Multipole magnet
Multipole magnets are magnets built from multiple individual magnets, typically used to control beams of charged particles. Each type of magnet serves a particular purpose.
- Dipole magnets are used to bend the trajectory of particles
- Quadrupole magnets are used to focus particle beams
- Sextupole magnets are used to correct for chromaticity introduced by quadrupole magnets [1]
Magnetic field equations
The magnetic field of an ideal multipole magnet in an accelerator is typically modeled as having no (or a constant) component parallel to the nominal beam direction ( direction) and for the transverse components can be written as complex numbers:[2]
where and are the coordinates in the plane transverse to the nominal beam direction. is a complex number specifying the orientation and strength of the magnetic field. and are the components of the magnetic field in the corresponding directions. Fields with a real are called 'normal' while fields with purely imaginary are called 'skewed'.
n | name | magnetic field lines | example device |
---|---|---|---|
1 | dipole | | |
2 | quadrupole | | |
3 | sextupole | | |