Particle beam

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A particle beam is a stream of charged or neutral 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.

Contents

Sources

Charged particles such as electrons, positrons, and protons may be separated from their common surrounding. This can be accomplished by e.g. thermionic emission or arc discharge. The following devices are commonly used as sources for particle beams:

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 (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 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

Electron beams 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 (XAS, XANES, EXAFS, µ-XRF, µ-XRD) 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 (also called particle microbeams) may also be used for cancer treatment in particle therapy.

Astrophysics

Many phenomena in astrophysics are attributed to particle beams of various kinds. [3] 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. [4]

Military

The U.S. Advanced Research Projects Agency started work on particle beam weapons in 1958. [5] 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, [5] thus such weapons are not anticipated to be produced in the foreseeable future.

See also

Related Research Articles

Particle radiation is the radiation of energy by means of fast-moving subatomic particles. Particle radiation is referred to as a particle beam if the particles are all moving in the same direction, similar to a light beam.

<span class="mw-page-title-main">Fusor</span> An apparatus to create nuclear fusion

A fusor is a device that uses an electric field to heat ions to a temperature in which they undergo nuclear fusion. The machine induces a potential difference between two metal cages, inside a vacuum. Positive ions fall down this voltage drop, building up speed. If they collide in the center, they can fuse. This is one kind of an inertial electrostatic confinement device – a branch of fusion research.

<span class="mw-page-title-main">Cyclotron</span> Type of particle accelerator

A cyclotron is a type of particle accelerator invented by Ernest Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. A cyclotron accelerates charged particles outwards from the center of a flat cylindrical vacuum chamber along a spiral path. The particles are held to a spiral trajectory by a static magnetic field and accelerated by a rapidly varying electric field. Lawrence was awarded the 1939 Nobel Prize in Physics for this invention.

<span class="mw-page-title-main">DESY</span> German national research center

DESY, short for Deutsches Elektronen-Synchrotron, is a national research centre for fundamental science located in Hamburg and Zeuthen near Berlin in Germany. It operates particle accelerators used to investigate the structure, dynamics and function of matter, and conducts a broad spectrum of interdisciplinary scientific research in four main areas: particle and high energy physics; photon science; astroparticle physics; and the development, construction and operation of particle accelerators. Its name refers to its first project, an electron synchrotron. DESY is publicly financed by the Federal Republic of Germany and the Federal States of Hamburg and Brandenburg and is a member of the Helmholtz Association.

<span class="mw-page-title-main">SLAC National Accelerator Laboratory</span> Research center at Stanford University

SLAC National Accelerator Laboratory, originally named the Stanford Linear Accelerator Center, is a federally funded research and development center in Menlo Park, California, United States. Founded in 1962, the laboratory is now sponsored by the United States Department of Energy and administrated by Stanford University. It is the site of the Stanford Linear Accelerator, a 3.2 kilometer (2-mile) linear accelerator constructed in 1966 that could accelerate electrons to energies of 50 GeV.

<span class="mw-page-title-main">Synchrotron radiation</span> Electromagnetic radiation emitted by charged particles accelerated perpendicular to their velocity

Synchrotron radiation is the electromagnetic radiation emitted when relativistically charged particles are subject to an acceleration perpendicular to their velocity. It is produced artificially in some types of particle accelerators or naturally by fast electrons moving through magnetic fields. The radiation produced in this way has a characteristic polarization, and the frequencies generated can range over a large portion of the electromagnetic spectrum.

<span class="mw-page-title-main">Linear particle accelerator</span> Type of particle accelerator

A linear particle accelerator 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 beamline. The principles for such machines were proposed by Gustav Ising in 1924, while the first machine that worked was constructed by Rolf Widerøe in 1928 at the RWTH Aachen University. Linacs have many applications: they generate X-rays and high energy electrons for medicinal purposes in radiation therapy, serve as particle injectors for higher-energy accelerators, and are used directly to achieve the highest kinetic energy for light particles for particle physics.

<span class="mw-page-title-main">Synchrotron</span> Type of cyclic particle accelerator

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 path increases with time during the accelerating process, being synchronized to the increasing kinetic energy of the particles. The synchrotron is one of the first accelerator concepts to enable the construction of large-scale facilities, since bending, beam focusing and acceleration can be separated into different components. The most powerful modern particle accelerators use versions of the synchrotron design. The largest synchrotron-type accelerator, also the largest particle accelerator in the world, is the 27-kilometre-circumference (17 mi) Large Hadron Collider (LHC) near Geneva, Switzerland, built in 2008 by the European Organization for Nuclear Research (CERN). It can accelerate beams of protons to an energy of 13 tera electronvolts (TeV or 1012 eV).

A charged particle beam is a spatially localized group of electrically charged particles that have approximately the same position, kinetic energy, and direction. The kinetic energies of the particles are much larger than the energies of particles at ambient temperature. The high energy and directionality of charged particle beams make them useful for many applications in particle physics.

Elastic scattering is a form of particle scattering in scattering theory, nuclear physics and particle physics. In this process, the kinetic energy of a particle is conserved in the center-of-mass frame, but its direction of propagation is modified meaning the two particles in the collision do not lose energy. Furthermore, while the particle's kinetic energy in the center-of-mass frame is constant, its energy in the lab frame is not. Generally, elastic scattering describes a process in which the total kinetic energy of the system is conserved. During elastic scattering of high-energy subatomic particles, linear energy transfer (LET) takes place until the incident particle's energy and speed has been reduced to the same as its surroundings, at which point the particle is "stopped".

<span class="mw-page-title-main">KEK</span> Japanese high-energy physics organization

The High Energy Accelerator Research Organization, known as KEK, is a Japanese organization whose purpose is to operate the largest particle physics laboratory in Japan, situated in Tsukuba, Ibaraki prefecture. It was established in 1997. The term "KEK" is also used to refer to the laboratory itself, which employs approximately 695 employees. KEK's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics, material science, structural biology, radiation science, computing science, nuclear transmutation and so on. Numerous experiments have been constructed at KEK by the internal and international collaborations that have made use of them. Makoto Kobayashi, emeritus professor at KEK, is known globally for his work on CP-violation, and was awarded the 2008 Nobel Prize in Physics.

<span class="mw-page-title-main">Aneutronic fusion</span> Form of fusion power

Aneutronic fusion is any form of fusion power in which very little of the energy released is carried by neutrons. While the lowest-threshold nuclear fusion reactions release up to 80% of their energy in the form of neutrons, aneutronic reactions release energy in the form of charged particles, typically protons or alpha particles. Successful aneutronic fusion would greatly reduce problems associated with neutron radiation such as damaging ionizing radiation, neutron activation, reactor maintenance, and requirements for biological shielding, remote handling and safety.

Plasma acceleration is a technique for accelerating charged particles, such as electrons or ions, using the electric field associated with electron plasma wave or other high-gradient plasma structures. These plasma acceleration structures are created using either ultra-short laser pulses or energetic particle beams that are matched to the plasma parameters. The technique offers a way to build affordable and compact particle accelerators.

A particle-beam weapon uses a high-energy beam of atomic or subatomic particles to damage the target by disrupting its atomic and/or molecular structure. A particle-beam weapon is a type of directed-energy weapon, which directs energy in a particular and focused direction using particles with minuscule mass. Some particle-beam weapons have potential practical applications, e.g. as an antiballistic missile defense system. They have been known by myriad names: particle accelerator guns, ion cannons, proton beams, lightning rays, rayguns, etc.

<span class="mw-page-title-main">AWAKE</span>

The AWAKE facility at CERN is a proof-of-principle experiment, which investigates wakefield plasma acceleration using a proton bunch as a driver, a world-wide first. It aims to accelerate a low-energy witness bunch of electrons from 15 to 20 MeV to several GeV over a short distance by creating a high acceleration gradient of several GV/m. Particle accelerators currently in use, like CERN's LHC, use standard or superconductive RF-cavities for acceleration, but they are limited to an acceleration gradient in the order of 100 MV/m.

NICA is a particle collider complex being constructed by the Joint Institute for Nuclear Research in Dubna, Russia to perform experiments such as Nuclotron ion beams extracted to a fixed target and colliding beams of ions, ions-protons, polarized protons and deuterons. The projected maximum kinetic energy of the accelerated ions is 4.5 GeV per nucleon, and 12.6 GeV for protons.

<span class="mw-page-title-main">Particle accelerator</span> Research apparatus for particle physics

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.

<span class="mw-page-title-main">Helmholtz-Zentrum Dresden-Rossendorf</span> Research laboratory in Germany

The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is a Dresden-based research laboratory. It conducts research in three of the Helmholtz Association's areas: materials, health, and energy. HZDR is a member of the Helmholtz Association of German Research Centres.

An energy recovery linac (ERL) is a type of linear particle accelerator that provides a beam of electrons used to produce x-rays by synchrotron radiation. First proposed in 1965 the idea gained interest since the early 2000s.

Heavy ion fusion is a fusion energy concept that uses a stream of high-energy ions from a particle accelerator to rapidly heat and compress a small pellet of fusion fuel. It is a subclass of the larger inertial confinement fusion (ICF) approach, replacing the more typical laser systems with an accelerator.

References

  1. 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
  2. Petawatt proton beams at Lawrence Livermore
  3. Anthony Peratt (1988). "The role of particle beams and electrical currents in the plasma universe" (PDF). Laser and Particle Beams. 6 (3): 471–491. Bibcode:1988LPB.....6..471P. doi:10.1017/S0263034600005401 . Retrieved 26 January 2023.
  4. Reid, Hamish Andrew Sinclair; Ratcliffe, Heather (July 2014). "A review of solar type III radio bursts". Research in Astronomy and Astrophysics. 14 (7): 773–804. arXiv: 1404.6117 . Bibcode:2014RAA....14..773R. doi:10.1088/1674-4527/14/7/003. ISSN   1674-4527. S2CID   118446359.
  5. 1 2 Roberds, Richard M. (1984). "Introducing the Particle-Beam Weapon". Air University Review. July–August. Archived from the original on 2012-04-17. Retrieved 2005-01-03.