dipoolmagnets

Dipole magnets are magnets characterized by two opposite magnetic poles, north and south, separated by a finite distance. The simplest example is a bar magnet; in practice, many dipole magnets are electromagnets with a coil wound around a magnetic yoke or permanent magnets with fixed magnetization. Each dipole possesses a magnetic moment, a vector that indicates the strength and direction of the field it tends to generate.

Far from a dipole, the magnetic field approximates that of an ideal dipole, decreasing roughly with the cube of distance. The field lines emerge from the north pole and loop to the south pole, with the strongest flux near the poles. In accelerator and beamline technology, dipole magnets provide a uniform bending field to steer charged particles along curved trajectories.

Dipole magnets can be either permanent magnets or electromagnets. Electromagnets use iron yokes and carefully shaped pole pieces, with the field controlled by the coil current; permanent magnets rely on intrinsic magnetization of materials such as NdFeB or SmCo. Design goals include maximizing field in the gap, minimizing fringe fields, and managing saturation and temperature dependence.

Applications span science and industry. In physics facilities, dipole magnets bend particle beams in accelerators and define reference fields in diagnostic systems. In research and medical settings, large electromagnets generate uniform fields for imaging and spectroscopy. Magnetic dipoles also appear in electric machines, where rotor magnets create the primary dipole field that underpins operation.