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Radiative Damping
Radiation damping in accelerator physics is a way of reducing the beam emittance of a high-velocity charged particle beam by synchrotron radiation. The two main ways of using radiation damping to reduce the emittance of a particle beam are the use of ''undulators'' and ''damping rings'' (often containing undulators), both relying on the same principle of inducing synchrotron radiation to reduce the particles' momentum, then replacing the momentum only in the desired direction of motion. Damping rings As particles are moving in a closed orbit, the lateral acceleration causes them to emit synchrotron radiation, thereby reducing the size of their momentum vectors (relative to the design orbit) without changing their orientation (ignoring quantum effects for the moment). In longitudinal direction, the loss of particle impulse due to radiation is replaced by accelerating sections ( RF cavities) that are installed in the beam path so that an equilibrium is reached at the design energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 and their interaction with accelerator structures by electromagnetic fields. It is also related to other fields: *Microwave engineering (for acceleration/deflection structures in the radio frequency range). *Optics with an emphasis on geometrical optics (beam focusing and bending) and laser physics (laser-particle interaction). *Computer technology with an emphasis on digital signal processing; e.g., for automated manipulation of the particle beam. *Plasma physics, for the description of intense beams. The experiments conducted with particle accelerators are not regarded as part of accelerator physics, but belong (according to the objectives of the experiments) to, e.g., particle physics, nuclear physics, condensed matter physics or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beam Emittance
In accelerator physics, emittance is a property of a charged particle beam. It refers to the area occupied by the beam in a position-and-momentum phase space. Each particle in a beam can be described by its position and momentum along each of three orthogonal axes, for a total of six position and momentum coordinates. When the position and momentum for a single axis are plotted on a two dimensional graph, the average spread of the coordinates on this plot are the emittance. As such, a beam will have three emittances, one along each axis, which can be described independently. As particle momentum along an axis is usually described as an angle relative to that axis, an area on a position-momentum plot will have dimensions of length × angle (for example, millimeters × milliradian). Emittance is important for analysis of particle beams. As long as the beam is only subjected to conservative forces, Liouville's Theorem shows that emittance is a conserved quantity. If t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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 (see Particle beam#Applications and Electron-beam technology). Such beams can be split into two main classes: # ''unbunched beams'' (''coasting beams'' or ''DC beams''), which have no longitudinal substructure in the direction of beam motion. # ''bunched beams'', in which the particles are distributed into pulses (bunches) of particles. Bunched beams are most common in modern facilities, since the most modern particle accelerators require bunched beams for acceleration. Assuming a normal distribution of particle positions and impulses, a charged particle bea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchrotron Radiation
Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when relativistic 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. Synchrotron radiation is similar to bremsstrahlung radiation, which is emitted by a charged particle when the acceleration is parallel to the direction of motion. The general term for radiation emitted by particles in a magnetic field is ''gyromagnetic radiation'', for which synchrotron radiation is the ultra-relativistic special case. Radiation emitted by charged particles moving non-relativistically in a magnetic field is called cyclotron emission. For particles in the mildly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale. Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values ( quantization); objects have characteristics of both particles and waves (wave–particle duality); and there are limits to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RF Cavity
A microwave cavity or ''radio frequency (RF) cavity'' is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between the walls of the cavity. At the cavity's resonant frequencies they reinforce to form standing waves in the cavity. Therefore, the cavity functions similarly to an organ pipe or sound box in a musical instrument, oscillating preferentially at a series of frequencies, its resonant frequencies. Thus it can act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at nearby frequencies. A microwave cavity acts similarly to a resonant circuit with extremely low loss at its frequency of operation, resulting in quality factors (Q factors) up to the order of 106, compared to 102 for circuits made wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiative Equilibrium
Radiative equilibrium is the condition where the total thermal radiation leaving an object is equal to the total thermal radiation entering it. It is one of the several requirements for thermodynamic equilibrium, but it can occur in the absence of thermodynamic equilibrium. There are various types of radiative equilibrium, which is itself a kind of dynamic equilibrium. Definitions Equilibrium, in general, is a state in which opposing forces are balanced, and hence a system does not change in time. Radiative equilibrium is the specific case of thermal equilibrium, for the case in which the exchange of heat is done by radiative heat transfer. There are several types of radiative equilibrium. Prevost's definitions An important early contribution was made by Pierre Prevost in 1791. Prevost considered that what is nowadays called the photon gas or electromagnetic radiation was a fluid that he called "free heat". Prevost proposed that free radiant heat is a very rare fluid, rays of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curvature
In mathematics, curvature is any of several strongly related concepts in geometry. Intuitively, the curvature is the amount by which a curve deviates from being a straight line, or a surface deviates from being a plane. For curves, the canonical example is that of a circle, which has a curvature equal to the reciprocal of its radius. Smaller circles bend more sharply, and hence have higher curvature. The curvature ''at a point'' of a differentiable curve is the curvature of its osculating circle, that is the circle that best approximates the curve near this point. The curvature of a straight line is zero. In contrast to the tangent, which is a vector quantity, the curvature at a point is typically a scalar quantity, that is, it is expressed by a single real number. For surfaces (and, more generally for higher-dimensional manifolds), that are embedded in a Euclidean space, the concept of curvature is more complex, as it depends on the choice of a direction on the surface or man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storage Ring
A storage ring is a type of circular particle accelerator in which a continuous or pulsed particle beam may be kept circulating typically for many hours. Storage of a particular particle depends upon the mass, momentum and usually the charge of the particle to be stored. Storage rings most commonly store electrons, positrons, or protons. Storage rings are most often used to store electrons that radiate synchrotron radiation. Over 50 facilities based on electron storage rings exist and are used for a variety of studies in chemistry and biology. Storage rings can also be used to produce polarized high-energy electron beams through the Sokolov-Ternov effect. The best-known application of storage rings is their use in particle accelerators and in particle colliders, where two counter-rotating beams of stored particles are brought into collision at discrete locations. The resulting subatomic interactions are then studied in a surrounding particle detector. Examples of such facilities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undulator
An undulator is an insertion device from high-energy physics and usually part of a larger installation, a synchrotron storage ring, or it may be a component of a free electron laser. It consists of a periodic structure of dipole magnets. These can be permanent magnets or superconducting magnets. The static magnetic field alternates along the length of the undulator with a wavelength \lambda_u. Electrons traversing the periodic magnet structure are forced to undergo oscillations and thus to radiate energy. The radiation produced in an undulator is very intense and concentrated in narrow energy bands in the spectrum. It is also collimated on the orbit plane of the electrons. This radiation is guided through beamlines for experiments in various scientific areas. The undulator strength parameter is: :K=\frac, where ''e'' is the electron charge, ''B'' is the magnetic field, ''\lambda_u'' is the spatial period of the undulator magnets, ''m_'' is the electron rest mass, and ''c'' is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wiggler (synchrotron)
A wiggler is an insertion device in a synchrotron. It is a series of magnets designed to periodically laterally deflect ('wiggle') a beam of charged particles (invariably electrons or positrons) inside a storage ring of a synchrotron. These deflections create a change in acceleration which in turn produces emission of broad synchrotron radiation tangent to the curve, much like that of a bending magnet, but the intensity is higher due to the contribution of many magnetic dipoles in the wiggler. Furthermore, as the wavelength (λ) is decreased this means the frequency (ƒ) has increased. This increase of frequency is directly proportional to energy, hence, the wiggler creates a wavelength of light with a larger energy. A wiggler has a broader spectrum of radiation than an undulator. Typically the magnets in a wiggler are arranged in a Halbach array. The design shown above is usually known as a Halbach wiggler. History The first suggestion of a wiggler magnet to produce synchr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Beam Cooling
Particle beam cooling is the process of improving the quality of particle beams produced by particle accelerators, by reducing the emittance. Techniques for particle beam cooling include: * Stochastic cooling * Electron coolingI. Meshkov, Electron Cooling: Status and Perspectives, Physics of Particles and Nuclei, Vol. 25, Issue 6, pp. 631-661, 1994 * Ionization cooling * Laser cooling * Radiation damping Radiation damping in accelerator physics is a way of reducing the beam emittance of a high-velocity charged particle beam by synchrotron radiation. The two main ways of using radiation damping to reduce the emittance of a particle beam are the us ... * Buffer-gas cooling within RF quadrupoles References Accelerator physics {{Accelerator-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
