Anomalous Loss Research Articles

Investigation of anomalous losses in thick Cu ferromagnetic spiral inductors

Ferromagnetic spiral inductors were fabricated using thick copper technology. 30% increase in L is shown over the air core value. However, we observe a large restriction in Q when frequency is beyond 1 GHz. This strongly contrasts with the high ferromagnetic resonance (FMR) frequency measured at 6 GHz. Also still increasing the FMR up to 10 GHz using multipatterning do not improve Q. The highlight is on excess losses not originating from magnetic losses (/spl mu/'') and the Joule effect. Additionally, when comparing multiturn inductor to single strip inductor, proximity effect or current crowding is shown responsible.

A new current transformer model

This paper presents a current transformer model that is useful on low frequency applications. To describe the iron core magnetic behaviour of the iron core, a hysteresis model is proposed, which is able to generate minor asymmetric loops and remanent flux. The effects of classic eddy current losses and anomalous losses are represented by linear and nonlinear resistors, respectively. The obtained results are compared with those calculated by Preisach's model and measured in laboratory. This model may be applied in power system protection studies, as it is the case of numeric correction of distorted secondary currents in current transformers (CT's).

Comment on: “UCN anomalous losses and the UCN capture cross section on material defects” [Phys. Lett. A 335 (2005) 327

We present correct solution of the problem about a scattering of the neutron on a point-like defect existing in a medium and show that this mechanism cannot explain anomalous losses of UCN in storage bottles.

The optimum grain size for minimizing energy losses in iron

A model able to predict the optimum grain size for textured electrical steels used in motors or transformers is presented. The model is based on the Pry and Bean model for the anomalous losses. The validity of the model is restricted to the frequency range of 1–1000 Hz. The model predicts that the optimum grain size decreases as: resistivity decreases or frequency increases or thickness of steel sheet increases. The predictions of the model are compared with experimental results.

Influence of random nonlinear internal wave parameters on resonant acoustic mode coupling

Shallow water transmissions sometimes suffer anomalous amplification or loss caused by mode coupling due to the presence of nonlinear internal wave packets. The possibility of coupling between two acoustic modes is specified by an internal wave-acoustic resonance condition, which relates acoustic wavenumber differences to peak locations of the packet spectrum. This mechanism is critical in a recent analysis [S. D. Frank et al., J. Acoust. Soc. Am. 116, 3404–3422 (2004)] of some broadband intensity variations from the SWARM 95 experiment. That investigation used regularly spaced, evenly-sized nonlinear internal wave packets and it is important to determine how random variations in the wave widths and inter-wave spacings affect propagation results. An analytic expression for the wavenumber spectrum of an idealized packet is obtained in terms of these parameters. This expression predicts spectral peak locations for parameters from the SWARM 95 model that correspond with observed data. Estimates of peak location statistics arising from random packet parameter variations are analyzed computationally and analytically. Variability of internal wave spectral peak locations is correlated with broadband intensity fluctuations obtained from parabolic equation computations. [Work partially supported by ONR.]

Steady solutions to neoclassical transport equations and the absence of bifurcated states

The question of whether two-valued solutions can exist for an ambipolar electric field in stellarators and rippled tokamaks is considered. Steady solutions to transport equations in the limit of infrequent collisions are obtained in the purely neoclassical transport theory (that is, without allowance for possible anomalous losses). It is shown that, given the particle and heat sources, these equations have only one steady continuous solution, i.e., the steady states are nonbifurcating.

UCN anomalous losses and the UCN capture cross section on material defects

Experimental data shows anomalously large ultra cold neutrons (UCN) reflection losses and that the process of UCN reflection is not completely coherent. UCN anomalous losses under reflection cannot be explained in the context of neutron optics calculations. UCN losses by means of incoherent scattering on material defects are considered and cross-section values calculated. The UCN capture cross section on material defects is enhanced by a factor of 10 4 due to localization of UCN around defects. This phenomenon can explain anomalous losses of UCN.

Influence of geometry and wave shape on magnetic amorphous material

The magnetic performance of 0.03 mm thick Co-based and 0.026 mm thick Fe-based amorphous ribbon in toroidal and strip form was measured under sine and pulse width modulation (PWM) waveform conditions. The measured loss, at 100 Hz fundamental frequency and a peak flux density of 91% of the saturation of each material, was separated into classical eddy current, hysteresis and anomalous loss components and the effect of geometry and waveform on these loss components was analysed. The results in general show a dimensional and waveform dependence which is not so great as in electrical steels.

The Barkhausen Effect and the Anomalous Magnetization Losses in Metallic Ferromagnets

The aim of this work is calculation of the contribution of the irreversible domain wall shifts to the total remagnetization losses. It has been shown that the irreversible remagnetization losses are approximately 2.4 times higher in comparison with the reversible one.

Analytical Percolation Model for Predicting Anomalous Charge Loss in Flash Memories

Data retention in flash memories is limited by anomalous charge loss. In this work, this phenomenon is modeled with a percolation concept. An analytical model is constructed that relates the charge-loss distribution of moving bits in flash memories with the geometric distribution of oxide traps. The oxide is characterized by a single parameter, the trap density. Combined with a trap-to-trap direct tunneling model, the physical parameters of the electron traps involved in the leakage mechanism are determined. Flash memory failure rate predictions for different oxide qualities, thicknesses and tunnel-oxide voltages are calculated.

RF Planar Ferromagnetic Inductors on Silicon

Two-port coplanar ferromagnetic inductors using solid magnetic planes were fabricated on silicon. L, R, and Q measurements are presented. Cutoff frequencies exceed 10 GHz, indicating no capacitance limitation. The increase in L over the air-core value is /spl sim/15%, and the quality factor Q is of /spl sim/10 up to 1.5 GHz. The inductance scales with HA-alignment and spiral excitation ratio. Agreement with High-Frequency Structure Simulator simulations including ferromagnetic resonance led to a better understanding in terms of L and Q. Current increase in L is limited by the film thickness (0.2 /spl mu/m). Thicker films (0.5-1 /spl mu/m) would lead to larger gain over L (23% to 31%) with similar Q (/spl sim/10). The restriction in Q from the air-core inductor consists in magnetic losses but not only. Another contribution would come from anomalous ohmic losses from the spiral itself enhanced by the proximity of the magnetic planes.

Characterization of moving bits (MBs) and QBD in wet/dry tunnel oxides for floating gate type nonvolatile memory (FG-NVM) applications

A critical problem of floating gate type nonvolatile memories (FG-NVMs) used in flash memories or EEPROMs is anomalous charge loss which leads to threshold voltage ( V t) shifts on a time scale of months or years at room temperature. The number of these moving bits (MB's) is greatly affected by the nature and properties of the tunnel oxide that is used in the NVM technology. In this paper we compare different types of tunnel oxides and determine the impact on the MB issue with different measurement techniques. The appearance of MB is demonstrated by a low electric field test. This test is a close match to real lifetime conditions and as such gives a good indication of the MB performance of the device. Nevertheless since this test is very time consuming it is not feasible to use it for monitoring during manufacturing. It is demonstrated that a fast QBD measurement correlates very well with MB test itself. As such the QBD test is a valid tool for fast NVM reliability evaluation. Oxide leakage measurements, on the other hand, do not give any indication of MB characteristics. Wet oxide grown at 750 °C proves to be far superior in terms of MB performance compared to the dry oxides grown at 900 or 960 °C. The initial MB measurements before write–erase cycling show a strong impact of the thickness and the type of oxide. This is still valid after 10K write–erase cycles: increasing the thickness of the tunnel oxide from 7.5 to 10 nm decreases the number of MB's by at least three orders of magnitude. After 10K cycles, one order of magnitude less MB's are observed for the wet oxide versus the dry oxide.

Critical assessment of a two-dimensional hybrid Hall thruster model: Comparisons with experiments

A discussion is presented on the results and predictive capabilities of a two-dimensional (2D) hybrid Hall effect thruster (HET) model. It is well known that classical (collision-induced) cross-field electron transport and energy losses are not sufficient to explain the observed HET characteristics. The 2D, quasineutral, hybrid discharge model uses empirical parameters to describe additional, anomalous electron transport and energy loss phenomena. It is shown that, for properly adjusted empirical parameters, the model can qualitatively reproduce the observed thruster behavior over a large range of operating conditions. The ionization and transit-time oscillations predicted by the model are described, and their consequences on the time-averaged thruster properties are discussed. Finally, the influence of the empirical parameters on the model results is shown, especially on quantities that can be measured experimentally.

Process Window Enlargement for Borderless Contact Formation by BPSG Stack Structure

Anomalous oxynitride loss after steam borophosphosilicate glass (BPSG) flow is observed for a borderless contact structure, and such loss engenders possible bit line shorts to word line. This phenomenon becomes more severe for BPSG film with higher phosphorous concentration. Phosphoric acid generation is deduced as the major mechanism. To enlarge process windows, a BPSG/undoped silicate glass stack has been proposed to withstand etch by acid. From practical application to 256 Mb dynamic random access memory process, this stack also shows a higher bit line contact yield and comparable contact sheet resistance with conventional stacks. More important, this technique could be fully integrated into incumbent ultralarge scale integrated technologies.

Investigation of anomalous room temperature conduction losses in normal metals at terahertz frequencies

A number of research groups worldwide have reported discrepancies between loss measurements and classical theoretical predictions for simple millimetre wave and sub-millimetre-wave structures. For the first time, a comprehensive survey of published experimental data for the room temperature surface resistance of normal metals, from DC up to the edge of the mid-infrared frequency range, has been undertaken. It has been found that, with the optical measurements performed within the far-IR region, there does not appear to be an anomalous intrinsic conduction loss phenomenon at room temperature; this is in direct contradiction to the findings of other research groups. This is because the non-optical measurement approaches adopted by Tischer, Schwab et al. and Batt et al. are fundamentally flawed, since anomalous findings could be attributed to one or more of the factors discussed in this paper.

Anomalous sound propagation due to the horizontal variation of� seabed acoustic properties

The sound propagation in shallow water is greatly influenced by the acoustic properties of seabed. An anomalous transmission loss was observed in an experiment, and a range dependent bottom model with horizontal variation of seabed acoustic property is proposed and could be well used to explain the anomalous phenomena. It is shown that the horizontal variation of bottom properties has a great effect on underwater sound propagation, and it should be given much attention in sound propagation and geoacoustic inversion problems.

Stability of the ion-temperature-gradient-driven mode with negative magnetic shear

A model for transition to the enhanced reverse shear or negative central shear mode triggered in tokamaks is proposed. This model takes into account the linear behavior of the ion temperature gradient (ITG) driven perturbation, considered nowadays as the dominant source of anomalous energy losses in the low confinement mode, in the presence of a radially varying parallel velocity. Analytic and numerical studies show that when the magnetic shear has the same sign as the second derivative of the parallel velocity with respect to the radial coordinate, the ITG mode may become more unstable. On the other hand, when the magnetic shear has the opposite sign to the second derivative of the parallel velocity, the linear ITG mode may be completely stabilized. This result is similar to our earlier works on parallel velocity shear instability [S. Sen et al., Phys. Plasmas 7, 1192 (2000); D. R. McCarthy et al., Phys. Plasmas 8, 3645 (2001)].

Parameter identification of Jiles–Atherton model with nonlinear least-square method

A new method to the parameter identification of the widely used scalar Jiles–Atherton (J–A) model of hysteresis is detailed in this paper. The extended J–A model is also investigated including the eddy-current and the anomalous loss terms, which are taken into account by modeling the frequency dependence of the hysteresis. The five parameters of the classical J–A model can be determined from low-frequency hysteresis measurement. At higher frequency the effect of the eddy currents is not negligible, the J–A model must be extended. The loss of the hysteresis characteristics and the coercitive field are increasing with the frequency. Nonlinear least-squares method is used for parameter fitting of classical and extended J–A model, as well. The curve fitting is executed automatically based on the initial parameters and the measured data.

Core losses in claw pole permanent magnet machines with soft magnetic composite stators

This paper presents the core loss calculation in soft magnetic composite (SMC) samples and a claw pole permanent magnet machine with SMC stator. By using finite-element analysis of the magnetic field, the total core loss is computed by separating the hysteresis (alternating and rotational, both purely circular and elliptical), eddy current, and anomalous losses in each element when the rotor rotates. The coefficients for each loss component are determined by a loss separation procedure and the experimental data obtained by a single sheet two-dimensional core loss testing system.

Assessment of power losses of an inverter-driven induction machine with its experimental validation

Detailed power loss distribution in induction machines is assessed using time-stepped finite-element analysis coupled to circuit equations of an inverter. Losses are examined for various load conditions. Iron losses are largely unexplored and so particular attention is paid to them here. The simulation has revealed the division between ohmic, hysteresis, classic eddy-current, and anomalous losses; and the distribution in the frequency spectrum between fundamental, slotting, and multiples of the switching frequency. Insight is also gained into the spatial location of the loss. Experimental validation is provided for several fundamental frequencies from full-load to light-load conditions.