Conductor Skin Research Articles

Magnetic-field-induced surface quantum states in organic conductors

ABSTRACT Analysis of the surface quantum states in quasi-two dimensional organic conductors induced by an external magnetic field is carried out within the quasi-classical approximation. In a magnetic field parallel to the surface along the y direction, these states result from the electronic transitions between the small closed orbits in the vicinity of the Fermi surface which are extremal cross-sections of the Fermi surface by the plane , . The magnetic surface levels are calculated for the electrons moving on skipping orbits near the conductor's surface with a centre of rotation outside and inside the conductor, respectively. The former are the shallow skipping electrons as their motion is very close to the surface so they are practically sliding along the surface and the latter have trajectories that span deeper in the conductor's skin layer and therefore are more affected by the bulk electrons. The features of their corresponding magnetic surface levels are revealed and differences in the unperturbed energy spectrum of both type of skipping electrons are addressed. The magnetic field values at which the resonance peaks in the oscillation spectrum, associated with the surface resonance transitions, should be observed are obtained. Further theoretical and experimental studies on the surface states and related to them effects might give new important and more precise information on the properties, Fermi surface parameters and transport processes in organic conductors.

Parameter estimation technique for the semi-conducting layers in single-core XLPE cable

Partial discharge (PD) detection and location is of great significance for the power cable insulation condition monitoring, where the high-frequency (HF) model is needed to analyze PD propagation. Considering the influences of conductor skin effects and semi-conducting layers (SCL), this paper presents the equivalent Γ-section lumped parameter model for single-core cross-linked polyethylene (XLPE) insulation cables. The longitudinal parameters per-unit-length in the model are obtained using available geometric data by vector fitting method. Unfortunately, the dielectric characteristics of SCL in XLPE cables, especially for an installed one, are usually unknown and hard to measure. To address this issue, based on the simulated annealing algorithm, an optimization approach for estimating the transversal parameters in the Γ-circuit model is developed. The proposed technique is then carried out on the XLPE cable with simulated and real SCL, respectively. Furthermore, the estimation results of the real case are validated on a 603 m cable with kinds of HF pulses responses.

A Comparative Analysis of Inductors with Square and Conical Contours

Winding pattern and contour are important factors in power inductors with multiple layer windings, since power inductors with multiple layers are prone to proximity effect, as multiple stacking increases the resistance stress of a conductor, eventually leading to failure of the inductor. This paper presents a comparison of winding losses for cone and square contour inductors, and discusses possible causes for the discrepancy. Conical contour inductors within a fixed core window are comparatively better than square contour winding inductors. A cross sectional analysis after winding revealed that the conical contour inductor has a gap between the conductors, indicating no melting and diffusion between layers. The absence of diffusion due to thermal degradation in conical contour winding is believed to be due to the conductor skin thickness, which is on average smaller, owing to the lower winding stresses. For a fixed dimension core and number of turns, winding losses can be reduced using a cone-shape contour compared to a square-shape contour

Flow transients performance in an MTR-type research reactor

During a flow coastdown event leading to slowing down coolant flow, the rate of heat removal from the fuel element must be sufficiently high to prevent meltdown. It is essential to estimate the flow rate change and the decay heat removal capability. In many studies complete pump operating characteristics are used in analytical solutions of the problem. Under the coastdown phenomenon, retarding torque replaces motor torque. In order to determine this torque, all the induction motor losses during the event are identified and where possible these loss parameters are measured. Stator and rotor core losses, stator and rotor stray load losses and magnetizing saturation and rotor conductor skin effects are taken into account. The basics equations for coolant flow and for the rotating parts of the centrifugal pump are subsequently derived for an MTR-type research reactor such Tehran Research Reactor (TRR). Then the equation of flow motion is solved with another one which predicts the pump speed during the coastdown transient. The results of the present work are validated by comparison with experimental and analytical studies of the similar work. The model shows good agreement with the present literature.

Calculation of Energy-Related Quantities of Conductors Using Surface Impedance Concept

This paper focuses on the application of surface impedance concept in a post-processing stage for the calculation of such characteristics of conductors such as energy stored in the conductor's skin layer, power losses, inductance, and resistance per unit length. Derivations are performed in terms of - and - formalisms. Numerical examples are included to illustrate the method and validate the results.

Modeling of double-π equivalent circuit for on-chip symmetric spiral inductors

We present a novel methodology to extract model parameters from measured S-parameters for silicon on-chip center-tapped symmetric spiral inductors. The double-π equivalent circuit topology is employed in which conductor skin effect is considered. The automated extraction procedure based on modified differential evolution is demonstrated to be efficient and effective. To verify the accuracy of the new methodology, 17 center-taped symmetric inductors were fabricated and the equivalent circuit parameters were extracted from two-port S-parameters measurements over the frequency range of 0.3–8.5GHz. The excellent accuracy of the results demonstrates the flexibility of the modeling methodology. The new methodology should be useful in the design of RF ICs and mixed signal ICs.

High frequency modelling approach of on‐chip interconnects considering conductor and substrate skin effects

Simple and accurate high frequency modelling approach of on‐chip interconnects on a lossy silicon substrate, that considers conductor and substrate skin effects, is presented. The closed‐form formulas for the frequency‐dependent series impedance parameters are obtained using a closed‐form integration method and the vector magnetic potential equation. The proposed frequency‐dependent inductance L(f) and resistance R(f) per unit length formulas are shown to be in good agreement with the electromagnetic solutions.

A physics-based VLSI interconnect model including substrate and conductor skin effects

The goal of this work was to model the influence of the substrate and conductor skin effects on the RL line characteristics of on-chip interconnects. The proposed modelling approach is based on the skin-effect theory results for rectangular wires and the complex integration technique for perturbation series per unit length impedance of silicon substrate. It is shown that the calculated frequency-dependent distributed inductance and the associated resistance are in good agreement with the results obtained from rigorous full-wave solutions and CAD-oriented analytic modelling technique.

Measurement and analysis of the pulsed magnetic field phase lag in the ceramic case

Due to the damping action during the magnetic moment precession, the magnetic flux generated by a pulsed magnetic field commonly will lag behind the field,so the phase of the pulsed magnetic field lags behind after it penetrates a coated metal. For the nonferromagnetic metal, the phaselag is very faint, and owing to the influence of conductor skin effect and eddy current, it can hardly be detected. An experimental method and the result obtained have been presented in this paper.In this method by using an ultrathin coating with zonal stripe to isolate and select an appropriate position to measure, thus the influences of conductor skin effect and eddy current have been reduced to a minimum. An analysis has been presented in this paper.

Characterization and modeling of multiple coupled on-chip interconnects on silicon substrate

A quasi-magnetostatic integral formulation approach is applied to compute the frequency-dependent series resistance and inductance parameters for coupled microstrip on-chip interconnects on silicon. The method is based on the simultaneous discretization of interconnect conductors and silicon substrate, and takes into account the substrate skin effect (eddy currents), as well as the conductor skin and proximity effects. An efficient equivalent-circuit model based on "effective substrate current loops" is extracted from the frequency-dependent R and L parameters for a class of coupled microstrip-type on-chip interconnects. The frequency response of the proposed model consisting of only passive R, L elements agrees well with the broad-band characteristics of the distributed resistance and inductance parameters of the interconnect obtained by electromagnetic simulation. Model extraction results are presented for asymmetric coupled interconnects to demonstrate the proposed method.

High-field NMR spectroelectrochemistry of spinning solutions: simultaneous in situ detection of electrogenerated species in a standard probe under potentiostatic control

This report summarizes the design and performance of the first practicable in situ electrogenerative high-field solution-NMR cell, designed for simultaneous NMR spectroelectrochemistry in a conventional 10- or 16-mm 300 MHz probe. The axially symmetric three-electrode assembly is stationary and self-aligning. It dips into a standard spinning 10-mm sample tube and is adapted for convenient operation in any commercial high-field, multi-nuclear, variable-temperature FT NMR spectrometer. The tubular, rf-transparent working electrode (presently consisting of a gold film, coated on glass) completely spans the detection region; the recommended coating thickness is ≤0.01 δ, where δ is the rf-absorbing conductor skin depth. With careful shimming, very narrow 1H signals (∼1 Hz) can be obtained. The performance of the in situ NMR-electrochemical cell is illustrated by monitoring the progressive reduction of ‘ p-quinone’ (1,4-benzoquinone) to its dihydro-form by controlled-potential electrolysis in an acidic medium.

Modeling of picosecond pulse propagation in microstrip interconnections of integrated circuits

Theoretical time-domain analyses of the dispersion and loss of square-wave and exponential pulses on microstrip transmission line interconnections on silicon integrated-circuit substrates, performed using the quasi-TEM approximation, are discussed. Geometric dispersion and conductor line width, as well as losses from conductor resistance, conductor skin effect, and substrate conductance, are considered over the frequency range from 100 MHz to 100 GHz. Results show the enormous significance of the substrate losses and demonstrate the need for substrate resistivities >10 Omega -cm for high-performance circuits. The results also show the effects of geometric dispersion for frequencies above 10 GHz, the unimportance of conductor skin-effect losses for frequencies up to 100 GHz, and the transition from a high-frequency regime where losses do not affect phase velocity to a low-frequency regime where the ratio of he conductor and substrate loss coefficients determines phase velocity. >

Design theory and characteristics of solid‐state mutual coupling cable

AbstractPreviously, the author reported the theory of the solid‐state mutual coupling cable (hereafter, called SSMCC) which utilizes active coupling among three conductors to compensate the cable losses. In this paper, the optimum design theory of the SSMCC is presented with consideration of the realization condition. The design procedure is described for given transistor characteristics and cable conductor resistances. The design example of an experimental SSMCC and its transfer characteristics are presented. The SSMCC is lossless at the lossless frequency in the transmission band and has almost identical loss at frequencies above and below this lossless frequency. In the analysis, the conductor skin effect is ignored.

Electromagnetic induction in rotating conductors

This paper describes an experimental and theoretical investigation of induction in a rotating conductor surrounded by a rigid conductor of finite or infinite extent. The results are applied to a discussion of induction in rotating eddies in the fluid core of the earth as a possible origin of the geomagnetic non-dipole field. Model experiments were made with rigid rotators in a steady magnetic field; the induced magnetic field was measured outside the conductors. The results confirmed the appropriate parts of the theoretical work. In the theoretical work solutions are first obtained for a rotator embedded in a solid conductor of infinite extent; a method is then developed for extending this solution to a finite surrounding conductor. Charts are given for the induced field on the surface of the earth due to a hypothetical rotator in the earth’s core. The analysis is based on integral solutions of the field equations; wherever possible the field vectors themselves are used rather than a vector potential. The induced magnetic fields depend on the relative symmetry of the rotator, the surrounding conductor, and the applied magnetic field. For an applied field parallel to the axis of rotation, the induced field is proportional to the angular velocity; for an applied field perpendicular to the axis, the induced field reaches a limit at high angular velocities. If both the surrounding conductor and the applied magnetic field have rotational symmetry about the axis there is no induced field outside the surrounding conductor. The conclusion of the geophysical discussion is that eddies must have radii of several hundred kilometres if they are to account for the observed magnitude of the non-dipole field. Because of the skin effect such large radii would not be tenable if the core material were effectively rigid. However, fluid motions must occur due to the electromagnetic forces, and the consequent magneto-hydrodynamic disturbances probably have decay lengths much larger than the rigid conductor skin depth; therefore arguments based on the rigid conductor skin depth are not applicable. Thus the eddy model might be satisfactory if the fluid motion does not seriously alter the basic induction mechanism.