally, with this approach, shifting of the heat focus can be achieved by applying different amounts of currents to individual dc solenoids. In vivo experiments were performed with adult rats, where magnetic fluids were injected percutaneously into the tails (with homogeneous fluid distribution inside the tails). Histological examination showed that, as we increased the dc solenoid current from 0.5 to 1.8 A, the total burned volume decreased from 1.6 to 0.2 cm3 verifying the focusing capability of the system. The authors believe that the studies conducted in this work show that MFH can be a much more effective method with better heat localization and focusing abilities.

Design of Open High Magnetic Field MRI Superconducting Magnet With Continuous Current and Genetic Algorithm Method

Abstract: An optimization design method of short-length actively shielded and open structure superconducting MRI magnets is suggested in the paper. Firstly, the section of the solenoid coil is simplified as a current loop with zero section to solve a linear programming problem. The position coordinates in the radius and axial, and current for the loop can be calculated by the linear programming method. Then, the cross-section of the coil is optimized with a genetic algorithm to get appropriate section size. The method of linear programming, especially combining with genetic algorithm, reduces optimizing variables, which makes the design of a magnet feasible. Based on the method, a full open MRI superconducting magnet is designed with maximum radii of 0.8 m and 1.2 m. In the paper, the detailed optimization technologies are presented.

Understanding the focusing of charged particle beams in a solenoid magnetic field

Abstract: The focusing of a charged particle beam in a solenoid is typically explained by invoking the concept of a Larmour frame and using Busch’s theorem. Often, there is some confusion about how a uniform magnetic field of a long solenoid focuses the electron beam because it is generally understood that a uniform magnetic field can only guide charged particles. We perform a simple analysis of the dynamics of a charged particle beam in a solenoid and emphasize an intuitive understanding of some of the interesting features.

Controller of hybrid construction machine

Abstract: A controller of a hybrid construction machine which can achieve minimization of a required number of sensors is provided. A sub pump driven by output of an electric motor is connected to discharge sides of main pumps. Proportional solenoid throttling valves are provided in connection process between the sub pump and the main pumps for controlling a flow rate supplied from the sub pump to the main pump. A control unit is provided for electrically controlling the openings of the proportional solenoid throttling valves. Pressure sensors are connected to the control unit which controls the openings of the proportional solenoid throttling valves in response to pressure signals from the pressure sensors.

High Temperature Superconductor Current Leads for WENDELSTEIN 7-X and JT-60SA

Abstract: Forschungszentrum Karlsruhe has taken over the responsibility for the design, construction and testing of the High Temperature Superconductor (HTS) current leads for two fusion experiments, i.e. the stellarator WENDELSTEIN 7-X (W7-X) and the satellite tokamak JT-60SA. W7-X is presently under construction at the Greifswald branch of the Max-Planck-Institute for Plasma Physics and consists of 50 non-planar and 20 planar coils with a maximum conductor current of 17.6 kA. In total 14 current leads are required with a nominal current of 14 kA that are mounted upside down with the warm end at the bottom. In the frame of the Broader Approach Agreement between Japan and the EU and concomitantly to the ITER project, the satellite tokamak project JT-60SA has been agreed in 2006. The magnet system of JT-60SA consists of 18 toroidal field coils, 4 central solenoid modules and 7 poloidal field coils. In total 26 leads mounted in vertical, normal position are required. For W7-X and JT-60SA a common basic design will be used which will be adapted to the special needs of the machines. All current leads will be of the Cu-HTS binary type. The HTS part covers the range between 4.5 K and 60 K and is cooled by heat conduction from the 4.5 K end, only. The Cu heat exchanger is cooled with 50 K He and covers the range between 60 K and room temperature. The paper describes the status of the HTS current lead development for W7-X and JT-60SA.

Starter with compact structure

Abstract: An electromagnetic switch is disclosed as having an electromagnetic switch, operative to open or close a main contact of a motor circuit, and a solenoid having a function to push a pinion gear to a position away from a motor. The electromagnetic switch and the solenoid are placed in series in a unitary structure such that the electromagnetic switch and the solenoid have a switch case and a solenoid case both of which are integrally formed with each other to be contiguous in an axial direction. Further, a stationary core for the electromagnet and a stationary core for the solenoid are integrally formed and an operational direction of a plunger for the electromagnet and an operational direction of a plunger for the solenoid are set to be opposite in direction.

Power transmission device

Abstract: PROBLEM TO BE SOLVED: To provide a power transmission device for an automatic transmission to perform appropriate fail safe, by identifying a malfunctioning solenoid or an oil pump without increase in cost SOLUTION: A target revolution number and an actual revolution number of a ring gear shaft based on a transmission ratio by engagement with a second brake, are compared to detect an abnormality of a power transmission state A transmission ratio when an abnormality is detected is changed, from a first linear solenoid different from a second linear solenoid corresponding to the second brake making the transmission ratio, to a new transmission ratio by engagement with a first brake to which hydraulic pressure is supplied When the abnormality of the power transmission state is detected based on difference in revolution number between the target revolution number and the actual revolution number of the ring gear shaft based on the new transmission ratio, an engine is started Depending on existence/nonexistence of the abnormality of the power transmission state based on the transmission ratio in the start of the engine, a malfunctioning pump or a malfunctioning solenoid is identified out of the remaining mechanical oil pump, an electric oil pump, and a three-way solenoid COPYRIGHT: (C)2009,JPO&INPIT

Design, Fabrication, and Test of a Superconducting Dipole Magnet Based on Tilted Solenoids

Abstract: Design, Fabrication, and Test of a Superconducting Dipole Magnet Based on Tilted Solenoids S. Caspi, D.R. Dietderich, P. Ferracin, N.R. Finney, M.J. Fuery, S.A. Gourlay and A.R. Hafalia Abstract— It can be shown that, by superposing two solenoid-like thin windings that are oppositely skewed (tilted) with respect to the bore axis, the combined current density on the surface is “cos- theta” like and the resulting magnetic field in the bore is a pure dipole. As a proof of principle, such a magnet was designed, built and tested as part of a summer undergraduate intern project. The measured field in the 25mm bore, 4 single strand layers using NbTi superconductor, exceeded 1 T. The simplicity of this high field quality design, void of typical wedges end-spacers and coil assembly, is especially suitable for insert-coils using High Temperature Superconducting wire as well as for low cost superconducting accelerator magnets for High Energy Physics. Details of the design, construction and test are reported. Index Terms— Superconducting magnet, pure dipole, insert magnet, tilted solenoid. I. I NTRODUCTION n a published paper by D.I. Meyer and R. Flasck in 1970 [1] the authors discussed the magnetic field resulting from the superposition of two oppositely skewed (tilted) solenoids with respect to the bore axis (Fig. 1). The resulting superimposed current density cancels the azimuthal component of the magnetic field and enhances its axial component in proportion to J 0 cos θ . The idea reappeared in a series of publications presently building a similar quadrupole magnet. Advantages of this concept are as follows: 1) high field quality in an extended dynamic range, 2) no field optimization required, 3) small number of components - wedges and spacers not needed, 4) coil assembly not needed (all poles are wound together around a single bore), 5) small bore sizes not limiting “cos-theta” windings, 6) continuous windings and ease of magnet “grading”. There are also other open issues such as magnet protection and pre-stress that will need to be addressed in the future. The concept can work well for “stand alone” accelerator magnet as well as insert coils to existing magnets. The technology is particularly suitable for Nb 3 Sn conductor as well as high temperature superconducting wires. In section II we give a short mathematical proof addressing the perfect dipole quality followed, in section III, with details on the magnet design and construction. In section IV we report test results and draw final conclusions. I [2]-[5] that, by not crediting the 1970’s publication, may have been unaware of it. With renewed interest in high field Nb 3 Sn magnets at LBNL and CERN [6], [7] the idea gained interest leading to the construction a small dipole magnet. As part of LBNL summer student program in 2005, we have designed, built and tested a superconducting dipole that is based on the concept of tilted solenoid windings. The design and analysis was done with the program MathCad® and carried out by two undergraduate students over a period of three weeks. Impressed by the simplicity of the design and low construction cost (in full agreement with all previously published conclusions) we have extended the concept and are Manuscript received August 27, 2006. This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, High Energy Physics Division, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231. Authors are with Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA (e-mail: s_caspi@lbl.gov). N.R. Finney and MJ. Furry are undergraduate students at UCB an USD. Fig. 1. Superposition of two alternating skewed solenoids generating a perfect dipole field. A. Mathematical Model A simplified mathematical proof is used to show that skewed windings on the surface of a cylindrical correspond to an axial current-density distribution that is cos ϑ like, and therefore produce a “pure” dipole field. The current density flow lines that are distributed on the surface of the cylinder are elliptical (inclination angle α with respect to the cylinder axis) with flow lines coordinates expressed as (see Fig. 1-2)

Methods, apparatus, and systems for magnetic stimulation

Abstract: A coil suitable for tissue stimulation and especially for transcranial magnetic stimulation (TMS) may be used in conjunction with a pulse generator to induce electric field in the brain with less attenuation in depth compared to existing TMS coils. In an example, a coil winding is formed in a solenoid configuration around the head. Various related features, methods, and embodiments are described.

Progress in Wind-and-React Bi-2212 Accelerator Magnet Technology

Abstract: We report on our progress in the development of the technology for the application of Bi2Sr2CaCu2O8+x(Bi-2212) in Wind-and-React accelerator magnets. A series of superconducting subscale coils has been manufactured at LBNL and reacted at the wire manufacturer SWCC. Selected coils are impregnated and tested in self-field, even though the coils exhibited leakage during the partial melt heat treatment. Other coils have been disassembled after reaction and submitted to critical current (Ic) tests on individual cable sections. We report on the results of the current carrying capacity of the coils. Voltage-current (VI) transitions were reproducibly measured up to a quench currents around 1400 A, which is 25% of the expected performance. The results indicate that the coils are limited by the inner windings. We further compare possibilities to use Bi-2212 and Nb3Sn tilted solenoid, and YBa2Cu3O7-delta (YBCO) racetrack inserts to increase the magnetic field in HD2, a 36 mm bore Nb3Sn dipole magnet which recently achieved a bore magnetic field of 13.8 T. The application of Bi-2212 and/or YBCO in accelerator type magnets, if successful, will open the road to higher magnetic fields, far surpassing the limitations of Nb3Sn magnet technology.

Reliability and Life Study of Hydraulic Solenoid Valve - Part 1 - A Multi-physics Finite Element Model

Abstract: A comprehensive multi-physics theoretical model of a solenoid valve used in an automobile transmission is constructed using the finite element method. The multi-physics model includes the coupled effects of electromagnetic, thermodynamics and solid mechanics. The resulting finite element model of the solenoid valve provides useful information on the temperature distribution, mechanical and thermal deformations, and stresses. The model results predict that the solenoid valve is susceptible to a coupled electrical–thermo-mechanical failure mechanism. The coil can generate heat which can cause compressive stress and high temperatures that in turn could fail the insulation between the coil wires. The model facilitates the characterization of the solenoid valve performance, life and reliability and can be used as a predictive tool in future solenoid design.

Design of HTS Magnets for a 2.5 MJ SMES

Abstract: A 600 kJ HTS SMES system has been developed for power system stabilization as a national project in Korea. Successful operating tests of the 600 kJ were recently completed. In this paper, a 2.5 MJ class SMES with HTS magnets of single solenoid, multiple solenoid and modular toroid type were optimized using a recently developed multi-modal optimization technique named multi-grouped particle swarm optimization (MGPSO). The objective of the optimization was to minimize the total length of HTS superconductor wires satisfying some equality and inequality constraints. The stored energy and constraints were calculated using 3-D magnetic field analysis techniques and an automatic tetrahedral mesh generator. Optimized results were verified by 3D finite element method (FEM).

Starter solenoid switch with improved arrangement of resistor

Abstract: In a solenoid switch according to the invention, a magnetic plate is disposed on one side of a solenoid coil in an axial direction of the solenoid coil. A contact cover is arranged with the magnetic plate interposed between the contact cover and the solenoid coil in the axial direction. First and second fixed contacts are received in the contact cover and respectively electrically connected to first and second terminals that are to be electrically connected to an electric circuit. A resistor is electrically connected between the first and second terminals to limit current flowing through the electric circuit when the first and second fixed contacts are electrically disconnected by a movable contact. The resistor is received in the contact cover and interposed between the magnetic plate and the first and second fixed contacts in the axial direction.

Solenoid valve device

Abstract: A pressure adjusting valve section 40 functioning as a linear solenoid valve for adjusting clutch pressure of a clutch C2 and a pump section 60 functioning as a solenoid pump for pumping hydraulic oil to a clutch C1 are formed by a sleeve 22 and a spool 24, and driven by a single solenoid section 30. In the pump section 60, when switching the solenoid section 30 off from on, the spool 24 is moved towards the solenoid section 30 by biasing force of a spring 28 and a pressure inside a pump chamber 70 becomes negative, thereby sucking hydraulic oil. When switching the solenoid section 30 on from off, the spool 24 is moved towards an end plate 26 by thrust force of the solenoid section 30 and a pressure inside the pump chamber 70 becomes positive, thereby discharging the hydraulic oil sucked.

Dual clutch transmission having area controlled clutch cooling circuit

Abstract: A dual clutch transmission having a hydraulic circuit for controlling and cooling the clutches of a dual clutch transmission having lube valves in fluid communication with a source of pressurized fluid and wherein the cooling flow is controlled by a solenoid which is adapted to move a valve member to produce a flow area through the valve that is an inverse function of the current delivered to the solenoid and so as to deliver a predetermined control solenoid pressure ultimately to each of the clutches of a dual dutch transmission.

Compact superconducting magnet configuration with active shielding having a shielding coil contributing to field formation

Abstract: A superconducting magnet configuration (4; 14) for generating a homogeneous magnetic field B0 in an examination volume (4 b), has an interior radial superconducting main field coil (1) which is disposed rotationally symmetrically about an axis (z-axis) and an oppositely driven coaxial radially exterior superconducting shielding coil (2) is characterized in that the magnet configuration (4; 14) consists of the main field coil (1), the shielding coil (2), and a ferromagnetic field formation device (3; 18), wherein the ferromagnetic field formation device (3; 18) is located at the radially inside of the main field coil (1), the main field coil (1) consisting of an unstructured solenoid coil or of several radially nested unstructured solenoid coils (15, 16) which are driven in the same direction, the axial extent Labs of the shielding coil (2) being smaller than the axial extent Lhaupt of the main field coil (1), wherein the axial magnetic field profile (5) generated by the main field coil (1) and the shielding coil (2) during operation has a minimum of the field strength along the axis (z-axis) in the center (4 a) and a maximum of the field strength on each side of the center (4 a), and wherein the axial magnetic field profile (6) generated by the ferromagnetic field formation device (3; 18) during operation has a maximum of the field strength along the axis (z-axis) in the center (4 a) and a minimum of the field strength on each side of the center (4 a). The magnet configuration in accordance with the invention has a very simple structure.

Powerful terahertz g yrotrons based on pulsed magnets

Abstract: A bstract: The terahertz radiation has been demonstrated in pulse gyrotrons. Pulsed coils with field intensity up to 50T have been developed and tested. After more than 3500 shorts no any variation at solenoid operation observed. The repetition rate one short per minute was limited by coil cooling. The output power 5 kW at 1 THz and 0.5 kW at 1.3 THz has been obtained with pulse duration 40 microseconds at the fundamental harmonic with 30 kV/5A electron beam. The design of a sub-THz sub-MW gyrotron has been presented.

The Design and Construction of the MICE Spectrometer Solenoids

Abstract: The purpose of the MICE spectrometer solenoid is to provide a uniform field for a scintillating fiber tracker. The uniform field is produced by a long center coil and two short end coils. Together, they produce 4T field with a uniformity of better than 1% over a detector region of 1000 mm long and 300 mm in diameter. Throughout most of the detector region, the field uniformity is better than 0.3%. In addition to the uniform field coils, we have two match coils. These two coils can be independently adjusted to match uniform field region to the focusing coil field. The coil package length is 2544 mm. We present the spectrometer solenoid cold mass design, the powering and quench protection circuits, and the cryogenic cooling system based on using three cryocoolers with re-condensers.

Analytic models of heterogenous magnetic fields for liquid metal flow simulations

Abstract: A physically consistent approach is considered for defining an external magnetic field as needed in computational fluid dynamics problems involving magnetohydrodynamics (MHD). The approach results in simple analytical formulae that can be used in numerical studies where an inhomogeneous magnetic field influences a liquid metal flow. The resulting magnetic field is divergence and curl-free, and contains two components and parameters to vary. As an illustration, the following examples are considered: peakwise, stepwise, shelfwise inhomogeneous magnetic fields, and the field induced by a solenoid. Finally, the impact of the streamwise magnetic field component is shown qualitatively to be significant for rapidly changing fields.

Magnetic and Cryogenic Design of MICE Coupling Solenoid Magnet System

Abstract: The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory in the UK. The coupling magnet is a superconducting solenoid mounted around four 201 MHz RF cavities, which produces magnetic field up to 2.6 T on the magnet centerline to keep muons within the iris of RF cavities windows. The coupling coil with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm will be cooled by a pair of 1.5 W at 4.2 K small coolers. This paper will introduce the updated engineering design of the coupling magnet made by ICST in China. The detailed analyses on magnetic fields, stresses induced during the processes of winding, cool down and charging, and cold mass support assembly are presented as well.

Damping force variable valve of shock absorber

Abstract: A damping force variable valve includes a retainer including a spool rod part having a hollow portion formed at a central portion thereof to allow a spool to be inserted in the hollow portion, a solenoid part coupled to a lower side of the retainer and having a bobbin provided therein, the bobbin having a coil wound therearound for allowing a pressurizing rod in contact with the spool to move when voltage is applied, and a connector for connecting to a power supply part formed integrally with the bobbin.

Starting device for engines

Abstract: An electromagnetic switch unit comprises a solenoid device that pushes out a pinion gear to a ring gear side of an engine, and an electromagnetic switch that opens and closes a main point of contact of a motor circuit. The solenoid device and the electromagnetic switch are arranged in series in an axial direction, while a magnetic plate that forms a part of magnetic circuit between a first coil used for the solenoid device and a second coil used for the electromagnetic switch is shared by the solenoid device and the electromagnetic switch.