An apparatus for magnetic field compression includes a toroid and a plurality of separate coils wound around the toroid. The coils are spaced about a circumference of the toroid and each coil generates a magnetic field in response to electric current flowing in the coil. The toroid and a group of the coils each include a size that respectively gradually decreases over a predetermined portion of the toroid. The magnetic field is compressed or has a highest magnetic flux density proximate a central region of the coils around the toroid.