Mechanical pre-stressing a transducer through a negative DC biasing field

With the advent of power electronic technology, the excitation conditions applied to transformers, motors, etc. could be very atypical. DC bias excitation is an undesired working condition of AC power transformers, the asymmetrical saturation of the transformer core, the heavy noise, the serious vibration, and the local loss concentration can all potentially occurred in dc-biased transformers. The effect of the exciting current under different dc-biased magnetization on eddy-current loss in copper plate based on a reduced engineering-oriented benchmark model (TEAM Problem 21) is investigated. Experiment scheme for dc biasing is presented and the distribution of the eddy current loss under different dc-biased excitation conditions was studied in detail. The engineering applicability of three dimensional eddy current analysis methods for dc-biased magnetization field computation and the practical loss modeling are examined, which has been demonstrated via the numerical modeling results and the measured data.

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A Comparative Study of Nucleation Enhancement Techniques for Plasma Cvd of Diamond Thin Films

MRS Proceedings ◽

10.1557/proc-349-409 ◽

1994 ◽

Vol 349 ◽

Author(s):

R.J. Meilunas ◽

A. Tobin

Keyword(s):

Thin Film ◽

Microwave Plasma ◽

Chemical Vapor ◽

Processing Parameters ◽

Carbon Cluster ◽

Nucleation Density ◽

Plasma Cvd ◽

Diamond Nucleation ◽

Diamond Surfaces ◽

Dc Biasing

ABSTRACTThree methods recently proposed for enhancing the nucleation density of thin film diamond on non-diamond surfaces during microwave plasma assisted chemical vapor deposition are investigated. The results of a series of nucleation and growth studies utilizing a dc biasing technique, carbon cluster (C70) thin film overlayers, and thin film metal (Fe) overlayers for diamond nucleation enhancement are presented. The influence of the substrate and plasma processing parameters under which the above nucleation enhancement effects occur has been determined for the three respective techniques.

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Planar Ferrite Materials for Millimeter-Wave Applications

MRS Proceedings ◽

10.1557/proc-631-aa2.4 ◽

2000 ◽

Vol 631 ◽

Author(s):

Stephen W. McKnight ◽

Steven A. Oliver ◽

Hoton How ◽

Carmine Vittoria

Keyword(s):

Pulsed Laser ◽

Barium Hexaferrite ◽

Laser Deposition ◽

Yttrium Iron ◽

Garnet Films ◽

Active Circuit ◽

Circuit Components ◽

Iron Garnet ◽

Insertion Losses ◽

Dc Biasing

ABSTRACTTransferred-film technology provides a path to the integration of self-biased hexaferrite film devices into MMIC circuits. While progress is being made on the growth of thick oriented films of barium hexaferrite doped with aluminum and scandium by pulsed laser deposition or liquidphase epitaxy, we have demonstrated prototype devices using available yttrium-iron-garnet films and thinned bulk hexaferrites. Insertion losses less than 2dB and isolation greater than 20dB have been demonstrated, and theoretical modeling indicates that insertion losses less than 0.5 dB are accessible with optimized materials and through matching the active circuit components to the ferrite device. The prospects of accessing ferrite non-reciprocal, non-linear, and tunable functions at frequencies up to and exceeding 100 GHz through devices integrated onto microwave IC substrates without the use of DC biasing magnets are the driving force of this research.

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