Issue Eur. Phys. J. Appl. Phys. Volume 32, Number 3, December 2005 Page(s) 167 - 175 Section Magnetism and Superconductivity DOI 10.1051/epjap:2005074 Published online 26 October 2005

Eur. Phys. J. Appl. Phys. 32, 167-175 (2005)
DOI: 10.1051/epjap:2005074

Magnetic compensation of gravity forces in liquid/gas mixtures: surpassing intrinsic limitations of a superconducting magnet by using ferromagnetic inserts

L. Quettier^{1, 2}, H. Félice^{1, 2}, A. Mailfert³, D. Chatain⁴ and D. Beysens<sup>4

1</sup>  GREEN, INPL-Nancy, 2 Av. de la Forêt de Haye, 54516 Vandoeuvre, France
²  SACM, CEA-Saclay, 91191 Gif-sur-Yvette, France
³  LEM, INPL-Nancy, 2 Av. de la Forêt de Haye, 54516 Vandoeuvre, France
⁴  SBT, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex, France

lionel.quettier@cea.fr

(Received: 17 September 2004 / Received in final form: 25 April 2005 / Accepted: 9 August 2005 / Published online: 26 October 2005)

Abstract
Magnetic compensation of gravity forces, similar to the space conditions of "microgravity", needs the production of a uniform magnetic force field. We derive here a basic mathematical result that shows the impossibility to establish exact gravity compensation in a finite volume. The imperfection of compensation can be, however, quantified and a relation is derived between homogeneity accuracy and compensation volume in a cylindrical symmetry. We study how the use of inserts made of saturated ferromagnetic materials can modify the homogeneity of magnetic force field. In order to illustrate this result, an iron insert has been numerically calculated for the particular case of gravity compensation of H₂ in a 10 T superconducting coil. An experimental test has been carried out on a H₂ vapour bubble very close to its gas-liquid critical point. Near the critical point the gas-liquid interfacial tension is vanishing, then any bubble deformation from the ideal spherical shape reveals the non-homogeneities in the magnetic compensation force.

PACS
85.70.Rp - Magnetic levitation, propulsion and control devices.
84.71.Ba - Superconducting magnets; magnetic levitation devices.
64.60.Fr - Equilibrium properties near critical points, critical exponents.
68.03.-g - Gas-liquid and vacuum-liquid interfaces.

© EDP Sciences 2005

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