No abstract available

[en] Flux pumps have been investigated for a number of years as a means of powering large magnets. In this paper a simple system consisting of one, or two, loops under a moving magnet is analysed theoretically. It is a circuit model using only Faraday’s law of induction and the V–I characteristic. However in contrast to distributed systems with tapes or sheets, the performance can be calculated from first principles and the results expressed in a few simple formulae. With one loop and a constant I _c no significant flux pumping occurs if the n value is large. However if I _c is a function of B the saturation current is approximately I _c1–I _c2 where these are the critical currents in zero field and under the magnet respectively. Nearly all the magnet flux is transferred in each cycle so the number of cycles needed to reach saturation is about 2(I _c1–I _c2) L ₂/ϕ where L ₂ is the inductance of the load magnet and ϕ the flux of the moving magnet. The loss is ϕI _c joules on each pass and the mean loss about ϕI _c /T watts, where T is the time of a pass. Adding another loop makes an even better flux pump even if I _c is constant. Now the saturation current is I _c and the number of cycles about 2I _c L ₂ /ϕ. If the current starts above the saturation value it decreases to saturation over a similar number of cycles, more of a ‘flux suck’ than a flux pump. (paper)

[en] This paper describes an improved method for the modeling of axial and radial eccentricities in induction motors (IM). The model is based on an extension of the modified winding function approach (MWFA) which allows for all harmonics of the magnetomotive force (MMF) to be taken into account. It is shown that a plane view of IM gets easily the motor inductances and reduces considerably the calculation process. The described technique includes accurately the slot skewing effect and leads to pure analytical expressions of the inductances in case of radial eccentricity. In order to model the static, dynamic or mixed axial eccentricity, three suitable alternatives are explained. Unlike the previous proposals, the discussed alternatives take into account all the harmonics of the inverse of air-gap function without any development in Fourier series. Simulation results as well as experimental verifications prove the usefulness and the effectiveness of the proposed model.

[en] We study a system of two RLC oscillators coupled through a variable mutual inductance. The system is interesting because it exhibits some peculiar features of coupled oscillators: (i) there are two natural frequencies; (ii) in general, the resonant frequencies do not coincide with the natural frequencies; (iii) the resonant frequencies of both oscillators differ; (iv) for certain choices of parameters, there is only one resonant frequency, instead of the two expected

[en] This paper presents the numerical modeling (using the Finite Difference Method-FDM, and Finite Element Method- FEM) of the electromagnetic and thermal fields in a steel piece heated up inside an induction crucible furnace, and the experimental validations. Both modeling have been validated experimentally, so they can be used in designing the equipment and in the numerical control of induction heating process. The program based on FDM can be used in the first stage of designing due to the reduced CPU time. In this stage the inductor parameters and heating time can be estimated, and a study of the influence of diverse factors upon the heating process can be achieved. The FLUX 2D program can be used in the optimization stage, because it allows a more thorough analysis of the phenomena. (Author) 29 refs

[en] Role of self-inductance in superconducting quantum interference device (SQUID) charge qubit is considered. It is found that when an SQUID charge qubit is coupled to a quantum LC resonator, the SQUID voltage operator equation is modified in accompanying with the modification of operator Faraday equation describing the inductance. It is shown that when the extra energy is applied to the junction, the mean phase will be squeezed according to a damping factor

[en] Introductory electromagnetism courses usually start the exposition of Faraday's induction law discussing the ordinary situation in which the induced electromotive force arises due to the motion of a resistive circuit in the presence of a magnetic field. In this paper we extend the discussion to cover the application of Faraday's law to perfectly conducting as well as to superconducting circuits rather than resistive circuits. While in resistive circuits the work done by the external agent is transformed into heat, the situation is quite different in either perfectly conducting or superconducting circuits. In superconducting circuits the work done by the external agent is used to accelerate the charge carriers, and magnetic energy is transferred from the magnet's magnetic field to the circuit where it is stored in the trapped field. The total flux trapped inside a perfectly conducting circuit is initially conserved but decays with time. In superconducting circuits what is conserved is a quantity called 'fluxoid'. The overall problem is very instructive since it employs the concept of self-inductance also, and it may be used to increase the student's interest on the important topic of superconductivity

[en] A resonant structure, induced by parasitic capacitance and inductance, was studied in a solid state pulsed power modulator for an induction synchrotron. Parasitic capacitors form a resonant structure in a switching arm with a self-inductance of the modulator circuit. The resonance induces a ringing in an acceleration voltage, causing an extra force to particles in the longitudinal direction. This effect is serious around the transition energy, because a mismatch exists between the particle distribution before the transition and a bucket shape after the transition. It was found that the most promising way to avoid this situation is to reduce the self-inductance of the modulator circuit. By sufficient reduction, an output waveform without any serious deterioration of flatness has been achieved by a newly developed power modulator

[en] The US is developing the physics and technology of induction accelerators for heavy-ion beam-driven inertial fusion. The recirculating induction accelerator repeatedly passes beams through the same set of accelerating and focusing elements, thereby reducing both the length and gradient of the accelerator structure. This promises an attractive driver cost, if the technical challenges associated with recirculation can be met. Point designs for recirculator drivers were developed in a multi-year study by LLNL, LBNL, and FM Technologies, and that work is briefly reviewed here. To validate major elements of the recirculator concept, we are developing a small (4-5-m diameter) prototype recirculator which will accelerate a space-charge-dominated beam of K⁺ ions through 15 laps, from 80 to 320 keV and from 2 to 8 mA. Transverse beam confinement is effected via permanent-magnet quadrupoles; bending is via electric dipoles. This ''Small Recirculator'' is being developed in a build-and-test sequence of experiments. An injector, matching section, and linear magnetic channel using seven half-lattice periods of permanent-magnet quadrupole lenses are operational. A prototype recirculator half-lattice period is being fabricated. This paper outlines the research program, and presents initial experimental results

No abstract available