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A '''particle beam''' is a stream of [[charged particle|charged]] or [[neutral particle]]s |
A '''particle beam''' is a stream of [[charged particle|charged]] or [[neutral particle]]s. In particle-accelerators these particles can move with a velocity close to the [[speed of light]]. |
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There is a difference between the creation and control of [[charged particle beam]]s 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 accelerator]]s are main topics of [[accelerator physics]]. |
There is a difference between the creation and control of [[charged particle beam]]s 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 accelerator]]s are main topics of [[accelerator physics]]. |
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Aparticle beam is a stream of chargedorneutral particles. 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.
Charged particles such as electrons, positrons, and protons may be separated from their common surrounding. This can be accomplished by e.g. thermionic emissionorarc discharge. The following devices are commonly used as sources for particle beams:
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.
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.
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.
Electron beams are employed in synchrotron light sources to produce electromagnetic radiation with a continuous spectrum over a wide frequency band which is called synchrotron radiation. This radiation may be used at beamlines of the synchrotron storage ring for a variety of experiments.
Energetic particle beams consisting of protons, neutrons, or positive ions (also called particle microbeams) may also be used for cancer treatment in particle therapy.
Many phenomena in astrophysics are attributed to particle beams of various kinds. Perhaps of these the most iconic is the solar Type III radio burst, due to a mildly relativistic electron beam.
Though particle beams are perhaps most famously employed as directed-energy weapon systems in science fiction, the U.S. Advanced Research Projects Agency started work on particle beam weapons in 1958.[3] The general idea of such weaponry is to hit a target object with a stream of accelerated particles with high kinetic energy, which is then transferred to the molecules of the target. The power needed to project a high-powered beam of this kind surpasses the production capabilities of any standard battlefield powerplant,[3] thus such weapons are not anticipated to be produced in the foreseeable future.
Proton beams such as "laser-generated proton beams"[4] may be used as a way to generate hydrogen for the production of water on planets, such as Mars, where hydrogen is scarce and oxygen is relatively rich in the atmosphere in the form of CO2. In a Mars economy where the initial cost of water would be very high due to expense of transport from Earth to Mars, a machine that can generate hydrogen using nuclear alchemy, i.e., conversion of titanium into hydrogen ions using petawatt lasers, for example, is economical and may actually be cheaper and faster than transporting water from Earth to Mars if the technology is fully developed.[5]
