Particle beam
A particle beam is a stream of charged or neutral particles other than photons. In particle accelerators, these particles can move with a velocity close to the speed of light. There is a difference between the creation and control of charged particle beams and neutral particle beams, as only the first type can be manipulated to a sufficient extent by devices based on electromagnetism. The manipulation and diagnostics of charged particle beams at high kinetic energies using particle accelerators are main topics of accelerator physics.
Manipulation
Acceleration
Charged beams may be further accelerated by use of high resonant, sometimes also superconducting, microwave cavities. These devices accelerate particles by interaction with an electromagnetic field. Since the wavelength of hollow macroscopic, conducting devices is in the radio frequency band, the design of such cavities and other RF devices is also a part of accelerator physics.More recently, plasma acceleration has emerged as a possibility to accelerate particles in a plasma medium, using the electromagnetic energy of pulsed high-power laser systems or the kinetic energy of other charged particles. This technique is under active development, but cannot provide reliable beams of sufficient quality at present.
Guidance
In all cases, the beam is steered with dipole magnets and focused with quadrupole magnets. With the end goal of reaching the desired position and beam spot size in the experiment.Applications
High-energy physics
High-energy particle beams are used for particle physics experiments in large facilities; the most common examples being the Large Hadron Collider and the Tevatron.Synchrotron radiation
s are employed in synchrotron light sources to produce X-ray radiation with a continuous spectrum over a wide frequency band which is called synchrotron radiation. This X-ray radiation is used at beamlines of the synchrotron light sources for a variety of spectroscopies in order to probe and to characterize the structure and the chemical speciation of solids and biological materials.Particle therapy
Energetic particle beams consisting of protons, neutrons, or positive ions may also be used for cancer treatment in particle therapy.Linear accelerators use electron beam at near speed of light to treat deep cancers in patients. A tungsten/molybdenum target can be moved into the beam to create x-rays to treat surface cancers.