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Статті в журналах з теми "Acceleraton of particles"
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Nishida, Yasushi. "Electron linear accelerator based on cross field acceleration principle." Laser and Particle Beams 7, no. 3 (1989): 561–79. http://dx.doi.org/10.1017/s0263034600007540.
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Powerful lasers have the potential to be used for power sources of the high energy particle accelerators. However, we have to convert the transverse wave into a longitudinal one which can trap the charged particles in the wave trough to accelerate them. In order to obtain a high field-gradient in an accelerator, several new concepts have been proposed. One of them is a beat wave accelerator (BWA) which uses a nonlinear optical mixing of two laser beams. Another concept is a Cross Field Acceleration (or a Vp × B acceleration) scheme, in which the trapped particles in the wave trough are accelerated along the wavefront and across the static magnetic field applied externally. An overview is presented including some new results.
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Guidoni, S. E., J. T. Karpen, and C. R. DeVore. "Spectral Power-law Formation by Sequential Particle Acceleration in Multiple Flare Magnetic Islands." Astrophysical Journal 925, no. 2 (2022): 191. http://dx.doi.org/10.3847/1538-4357/ac39a5.
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Abstract We present a first-principles model of pitch-angle and energy distribution function evolution as particles are sequentially accelerated by multiple flare magnetic islands. Data from magnetohydrodynamic (MHD) simulations of an eruptive flare/coronal mass ejection provide ambient conditions for the evolving particle distributions. Magnetic islands, which are created by sporadic reconnection at the self-consistently formed flare current sheet, contract and accelerate the particles. The particle distributions are evolved using rules derived in our previous work. In this investigation, we assume that a prescribed fraction of particles sequentially “hops” to another accelerator and receives an additional boost in energy and anisotropy. This sequential process generates particle number spectra that obey an approximate power law at mid-range energies and presents low- and high-energy breaks. We analyze these spectral regions as functions of the model parameters. We also present a fully analytic method for forming and interpreting such spectra, independent of the sequential acceleration model. The method requires only a few constrained physical parameters, such as the percentage of particles transferred between accelerators, the energy gain in each accelerator, and the number of accelerators visited. Our investigation seeks to bridge the gap between MHD and kinetic regimes by combining global simulations and analytic kinetic theory. The model reproduces and explains key characteristics of observed flare hard X-ray spectra as well as the underlying properties of the accelerated particles. Our analytic model provides tools to interpret high-energy observations for missions and telescopes, such as RHESSI, FOXSI, NuSTAR, Solar Orbiter, EOVSA, and future high-energy missions.
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Hogan, Mark J. "Electron and Positron Beam–Driven Plasma Acceleration." Reviews of Accelerator Science and Technology 09 (January 2016): 63–83. http://dx.doi.org/10.1142/s1793626816300036.
Повний текст джерелаАнотація:
Particle accelerators are the ultimate microscopes. They produce high energy beams of particles — or, in some cases, generate X-ray laser pulses — to probe the fundamental particles and forces that make up the universe and to explore the building blocks of life. But it takes huge accelerators, like the Large Hadron Collider or the two-mile-long SLAC linac, to generate beams with enough energy and resolving power. If we could achieve the same thing with accelerators just a few meters long, accelerators and particle colliders could be much smaller and cheaper. Since the first theoretical work in the early 1980s, an exciting series of experiments have aimed at accelerating electrons and positrons to high energies in a much shorter distance by having them “surf” on waves of hot, ionized gas like that found in fluorescent light tubes. Electron-beam-driven experiments have measured the integrated and dynamic aspects of plasma focusing, the bright flux of high energy betatron radiation photons, particle beam refraction at the plasma–neutral-gas interface, and the structure and amplitude of the accelerating wakefield. Gradients spanning kT/m to MT/m for focusing and 100[Formula: see text]MeV/m to 50[Formula: see text]GeV/m for acceleration have been excited in meter-long plasmas with densities of 10[Formula: see text]–10[Formula: see text][Formula: see text]cm[Formula: see text], respectively. Positron-beam-driven experiments have evidenced the more complex dynamic and integrated plasma focusing, 100[Formula: see text]MeV/m to 5[Formula: see text]GeV/m acceleration in linear and nonlinear plasma waves, and explored the dynamics of hollow channel plasma structures. Strongly beam-loaded plasma waves have accelerated beams of electrons and positrons with hundreds of pC of charge to over 5[Formula: see text]GeV in meter scale plasmas with high efficiency and narrow energy spread. These “plasma wakefield acceleration” experiments have been mounted by a diverse group of accelerator, laser and plasma researchers from national laboratories and universities around the world. This article reviews the basic principles of plasma wakefield acceleration with electron and positron beams, the current state of understanding, the push for first applications and the long range R&D roadmap toward a high energy collider.
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Ogata, Atsushi, and Kazuhisa Nakajima. "Recent progress and perspectives of laser–plasma accelerators." Laser and Particle Beams 16, no. 2 (1998): 381–96. http://dx.doi.org/10.1017/s0263034600011654.
Повний текст джерелаАнотація:
Recent progress in laser-plasma accelerators has matured a concept of particle acceleration as a possible next-generation particle accelerator promising ultrahigh accelerating gradients in a compact size. Four major concepts of laser-plasma accelerators—the plasma beat wave accelerator, the laser wakefield accelerator, the self-modulated laser wakefield accelerator, and the plasma wakefield accelerator—are reviewed on accelerator physics issues and experiments demonstrating the basic mechanisms of their concepts. As a perspective to the future practical application, a design of 5-TeV linear colliders based on the laser wakefield accelerator is discussed.
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Kalmykov, S., O. Polomarov, D. Korobkin, J. Otwinowski, J. Power, and G. Shvets. "Novel techniques of laser acceleration: from structures to plasmas." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1840 (2006): 725–40. http://dx.doi.org/10.1098/rsta.2005.1734.
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Compact accelerators of the future will require enormous accelerating gradients that can only be generated using high power laser beams. Two novel techniques of laser particle acceleration are discussed. The first scheme is based on a solid-state accelerating structure powered by a short pulse CO 2 laser. The planar structure consists of two SiC films, separated by a vacuum gap, grown on Si wafers. Particle acceleration takes place inside the gap by a surface electromagnetic wave excited at the vacuum/SiC interface. Laser coupling is accomplished through the properly designed Si grating. This structure can be inexpensively manufactured using standard microfabrication techniques and can support accelerating fields well in excess of 1 GeV m −1 without breakdown. The second scheme utilizes a laser beatwave to excite a high-amplitude plasma wave, which accelerates relativistic particles. The novel aspect of this technique is that it takes advantage of the nonlinear bi-stability of the relativistic plasma wave to drive it close to the wavebreaking.
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Fang, Jun, Qi Xia, Shiting Tian, Liancheng Zhou, and Huan Yu. "Kinetic simulation of electron, proton and helium acceleration in a non-relativistic quasi-parallel shock." Monthly Notices of the Royal Astronomical Society 512, no. 4 (2022): 5418–22. http://dx.doi.org/10.1093/mnras/stac886.
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ABSTRACT In addition to accelerating electrons and protons, non-relativistic quasi-parallel shocks are expected to possess the ability to accelerate heavy ions. The shocks in supernova remnants are generally supposed to be accelerators of Galactic cosmic rays, which consist of many species of particles. We investigate the diffusive shock acceleration of electrons, protons and helium ions in a non-relativistic quasi-parallel shock through a 1D particle-in-cell simulation with a helium-to-proton number density ratio of 0.1, which is relevant for Galactic cosmic rays. The simulation indicates that waves can be excited by the flow of energetic protons and helium ions upstream of a non-relativistic quasi-parallel shock with a sonic Mach number of 14 and an Alfvén Mach number of 19.5 in the shock rest frame, and that the charged particles are scattered by the self-generated waves and accelerated gradually. Moreover, the spectra of the charged particles downstream of the shock are thermal with a non-thermal tail, and the acceleration is efficient, with about $7{{\ \rm per\ cent}}$ and $5.4{{\ \rm per\ cent}}$ of the bulk kinetic energy transferred into the non-thermal protons and helium ions, respectively, in the near downstream region by the end of the simulation.
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Sow Mondal, Shanwlee, Aveek Sarkar, Bhargav Vaidya, and Andrea Mignone. "Acceleration of Solar Energetic Particles by the Shock of Interplanetary Coronal Mass Ejection." Astrophysical Journal 923, no. 1 (2021): 80. http://dx.doi.org/10.3847/1538-4357/ac2c7a.
Повний текст джерелаАнотація:
Abstract Interplanetary coronal mass ejection (ICME) shocks are known to accelerate particles and contribute significantly to solar energetic particle events. We have performed magnetohydrodynamic-particle in cell simulations of ICME shocks to understand the acceleration mechanism. These shocks vary in Alfvénic Mach numbers as well as in magnetic field orientations (parallel and quasi-perpendicular). We find that diffusive shock acceleration plays a significant role in accelerating particles in a parallel ICME shock. In contrast, shock drift acceleration (SDA) plays a pivotal role in a quasi-perpendicular shock. High-Mach shocks are seen to accelerate particles more efficiently. Our simulations suggest that background turbulence and local particle velocity distribution around the shock can indirectly hint at the acceleration mechanism. Our results also point toward a few possible in situ observations that could validate our understanding of the topic.
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Kocharov, L. G., G. A. Kovaltsov, G. E. Kocharov, et al. "Electromagnetic and corpuscular emission from the solar flare of 1991 June 15: Continuous acceleraton of relativistic particles." Solar Physics 150, no. 1-2 (1994): 267–83. http://dx.doi.org/10.1007/bf00712889.
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D’Arcy, R., J. Chappell, J. Beinortaite, et al. "Recovery time of a plasma-wakefield accelerator." Nature 603, no. 7899 (2022): 58–62. http://dx.doi.org/10.1038/s41586-021-04348-8.
Повний текст джерелаАнотація:
AbstractThe interaction of intense particle bunches with plasma can give rise to plasma wakes1,2 capable of sustaining gigavolt-per-metre electric fields3,4, which are orders of magnitude higher than provided by state-of-the-art radio-frequency technology5. Plasma wakefields can, therefore, strongly accelerate charged particles and offer the opportunity to reach higher particle energies with smaller and hence more widely available accelerator facilities. However, the luminosity and brilliance demands of high-energy physics and photon science require particle bunches to be accelerated at repetition rates of thousands or even millions per second, which are orders of magnitude higher than demonstrated with plasma-wakefield technology6,7. Here we investigate the upper limit on repetition rates of beam-driven plasma accelerators by measuring the time it takes for the plasma to recover to its initial state after perturbation by a wakefield. The many-nanosecond-level recovery time measured establishes the in-principle attainability of megahertz rates of acceleration in plasmas. The experimental signatures of the perturbation are well described by simulations of a temporally evolving parabolic ion channel, transferring energy from the collapsing wake to the surrounding media. This result establishes that plasma-wakefield modules could be developed as feasible high-repetition-rate energy boosters at current and future particle-physics and photon-science facilities.
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Papini, Giorgio. "Maximal acceleration and radiative processes." Modern Physics Letters A 30, no. 31 (2015): 1550166. http://dx.doi.org/10.1142/s0217732315501667.
Повний текст джерелаАнотація:
We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass [Formula: see text] has the upper limit [Formula: see text]. We find two power laws, one applicable to lower accelerations, the other more suitable for accelerations closer to [Formula: see text] and to the related physical singularity in the Ricci scalar. Geometrical constraints and power spectra are also discussed. By comparing the power laws due to the maximal acceleration (MA) with that for particles in gravitational fields, we find that the model of Caianiello allows, in principle, the use of charged particles as tools to distinguish inertial from gravitational fields locally.
Дисертації з теми "Acceleraton of particles"
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Waldman, Zachary J. "Majorana Neutrinos in the Jacob-Wick phase convention." Diss., Online access via UMI:, 2008.
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Verhagen, Erik. "Development of the new trigger and data acquisition system for the CMS forward muon spectrometer upgrade." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209110.
Повний текст джерелаАнотація:
La physique des particules élémentaires, aussi appelé physique des hautes énergies, est l'étude de l'infiniment petit, popularisée récemment par la découverte de nouvelles particules fondamentales permettant de consolider notre connaissance de la matière. Pour réaliser des mesures à une échelle aussi réduite, une méthode consiste à augmenter l’énergie des constituants de la matière, à l'aide d'accélérateur de particules, puis de les briser pour révéler leur constitution. Au-delà de l'intérêt en termes de physique expérimentale, réaliser des expériences de ce type est devenu une prouesse technologique grandissante avec les niveaux d’énergie atteints. La complexité de l’expérience CMS, cadre dans laquelle ce travail a été réalisé, donne une bonne mesure des défis technologiques relevés.<p>Afin d'affiner encore notre connaissance des processus mis en jeu lors collision de particules dans CMS, une mise à niveau du détecteur est prévue avant la fin de cette décennie. Certains sous-détecteurs actuellement installés, et notamment le spectromètre à muon dans la zone des bouchons, sont d’ores et déjà identifiés comme offrant des performances trop faibles pour l'augmentation du nombres d’événements prévu après cette mise à jour. Ce travail propose de réaliser une étude de faisabilité sur l'utilisation d'une technologie alternative pour ce sous-détecteur, notamment le Triple-GEM, pour combler ces limitations.<p>Une première partie de ce travail consiste en l'étude de cette nouvelle technologie de détecteur à gaz. Cependant, la mise en œuvre de cette technologie conduit à des modifications dans le système d'acquisition de données de CMS. La situation actuelle puis les implications d'un point de vue technique des modifications sont donc détaillées par la suite. Enfin, après avoir identifié les composants et les solutions permettant la collecte de résultats à l’échelle de l'ensemble du sous-détecteur, un système d'acquisition de données similaire a été réalisé et est décrit dans une dernière partie de ce travail.<br>Doctorat en Sciences<br>info:eu-repo/semantics/nonPublished
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Johnson, Samantha. "Optimizing the ion source for polarized protons." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
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Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced.
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Weathersby, Stephen. "Damping higher order modes in the PEP-II B-factory storage ring collider." Diss., Connect to online resource - MSU authorized users, 2007.
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Thesis (Ph.D.)--Michigan State University. Dept. of Physics and Astronomy, 2007.<br>Title from PDF t.p. (viewed on August 18, 2009) Includes bibliographic references (p. 175-179). Also issued in print.
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Williams, Logan Todd. "Ion acceleration mechanisms of helicon thrusters." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47691.
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A helicon plasma source is a device that can efficiently ionize a gas to create high density, low temperature plasma. There is growing interest in utilizing a helicon plasma source in propulsive applications, but it is not yet known if the helicon plasma source is able to function as both an ion source and ion accelerator, or whether an additional ion acceleration stage is required. In order to evaluate the capability of the helicon source to accelerate ions, the acceleration and ionization processes must be decoupled and examined individually. To accomplish this, a case study of two helicon thruster configurations is conducted. The first is an electrodeless design that consists of the helicon plasma source alone, and the second is a helicon ion engine that combines the helicon plasma source with electrostatic grids used in ion engines. The gridded configuration separates the ionization and ion acceleration mechanisms and allows for individual evaluation not only of ion acceleration, but also of the components of total power expenditure and the ion production cost.
In this study, both thruster configurations are fabricated and experimentally characterized. The metrics used to evaluate ion acceleration are ion energy, ion beam current, and the plume divergence half-angle, as these capture the magnitude of ion acceleration and the bulk trajectory of the accelerated ions. The electrode-less thruster is further studied by measuring the plasma potential, ion number density, and electron temperature inside the discharge chamber and in the plume up to 60 cm downstream and 45 cm radially outward. The two configurations are tested across several operating parameter ranges: 343-600 W RF power, 50-450 G magnetic field strength, 1.0-4.5 mg/s argon flow rate, and the gridded configuration is tested over a 100-600 V discharge voltage range.
Both configurations have thrust and efficiency below that of contemporary thrusters of similar power, but are distinct in terms of ion acceleration capability. The gridded configuration produces a 65-120 mA ion beam with energies in the hundreds of volts that is relatively collimated. The operating conditions also demonstrate clear control over the performance metrics. In contrast, the electrodeless configuration generally produces a beam current less than 20 mA at energies between 20-40 V in a very divergent plume. The ion energy is set by the change in plasma potential from inside the device to the plume. The divergence ion trajectories are caused by regions of high plasma potential that create radial electric fields.. Furthermore, the operating conditions have limited control of the resulting performance metrics. The estimated ion production cost of the helicon ranged between 132-212 eV/ion for argon, the lower bound of which is comparable to the 157 eV/ion in contemporary DC discharges. The primary power expenditures are due to ion loss to the walls and high electron temperature leading to energy loss at the plasma sheaths.
The conclusion from this work is that the helicon plasma source is unsuitable as a single-stage thruster system. However, it is an efficient ion source and, if paired with an additional ion acceleration stage, can be integrated into an effective propulsion system.
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Linz, Thomas M. "Self-Force on Accelerated Particles." Thesis, The University of Wisconsin - Milwaukee, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3712619.
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<p> The likelihood that gravitational waves from stellar-size black holes spiraling into a supermassive black hole would be detectable by a space based gravitational wave observatory has spurred the interest in studying the extreme mass-ratio inspiral (EMRI) problem and black hole perturbation theory (BHP). In this approach, the smaller black hole is treated as a point particle and its trajectory deviates from a geodesic due to the interaction with its own field. This interaction is known as the gravitational self-force, and it includes both a damping force, commonly known as radiation reaction, as well as a conservative force. The computation of this force is complicated by the fact that the formal expression for the force due to a point particle diverges, requiring a careful regularization to find the finite self-force. </p><p> This dissertation focuses on the computation of the scalar, electromagnetic and gravitational self-force on accelerated particles. We begin with a discussion of the "MiSaTaQuWa" prescription for self-force renormalization (Mino, Sasaki, Takasugi 1999 and Quinn and Wald, 1999) along with the refinements made by Detweiler and Whiting (2003), and demonstrate how this prescription is equivalent to performing an angle average and renormalizing the mass of the particle. With this background, we shift to a discussion of the "mode-sum renormalization" technique developed by Barack and Ori (2000), who demonstrated that for particles moving along a geodesic in Schwarzschild spacetime (and later in Kerr spacetime), the regularization parameters can be described using only the leading and subleading terms (known as the A and B terms). We extend this to demonstrate that this is true for fields of spins 0, 1, and 2, for accelerated trajectories in arbitrary spacetimes. </p><p> Using these results, we discuss the renormalization of a charged point mass moving through an electrovac spacetime; extending previous studies to situations in which the gravitational and electromagnetic contributions are comparable. We renormalize by using the angle average plus mass renormalization in order to find the contribution from the coupling of the fields and encounter a striking result: Due to a remarkable cancellation, the coupling of the fields does not contribute to the renormalization. This means that the renormalized mass is obtained by subtracting (1) the purely electromagnetic contribution from a point charge moving along an accelerated trajectory and (2) the purely gravitational contribution of an electrically neutral point mass moving along the same trajectory. In terms of the mode-sum regularization, the same cancellation implies that the regularization parameters are merely the sums of their purely electromagnetic and gravitational values. </p><p> Finally, we consider the scalar self-force on a point charge orbiting a Schwarzschild black-hole following a non-Keplerian circular orbit. We utilize the techniques of Mano, Suzuki, and Takasugi (1996) for generating analytic solutions. With this tool, it is possible to generate a solution for the field as a series in the Fourier frequency, which allows researchers to naturally express the solutions in a post Newtonian series (see Shah et. al. 2014). We make use of a powerful insight by Hikida et. al.(2005), which allows us to perform the renormalization analytically. We investigate the details of this procedure and illuminate the mechanisms through which it works. We finish by demonstrating the power of this technique, showing how it is possible to obtain the post Newtonian expressions by only explicitly computing a handful of modes.</p>
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Alton, Andrew K. "Evidence for the existence of jets in photon-parton interaction events at center of mass energies from 18 to 28 GEV." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/1014850.
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Experiment E683 at Fermi National Accelerator Laboratory (FNAL) in Batavia, Illinois, uses a modular, high-energy sampling calorimeter as the basis of the detector system. This detector provides information on the energy and position of particles that exit a collision of a photon or pion with a target proton. While exiting particles are thought to form what are described as "jets", and several E683 projects involve working with these jets, it has not yet been demonstrated that jets indeed have been detected.The solution proposed here involves demonstrating that E683 data has a statistically significant "jettiness" even in a data sample which has not been biased. Towards this, a data sample was selected based on criteria unrelated to the presumption of jets. Planarity and the Et Flow were chosen as measures of how oblong(jetlike) an event is. The sample was then examined for planarity and Et flow in a number of kinematic ranges and the results demonstrate that over a certain kinematic range, events in our sample are increasingly planar, as we hypothesized.<br>Department of Physics and Astronomy
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Hosack, Michael G. "Optimization of particle tracking for experiment E683 at Fermi National Laboratory." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941370.
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The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations.<br>Department of Physics and Astronomy
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Guo, Fan. "Effects of Turbulent Magnetic Fields on the Transport and Acceleration of Energetic Charged Particles: Numerical Simulations with Application to Heliospheric Physics." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/255156.
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Turbulent magnetic fields are ubiquitous in space physics and astrophysics. The influence of magnetic turbulence on the motions of charged particles contains the essential physics of the transport and acceleration of energetic charged particles in the heliosphere, which is to be explored in this thesis. After a brief introduction on the energetic charged particles and magnetic fields in the heliosphere, the rest of this dissertation focuses on three specific topics: 1. the transport of energetic charged particles in the inner heliosphere, 2. the acceleration of ions at collisionless shocks, and 3. the acceleration of electrons at collisionless shocks. We utilize various numerical techniques to study these topics. In Chapter 2 we study the propagation of charged particles in turbulent magnetic fields similar to the propagation of solar energetic particles in the inner heliosphere. The trajectories of energetic charged particles in the turbulent magnetic field are numerically integrated. The turbulence model includes a Kolmogorov-like magnetic field power spectrum containing a broad range of scales from those that lead to large-scale field-line random walk to small scales leading to resonant pitch-angle scattering of energetic particles. We show that small-scale variations in particle intensities (the so-called "dropouts") and velocity dispersions observed by spacecraft can be reproduced using this method. Our study gives a new constraint on the error of "onset analysis", which is a technique commonly used to infer information about the initial release of energetic particles. We also find that the dropouts are rarely produced in the simulations using the so-called "two-component" magnetic turbulence model (Matthaeus et al., 1990). The result questions the validity of this model in studying particle transport. In the first part of Chapter 3 we study the acceleration of ions in the existence of turbulent magnetic fields. We use 3-D self-consistent hybrid simulations (kinetic ions and fluid electrons) to investigate the acceleration of low-energy particles (often termed as "injection problem") at parallel shocks. We find that the accelerated particles always gain the first amount of energy by reflection and acceleration at the shock layer. The protons can move off their original field lines in the 3-D electric and magnetic fields. The results are consistent with the acceleration mechanism found in previous 1-D and 2-D simulations. In the second part of Chapter 3, we use a stochastic integration method to study diffusive shock acceleration in the existence of large-scale magnetic variations. We show that the 1-D steady state solution of diffusive shock acceleration can be significantly modified in this situation. The results suggest that the observations of anomalous cosmic rays by Voyager spacecraft can be explained by a 2-D shock that includes the large-scale magnetic field variations. In Chapter 4 we study electron acceleration at a shock passing into a turbulent magnetic field by using a combination of hybrid simulations and test-particle electron simulations. We find that the acceleration of electrons is greatly enhanced by including the effect of large-scale magnetic turbulence. Since the electrons mainly follow along the magnetic lines of force, the large-scale braiding of field lines in space allows the fast-moving electrons interacting with the shock front multiple times. Ripples in the shock front occurring at various scales also contribute to the acceleration by mirroring the electrons. Our calculation shows that this process favors electron acceleration at perpendicular shocks. We discuss the application of this process in interplanetary shocks and flare termination shocks. We also discuss the implication of this study to solar energetic particles (SEPs) by comparing the acceleration of electrons with that of protons. The intensity correlation of electrons and ions in SEP events indicates that perpendicular or quasi-perpendicular shocks play an important role in accelerating charged particles. In Chapter 5 we summarize the results of this thesis and discuss possible future work.
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Rosencranz, Daniela Necsoiu. "Monte Carlo simulation and experimental studies of the production of neutron-rich medical isotopes using a particle accelerator." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3077/.
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The developments of nuclear medicine lead to an increasing demand for the production of radioisotopes with suitable nuclear and chemical properties. Furthermore, from the literature it is evident that the production of radioisotopes using charged-particle accelerators instead of nuclear reactors is gaining increasing popularity. The main advantages of producing medical isotopes with accelerators are carrier free radionuclides of short lived isotopes, improved handling, reduction of the radioactive waste, and lower cost of isotope fabrication. Proton-rich isotopes are the result of nuclear interactions between enriched stable isotopes and energetic protons. An interesting observation is that during the production of proton-rich isotopes, fast and intermediately fast neutrons from nuclear reactions such as (p,xn) are also produced as a by-product in the nuclear reactions. This observation suggests that it is perhaps possible to use these neutrons to activate secondary targets for the production of neutron-rich isotopes. The study of secondary radioisotope production with fast neutrons from (p,xn) reactions using a particle accelerator is the main goal of the research in this thesis.
Книги з теми "Acceleraton of particles"
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CERN Accelerator School Superconductivity in Particle Accelerators (1995 Haus Rissen, Hamburg, Germany). CAS, CERN Accelerator School Superconductivity in Particle Accelerators: Haus Rissen, Hamburg, Germany, 17-24 May 1995 : proceedings. Edited by Turner S. 1935- and European Organization for Nuclear Research. CERN, European Organization for Nuclear Research, 1996.
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Klapdor-Kleingrothaus, H. V. Non-accelerator particle physics. Institute of Physics Pub., 1998.
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Edwards, D. A. An introduction to the physics of high energy accelerators. Wiley, 1993.
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Blondel, Alain. ECFA/CERN studies of a European neutrino factory complex. CERN, 2004.
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Wiedemann, Helmut. Particle Accelerator Physics. Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-662-02903-9.
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Wiedemann, Helmut. Particle Accelerator Physics. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18317-6.
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Wiedemann, Helmut. Particle Accelerator Physics. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-05034-7.
Повний текст джерелаЧастини книг з теми "Acceleraton of particles"
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Otto, Thomas. "Risks and Hazards of Particle Accelerator Technologies." In Safety for Particle Accelerators. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57031-6_2.
Повний текст джерелаАнотація:
AbstractIn this section, the motivation and operation of particle accelerators are briefly introduced. Then, safety aspects of the key building blocks are treated. Magnets provide the steering forces for accelerated particles. Cryogenics provides the low temperatures required for the operation of superconducting magnets; radiofrequency technologies impart energy to accelerated particles. A byproduct of their operation is Non-ionising radiation. Another type of NIR is represented by lasers which find increasing use in accelerator applications. Finally, collimators shape the particle beams and protect sensitive elements, while dumps absorb the particles at the end of their course.
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Seeman, J., D. Schulte, J. P. Delahaye, et al. "Design and Principles of Linear Accelerators and Colliders." In Particle Physics Reference Library. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34245-6_7.
Повний текст джерелаАнотація:
AbstractLinear accelerators (linacs) use alternating radiofrequency (RF) electromagnetic fields to accelerate charged particles in a straight line. Linacs were invented about 95 years ago and have seen many significant technical innovations since. A wide range of particle beams have been accelerated with linacs including beams of electrons, positrons, protons, antiprotons, and heavy ions. Linac parameter possibilities include pulsed versus continuous wave, low and high beam powers, low and high repetition rates, low transverse emittance beams, short bunches with small energy spreads, and accelerated multiple bunches in a single pulse. The number of linacs around the world has grown tremendously with thousands of linacs in present use, many for medical therapy, in industry, and for research and development in a broad spectrum of scientific fields. Researchers have developed accelerators for scientific tools in their own right, being awarded several Nobel prizes. Moreover, linacs and particle accelerators in general have enabled many discovery level science experiments in related fields, resulting in many Nobel prizes as well.
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Minty, Michiko G., and Frank Zimmermann. "Introduction." In Particle Acceleration and Detection. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-08581-3_1.
Повний текст джерелаАнотація:
AbstractParticle accelerators were originally developed for research in nuclear and high-energy physics for probing the structure of matter. Over the years advances in technology have allowed higher and higher particle energies to be attained thus providing an ever more microscopic probe for understanding elementary particles and their interactions. To achieve maximum benefit from such accelerators, measuring and controlling the parameters of the accelerated particles is essential. This is the subject of this book.
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Minty, Michiko G., and Frank Zimmermann. "Collimation." In Particle Acceleration and Detection. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-08581-3_6.
Повний текст джерелаАнотація:
AbstractParticles at large betatron amplitudes or with a large momentum error constitute what is generally referred to as a beam halo. Such particles are undesirable since they produce a background in the particle-physics detector. The background arises either when the halo particles are lost at aperture restrictions in the vicinity of the detector, producing electro-magentic shower or muons, or when they emit synchrotron radiation that is not shielded and may hit sensitive detector components. In superconducting hadron storage rings, a further concern is localized particle loss near one of the superconducting magnets, which may result in the quench of the magnet, i.e., in its transition to the normalconducting state.
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Reames, Donald V. "Gradual SEP Events." In Solar Energetic Particles. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66402-2_5.
Повний текст джерелаАнотація:
AbstractGradual solar energetic-particle (SEP) events are “big proton events” and are usually much more “gradual” in their decay than in their onset. As their intensities increase, particles streaming away from the shock amplify Alfvén waves that scatter subsequent particles, increasing their acceleration, eventually limiting ion flow at the “streaming limit.” Waves generated by higher-speed protons running ahead can also throttle the flow of lower-energy ions, flattening spectra and altering abundances in the biggest SEP events. Thus, we find that the A/Q-dependence of scattering causes element-abundance patterns varying in space and time, which define source-plasma temperatures T, since the pattern of Q values of the ions depends upon temperature. Differences in T explain much of the variation of element abundances in gradual SEP events. In nearly 70% of gradual events, SEPs are shock-accelerated from ambient coronal plasma of ~0.8–1.6 MK, while 24% of the events involve material with T ≈ 2–4 MK re-accelerated from residual impulsive-suprathermal ions with pre-enhanced abundances. This source-plasma temperature can occasionally vary with solar longitude across the face of a shock. Non-thermal variations in ion abundances in gradual SEP events reaccelerated from the 2–4 MK impulsive source plasma are reduced, relative to those in the original impulsive SEPs, probably because the accelerating shock waves sample a pool of ions from multiple jet sources. Late in gradual events, SEPs become magnetically trapped in a reservoir behind the CME where spectra are uniform in space and decrease adiabatically in time as the magnetic bottle containing them slowly expands. Finally, we find variations of the He/O abundance ratio in the source plasma of different events.
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Otto, Thomas. "Industrial Safety at Particle Accelerators." In Safety for Particle Accelerators. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57031-6_4.
Повний текст джерелаАнотація:
AbstractThe construction and operation of particle accelerators implies the use of numerous technologies and trades which are well-known from the manufacturing and construction industries. Consequently, their safety hazards are described in the literature and standard best practice solutions exist for controlling the risks emerging from these activities. In this section, the occupational hazards of electricity, mechanical equipment and pressure vessels are illustrated with examples from particle accelerator facilities. Further sections are dedicated to accelerator-specific protection against fire, occupational noise, and environmental damage.
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Brugger, M., H. Burkhardt, B. Goddard, F. Cerutti, and R. G. Alia. "Interactions of Beams with Surroundings." In Particle Physics Reference Library. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34245-6_5.
Повний текст джерелаАнотація:
AbstractWith the exceptions of Synchrotron Radiation sources, beams of accelerated particles are generally designed to interact either with one another (in the case of colliders) or with a specific target (for the operation of Fixed Target experiments, the production of secondary beams and for medical applications). However, in addition to the desired interactions there are unwanted interactions of the high energy particles which can produce undesirable side effects. These interactions can arise from the unavoidable presence of residual gas in the accelerator vacuum chamber, or from the impact of particles lost from the beam on aperture limits around the accelerator, as well as the final beam dump. The wanted collisions of the beams in a collider to produce potentially interesting High Energy Physics events also reduces the density of the circulating beam and can produce high fluxes of secondary particles.
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Reames, Donald V. "Distinguishing the Sources." In Solar Energetic Particles. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66402-2_3.
Повний текст джерелаАнотація:
AbstractOur discussion of history has covered many of the observations that have led to the ideas of acceleration by shock waves or by magnetic reconnection in gradual and impulsive solar energetic particle (SEP) events, respectively. We now present other compelling observations, including onset timing, SEP-shock correlations, injection time profiles, high-energy spectral knees, e/p ratios, and intensity dropouts caused by a compact source, that have helped clarify these acceleration mechanisms and sources. However, some of the newest evidence now comes from source-plasma temperatures. In this and the next two chapters, we will find that impulsive events come from solar active regions at ≈ 3 MK, controlling ionization states Q, hence A/Q, and, in most gradual events, shocks accelerate ambient coronal material from ≤1.6 MK. When SEPs are trapped on closed loops they supply the energy for flares. In addition to helping to define their own origin, SEPs also probe the structure of the interplanetary magnetic field.
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Minty, Michiko G., and Frank Zimmermann. "Cooling." In Particle Acceleration and Detection. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-08581-3_11.
Повний текст джерелаАнотація:
AbstractMany applications of particle accelerators require beam cooling, which refers to a reduction of the beam phase space volume or an increase in the beam density via dissipative forces. In electron and positron storage rings cooling naturally occurs due to synchrotron radiation, and special synchrotron-radiation damping rings for the production of low-emittance beams are an integral part of electron-positron linear colliders. For other types of particles different cooling techniques are available. Electron cooling and stochastic cooling of hadron beams are used to accumulate beams of rare particles (such as antiprotons), to combat emittance growth (e.g., due to scattering on an internal target), or to produce beams of high quality for certain experiments. Laser cooling is employed to cool ion beams down to extremely small temperatures. Here the laser is used to induce transitions between the ion electronic states and the cooling exploits the Dopper frequency shift. Electron beams of unprecedentedly small emittance may be obtained by a different type of laser cooling, where the laser beam acts like a wiggler magnet. Finally, designs of a future muon collider rely on the principle of ionization cooling. Reference [1] gives a brief review of the principal ideas and the history of beam cooling in storage rings; a theoretical dicussion and a few practical examples can be found in [2].
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Vlahos, L., M. E. Machado, R. Ramaty, et al. "Particle Acceleration." In Energetic Phenomena on the Sun. Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2331-7_2.
Повний текст джерелаТези доповідей конференцій з теми "Acceleraton of particles"
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Kotaki, H., K. Nakajima, M. Kando, et al. "Laser Wakefield Acceleration Experiments." In Applications of High Field and Short Wavelength Sources. Optica Publishing Group, 1997. http://dx.doi.org/10.1364/hfsw.1997.the24.
Повний текст джерелаАнотація:
Laser-driven particle accelerators have been conceived over the past decade to be the next-generation particle accelerators, promising super-high field particle acceleration and a compact size compared with conventional accelerators 1). Among a number of laser accelerator concepts, laser wakefield accelerators have great potential to produce ultra-high-field gradients of plasma waves excited by intense ultrashort laser pulses 2). Recently wakefield excitation of the order of ~10GeV/m in a plasma has been directly confirmed by the use of a table-top-terawatt (T3) laser 3).
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Jen, Tien-Chien, Longjian Li, Qinghua Chen, Wenzhi Cui, and Xinming Zhang. "The Acceleration of Micro- and Nano-Particles in Supersonic De-Laval-Type Nozzle." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42583.
Повний текст джерелаАнотація:
The particle velocity in cold gas dynamic spraying (CGDS) is one of the most important factors that can determine the properties of the bonding to the substrate. The acceleration of gas to particles is strongly dependent on the densities of particles and the particle size. In this paper, the acceleration process of micro-scale and nano-scale copper (Cu) and platinum (Pt) particles in De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100nm to 50μm, which are accelerated by carrier gas Nitrogen in a supersonic De-Laval-type nozzle. The results show that cone-shape weak shocks (compression waves) occur at the exit of divergent section and the particle density has significant effect on the accele ration of micro-scale particles. At same inlet condition, the velocity of the smaller particles is larger than the larger particles at the exit of the divergent section of the nozzle.
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Fukanuma, H., N. Ohno, B. Sun, and R. Huang. "The Influence of Particle Morphology on In-flight Particle Velocity in Cold Spray." In ITSC2006, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, R. S. Lima, and J. Voyer. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.itsc2006p0097.
Повний текст джерелаАнотація:
Abstract Cold spray is a relatively recent spray coating technology in which metal or alloy particles are plastically deformed by the kinetic energy of the particles accelerated in a supersonic gas flow through a convergent-divergent nozzle before hitting the substrate. The particle velocity at impact onto the substrate is a key factor in determining the characteristics of the cold spray deposit. Therefore, various studies have been carried out on particle acceleration with the aim of obtaining faster cold spray particle velocities. Mathematical modeling has also been carried out on spherical particle acceleration in a supersonic gas flow in a Laval nozzle. To understand better how a non-spherical particle behaves in a supersonic gas flow, experiments were carried out on the affect of morphology on particle acceleration in cold spray. Two types of powder morphology were used for the experiment, one was spherical and the other was angular and jagged. The particle size distributions were almost the same. In-flight particle velocities of the spherical and angular particles were measured with a DPV-2000. It was found that the particle morphology greatly influenced the in-flight particle velocity and deposit efficiency.
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Yagami, Hisanori, and Tomomi Uchiyama. "Vortex Simulation for Behavior of Solid Particles Falling in Air." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-12019.
Повний текст джерелаАнотація:
The behavior of small solid particles falling in an unbounded air is simulated. The particles, initially arranged within a spherical region in a quiescent air, are made to fall, and their fall induces the air flow around them, resulting in the gas-particle two-phase flow. The particle diameter and density are 1 mm and 7.7 kg/m3 respectively. A three-dimensional vortex method proposed by one of the authors is applied. The simulation demonstrates that the particles are accelerated by the induced downward air flow just after the commencement of their fall. It also highlights that the particles are whirled up by a vortex ring produced around the downward air flow after the acceleration. The effect of the particle volume fraction at the commencement of the fall is also explored.
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Han, T., W. Li, X. Guo, and X. Yang. "Design of Cold Spray Nozzle to Optimize the Particle Velocity by Numerical Simulation." In ITSC2017, edited by A. Agarwal, G. Bolelli, A. Concustell, et al. DVS Media GmbH, 2017. http://dx.doi.org/10.31399/asm.cp.itsc2017p0595.
Повний текст джерелаАнотація:
Abstract This study investigated the accelerating behavior of spray particles during cold spraying (CS) by employing a computational fluid dynamics program, FLUENT. Optimization of the dimensions of CS nozzle was conducted to maximize particle velocity. The results show that the expansion ratio, divergent length, particle density and size, operating temperature significantly influence particle acceleration. It is found that the spray particles in nozzles with long divergent length can obtain a relatively higher impact velocity, but too long divergent length will reduce the particle velocity. Besides, the particle impact velocity shows a downward trend with increasing the particle size or density. Hence, the optimal divergent length should increase with the increase of particle mass. Moreover, higher gas temperature leads to a higher particle velocity, but it has no influence on the optimal divergent length.
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Leitz, K. H., M. O’Sullivan, A. Plankensteiner, H. Kestler, and L. S. Sigl. "Open FOAM Modelling of Particle Heating and Acceleration in Cold Spraying." In ITSC2017, edited by A. Agarwal, G. Bolelli, A. Concustell, et al. DVS Media GmbH, 2017. http://dx.doi.org/10.31399/asm.cp.itsc2017p0589.
Повний текст джерелаАнотація:
Abstract In cold spraying a powder material is accelerated and heated in the gas flow of a supersonic nozzle to velocities and temperatures that are sufficient to obtain cohesion of the particles to a substrate due to plastic deformation. The deposition efficiency of the powder particles is significantly determined by their velocity and temperature. The particle velocity correlates with the kinetic energy of the particles and thereby with the amount of energy that is converted to plastic deformation and thermal heating. The initial particle temperature significantly influences the mechanical properties of the particle. Velocity and temperature of the particles have nonlinear dependence on the pressure and temperature of the gas at the nozzle entrance. Whereas the particle velocity can easily be measured during the process, the particle temperature is not directly accessible by experimental techniques. Generally information about the particle temperature can be obtained based on theoretical models. In this contribution a simulation model based on the reactingParcelFoam solver of OpenFOAM is presented and applied for an analysis of the cold spray process. The model combines a compressible description of the gas flow in the nozzle with a Lagrangian particle tracking. The predictions of the simulation model are verified based on an analytical description of the gas flow, the particle acceleration and heating in the nozzle. Based on experimental data the drag model according to Plessis and Masliyah is identified to be best suited for OpenFOAM modelling particle heating and acceleration in cold spraying.
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Afanasiev, A. V., I. V. Bandurkin, A. M. Gorbachev, et al. "Development of photoinjector in IAP RAS." In 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.s1-p-038101.
Повний текст джерелаАнотація:
A photoinjector electron accelerator is being developed at the Institute of Applied Physics of the Russian Academy of Sciences, in which it is planned to implement sequential acceleration of particles up to energies of about 20 MeV. The first section of the complex, designed for an output particle energy of 3.5 MeV, can be used for experimental study of promising regimes of terahertz radiation from short electron bunches. After additional acceleration in the second section, bunches with small transverse emittance and velocity spread can be injected into a plasma accelerator cell to further increase their average energy to the GeV level and to use them as an active medium in an X-ray FEL. In addition, work is underway to study photocathodes based on diamond films.
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Akin, Semih, Puyuan Wu, Chandra Nath, Jun Chen, and Martin Byung-Guk Jun. "A Study on the Effect of Nozzle Geometrical Parameters on Supersonic Cold Spraying of Droplets." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85703.
Повний текст джерелаАнотація:
Abstract Supersonic cold spraying of droplets containing functional nanomaterials is of particular interest in advanced thin-film coating, that enabling high-adhesion strength particle deposition. In this method, coating occurs when the particles are accelerated to supersonic velocities in a converging-diverging nozzle, and then impact onto a target surface. Here, the optimum design of the nozzle is essential to deal with low-inertia particles like droplets. In particular, nozzle geometrical parameters (i.e., throat diameter, exit diameter, divergent length) determine droplets’ acceleration and deposition characteristics under supersonic flow conditions. To this end, we thoroughly investigate the influence of nozzle geometrical parameters on droplets acceleration by numerical modeling followed by experimental validation, and a case study on surface coating application. Two-phase flow modeling was used to predict droplets’ behavior in continuous gas flow for different nozzle configurations. The results show that the nozzle expansion ratio — a function of throat and exit diameters — has a significant influence on droplet velocity, followed by divergent length. In particular, to correctly accelerate low-inertia liquid droplets, optimum nozzle expansion ratio for an axisymmetric convergent-divergent nozzle is found to be in a range of 1.5–2.5 for various sets of parameters, which is different than the recommended expansion ratio (i.e., 5–9) for cold spraying of micro-scale metal particles. The findings can help determine the ideal design of a supersonic nozzle to minimize turbulent velocity fluctuation and shock wave formation that in turn assist to effectively spray low-inertia particles like micro-scale droplets. Based on the simulation results, an optimal design of supersonic nozzle is selected and prototyped for the experimental studies. Numerical modeling results are validated by particle image velocimetry (PIV) measurements. Moreover, coating experiments confirm the adaptability of the optimized nozzle for supersonic cold spraying of droplets containing nanoparticles, which thereby has the potential for rapid production of advanced thin films.
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Olson, C. L., C. A. Frost, E. L. Patterson, J. P. Anthes, and J. W. Poukey. "Ionization front accelerator: High gradients, demonstrated particle acceleration, and a proposed relativistic accelerator." In AIP Conference Proceedings Volume 130. AIP, 1985. http://dx.doi.org/10.1063/1.35281.
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Li, Longjian, Qinghua Chen, Wenzhi Cui, et al. "The Effects of the Distance Between Nozzle and Substrate on Cold Gas Dynamic Spray Process." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10501.
Повний текст джерелаАнотація:
In this paper, numerical simulations were performed for the gas-particle two phase flow in the Cold Gas Dynamic Spray (CGDS) process to investigate the acceleration of micro- and nanoparticles with diameters ranging from 100nm to 50μm. Nitrogen (N2) and Helium (He) were chosen as the carrier gas, respectively. The acceleration of carrier gas to particles in the De-Laval-Type supersonic nozzle was strongly dependent on the characteristics of flow field, as well as the densities and the size of the particles. Copper particles (Cu) were chosen as the spraying materials. The computed results showed that the flow structures of the carrier gas were very different for different gas and different spraying distance, which resulted in consequently different accelerating features. The cone-shape weak shocks (compression waves) occurred at the exit of divergent section, and the bow-shaped strong shock wave was found right before the substrate, which played a resistance role to the particles and prevented the smaller particles from approaching on the substrate.
Звіти організацій з теми "Acceleraton of particles"
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Pullammanappallil, Pratap, Haim Kalman, and Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, 2015. http://dx.doi.org/10.32747/2015.7600038.bard.
Повний текст джерелаАнотація:
Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.
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Steinberg, R. I., and C. E. Lane. Non-accelerator particle physics. Office of Scientific and Technical Information (OSTI), 1991. http://dx.doi.org/10.2172/5043726.
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Guo, Fan. Particle acceleration/energization during reconnection. Office of Scientific and Technical Information (OSTI), 2017. http://dx.doi.org/10.2172/1340946.
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Dimits, A. M., and J. A. Krommes. Stochastic particle acceleration and statistical closures. Office of Scientific and Technical Information (OSTI), 1985. http://dx.doi.org/10.2172/5111904.
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Guo, Fan. Nonthermal Particle Acceleration in Magnetic Reconnection. Office of Scientific and Technical Information (OSTI), 2017. http://dx.doi.org/10.2172/1345962.
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Mosko, S. (Power converters for particle accelerators). Office of Scientific and Technical Information (OSTI), 1990. http://dx.doi.org/10.2172/6948922.
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Ogitsu, T., A. Devred, and K. Kim. Quench antenna for superconducting particle accelerator magnets. Office of Scientific and Technical Information (OSTI), 1993. http://dx.doi.org/10.2172/91952.
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Birn, J., J. E. Borovsky, M. F. Thomsen, et al. Particle acceleration from reconnection in the geomagnetic tail. Office of Scientific and Technical Information (OSTI), 1997. http://dx.doi.org/10.2172/522543.
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Guo, Fan. Relativistic Magnetic Reconnection: A Powerful Cosmic Particle Accelerator. Office of Scientific and Technical Information (OSTI), 2014. http://dx.doi.org/10.2172/1159566.
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Bhat, Chandrashekara. Particle Accelerators at the Intensity Frontier for Elementary Particle Physics Research. Office of Scientific and Technical Information (OSTI), 2023. http://dx.doi.org/10.2172/1922104.
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