Showing papers on "Solenoid published in 2008"

Magnetic linear actuator for deployable catheter tools

Abstract: Using the linear forces that are provided by an electromagnetic solenoid applied near the distal end of a medical catheter (26), various surgical instruments can be actuated or deployed for use in interventional medicine. The linear actuator (101) uses the principles of magnetic repulsion and attraction as a means for moving a bobbin (13) that can be attached to various types of moving components that translate linear movements into the actuation of a tool that is attached to the linear actuator. Using independent solenoid coils (14), movement modality is increased from two possible positions to three.

Generation of 1.5-kW, 1-THz coherent radiation from a gyrotron with a pulsed magnetic field.

Abstract: To cover a so-called terahertz gap in available sources of coherent electromagnetic radiation, the gyrotron with a pulsed solenoid producing up to a 40 T magnetic field has been designed, manufactured, and tested. At a 38.5 T magnetic field, the gyrotron generated coherent radiation at 1.022 THz frequency in 50 musec pulses. The microwave power and energy per pulse were about 1.5 kW and 75 mJ, respectively. Details of the gyrotron design, manufacturing, operation and measurements of output radiation are given.

Fabrication and Analysis of High-Performance Integrated Solenoid Inductor With Magnetic Core

Abstract: Integrated solenoid inductors with magnetic core were fabricated and analyzed. An inductance above 70 nH was achieved while keeping the coil resistance below 1 Omega and the device area below 1 mm2 using a solenoid design with a single magnetic layer. The inductance of the magnetic inductor was more than 30 times that of the air core inductor of the identical geometry, and the quality factor of the magnetic inductor was >5. Novel inductor designs and the scalability were also examined, and an inductance density higher than 200 nH/mm2 was obtained. The measured device properties and engineering tradeoffs were well explained by analytical models we developed.

High-resolution liquid- and solid-state nuclear magnetic resonance of nanoliter sample volumes using microcoil detectors.

Abstract: The predominant means to detect nuclear magnetic resonance(NMR) is to monitor the voltage induced in a radiofrequency coil by the precessing magnetization. To address the sensitivity of NMR for mass-limited samples it is worthwhile to miniaturize this detector coil. Although making smaller coils seems a trivial step, the challenges in the design of microcoil probeheads are to get the highest possible sensitivity while maintaining high resolution and keeping the versatility to apply all known NMRexperiments. This means that the coils have to be optimized for a given sample geometry, circuit losses should be avoided, susceptibility broadening due to probe materials has to be minimized, and finally the B 1 -fields generated by the rf coils should be homogeneous over the sample volume. This contribution compares three designs that have been miniaturized for NMR detection: solenoid coils, flat helical coils, and the novel stripline and microslot designs. So far most emphasis in microcoil research was in liquid-state NMR. This contribution gives an overview of the state of the art of microcoil solid-state NMR by reviewing literature data and showing the latest results in the development of static and micro magic angle spinning (microMAS) solenoid-based probeheads. Besides their mass sensitivity, microcoils can also generate tremendously high rf fields which are very useful in various solid-state NMRexperiments. The benefits of the stripline geometry for studying thin films are shown. This geometry also proves to be a superior solution for microfluidic NMR implementations in terms of sensitivity and resolution.

Zero-field remote detection of NMR with a microfabricated atomic magnetometer

Abstract: We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxation-free (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 × 1013 protons in a volume of 1 mm3, prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of ≈3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

Flatness-Based Tracking of an Electromechanical Variable Valve Timing Actuator With Disturbance Observer Feedforward Compensation

Abstract: A comprehensive control strategy for an automotive solenoid variable valve timing actuator is presented that addresses the issues of feedback sensors, soft seating or landing control, disturbance rejection and feedforward design. In particular, the motion control of the engine exhaust valve actuator subject to large cycle-to-cycle gas force variations is successfully demonstrated in simulation and on an experimental test-bench. Also provided is a method of characterization and online cycle-to-cycle identification of combustion gas force disturbances. The identified gas forces are used in energy-based feedforward and flatness-based landing algorithms. Simulated and experimental results indicate the proposed control methodology is capable of compensating for the combustion gas force disturbances experienced by exhaust valve solenoid actuators.

The ATLAS central solenoid

Abstract: The ATLAS detector at the CERN LHC is equipped with a superconducting magnet system consisting of three large toroids and a solenoid. The 2.3 m diameter, 5.3 m long solenoid is located at the heart of the experiment where it provides a 2 T field for spectrometry of the particles emanating from the interaction of the counter-rotating beams of hadrons. As the electromagnetic calorimeter of the experiment is situated outside the solenoid, the coil must be as transparent as possible to traversing particles. The magnet, which was designed at KEK, incorporates progress in technology coming from the development of previous solenoids of this type, in particular that of a new type of reinforced superconductor addressing the requirement of transparency. Special attention has been paid to ensuring reliability and ease of operation of the magnet, through the application of sufficiently conservative guidelines for the mechanical and electrical design, stringent testing during manufacture, and a comprehensive commissioning program. This report gives an overview of the design, manufacture, test, installation and commissioning of the ATLAS central solenoid.

Improved Wireless, Transcutaneous Power Transmission for In Vivo Applications

Abstract: Electric power, sufficient for many in vivo applications, can be transmitted wirelessly from a small external solenoid (filled with a soft magnetic core), to a novel, magnetoelectric (ME) receiver a few centimeter (cm) inside the body. The ME receiver is a sandwich of electroactive (e.g., piezoelectric) material bonded between two magnetostrictive layers. The electroactive layer may be poled in its plane so that it can function in the stronger g33 mode (induced voltage parallel to the direction of principal magnetostrictive stress). Preliminary experimental results indicate that a 7 cm long ferrite-filled solenoid (NI ap 122 Amp-turns) producing an RMS magnetic field of order 1600 A/m (20 Oe) at the ME receiver (of volume 0.1 cm3) 3 cm from the field source, generates in the ME receiver a power of 200 mW (2 W/cm3). The receiver, in turn, generates a power of 160 mW.

Ion acceleration in a solenoid-free plasma expanded by permanent magnets

Abstract: Ion acceleration is achieved in a low-pressure solenoid-free plasma expanded by permanent magnet arrays. Although a permanent magnet normally forms cusp magnetic fields which prevents plasma diffusion and double layer formation, by employing double concentric arrays of permanent magnets, a constant field area, and a diverging magnetic field can be generated near the outlet of the plasma source. In the source, a rapid potential drop with 4cm thickness from 50V to 20V is generated at the diverging field area for 0.35mTorr and a supersonic ion beam accelerated through the potential drop is observed in the diffusion chamber. The beam energy can be increased up to over 40eV with a decrease in gas pressure.

Solenoid operated valve

Abstract: A solenoid operated valve is provided for controlling liquid or gaseous media, the valve comprising at least two media ports opened and closed by an armature and a solenoid with a yoke and a coil, wherein the armature includes a magnetizable material is movably arranged inside a valve body housing having a non-magnetic material, wherein the media ports empty into the valve body housing, and wherein the valve body housing is arranged between the yoke and an additional element for magnetically interacting with the armature.

A novel heat engine for magnetizing superconductors

Abstract: The potential of bulk melt-processed YBCO single domains to trap significant magnetic fields (Tomita and Murakami 2003 Nature 421 517–20; Fuchs et al 2000 Appl. Phys. Lett. 76 2107–9) at cryogenic temperatures makes them particularly attractive for a variety of engineering applications including superconducting magnets, magnetic bearings and motors (Coombs et al 1999 IEEE Trans. Appl. Supercond. 9 968–71; Coombs et al 2005 IEEE Trans. Appl. Supercond. 15 2312–5). It has already been shown that large fields can be obtained in single domain samples at 77 K. A range of possible applications exist in the design of high power density electric motors (Jiang et al 2006 Supercond. Sci. Technol. 19 1164–8). Before such devices can be created a major problem needs to be overcome. Even though all of these devices use a superconductor in the role of a permanent magnet and even though the superconductor can trap potentially huge magnetic fields (greater than 10 T) the problem is how to induce the magnetic fields. There are four possible known methods: (1) cooling in field; (2) zero field cooling, followed by slowly applied field; (3) pulse magnetization; (4) flux pumping. Any of these methods could be used to magnetize the superconductor and this may be done either in situ or ex situ. Ideally the superconductors are magnetized in situ. There are several reasons for this: first, if the superconductors should become demagnetized through (i) flux creep, (ii) repeatedly applied perpendicular fields (Vanderbemden et al 2007 Phys. Rev. B 75 (17)) or (iii) by loss of cooling then they may be re-magnetized without the need to disassemble the machine; secondly, there are difficulties with handling very strongly magnetized material at cryogenic temperatures when assembling the machine; thirdly, ex situ methods would require the machine to be assembled both cold and pre-magnetized and would offer significant design difficulties. Until room temperature superconductors can be prepared, the most efficient design of machine will therefore be one in which an in situ magnetizing fixture is included. The first three methods all require a solenoid which can be switched on and off. In the first method an applied magnetic field is required equal to the required magnetic field, whilst the second and third approaches require fields at least two times greater. The final method, however, offers significant advantages since it achieves the final required field by repeated applications of a small field and can utilize a permanent magnet (Coombs 2007 British Patent GB2431519 granted 2007-09-26). If we wish to pulse a field using, say, a 10 T magnet to magnetize a 30 mm × 10 mm sample then we can work out how big the solenoid needs to be. If it were possible to wind an appropriate coil using YBCO tape then, assuming an Ic of 70 A and a thickness of 100 µm, we would have 100 turns and 7000 A turns. This would produce a B field of approximately 7000/(20 × 10−3) × 4π × 10−7 = 0.4 T. To produce 10 T would require pulsing to 1400 A! An alternative calculation would be to assume a Jc of say 5 × 108A m−1 and a coil 1 cm2 in cross section. The field would then be 5 × 108 × 10−2 × (2 × 4π × 10−7) = 10 T. Clearly if the magnetization fixture is not to occupy more room than the puck itself then a very high activation current would be required and either constraint makes in situ magnetization a very difficult proposition. What is required for in situ magnetization is a magnetization method in which a relatively small field of the order of millitesla repeatedly applied is used to magnetize the superconductor. This paper describes a novel method for achieving this.

Experimental study and mathematical modelling of a new of vibro-impact moling device

Abstract: In this paper experimental study and mathematical modelling of newly designed vibro-impact moling rig are presented. The design is based on electro-mechanical interactions of a conductor with an oscillating magnetic field. The rig consists of a metal bar placed within a solenoid which is connected to an RLC circuit, and an obstacle block positioned nearby. Both the solenoid and the block are attached to a base board. Externally supplied alternating voltage causes the bar to oscillate and hit the block resulting in the forward motion of the base board mimicking a mole penetration through the soil. By varying the excitation voltage and the capacitance in the circuit, a variety of system responses can be obtained. In the paper the rig design and experimental procedure are explained in detail, and the mathematical modelling of the rig is described. Then the obtained coupled electro-mechanical equations of motion are integrated numerically, and a comparison between experimental results and numerical predictions is presented.

Design and fabrication of integrated solenoid inductors with magnetic cores

Abstract: Integrated solenoid inductors with magnetic core were designed and fabricated. An inductance above 70 nH was achieved while keeping the coil resistance below 1 Omega and the device area below 1 mm2. The inductance of the magnetic inductor was more than 30 times that of the air core inductor of the identical geometry, and the inductance density reached above 200 nH/mm2. Comparison with the planar spiral inductor shows that the solenoid inductor is significantly more efficient when the magnetic core is used. Our results indicate that integrated magnetic inductors suitable for mobile power conversion and RF system-on-chip circuits can be reliably designed and fabricated.

Improved performance of the electromagnetic fuel injector solenoid actuator using a modelling approach

Abstract: The aim of this investigation was to develop a specific modelling approach capable of reducing the size of the fuel injector solenoid device while improving its response time and attraction force. Several developed modelling and simulation procedures have focused on various aspects of solenoid component modifications in order to develop an evolution process of miniaturising a fuel injector solenoid, using the latest finite element method (FEM) tool software. The specific factors that influenced the optimum operation of the fuel injector solenoid were the geometrical shape of individual solenoid components, material properties, air-gap constraints, boundary conditions, current source conditions, mass constants, and damping coefficients of the plunger. The attraction force distribution in the main air-gap was directly influenced by the taper angle of the 2D and 3D plunger pole faces, plunger length and the permanent magnetism. The precise definition of the electro-mechanical motion of plunger was of enormous importance in reducing the fuel injector solenoid response time, closely related to stroke and mass of the plunger, spring characteristics, motion and rebound of the plunger. Using the developed approach, the initial size of the fuel injector has been reduced by 35%, the attraction force increased by 26% and the response time reduced by 76%. However, by frequently repeating the design trials and conducting a thorough experimental investigation, the final minimum response time was achieved by the virtual rebound delay model. The reduction in response time from the 'optimal' experimental to virtual model was by 35%. The simplicity and effectiveness of the developed methods, allowed for quick and accurate evaluation.

The ATLAS superconducting magnet system at the Large Hadron Collider

Abstract: A magnet system of three superconducting toroids and a solenoid with record overall system dimensions of 25 m in length and 22 m in diameter, generate the magnetic field for particle bending in, respectively, the muon and inner detectors in the ATLAS experiment at the Large Hadron Collider. The magnet technology is based on aluminum stabilized NbTi superconducting cables wound into impregnated windings which are conduction cooled and operate at 4.6 K. Magnetic field is generated in the usable detector area of about 12000 m 3 and the peak field in the coil windings is 4.1 T. The magnet system stored energy is 1.6 GJ. After successful on-surface tests the magnets were installed in the ATLAS cavern 100 m underground. The Barrel Toroid and Solenoid were charged to full field in autumn 2006 while both End Cap Toroids are powered in November 2007 thereby completing this very challenging and largest magnet system successfully constructed so far.

Progress on the BIPM watt balance

Abstract: Since beginning the construction early in 2005, considerable progress has been made on the watt balance of the Bureau International des Poids et Mesures (BIPM). We have continued the development of a room-temperature version to test the feasibility of simultaneous force and velocity measurements. Preliminary measurements of the voltage-velocity ratio have been carried out with a reproducibility of the order of 1 part in 104. The coil suspension has been improved to reduce the undesired coil movement in the 5 degrees of freedom different from a perfectly vertical movement. Further work on the current source has reduced its long-term drift to a few parts in 109 per minute with a satisfactory short-term stability. A technique needed to separate the voltage induced in the coil from the voltage drop due to the current flow based on the use of a second noninductive coil has been tested. The second coil is now being integrated into the apparatus. Work has started on the geometrical and magnetic characterizations of a large precision solenoid that will become the reference for the magnetic field alignment. The collaboration with a university on the fabrication of our magnetic circuit is being continued. This paper briefly outlines the main ideas of the BIPM watt balance and reports the progress to date.

Measurement of the ATLAS solenoid magnetic field

Abstract: ATLAS is a general purpose detector designed to explore a wide range of physics at the Large Hadron Collider. At the centre of ATLAS is a tracking detector in a 2 T solenoidal magnetic field. This paper describes the machine built to map the field, the data analysis methods, the final results, and their estimated uncertainties. The remotely controlled mapping machine used pneumatic motors with feedback from optical encoders to scan an array of Hall probes over the field volume and log data at more than 20 000 points in a few hours. The data were analysed, making full use of the physical constraints on the field and of our knowledge of the solenoid coil geometry. After a series of small corrections derived from the data itself, the resulting maps were fitted with a function obeying Maxwell's equations. The fit residuals had an r.m.s. less than 0.5 mT and the systematic error on the measurement of track sagitta due to the field uncertainty was estimated to be in the range 0.02% to 0.12% depending on the track rapidity.

Latching linear solenoid

Abstract: A linear solenoid includes a pair of soft iron pole members which are in a spaced apart linear arrangement. A permanent magnet is attached to the end of a plunger which rides between the pole members. When a first of two electro-magnet coils is energized the plunger which is latched to one of the pole members is repelled to the opposite pole member and latched. When the second coil is energized the plunger returns to the original pole member and is latched.

Servo-assisted control system for the gears of a double clutch gearbox of a motor vehicle

Abstract: The control system comprises: a first hydraulically-operated actuator device for controlling the engagement of a first set of gears by selection and engagement movements; a second hydraulically-operated actuator device for controlling the engagement of a second set of gears by selection and engagement movements; a first solenoid valve of the ON/OFF type arranged to put the first or the second actuator device alternatively into communication with a supply of fluid under pressure; a second solenoid valve of the ON/OFF type arranged to control the selection movements of the actuator device which from time to time is in communication with the fluid supply; a distributor interposed between the fluid supply and the two actuator devices and displaceable under the control of the first solenoid valve between a first working position in which it puts the fluid supply into communication with the first actuator device and a second working position in which it puts the fluid supply into communication with the second actuator device; a third proportional pressure solenoid valve and a fourth proportional pressure solenoid valve arranged to control the engagement movements of the actuator device which from time to time is in communication with the fluid supply. With such a control system the gear change operation thus requires the intervention of at most four solenoid valves.

The MERIT High-Power Target Experiment at the CERN PS.

Abstract: The MERIT experiment was designed as a proof-of-principle test of a target system based on a free mercury jet inside a 15-T solenoid that is capable of sustaining proton beam powers of up to 4 MW. The experiment was run at CERN in the fall of 2007. We describe the results of the tests and their implications. Plans are being discussed for possible future machines which can deliver proton beams with multi-MW beam powers. A prominent application for these powerful beams will be to produce intense secondary beams suitable for investigating important physics issues. Examples include investigations of rare decay processes and neutrino oscillations. The Neutrino Factory and Muon Collider Collaboration [1] has proposed a target system [2, 3] which will be capable of supporting proton beam powers of 4 MW with the purpose of producing and collecting intense muon beams for eventual use in storage rings. The core of this proposed target system consists of a high-Z, free-flowing liquid mercury jet which intercepts the proton beam within the confines of a high-field (15-20 T) solenoid. An important attribute of this system is that the liquid jet target can be replaced for subsequent proton pulses. The experiment described in this paper was designed to provide a proof-of-principle demonstration of this concept. Preparations for this experiment have been previously reported [4].

Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage dc gun

Abstract: We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The data are compared with detailed simulations using the 3D space charge codes GPT and Parmela3D. The initial particle distributions were generated from measured transverse and temporal laser beam profiles at the photocathode. The beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach within a factor of 2 the theoretical maximum set by the thermal energy and the accelerating field at the photocathode.

Solenoid diagnostic systems for cylinder deactivation control

Abstract: A solenoid diagnostic system includes a pressure monitoring module that determines a first pressure in an intake cam phaser for an intake camshaft and a second pressure in an exhaust cam phaser for an exhaust camshaft associated with a cylinder. A fuel injection monitoring module determines a fuel injection status associated with the cylinder. A fault determination module diagnoses a fault in a solenoid associated with the cylinder based on the first pressure, the second pressure, and the fuel injection status.

Measurement of the CMS Magnetic Field

Abstract: The measurement of the magnetic field in the tracking volume inside the superconducting coil of the Compact Muon Solenoid (CMS) detector under construction at CERN is done with a fieldmapper designed and produced at Fermilab. The fieldmapper uses 10 3-D B-sensors (Hall probes) developed at NIKHEF and calibrated at CERN to precision 0.05% for a nominal 4 T field. The precise fieldmapper measurements are done in 33840 points inside a cylinder of 1.724 m radius and 7 m long at central fields of 2, 3, 3.5, 3.8, and 4 T. Three components of the magnetic flux density at the CMS coil maximum excitation and the remanent fields on the steel-air interface after discharge of the coil are measured in check-points with 95 3-D B-sensors located near the magnetic flux return yoke elements. Voltages induced in 22 flux-loops made of 405-turn installed on selected segments of the yoke are sampled online during the entire fast discharge (190 s time-constant) of the CMS coil and integrated offline to provide a measurement of the initial magnetic flux density in steel at the maximum field to an accuracy of a few percent. The results of the measurements made at 4 T are reported and compared with a three-dimensional model of the CMS magnet system calculated with TOSCA.

Quench studies on a layer-wound Bi2Sr2CaCu2Ox/AgX coil at 4.2 K

Abstract: To evaluate the controlled quench behavior of high temperature superconducting (HTS) coils, particularly when using HTS coils in a hybrid configuration as an insert in a low temperature superconducting magnet, a layer-wound solenoid using Bi2Sr2CaCu2O wire was instrumented with several strip heaters to generate quenches in the axial and azimuthal directions. An array of distributed voltage taps and thermocouples were used to monitor the quench signals. Minimum quench energies (MQE) and quench propagation velocities (NZPVs) were determined. Results show that quench energies were moderate. NZPVs were slow but quench reaction times were of the same order as reaction times obtained at low quench energy densities in Nb3Sn coils.

The Engineering Design of the 1.5 m Diameter Solenoid for the MICE RFCC Modules

Abstract: The RF coupling coil (RFCC) module of MICE is where muons that have been cooled within the MICE absorber focus (AFC) modules are re-accelerated to their original longitudinal momentum. The RFCC module consists of four 201.25 MHz RF cavities in a 1.4 meter diameter vacuum vessel. The muons are kept within the RF cavities by the magnetic field generated by a superconducting coupling solenoid that goes around the RF cavities. The coupling solenoid will be cooled using a pair of 4 K pulse tube cooler that will generate 1.5 W of cooling at 4.2 K. The magnet will be powered using a 300 A two-quadrant power supply. This report describes the ICST engineering design of the coupling solenoid for MICE.

Magnetic steering of a helicon double layer thruster

Abstract: The ion beam generated by a helicon double layer has been electrically steered up to 20° off axis by using a solenoid placed normal to the two axial solenoids of the helicon plasma source without significantly changing the beam exhaust velocity.

Solenoid-valve unit for an electropneumatic controller

Abstract: A solenoid-valve unit for an electropneumatic controller, especially a pilot-control unit of an electropneumatic pressure modulator of a vehicle, includes a solenoid-valve unit having a valve-housing bottom with compressed-air bores, and solenoid valves having solenoids and displaceable magnet armatures. The solenoids are disposed outside of the valve-housing bottom. At least one pressure sensor for measuring pneumatic pressure in a compressed-air bore of the valve-housing bottom is placed in or on the valve-housing bottom. Electric leads to the solenoids and to the pressure sensor are routed to a common electrical interface.