Topic
Levitron
About: Levitron is a research topic. Over the lifetime, 70 publications have been published within this topic receiving 912 citations.
Papers published on a yearly basis
Papers
TL;DR: In this article, it was shown that stable zones always exist on the axis of a field with rotational symmetry, and include the inflection point of the magnitude of the field.
Abstract: Diamagnetic objects are repelled by magnetic fields. If the fields are strong enough, this repulsion can balance gravity, and objects levitated in this way can be held in stable equilibrium, apparently violating Earnshaw's theorem. In fact Earnshaw's theorem does not apply to induced magnetism, and it is possible for the total energy (gravitational+magnetic) to possess a minimum. General stability conditions are derived, and it is shown that stable zones always exist on the axis of a field with rotational symmetry, and include the inflection point of the magnitude of the field. For the field inside a solenoid, the zone is calculated in detail; if the solenoid is long, the zone is centred on the top end, and its vertical extent is about half the radius of the solenoid. The theory explains recent experiments by Geimet al, in which a variety of objects (one of which was a living frog) was levitated in a field of about 16 T. Similar ideas explain the stability of a spinning magnet (Levitron TM ) above a magnetized base plate. Stable levitation
505 citations
TL;DR: In this paper, the authors reported the observation of a reverse electron current excited by the injection of fast neutral atoms into a toroidal plasma, and the induced electron current was measured in the Culham Superconducting Levitron as a function of electron temperature.
Abstract: We report the observation of a reverse electron current excited by the injection of fast neutral atoms into a toroidal plasma. The induced electron current was measured in the Culham Superconducting Levitron as a function of electron temperature and found to be larger than that calculated using a shifted Maxwellian electron distribution.
25 citations
TL;DR: In this paper, the two-dimensional eigenvalue equation for electrostatic drift waves in axisymmetric toroidal geometry is investigated, and a model version, relevant for the Culham levitron, is constructed, and solutions are obtained when poloidal variations of shear, curvature and magnetic field are included.
Abstract: The two-dimensional eigenvalue equation for electrostatic drift waves in axisymmetric toroidal geometry is investigated. A model version, relevant for the Culham levitron, is constructed, and solutions are obtained when poloidal variations of shear, curvature and magnetic field are included. General criteria for the existence of localized undamped eigenmodes are established, and it is found that for sufficiently strong modulations of various equilibrium quantities, the stabilizing effect of magnetic shear is completely nullified. Equivalent criteria are obtained for the large-aspect-ratio tokamak. Investigation of the electron Landau resonance in strongly modulated magnetic fields indicates that for electron drift waves the growth rate will be only logarithmically weaker than in the equivalent slab-model calculation.
22 citations
1 Jan 2004
TL;DR: An explicit second order reversible Poisson integrator for symmetric rigid bodies in space (i.e. without a fixed point) is derived by applying a splitting method to the Hamiltonian after reduction by the S1 body symmetry.
Abstract: We derive an explicit second order reversible Poisson integrator for
symmetric rigid bodies in space (i.e. without a fixed point). The integrator
is obtained by applying a splitting method to the Hamiltonian
after reduction by the S1 body symmetry. In the particular case of a
magnetic top in an axisymmetric magnetic field (i.e. the Levitron) this
integrator preserves the two momentum integrals. The method is used
to calculate the complicated boundary of stability near a linearly stable
relative equilibrium of the Levitron with indefinite Hamiltonian.
16 citations
TL;DR: In this paper, the first horizontal axis Levitron was reported and the principle of gentle superposition of two traps, the micro-precessional and the macro-trap, was explained.
Abstract: After a brief history of the Levitron, the first horizontal axis Levitron is reported. Because it is easy to operate, it lends itself to educational physics experiments and analogies. Precession and nutation are visualized by reflecting the beam from a laser pointer off the 'spignet'. Precession is fundamental to nuclear magnetic resonance, magnetic resonance imaging, particle traps and the movement of bodies in space. Longitudinal and lateral bounce behaviour is explained via 'the principle of gentle superposition' of two traps: the micro-precessional and the macro-trap. Theory is initiated. Scaling experiments are mentioned. Industrial applications might follow.
12 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2019 | 1 |
| 2017 | 1 |
| 2016 | 3 |
| 2015 | 4 |
| 2014 | 6 |