  In this paper a novel compressor for static magnetic fields is proposed based
on finite embedded transformation optics. When the DC magnetic field passes
through the designed device, the magnetic field can be compressed inside the
device. After it passes through the device, one can obtain an enhanced static
magnetic field behind the output surface of the device (in a free space
region). We can also combine our compressor with some other structures to get a
higher static magnetic field enhancement in a free space region. In contrast
with other devices based on transformation optics for enhancing static magnetic
fields, our device is not a closed structure and thus has some special
applications (e.g., for controlling magnetic nano-particles for gene and drag
delivery). The designed compressor can be constructed by using currently
available materials or DC meta-materials with positive permeability. Numerical
simulation verifies good performance of our device.
