Optimization of levitation forces

In this contribution we present a systematic approach to the calculation of levitation forces in plane-parallel (infinitely extended in one direction) arrangements of permanent magnets and superconductors. Starting from an ex tremely idealized geometry with a very simple expression for the levitation force, we go step by step to more realistic arrangements and present the c orrections in the force equations. In particular, magnet configurations wit h an increased field gradient which allow a higher stiffness are investigat ed. Finally, numerical calculations are presented which show the dependance of the levitation force on the size and the critical current density of th e superconductor and the effect of magnet-iron combinations instead of magn ets without iron. The calculations show that the stiffness can be increased by using magnets which consist of several sections with alternating polari ty. However, this improvement can only be used for reduced bearing gaps and increased critical current density. The use of magnet-iron combinations ha s only little advantages.