arXiv subjects

Osvaldo F. Schilling

Publications and source records attributed to Osvaldo F. Schilling.

9 recordsLinked to original sources

arXiv2018

The design of a very high-Q superconductor electromechanical clock

We discuss theoretically the properties of an electromechanical oscillator whose operation is based upon the cyclic, quasi-conservative conversion between gravitational potential, kinetic, and magnetic energies. The system consists of a strong-pinning type-II superconductor square loop subjected to a constant external force and to magnetic fields. The loop oscillates in the upright position at a frequency that can be tuned in the range 10-1000 Hz, and has induced in it a rectified electrical current. The emphasis of this paper is on the evaluation of the major remaining source of losses in the oscillations. We argue that such losses should be associated with the viscous vibration of pinned flux lines in the superconductor Nb-Ti wire, provided the oscillator is kept close to zero Kelvin, under high-vacuum, and the magnetic field is sufficiently uniform. We discuss how other different sources of loss would become negligible for such operational conditions, so that a very high quality factor Q exceeding 10^(10) might in principle be reached by the oscillator. The prospective utilization of such oscillator as a low-frequency high-Q clock is analyzed.Since publication the ideas in this paper have been explored both by the author and elsewhere, in applications covering Metrology, quantum systems, and gravimetry.

cond-mat.supr-con↗

arXiv2015

Thermo-magnetic properties of the magnetocaloric layered materials based upon FeMnAsP: a Green function-method approach

The compounds FeMnAsxP1-x are very promising as far as commercial applications of the magnetocaloric effect are concerned. However, the theoretical literature on magnetocaloric materials still adopts simple molecular-field models in the description of important properties like the entropy variation that accompanies applied isothermal magnetic field cycling, for instance. We apply a Green function theoretical treatment for such analysis. The advantages of such approach are well-known since the details of the crystal structure are incorporated in the model, as well as a precise description of correlations between spins of the transition metal ions can be obtained. For the sake of simplcity we adopt a simple one-exchange parameter Heisenberg model, and the observed first-order phase transitions are reproduced by the introduction of a biquadratic term in the hamiltonian. Good agreement with experimental magnetocaloric data for FeMnAsxP1-x compounds is obtained, as well as an agreement with the magnetic field dependence for these properties predicted from the Landau theory of continuous phase transitions.

cond-mat.mtrl-sci↗

arXiv2013

The precise determination of mass through the oscillations of a very high-Q superconductor oscillating system

The present paper is based upon the fact that if an object is part of a highly stable oscillating system, it is possible to obtain an extremely precise measure for its mass in terms of the energy trapped in this resonance. The subject is timely since there is great interest in Metrology on the establishment of a new electronic standard for the kilogram. Our contribution to such effort includes both the proposal of an alternative definition for mass in terms of energy, as well as the description of a realistic experimental system in which this definition might actually be applied. The setup consists of an oscillating type-II superconducting loop (the SEO system) subjected to the gravity and magnetic fields. The system is shown to be able to reach a dynamic equilibrium by trapping energy up to the point it levitates against the surrounding magnetic and gravitational fields, behaving as an extremely high-Q spring-load system. The proposed energy-mass equation applied to the electromechanical oscillating system eventually produces a new experimental relation between mass and standardized constants.

physics.gen-ph↗

arXiv2009

A Comparison between two methods for the measurement of the Planck constant h, the watt balance and the superconductor electromechanical oscillator methods

The purpose of this note is to make a brief analysis of the physical principles upon which two methods for relating the mass of an object to fundamental physical constants are based. The two methods are, namely, the watt balance method, and a still untested experimental technique based upon a superconductor electromechanical oscillator. We show that both these methods are governed by similar equations.

physics.gen-ph↗

arXiv2008

Application of Conformal Mapping to the determination of Magnetic Moment Distributions in typical Antidot Film Nanostructures

There has been an increasing technological interest on magnetic thin films containing antidot arrays of hexagonal or square symmetry. Part of this interest is related to the possibility of domain formation and pinning at the antidots boundaries. In this paper, we develop a method for the calculation of the magnetic moment distribution for such arrays which concentrates on the immediate vicinity of each antidot. For each antidot distribution (square or hexagonal) a suitable system of coordinates is defined to exploit the shape of the unit-cells of the overall nanostructure. The Landau-Lifshitz-Gilbert-Brown equations that govern the distribution of moments are rewritten in terms of these coordinates. The equilibrium moments orientation is calculated for each position in a Cartesian grid defined for these new coordinate systems, and then a conformal transformation is applied to insert the moment vectors into the actual unit-cell. The resulting vector maps display quite clearly regions of different moment orientation around the antidots, which can be associated with nanoscale domains. These results are similar to the ones obtained by other authors[1-4] using the NIST oommf method.

physics.comp-ph↗

arXiv2005

A superconductor electromechanical oscillator and its potential application in energy storage (with corrections)

We discuss theoretically the properties of an electromechanical oscillating system whose operation is based upon the cyclic conservative conversion between gravitational potential, kinetic, and magnetic energies. The system consists of a superconducting coil subjected to a constant external force and to magnetic fields. The coil oscillates and has induced in it a rectified electrical current whose magnitude may reach hundreds of Ampere. The design differs from that of most conventional superconductor machines since the motion is linear (and practically unnoticeable depending on frequency) rather than rotatory, and it does not involve high speeds. Furthermore, there is no need for an external electrical power source for the system to start out. We also show that the losses for such a system can be made extremely small for certain operational conditions, so that by reaching and keeping resonance the system main application should be in the generation and storage of electromagnetic energy.

cond-mat.supr-con↗

arXiv2003

The Ideal Electromechanical Oscillator System

Oscillators and rotators are among the most important physical systems. For centuries the only known rotating systems that actually reached the limits of the ideal situation of undamped periodical motion were the planets in their orbits. Physics had to develop quantum mechanics to discover new systems that actually behaved like ideal, undamped, oscillators or rotators. However, all examples of this latter systems occur in atomic or molecular scale. The objective of the present letter is to show how the limit of ideal oscillating motion can be challenged by a man-made system. We demonstrate how a simple model electromechanical system consisting of a superconducting coil and a magnet can be made to display both mechanical and electrical undamped oscillations for certain experimental conditions. The effect might readily be attainable with the existing materials technologies and we discuss the conditions to circumvent energy losses. The result is a lossless system that might generate hundreds of Ampere of rectified electrical current by means of the periodical conversion between gravitational potential, kinetic, and magnetic energies.

physics.gen-ph↗

arXiv2003

Electric energy by direct conversion from gravitational energy: a gift from superconductivity

We theoretically demonstrate that electromagnetic energy can be obtained by direct, lossless, conversion from gravitational and kinetic energies. For this purpose we discuss the properties of an electromechanical system which consists of a superconducting coil submitted to a constant external force and to magnetic fields. The coil oscillates and has induced in it a rectified electrical current whose magnitude may reach hundreds of Ampere. There is no need for an external electrical power source for the system to start out and it can be kept working continuously if linked to large capacitors. We extensively discuss the issue of energy dissipation in superconductors and show that the losses for such a system can be made extremely small for certain operational conditions, so that by reaching and keeping resonance the system main application should be in magnetic energy storage and transmission.

cond-mat.supr-con↗

arXiv2003

Mechanical and Electrical Oscillations of a Superconductor Coil and its Applications

In this paper we discuss the phenomenon of resonance that we predict will occur when a superconducting coil is submitted simultaneously to a magnetic field and to an external force. When both the force and the magnetic field are constant in time the coil should oscillate mechanically around an equilibrium position like an ideal harmonic oscillator, and should have induced in it an alternating current of same frequency. We obtain an expression for the resonance frequency, which is directly proportional to the applied magnetic field and depends also on the wire superconducting properties. We discuss also a setup with no built-in magnet, in which the coil is driven by a mechanical oscillator, and thus the force varies cyclically with time. A measurable alternating current may be induced in the device for an amount of magnetic flux as small as one flux quantum, so that the device is an excellent magnetometer.

cond-mat.supr-con↗