accelerator physics Accelerator physics is a branch of applied physics, concerned with designing, building and operating particle accelerators. As such, it can be described as the study of motion, manipulation and observation of relativistic charged particle beams ...

, a magnetic lattice is a composition of

electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the ...

s at given longitudinal positions around the vacuum tube of a

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for fundamental research in particle ...

, and thus along the path of the enclosed

charged particle beam A charged particle beam is a spatially localized group of electrically charged particles that have approximately the same position, kinetic energy (resulting in the same velocity), and direction. The kinetic energies of the particles are much lar ...

. The lattice properties have a large influence on the properties of the particle beam, which is shaped by magnetic fields. Lattices can be closed (cyclic accelerators like the

synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed p ...

s), linear (for

linac A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear beam ...

facilities) and are also used at interconnects between different accelerator structures (transfer beamlines). Such a structure is needed for focusing of the particle beam in modern, large-scale facilities. Its basic elements are

dipole magnet A dipole magnet is the simplest type of magnet. It has two poles, one north and one south. Its magnetic field lines form simple closed loops which emerge from the north pole, re-enter at the south pole, then pass through the body of the magnet. T ...

s for deflection,

quadrupole magnet Quadrupole magnets, abbreviated as Q-magnets, consist of groups of four magnets laid out so that in the planar multipole expansion of the field, the dipole terms cancel and where the lowest significant terms in the field equations are quadrupole. ...

s for

strong focusing In accelerator physics strong focusing or alternating-gradient focusing is the principle that, using sets of multiple electromagnets, it is possible to make a particle beam simultaneously converge in both directions perpendicular to the direction ...

sextupole magnet A sextupole magnet (also known as a hexapole magnet) consist of six magnetic poles set out in an arrangement of alternating north and south poles arranged around an axis. They are used in particle accelerators for the control of chromatic aberra ...

s for correction of

chromatic aberration In optics, chromatic aberration (CA), also called chromatic distortion and spherochromatism, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wave ...

, and sometimes even higher order magnets. Many lattices are composed of identical substructures or cells, which denote a special magnet arrangement that may reoccur at several positions along the path. While almost all accelerator lattices that are in use in modern facilities are specifically designed for their particular purpose, the lattice development starts at a given ideal lattice design with high periodicity and mostly using only one base cell. The most widely known are * FODO lattice, which is the simplest possible Strong focusing lattice * Chasman–Green lattice {{Accelerator-stub

References

Accelerator physics