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Efren Diez-Jimenez Jose-Luis Perez-Diaz 《Physica C: Superconductivity and its Applications》2011,471(1-2):8-11
The torque between a permanent magnet and a toroidal superconductor in the Meissner state is calculated using a model previously proposed based on London’s and Maxwell’s equations. A flip effect on the stable orientation of the magnet as a function of position is demonstrated. At large distances the magnet tends to be perpendicular to the axis of the torus, but when you approach it, at a certain point there is a flip and it tends to be parallel to that axis while being closer than a certain limit. This effect can be easily used as a binary detector for proximity. 相似文献
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It is shown, that a temperature gradient in a superconducting torus should lead to spontaneous generation of magnetic-flux quanta inside the ring. This effect is much weaker in a torus than in a hollow superconducting cylinder of comparable dimensions. The flux jumps and related hysteresis effects are predicted and the connection with experiment is discussed. 相似文献
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J.L. Perez-Diaz J.C. Garcia-Prada J.A. Diaz-Garcia 《Physica C: Superconductivity and its Applications》2009,469(7-8):252-255
The force and torque exerted by a magnetic dipole on a superconducting ring (or hollow cylinder) in the Meissner state at arbitrary position and orientation are calculated using a Maxwell-London model previously proposed by the authors. The center of the ring is an unstable equilibrium point for the magnet. At this point the ring tends to align the magnet but tends to expel it for any small axial deviation from the center. There is also a non-monotonic and oscillatory dependence of the forces and torques on the position caused by the finiteness of the ring and a torque arises when the magnet is displaced both radially and axially from the center of the cylinder which corresponds to the experimental data. Therefore, the use of a magnet in a Meissner superconducting ring as a self aligning bearing requires a centered position and that the axial unstability to be compensated by additional mechanical means. 相似文献
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V.V. Nemoshkalenko E.H. Brandt A.A. Kordyuk B.G. Nikitin 《Physica C: Superconductivity and its Applications》1990,170(5-6):481-485
The oscillation modes of a small spherical permanent magnet (1.7 mm diameter) above a flat high-Tc superconductor are investigated. From the attenuation and nonlinearity of the vertical oscillation we obtain the viscosity of the vortex lattice and the onset of hysteretic damping, which indicates depinning of flux lines. The shape of the potential well in which the magnet floats, rotates, and oscillates is found to depend on the magnetic history of the superconductor. 相似文献
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This paper describes a superconducting magnet system for the China Accelerator Driven System (CADS). The magnetic field is provided by one main, two bucking and four racetrack coils. The main coil produces a central field of up to 7 T and the effective length is more than 140 mm, the two bucking coils can shield most of the fringe field, and the four racetrack superconducting coils produce the steering magnetic field. Its leakage field in the cavity zone is about 5× 10-5 T when the shielding material Niobium and cryogenic permalloy are used as the Meissner shielding and passive shielding respectively. The quench calculations and protection system are also discussed. 相似文献
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N. Abdollahi J. Mahmoodi M. Abdollahi A.H. Ghorashi N. Alinejad 《Chinese Journal of Physics (Taipei)》2018,56(2):770-777
In this paper, an equivalent electrical circuit for response of a high-temperature superconductor (HTS) system for arbitrary time varying transport current is considered and as well as an analysis of the generated resistance losses is given. Also, for the pancake coil made with superconducting Bi-2223/AgMg tape, hysteresis behavior on the voltage-current curve is examined as a function of the current rate during ramp up and down at liquid nitrogen temperature. Behavior of voltage versus current is in good agreement with considered theory. 相似文献
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We define a CP violating Dalitz plot asymmetry αas and compare it to the usual CP violating rate asymmetry αsy. Depending on the decay mechanisms, αas can be larger than αsy. We calculate αas, αsy for different models for the decay \(B \to \pi p\bar p\) , using the final state interaction ofp, \(\bar p\) , π to provide the necessary strong interaction interference phase. The values for αas, αsy we find vary between 0.01 and 0.4%. 相似文献
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《中国物理C(英文版)》2015,(5)
A new 7.0 T asymmetric active shield superconducting magnet for Penning traps is proposed in this work. The magnet has two field regions whose homogeneity is better than 0.5 ppm. Linear and nonlinear methods are used for the asymmetric electromagnetic optimization. Stress analysis, mechanical design and a quench protection system design are also introduced in this paper. 相似文献
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N. G. Anishchenko V. V. Bekhterev S. L. Bogomolov P. G. Bondarenko V. F. Boreiko V. I. Datskov S. N. Dmitriev V. M. Drobin A. A. Efremov E. V. Ivanov I. E. Karpunina M. Leporis G. Malinovsky A. S. Nikiforov S. V. Pashchenko Yu. V. Romanov V. V. Seleznev G. P. Tsvineva V. F. Chumakov Yu. A. Shishov N. Yu. Yazvitsky B. I. Yakovlev 《Physics of Particles and Nuclei Letters》2006,3(1):27-36
A superconducting magnet system (SMS) for the multicharged ion source DECRIS-SC was designed and manufactured at the Joint Institute for Nuclear Research. Successful tests of the SMS were conducted in late 2003 and early 2004. The peculiarities of this system are stipulated by the use of a cryocooler 1 W in power for the cryostating of the magnet and also by the special configuration of the magnetic field demanded for the source of ions. Four coils ensure the induction of a magnetic field on the axes of the source of up to 3 T (the stopper ratio of ~6), which considerably extends the possibilities of the ion source from the point of view of producing intense highly charged ion beams. The problem of compensating the large forces of interaction between the coils and surrounding iron yoke in this magnet has been successfully solved, and a reliable suspension of the magnet in a cryostat realized. To compound the windings, which work in vacuum at indirect cryostating, prepreg (thermosetting fiberglass fabric impregnated with epoxide) is used. A new technology of superconducting magnet protection has been applied with the help of sectionalized windings, using passive elements of protection based on “cold” diodes and resistances. A new technology of active protection has also been applied, with normal zone detectors and heaters. 相似文献
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K. Yokoyama T. Oka K. Noto 《Physica C: Superconductivity and its Applications》2011,471(21-22):901-904
A pulsed-filed magnetization (PFM) is an important technique for industrial applications of superconducting bulk magnets, and several advanced PFM methods are proposed to enhance the trapped field. In the well-known IMRA method, the channel through the magnetic flux is formed by the flux flow caused by heat generation when applying the strong pulsed-field, and the magnetic flux is made to penetrate into the bulk through the channel in the following pulse application. On the other hand, large applied field leads to large heat generation, and, therefore, the trapped field is decreased greatly.This paper proposes an effective magnetizing method in which the channel composed of magnetic field is artificially formed by field-cooling (FC) using a permanent magnet and the magnetic flux by PFM is induced to the channel. To confirm the validity of this method, the bulk was magnetized by FC using Nd–Fe–B magnets of the rectangular and the ring shapes, and thereafter, a pulsed-field of 6.2 T was applied. As a result, the trapped field of the bulk magnetized by FC using the ring magnet was increased by about 20–25% as compared with that of the conventional PFM, and, moreover, it was observed that the channel was formed partially by measurement of the magnetic field distribution. 相似文献