24 research outputs found
Quantization of the Coulomb Chain in an External Focusing Field
With the appropriate choice of parameters and sufficient cooling, charged
particles in a circular accelerator are believed to undergo a transition to a
highly-ordered crystalline state. The simplest possible crystalline
configuration is a one-dimensional chain of particles. In this paper, we write
down the quantized version of its dynamics. We show that in a low-density
limit, the dynamics is that of a theory of interacting phonons. There is an
infinite sequence of -phonon interaction terms, of which we write down the
first orders, which involve phonon scattering and decay processes. The quantum
formulation developed here can serve as a first step towards a
quantum-mechanical treatment of the system at finite temperatures.Comment: 9 Pages, 6 figure
Quantum Ground State and Minimum Emittance of a Fermionic Particle Beam in a Circular Accelerator
In the usual parameter regime of accelerator physics, particle ensembles can
be treated as classical. If we approach a regime where
$\epsilon_x\epsilon_y\epsilon_s \approx N_{particles}\lambda_{Compton}^3\$,
however, the granular structure of quantum-mechanical phase space becomes a
concern. In particular, we have to consider the Pauli exclusion principle,
which will limit the minimum achievable emittance for a beam of fermions. We
calculate these lowest emittances for the cases of bunched and coasting beams
at zero temperature and their first-order change rate at finite temperature.Comment: 6 Pages, 1 figur
Recent Progress in a Beam-Beam Simulation Code for Circular Hadron Machines
While conventional tracking codes can readily provide higher-order optical quantities and give an estimate of dynamic apertures, they are unable to provide directly measurable quantities such as lifetimes and loss rates. The particle tracking framework Plibb aims at modeling a storage ring with sufficient accuracy and a sufficiently high number of turns and in the presence of beam-beam interactions to allow for an estimate of these quantities. We provide a description of new features of the codes; we also describe a novel method of treating chromaticity in ring sections in a symplectic fashion
Mikrostruktursimulation der mechanischen Deformation von Fasermaterialien
Die Deformation von porösen Natur- und Kunstfasermaterialien unter Zug-, Druck- oder Biegebelastung hängt sehr stark von den geometrischen und mechanischen Eigenschaften der verwendeten Fasern und den Eigenschaften der Faser-Faser-Kontaktstellen ab. In den betrachteten Materialien besitzen die Fasern häufig eine Orientierung, die zu elastisch anisotropen Eigenschaften führt. Um das Materialverhalten beim Herstellungsprozess und im Einsatz vorherzusagen werden in dieser Arbeit Fasernetzwerkmodelle zur Beschreibung der Mikrostruktur verwendet.
Im Vergleich zu ähnlichen Verfahren werden sehr komplizierte dreidimensionale Fasernetzwerke mit einem effizienten numerischen Verfahren gelöst. Das Lösungsverfahren basiert auf einer Formulierung der Elastizitätsgleichungen als Integralgleichung vom Lippmann-Schwinger-Typ. Diese Integralgleichungen werden iterativ mit Hilfe der schnellen Fourier-Transformation (FFT) gelöst. Die Anwendung dieser Lösungstechnik auf poröse Medien ist neu. Im Vortrag werden Simulationsergebnisse für verschiedene Fasermaterialien erläutert und diese mit entsprechenden Messungen verglichen. Dabei werden geometrisch und physikalisch nichtlineare Verformungen betrachtet.
Mit Hilfe der entwickelten Mikrostruktursimulationstechnik (Softwarepaket FeelMath) lässt sich die Abhängigkeit der makroskopischen Deformationseigenschaften von den Eigenschaften der Einzelfasern und der Faserorientierung analysieren. Damit kann die Anzahl der notwendigen Messungen reduziert werden und die Eigenschaften der Materialien lassen sich für den speziellen Einsatzzweck optimieren. Das vorgestellte Lösungsverfahren ist ebenfalls für nichtporöse Verbundwerkstoffe und zur Lösung von Wärmeleitproblemen in Fasernetzwerken geeignet
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Design and Optimization of Large Accelerator Systems through High-Fidelity Electromagnetic Simulations
Recommended from our members
Design and Optimization of Large Accelerator Systems through High-Fidelity Electromagnetic Simulations
SciDAC1, with its support for the 'Advanced Computing for 21st Century Accelerator Science and Technology' (AST) project, witnessed dramatic advances in electromagnetic (EM) simulations for the design and optimization of important accelerators across the Office of Science. In SciDAC2, EM simulations continue to play an important role in the 'Community Petascale Project for Accelerator Science and Simulation' (ComPASS), through close collaborations with SciDAC CETs/Institutes in computational science. Existing codes will be improved and new multi-physics tools will be developed to model large accelerator systems with unprecedented realism and high accuracy using computing resources at petascale. These tools aim at targeting the most challenging problems facing the ComPASS project. Supported by advances in computational science research, they have been successfully applied to the International Linear Collider (ILC) and the Large Hadron Collider (LHC) in High Energy Physics (HEP), the JLab 12-GeV Upgrade in Nuclear Physics (NP), as well as the Spallation Neutron Source (SNS) and the Linac Coherent Light Source (LCLS) in Basic Energy Sciences (BES)