A quadrupolar-solenoidal electro-magnet creates more nearly parallel field lines and a coaxial magnetic bias resulting in allowing deeper magnetic field penetration with reduced depth attenuation and greater focality than available with the commonly used Figure-8 dual toroidal magnets, thereby overcoming the trade-offs inherent in currently standard practice for transcranial magnetic stimulation magnetic field generation and the proposed transcranial magnetic stimulation coil designs. When quadrupole electro-magnets are used with solenoids, the axis of the electro-magnets can be focused at the target within the desired tissue and at greater depth.
