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Particle beam
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{{Short description|Stream of charged, or less frequently neutral particles}} {{Refimprove|date=November 2008}} A '''particle beam''' is a stream of [[charged particle|charged]] or [[neutral particle]]s. In [[Particle accelerator|particle accelerators]], these particles can move with a velocity close to the [[speed of light]].<ref>{{Cite web |title=LHC the guide FAQ {{!}} CERN |url=https://home.cern/resources/brochure/knowledge-sharing/lhc-facts-and-figures |access-date=2025-01-29 |website=home.cern}}</ref> 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]]. ==Sources== [[Charged particles]] such as [[electron]]s, [[positron]]s, and [[proton]]s may be separated from their common surroundings. This can be accomplished by processes such as [[thermionic emission]] or [[arc discharge]]. The following devices are commonly used as sources for particle beams: * [[Ion source]] * [[Cathode-ray tube]], or more specifically in one of its parts called [[electron gun]]. This is also part of traditional television and computer screens. * [[Photocathode]]s may also be built in as a part of an [[electron gun]], using the [[photoelectric effect]] to separate particles from their substrate.<ref>T. J. Kauppila et al. (1987), ''A pulsed electron injector using a metal photocathode irradiated by an excimer laser'', Proceedings of Particle Accelerator Conference 1987</ref> * [[Neutron]] beams may be created by energetic [[proton beam]]s which impact on a target, e.g. of [[beryllium]] material. (see article [[Particle therapy]]) * Bursting a petawatt laser onto a [[titanium]] foil to produce a proton beam<!-- and also water, and organic residue on the residual titanium foil as a side effect -->.<ref>[https://www.nextbigfuture.com/2018/04/petawatt-proton-beams-at-lawrence-livermore.html Petawatt proton beams at Lawrence Livermore]</ref> ==Manipulation== ===Acceleration=== {{See also|Accelerator physics|Superconducting radio frequency}} Charged beams may be further accelerated by use of high resonant, sometimes also [[superconducting]], [[microwave cavity|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]] (RF) 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 (physics)|plasma]] medium, using the [[Radiant energy|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 magnet]]s and focused with [[quadrupole magnet]]s. With the end goal of reaching the desired position and beam spot size in the experiment. ==Applications== ===High-energy physics=== {{See also|Particle collider|Large Hadron Collider}} 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=== {{Main|Synchrotron light source|Synchrotron radiation}} [[Electron beam]]s are employed in [[synchrotron light source]]s to produce [[X-ray|X-ray radiation]] with a continuous [[spectrum]] over a wide [[frequency]] band which is called [[synchrotron radiation]]. This X-ray radiation is used at [[beamline]]s of the synchrotron light sources for a variety of [[spectroscopy|spectroscopies]] ([[XAS]], [[XANES]], [[EXAFS]], [[X-ray fluorescence|''μ''-XRF]], [[X-ray crystallography|''μ''-XRD]]) in order to probe and to characterize the structure and the chemical speciation of solids and biological materials. ===Particle therapy=== {{Main|Particle therapy}} Energetic particle beams consisting of [[protons]], [[neutrons]], or positive [[ions]] (also called particle [[microbeam]]s) 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. ===Astrophysics and space physics=== Many phenomena in astrophysics are attributed to particle beams of various kinds.<ref>{{cite journal |author1=[[Anthony Peratt]] |title= The role of particle beams and electrical currents in the plasma universe |journal=Laser and Particle Beams |date=1988 |volume=6 |issue= 3 |pages=471–491 |doi= 10.1017/S0263034600005401 |bibcode= 1988LPB.....6..471P |url=https://plasmacosmology.info/downloads/Peratt_RolePartBeams.pdf |access-date=26 January 2023}}</ref> Solar Type III radio bursts, the most common impulsive radio signatures from the Sun, are used by scientists as a tool to better understand solar accelerated electron beams.<ref>{{cite journal |last1=Reid |first1=Hamish Andrew Sinclair |last2=Ratcliffe |first2=Heather |title=A review of solar type III radio bursts |journal=Research in Astronomy and Astrophysics |date=July 2014 |volume=14 |issue=7 |pages=773–804 |doi=10.1088/1674-4527/14/7/003 |arxiv=1404.6117 |bibcode=2014RAA....14..773R |s2cid=118446359 |url=https://iopscience.iop.org/article/10.1088/1674-4527/14/7/003 |issn=1674-4527}}</ref> Additionally, particle beams cause [[Hydrodynamic stability|instabilities]] when interacting with plasma, which may lead to conditions causing [[Electrostatic solitary wave|electrostatic solitary waves]].<ref>{{Cite journal |last=Omura |first=Y. |last2=Matsumoto |first2=H. |last3=Miyake |first3=T. |last4=Kojima |first4=H. |date=February 1996 |title=Electron beam instabilities as generation mechanism of electrostatic solitary waves in the magnetotail |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/95JA03145 |journal=Journal of Geophysical Research: Space Physics |language=en |volume=101 |issue=A2 |pages=2685–2697 |doi=10.1029/95JA03145 |issn=0148-0227|url-access=subscription }}</ref> ===Military=== The U.S. [[Defense Advanced Research Projects Agency|Advanced Research Projects Agency]] started work on [[particle beam weapon]]s in 1958.<ref name=roberds84>{{cite journal | last=Roberds | first=Richard M. | year=1984 | title=Introducing the Particle-Beam Weapon | journal=Air University Review | volume=July–August | url=http://www.airpower.maxwell.af.mil/airchronicles/aureview/1984/jul-aug/roberds.html | access-date=2005-01-03 | archive-url=https://web.archive.org/web/20120417021903/http://www.airpower.maxwell.af.mil/airchronicles/aureview/1984/jul-aug/roberds.html | archive-date=2012-04-17 | url-status=dead }}</ref> 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 atoms, or 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,<ref name=roberds84/> thus such weapons are not anticipated to be produced in the foreseeable future. ==See also== * [[Electron beam]] * [[Ion beam]] * [[Astrophysical jet]] * [[Atomic beam]] * [[Accelerator neutrino]] ==References== {{reflist}} {{DEFAULTSORT:Particle Beam}} [[Category:Accelerator physics]] [[pt:Feixe (física)]]
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