3D Modelling of the Currents Induced in a Superconducting Linear Halbach array

The combination of permanent magnets in a socalled
“Halbach array” is a commonly used method to generate
large magnetic flux density gradients with a compact system
and is of great interest in applications requiring a magnetic
force. The maximum magnetic force achievable with such systems
is, however, limited by the saturation magnetization of the
permanent magnets used. A superconducting Halbach array
could be an attractive alternative generating larger field gradients
as trapped field superconducting magnets do not suffer from an
intrinsic saturation of their magnetization. In this context, a 3D
finite-element model is developed in the GetDP environment in
order to investigate numerically the current density distribution
in three pre-magnetized cubic superconductors assembled in a
Halbach array configuration. The simulation shows that during
the assembly of the array, the approaching peripheral samples
induce a reorganisation of the current density distribution in
the central one. This modification results in a reduction of
the magnetic flux density generated above the centre of the
configuration, which is expected to limit the performance of the
system. The finite-element predictions are confronted both to
analytical calculations and to experimental results, which confirm
this picture.