Showing papers on "Magnetic potential published in 1980"

Magnetic resonances between massive and massless spin‐ 1/2 particles with magnetic moments

Abstract: The general effective radial potentials for a spin‐ 1/2 particle interacting with scalar, electric, and magnetic potentials are given. In the m=0 limit, it is shown that the magnetic potential provides a well deep enough to confine the massless particle. In particular, there are exact zero‐energy solutions in which two of the four components of the massless particle are confined; only two can leak out into the asymptotic region. The scattering amplitude is analytic in the entire j plane, hence consists only of Regge poles.

Derivation of Maxwell’s equations from the gauge invariance of classical mechanics

Abstract: The Lagrangian for a single classical charged particle is made form invariant under the addition of a total time derivative by adding an interaction Lagrangian which involves compensating fields. The compensating fields are the vector and scalar potentials of the electromagnetic field which couple to the current and charge densities, respectively. To insure form invariance of the Lagrangian, the vector and scalar potentials must undergo the usual gauge transformations of electromagnetism. The electric and magnetic fields, which are gauge invariant, are obtained by examining the equation of motion for the charged particle. Faraday’s law and the condition that there are no magnetic monopoles are obtained from the expressions for the electric and magnetic fields in terms of the potentials. The simplest possible gauge‐invariant Lagrangian which is quadratic in the electric and magnetic fields is constructed. From the principle of least action Gauss’ law and the Ampere–Maxwell law are obtained.

The direct sensitivity of particle probes to magnetic fields of hot, dense plasmas

Abstract: Diagnostic systems based on the injection of particle beams into hot, dense plasmas are shown to be directly sensitive to confining magnetic fields. In particular, the component of the magnetic vector potential in the direction of an ignorable coordinate of the field geometry can be determined by measuring the velocity of beam particles that undergo ionizing collisions in the plasma.

Apparatus and method for transfer of information by means of a curl-free magnetic vector potential field

Abstract: A system for transmission of information using a curl-free magnetic vector potential radiation field. The system includes current-carrying apparatus for generating a magnetic vector potential field with a curl-free component coupled to apparatus for modulating the current applied to the field generating apparatus. Receiving apparatus includes a detector with observable properties that vary with the application of an applied curl-free magnetic vector potential field. Analyzing apparatus for determining the information content of modulation imposed on the curl-free vector potential field can be established in materials that are not capable of transmitting more common electromagnetic radiation.

Apparatus and method for determination of a receiving device relative to a transmitting device utilizing a curl-free magnetic vector potential field

Abstract: Apparatus for determination of direction using the curl-free magnetic vector potential field. The apparatus includes apparatus for generating a predominantly curl-free magnetic vector potential field with a predetermined vector field spatial orientation. The field receiving apparatus includes a detecting apparatus with observable properties that vary with magnitude and orientation of an applied curl-free magnetic vector potential field. The apparatus can specify a direction of the field generating apparatus. A periodically rotating vector field can specify a path toward the field generating apparatus. The curl-free magnetic vector potential field can be established in conducting and opaque materials which are not capable of transmitting normal electromagnetic radiation.

Apparatus and method for modulation of a curl-free magnetic vector potential field

Abstract: Apparatus for producing and modulating a magnetic vector potential field having a substantially curl-free component. Detection and demodulation of the curl-free component of the magnetic vector potential field using a Josephson junction device are described of the curl-free magnetic vector field. Examples of modulation of the curl-free magnetic vector field suitable for detection and demodulation by the Josephson junction device are disclosed.

Apparatus and method for demodulation of a modulated curl-free magnetic vector potential field

Abstract: A system for determining the modulation imposed on a curl-free magnetic vector potential field. The system includes apparatus for detecting the curl-free magnetic vector potential field component by means of a Josephson junction. The magnetic vector potential field interacts with the Josephson junction by varying the phase of the argument of the sine function which determines the Josephson junction current. The output signals of the Josephson junction are coupled to apparatus that can determine the modulation of the detected field. Because the magnitude of the change in the detected curl-free vector potential field causes a proportional change in the phase of the Josephson junction current, the modulation of the field can be established.

Magnetic press machine

Abstract: PURPOSE:To shroten the processing time and enhance the magnetic characteristics of magnetic material, by casuing the impact magnetic field to act on the mold filler powder in pulse behavior. CONSTITUTION:An excitation power source circuit to generate impact magnetic field to the mold filler powder is constituted with a coil 7, an impact accumulator 8 charged by DC power source 9, and a start switch 10 inserted in a discharge circuit. In this circuit constitution, discharge by the accumulator 8 is completely in a short time, and a large current of a large crest value flows instantly to run into the coil 7 by means of the start switch 10. The coil 7 generates an impact magnetic field of large magnetic potential inclination dH/dt and large magnetic field strength H in proportion to the current, which acts on the powder to be pressed. Receiving a magnetic drive by this powerful magnetic field, the magnetic power is assorted in the crystal axes, so that arraying and arranging may be facilitated. Hence, the intended magnetic press may be completed at high efficiency.

Eddy-current losses computation in the armature slot- bars of a turbogenerator fitted up with superconducting field winding

Abstract: This paper describes a fast computing method of determining the losses due to the eddy currents which take place in the armature slot-bars of a turbogenerator provided with superconducting field winding. Since in such kind of machines there is no need for an iron structure in the rotor and in the stator, the tangential component of magnetic flux density in the armature winding air space turns out to be of the same magnitude as the radial one. By using the magnetic vector potential formulation, a computer program worked out by the authors is used to determine both the radial and tangential component of the magnetic flux density due to the excitation current. It is found that the total Joule losses can be expressed in the form of the asymptotic series replacing the resulting Kelvin functions and an approximate formula is derived by truncating the asymptotic series to the first term. The total amount of Joule losses per unit length in an elemental armature conductor of a two-pole three-phase turbogenerator is computed employing this technique which takes into account both magnetic flux density components along with their harmonic content. The eddy-current losses are found by comparing the actual Joule losses with their computed d.c. value.

Concept evaluation: Field feedback computation of electromagnetic scattering

Abstract: : A new method of numerical solution for time-harmonic field scattering problems involving inhomogeneous bodies of revolution is presented. A simple single-loop multiport feedback system is driven by the incident field. The forward path transfer matrix, found by use of the finite-element method, translates the total near-field into the body-surface field. The feedback path matrix is established by the magnetic vector potential formulation; it translates the body-surface currents into the scattered near-field. The thin-wire scattering problem is formulated in terms of this field feedback method. Results of this computation are compared in graphical form to those found by Hallen's integral equation solution of the scattering problem for several cases of interest. (Author)

Determination of efficiencies, loss mechanisms, and performance degradation factors in chopper controlled dc vehical motors. Section 2: The time dependent finite element modeling of the electromagnetic field in electrical machines: Methods and applications

Abstract: The time dependent solution of the magnetic field is introduced as a method for accounting for the variation, in time, of the machine parameters in predicting and analyzing the performance of the electrical machines. The method of time dependent finite element was used in combination with an also time dependent construction of a grid for the air gap region. The Maxwell stress tensor was used to calculate the airgap torque from the magnetic vector potential distribution. Incremental inductances were defined and calculated as functions of time, depending on eddy currents and saturation. The currents in all the machine circuits were calculated in the time domain based on these inductances, which were continuously updated. The method was applied to a chopper controlled DC series motor used for electric vehicle drive, and to a salient pole sychronous motor with damper bars. Simulation results were compared to experimentally obtained ones.