Topic

# Lorentz force

About: Lorentz force is a research topic. Over the lifetime, 5797 publications have been published within this topic receiving 83080 citations. The topic is also known as: electromagnetic force & Coulomb-Lorentz force.

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Bell Labs

^{1}TL;DR: In this paper, the authors show that the mechanism of flux creep is thermally activated motion of bundles of flux lines, aided by the Lorentz force, over free energy barriers coming from the pinning effect of inhomogeneities, strains, dislocations, or other physical defects.

Abstract: Previous investigations of the critical state of the hard superconductor have defined it in terms of constants alpha and B/sub O/; alpha (T) = J/sub cr/ (B/sub cr/ + B/sub 0/). If the current density J or the field B is increased beyond the critical values, a process called flux creep'' sets in, and flux leaks through the material and returns it to the critical state. alpha (T) is a structure-sensitive constant of the material. A theory is presented to show that this behavior of alpha can be explained by assuming that the mechanism of flux creep is thermally activated motion of bundles of flux lines, aided by the Lorentz force, over free energy barriers coming from the pinning effect of inhomogeneities, strains, dislocations, or other physical defects. The theory also explains B/sub 0/, and predicts time relaxation behavior similar to those of magnetic aftereffect and some forms of plastic creep. (H.D.R.)

1,373 citations

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TL;DR: In this paper, an attempt is made to obtain one-fluid hydromagnetic equations by expanding in the ion mass to charge ratio, but the results show that the electron degrees of freedom can be replaced by a macroscopic current, but true hydrodynamics still does not result unless some special circumstance suppresses the transport of pressure along magnetic lines of force.

Abstract: Starting from the Boltzmann equation for a completely ionized dilute gas with no interparticle collision term but a strong Lorentz force, an attempt is made to obtain one-fluid hydromagnetic equations by expanding in the ion mass to charge ratio. It is shown that the electron degrees of freedom can be replaced by a macroscopic current, but true hydrodynamics still does not result unless some special circumstance suppresses the transport of pressure along magnetic lines of force. If the longitudinal transport of pressure is ignored, a set of self-contained one-fluid hydromagnetic equations can be found even though the pressure is not a scalar.

1,240 citations

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TL;DR: In this article, expressions for flux-pinning in type II superconductors are derived from considerations of the nature of the interaction between individual flux-lines and pinning-centres, and of the geometry of th...

Abstract: Expressions for flux-pinning in type II superconductors are derived from considerations of the nature of the interaction between individual flux-lines and pinning-centres, and of the geometry of th...

908 citations

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Bell Labs

^{1}TL;DR: In this paper, the authors investigated persistent currents induced in hard superconductors (HSC) by measuring the resulting magnetic effects and found that the Lorentz force plays a crucial role in determining the critical current density and the critical persistent currents in decay with a measurable rate.

Abstract: Persistent currents induced in hard superconductors (HSC) were investigated by measuring the resulting magnetic effects. The tubular HSC examined were Nb powder, Nb/sub 3/Sn, and 3Nb- Zr samples of uniform wall thickness and length large compared to the diameter. Experimental evidence is presented that in HSC the Lorentz force plays a crucial role in determining the critical current density and the critical persistent currents in decay with a measurable rate. (H.D.R.)

901 citations

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TL;DR: This work experimentally realizes an optically synthesized magnetic field for ultracold neutral atoms, which is evident from the appearance of vortices in the authors' Bose–Einstein condensate, and uses a spatially dependent optical coupling between internal states of the atoms, yielding a Berry’s phase sufficient to create large synthetic magnetic fields.

Abstract: Neutral atomic Bose condensates and degenerate Fermi gases have been used to realize important many-body phenomena in their most simple and essential forms, without many of the complexities usually associated with material systems However, the charge neutrality of these systems presents an apparent limitation-a wide range of intriguing phenomena arise from the Lorentz force for charged particles in a magnetic field, such as the fractional quantum Hall effect in two-dimensional electron systems The limitation can be circumvented by exploiting the equivalence of the Lorentz force and the Coriolis force to create synthetic magnetic fields in rotating neutral systems This was demonstrated by the appearance of quantized vortices in pioneering experiments on rotating quantum gases, a hallmark of superfluids or superconductors in a magnetic field However, because of technical issues limiting the maximum rotation velocity, the metastable nature of the rotating state and the difficulty of applying stable rotating optical lattices, rotational approaches are not able to reach the large fields required for quantum Hall physics Here we experimentally realize an optically synthesized magnetic field for ultracold neutral atoms, which is evident from the appearance of vortices in our Bose-Einstein condensate Our approach uses a spatially dependent optical coupling between internal states of the atoms, yielding a Berry's phase sufficient to create large synthetic magnetic fields, and is not subject to the limitations of rotating systems With a suitable lattice configuration, it should be possible to reach the quantum Hall regime, potentially enabling studies of topological quantum computation

869 citations