Demagnetization Analysis of Permanent Magnets According to Rotor Types of Interior Permanent Magnet Synchronous Motor

Alternating current demagnetization of satellite components

Abstract The expression for the demagnetization of ringcores has evolved from the equation for the magnetic field inside simple-shaped objects whose magnetization is uniform. A modified expression that allows for the angular distribution of the magnetic field in the ringcore is developed from calculations for a infinite length tube. The modified expression is shown to provide a good fit to measured data. This modified equation is important when the product of the relative permeability and the demagnetization constant has a value around one or ...

Abstract The expression for the demagnetization of ringcores has evolved from the equation for the magnetic field inside simple-shaped objects whose magnetization is uniform. A modified expression that allows for the angular distribution of the magnetic field in the ringcore is developed from calculations for a infinite length tube. The modified expression is shown to provide a good fit to measured data. This modified equation is important when the product of the relative permeability and the demagnetization constant has a value around one or ...

Alternating current demagnetization of satellite components

Abstract We propose an optimized method to demagnetize ferromagnetic specimen taking into account its particularities. Based on a static algebraic model for magnetic hysteresis we calculated a demagnetization function which considers the reversible and irreversible processes during the passage through the hysteretic loops into the demagnetized state

An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determin...

The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capab...

The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capab...

Abstract To demagnetize small-scale objects (dimensions less than 1 m) fabricated from ferromagnetic materials, it is standard practice to expose the object to a continuous AC applied magnetic field with a steadily decaying amplitude. For objects of dimensions greater than 10 m, there are problems of scale, and a stepwise procedure is preferred. We have simulated two different stepwise demagnetization techniques with a scaled model of a magnetic treatment facility regularly used in the deperming of military vessels. We used a steel tube as the...

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