Coil Thickness Research Articles

On The Possibility of Looperless Rolling on Hot Rolling Process

We discuss the possibility of looperless control at finishing mill of hot rolling process in this paper. In recent years, the precision of thickness and width of hot coil is becoming more and more strict. So we must develop powerful controller which stabilizes the rolling process even if plant parameters are perturbed. It is cleared that performance of control system with the compensator designed by μ synthesis considering parameter perturbation is better than that with the compensator designed by H∞.

ＭＨｚ帯平面スパイラルインダクタの高性能化

A method for structural design of thin-film spiral inductors was studied, using FEM electromagnetic field simulation. By analyzing the direction of the eddy current, we found that specific divisions of magnetic layers effectively reduced the electric power loss in magnetic layers. A 3 mm x 13 mm thin-film inductor for which L = 0.9 μH Q = 14.5 and Ibias = 0.55 A at 5 MHz was developed, based on an analysis of the electromagnetic field simulation. With this structure, a thin-film inductor of Q = 20 was achieved by increasing the coil thickness.

An approach to next step device optimisation

The requirements for ITER EDA were to achieve ignition with a good safety margin, and controlled long inductive burn. These requirements lead to a big device, which requested a too ambitious step to be undertaken by the world fusion community. More realistic objectives for a next step device shall be to demonstrate the net production of energy with a high energy gain factor (Q) and a high boot strap current fraction (>60%) which is required for a Fusion Power Plant (FPP). The Next Step Device (NSD) shall also allow operation flexibility in order to explore a large range of plasma parameters to find out the optimum concept for the fusion power plant prototype. These requirements could be too demanding for one single device and could probably be better explored in a strongly integrated world programme. The cost of one or more devices is the decisive factor for the choice of the fusion power development programme strategy. The plasma elongation and triangularity have a strong impact in the cost of the device and are limited by the plasma vertical position control issue. The distance between plasma separatrix and the toroidal field conductor does not vary a lot between devices. It is determined by the summe of the distance between first wall-plasma sepratrix and the thickness of the nuclear shield required to protect the toroidal field coil insultation. The thickness of the TF coil is determined by the allowable stresses and superconducting characteristics. The outer radius of the central solenoid is the result of an optimisation to provide the magnetic flux to inductively drive the plasma. Therefore, in order to achieve the objectives for Q and boot-strap current fractions at the minimum cost, the plasma aspect ratio and magnetic field value shall be determined. The paper will present the critical issues for the next device and will make considerations on the optimal way to proceed towards the realisation of the fusion power plant.

Development of dual air gap printed coil BLDC motor

Small effective air gap is one of the major design considerations to improve performance in brushless DC motors. In axial gap motors, however, it is limited by thickness of armature coil as well as the friction loss in a bearing due to the axial magnetic force. This paper investigated the magnetic field, force, torque and loss in an axial gap motor using finite element method (FEM) and Maxwell stress tensor, and developed a novel shape of dual air gap printed coil motor which increases the performance as well as the manufacturing flexibility.

Apparent hydrodynamic thickness of densely grafted polymer layers in a theta solvent

We study the drainage of a near-theta solvent through densely grafted polymer layers and compare to recent notions that these layers display little permeabil- ity to solvent flow at surface separations less than a ''hydrodynamic thickness.'' The solvent is trans-decalin (a near-theta solvent at the experimental temperature of 247C). The polymer is polystyrene (PS) end-attached to two opposed mica surfaces via the selective adsorption of the polyvinylpyridine (PVP) block of a PS-PVP diblock copoly- mer. The experimental probe was a surface forces apparatus modified to apply small- amplitude oscillatory displacements in the normal direction. Out-of-phase responses reflected viscous flow of solvent alone—the PS chains did not appear to contribute to dissipation over the oscillation frequencies studied. The value of the hydrodynamic thickness (RH) was less than the coil thickness (Lo) measured independently from the onset of surface-surface interactions in the force-distance profile, implying significant penetration of the velocity field into the polymer layer. As the surface-surface separa- tion was reduced from 3Lo to 0.3Lo, the apparent hydrodynamic thickness (R*) de- creased monotonically to values R* ! RH. Physically, this indicates that the ''slip plane'' moved progressively closer to the solid surfaces with decreasing surface-surface separation. This was accompanied by augmentation of the effective viscosity by a factor of up to approximately 5, indicating somewhat diminished permeability of solvent through the overlapping polymer layers. Similar results hold for the flow through surface-anchored polymers in a good solvent. It is interesting to note the strong stretch- ing of densely end-grafted polymers in a theta solvent. q 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2961-2968, 1997

Initial fabrication of a micro-induction gyroscope

A planar coil design capable of levitating an aluminium rotor by electromagnetic induction is described. The coil is fabricated from Au onto a Si(001) substrate with a footprint size of 700 μm, and coil thickness and typical width of 1.3 μm and 50 μm respectively. The rotors are made from Al with a thickness of 12 μm and diameter of 400 μm. A maximum levitation height of 10 μm is measured with a coil excitation current of 800 mApk. This height is increased to 25 μm by the incorporation of a high permeability amorphous magnetic backing plane below the planar coils. Excellent quantitative agreement is observed between the predictions of modelling and experimental measurements of levitation height versus coil excitation current. The application of this levitated rotor to a wide range of applications, including a micromachined rotating gyroscope is described.

Characteristics and simulations of the planar multi-layer spiral coil and the miniature opto-electric transformer

The characteristics of a miniature optoelectric transformer (MOET) and simulations for the MOET based on the simple improved model for L, C and R of the multilayer coil with the outer closed core are shown. The circuit simulations are performed by a PSPICE simulator, and experimental results can be explained by these simulations. Simulations for a very small MOET of about 200 mu m are performed and discussed. A new method to form the substantially flat spiral coil, in which anodic oxidation of the deposited Al film is used, is proposed to overcome the unevenness problem arising from increasing the etched Al coil thickness.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Compact microphone and method of manufacture

A microphone has a diaphragm having a dome central portion being formed of laminate of a thin layer of synthetic resinous material and a thin wire mesh contacting the central portion. As surrounding attachment portion is provided so that the diaphragm is free to vibrate in a plane perpendicular to itself. An annular voice coil is attached to and circumscribes the central portion on the concave side of the diaphragm and a fixed permanent magnet is disposed within the voice coil. The magnet is formed of neodymium iron-boron and the voice coil has an internal diameter greater than its thickness and the thickness of the magnet is greater than the thickness of the voice coil. A method of forming the described microphone is also set forth.

Radial build between helical coil and plasma in the Large Helical Device

The Large Helical Device (LHD) is a heliotron/torsatron-type confinement device ( B = 4 T, R = 3.9 m) equipped with a helical divertor. In the LHD configuration, the plasma region is shifted inwards approximately a third of the plasma minor radius relative to the center of the two pairing helical coils, thus making the distance between the coil center and the edge plasma small, 328 mm on the small major radius side of the torus. Within this space, many components must be installed, such as the superconducting helical coil (163), its coil can (45), the thermal shield (30), the vacuum gap (35), the plasma vacuum vessel (15), the first wall (25) (the numbers in the parentheses are allocated radial space in mm for the respective components). Effective edge plasma control by the divertor requires a space of more than 15 mm between the plasma and the first wall. To meet the above space requirement, the thickness of the helical coil is designed to be as small as possible, yet the coil current density and maximum field strength are within the limits of reliable coil operation.

Development of a 48-turn thin-film head

A conventional 30-turn thin-film head does not yield sufficient output when applied to a small-size rigid disk drive, especially 3.5 in. or less. A head of higher output voltage with more turns is required to obtain larger signal-to-noise ratio. A 48-turn thin-film head with two-layered spiral coil has been successfully developed, and 1.6 times the output voltage and larger signal-to-noise ratio by about 3 dB compared with the conventional 30-turn head were obtained. The head has a 0.55-μm gap length, 17-μm track width, and 4-μm-thick Permalloy films on the 3370-type slider. Yoke length was designed to be the same as that of the 30-turn head to prevent the reduction of the head efficiency. To minimize the increase of the coil resistance due to increasing the coil turns, the copper coil was fabricated with a high-aspect-ratio process using oxygen-ion milling of photoresist. Coil width was 3 μm; coil pitch was 4.5 μm, and coil thickness was 4 μm. These heads were evaluated using a 3.5-in. sputtered disk and showed good electromagnetic performance.

Planar¿Type Micro¿Magnetic Cores

The characteristics of planar-type micro-magnetic cores, consisting of pairs of (primary and secondary) plane coils and Co-Fe amorphous magnetic ribbons in different configurations, are reported. The output was measured for sinusoidal exciting currents at different frequencies in different coils; results differed depending on whether an amorphous ribbon was inserted between coil pairs, and on the pitch between coils. Experimental results agreed well with calculations of the flux density distribution in the coil thickness direction, equivalent to the linkage flux.

An improved spin-flip switching system for neutron spectral modulation

The switching circuit for a spin-flip chopper developed by Badurek and Westphal has been modified to give improved time resolution for neutron time-of-flight spectrometry. With the modified system, the switching time constants can be reduced to as short as 200 ns or less, and the thickness of the flip coil can be reduced to as thin as 2 mm or less. Thus bursts of 3 μs duration of neutrons with a wavelength of 2.47 Å can be used for the conventional flip-chop mode of TOF experiments. A substantial improvement of the time resolution can be achieved with the improved switching system when combined with the neutron spectral modulation technique, as in NSM the wavelength spread of the incident beam is decoupled from the overall time resolution of the system.

Feasibility test of a shrink-fit assembly of a large-diameter superconducting solenoid for a colliding beam detector

A dummy solenoid coil of 3 m in diameter and 0.65 m in length was fabricated in order to establish a shrink-fit assembly procedure for a thin, large superconducting solenoid magnet without a permanent inner bobbin for a colliding beam detector. A dummy conductor of aluminum and actual insulation materials were used for the dummy coil. The coil thickness was 20 mm. After an outer support cylinder of aluminum alloy of 16 mm in thickness was shrink-fifted upon the coil, the temporary mandrel used for coil winding was removed. With this arrangement the solenoid can be built substantially thinner in terms of radiation thickness compared with those built with the conventional method. The interference between the coil and support cylinder to provide adequate pre-stress was determined. Various mechanical properties of the solenoid components required in the present method were studied.

Effect of finite coil thickness in a magnetic deflection system

The effect of finite coil thickness on the magnetic field produced by a magnetic deflection coil in the shape of a long right circular cylinder is calculated. It is found that the higher ‘‘multipole’’ contents of the field (i.e., the coefficients of higher order terms in a Fourier expansion about the coil axis) decrease by progressively larger percent amounts compared to their values for a coil of zero thickness.

Quench protection and design of large high current density superconducting magnets

Although most large superconducting magnets have been designed using the concept of cryostability, there is increased need for large magnets which operate at current densities above the cryostable limit (greater than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> Am <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). Large high current density superconducting magnets are chosen for the following reasons: reduced mass, reduced coil thickness or size, ana reduced cost. The design of large high current density, adiabatically stable, superconducting magnets requires a very different set of design rules than either large cryostable superconducting magnets or small self-protected high current density magnets. The problems associated with large high current density superconducting magnets fall into three categories; (a) quench protection, (b) stress and training, and (c) cryogenic design. The three categories must be considered simultaneously. The paper discusses quench protection and it implication for magnets of large stored energies (this includes strings of smaller magnets). Training and its relationship to quench protection and magnetic strain are discussed. Examples of magnets, built at the Lawrence Berkeley Laboratory and elsewhere using the design guidelines given in this report, are presented.

Optical fiber acoustical sensors

First Page

Design of a D-shaped toroidal field coil

A method for making a multilayer toroidal field coil free from the bending moment is studied by applying File’s theory to each layer of the coil. According to this method, the shape of a multilayer toroidal field coil is determined so that the layers in the winding are in pure tension and, therefore, are not subject to any bending moment. The winding thickness of the resultant coil is not uniform along the winding. Successive layers are no longer in contact, leaving some empty space between them. Tension on a conductor varies in magnitude from layer to layer and is constant in the same layer, as in a solenoidal coil. A toroidal field coil with a magnetomotive force of 18.8 MA T, a vertical bore of 1.51 m, and a horizontal bore of 1.07 m is designed with this method.

Design of a D-shaped Toroidal Field Coil

A method for making free a multi-layer toroidal field coil from bending moment is studied by appling File's theory to each winding layer. The theory seems to be valid for a line conductor in a toroidal magnetic field or for an ideal one-layer toroidal field coil. According to the present method, the shape of the multi-layer toroidal field coil is satisfactorily decided so that each winding layer is in pure tension or is not subject to any bending moment. The winding thickness of the resultant coil does not become uniform along the winding. The successive layers are no longer in contact leaving some empty space, and the tension on a conductor varies in magnitude from layer to layer. A practical toroidal field coil with a total ampere-turn of 18.8 MAT, a vertical bore of 1.51m, and a horizontal bore of 1.07m has deen designed by this method.

Homogeneous rf field delay line probe for pulsed nuclear magnetic resonance.

The analysis of delay line coils for use in pulsed nuclear magnetic resonance, as carried out by Lowe and Engelsberg, is extended to include magnetic coupling between coil sections. The predicted cutoff frequency for the delay line is found to be considerably extended, and this is experimentally verified. The rf magnetic field distribution is theoretically analyzed for the case of a wide flat coil. The conclusion is that the field should be relatively homogeneous as long as the coil thickness is much smaller than the wavelength of the electromagnetic wave traveling down the coil axis. Several different flat coil designs using distributed capacitance are then described, along with operating characteristics of constructed models. The most successful model had a time delay of 20 nsec and a measured inhomogeneity of 4% at 60 MHz.

A new type of spin-flip chopper for polarized neutron beams

A spin-flip chopper for polarized neutron beams has been developed, needing less electronic equipment and offering better time resolution than radio frequency chopper systems. Flipping is achieved by static magnetic fields only, which are set up by two coils of extremely low inductivity and can be pulsed within 2–3 μs by simple and reliable transistor switches, working in constant current mode. The effective switching length of the spin reversal device, being responsible for the flight path uncertainty, is reduced to the thickness of a single coil, which is only 0.65 cm, by delayed switching of the second coil according to the neutron transmission time through the first one. Neutron burst of 5 μs duration and a repetition rate of 100 kHz could be obtained with this chopper.