WorldWideScience

Sample records for beam dynamics

  1. Beam Dynamics for ARIA

    CERN Document Server

    Ekdahl, Carl

    2015-01-01

    Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.

  2. Beam Dynamics for ARIA

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-10-14

    Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.

  3. ICFA Beam Dynamics Newsletter

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi I.; Kuczewski A.; Altinbas, Z.; Beavis, D.; Belomestnykh,; Dai, J. et al

    2012-07-01

    The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation and control, Higher-Order Mode (HOM) issues, coherent emissions for the beam and high-brightness, high-power beam generation and preservation. The R&D ERL features a superconducting laser-photocathode RF gun with a high quantum efficiency photoccathode served with a load-lock cathode delivery system, a highly damped 5-cell accelerating cavity, a highly flexible single-pass loop and a comprehensive system of beam instrumentation. In this ICFA Beam Dynamics Newsletter article we will describe the ERL in a degree of detail that is not usually found in regular publications. We will discuss the various systems of the ERL, following the electrons from the photocathode to the beam dump, cover the control system, machine protection etc and summarize with the status of the ERL systems.

  4. Beam Dynamics and Beam Losses - Circular Machines

    CERN Document Server

    Kain, V

    2016-01-01

    A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.

  5. Beam dynamics issues for linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, R.D.

    1987-09-01

    In this paper we discuss various beam dynamics issues for linear colliders. The emphasis is to explore beam dynamics effects which lead to an effective dilution of the emittance of the beam and thus to a loss of luminosity. These considerations lead to various tolerances which are evaluated for a particular parameter set.

  6. Spacecraft Dynamic Characteristics While Deploying Flexible Beams

    Institute of Scientific and Technical Information of China (English)

    程绪铎; 李俊峰; 樊勇; 王照林

    2002-01-01

    The attitude dynamic equations of a spacecraft while deploying two flexible beams and the beam equations were developed from momentum theory. The dynamic equations were solved numerically using the Runge-Kutta method to calculate the vibration amplitudes of the flexible beams and the attitude angular velocity. The results show that the vibration amplitudes increase as the beam length increases or as the initial attitude angular velocity increases. The results also show that the vibration amplitudes decrease as the deployment velocity increases.

  7. Statics and rotational dynamics of composite beams

    CERN Document Server

    Ghorashi, Mehrdaad

    2016-01-01

    This book presents a comprehensive study of the nonlinear statics and dynamics of composite beams and consists of solutions with and without active elements embedded in the beams. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Two independent numerical solutions for the steady state and the transient responses are presented. The author illustrates that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. Other key areas considered include calculation of the effect of perturbing the steady state solution, coupled nonlinear flap-lag dynamics of a rotating articulated beam with hinge offset and aerodynamic damping, and static and dynamic responses of nonlinear composite beams with embedded anisotropic piezo-composite actuators. The book is intended as a t...

  8. Engineering parabolic beams with dynamic intensity profiles.

    Science.gov (United States)

    Ruelas, Adrian; Lopez-Aguayo, Servando; Gutiérrez-Vega, Julio C

    2013-08-01

    We present optical fields formed by superposing nondiffracting parabolic beams with distinct longitudinal wave-vector components, generating light profiles that display intensity fluxes following parabolic paths in the transverse plane. Their propagation dynamics vary depending on the physical mechanism originating interference, where the possibilities include constructive and destructive interference between traveling parabolic beams, interference between stationary parabolic modes, and combinations of these. The dark parabolic region exhibited by parabolic beams permits a straightforward superposition of intensity fluxes, allowing formation of a variety of profiles, which can exhibit circular, elliptic, and other symmetries.

  9. A contemporary guide to beam dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Forest, E. [Lawrence Berkeley Lab., CA (United States); Hirata, Kohji [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1992-09-01

    A methodological discussion is given for single particle beam dynamics in circular machines. The discussions are introductory, but (or, even therefore) we avoid to rely on too much simplified concepts. We treat things from a very general and fundamental point of view, because this is the easiest and rightest way to teach how to simulate particle motion and how to analyze its results. We give some principles of particle tracking free from theoretical prejudices. We also introduce some transparent methods to deduce the necessary information from the tracking: many of the traditional beam-dynamics concepts can be abstracted from them as approximate quantities which are valid in certain limiting cases.

  10. Dynamic Bowtie for Fan-beam CT

    CERN Document Server

    Liu, Fenglin; Cong, Wenxiang; Hsieh, Scott; Pelc, Norbert

    2013-01-01

    A bowtie is a filter used to shape an x-ray beam and equalize its flux reaching different detector channels. For development of spectral CT with energy-discriminative photon-counting (EDPC) detectors, here we propose and evaluate a dynamic bowtie for performance optimization based on a patient model or a scout scan. Our dynamic bowtie modifies an x-ray beam intensity profile by mechanical rotation and adaptive adjustment of the x-ray source flux. First, a mathematical model for dynamic bowtie filtering is established for an elliptical section in fan-beam geometry, and the contour of the optimal bowtie is derived. Then, numerical simulation is performed to compare the performance of the dynamic bowtie in the cases of an ideal phantom and a realistic cross-section relative to the counterparts without any bowtie and with a fixed bowtie respectively. Our dynamic bowtie can equalize the expected numbers of photons in the case of an ideal phantom. In practical cases, our dynamic bowtie can effectively reduce the dy...

  11. Beam Dynamics Studies for the SPARC Project

    Energy Technology Data Exchange (ETDEWEB)

    Ferrario, M.; Biagini, Maria E.; Boscolo, M.; Fusco, V.; Guiducci, S.; Migliorati, M.; Serafini, L.; Vaccarezza, C.; Bartolini, R.; Giannessi, L.; Quattromini, M.; Ronsivalle, C.; Limborg, C.G.; /Unlisted /Unlisted /ENEA, Frascati /SLAC

    2008-03-17

    The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities.

  12. Dynamic Beam Based Calibration of Beam Position Monitors

    CERN Document Server

    Dehning, Bernd; Galbraith, Peter; Mugnai, G; Placidi, Massimo; Sonnemann, F; Tecker, F A; Wenninger, J

    1998-01-01

    The degree of spin polarization at LEP is strongly dependent on the knowledge of the vertical orbit. Quadrupole magnet alignment and beam position monitor (BPM) offsets are the main source of the orbi t uncertainty. The error of the orbit monitor readings can be largely reduced by calibrating the monitor relative to the adjacent quadrupole. At LEP, 16 BPM offsets can be determined in parallel durin g 40 minutes. The error of the measure offset is about 30mm. During the LEP run 1997, more than 500 measurements were made and used for the optimisation of polarization. The method of dynamic beam bas ed calibration will be explained and the results will be shown.

  13. TRACK The New Beam Dynamics Code

    CERN Document Server

    Mustapha, Brahim; Ostroumov, Peter; Schnirman-Lessner, Eliane

    2005-01-01

    The new ray-tracing code TRACK was developed* to fulfill the special requirements of the RIA accelerator systems. The RIA lattice includes an ECR ion source, a LEBT containing a MHB and a RFQ followed by three SC linac sections separated by two stripping stations with appropriate magnetic transport systems. No available beam dynamics code meet all the necessary requirements for an end-to-end simulation of the RIA driver linac. The latest version of TRACK was used for end-to-end simulations of the RIA driver including errors and beam loss analysis.** In addition to the standard capabilities, the code includes the following new features: i) multiple charge states ii) realistic stripper model; ii) static and dynamic errors iii) automatic steering to correct for misalignments iv) detailed beam-loss analysis; v) parallel computing to perform large scale simulations. Although primarily developed for simulations of the RIA machine, TRACK is a general beam dynamics code. Currently it is being used for the design and ...

  14. Structural dynamic analysis of composite beams

    Science.gov (United States)

    Suresh, J. K.; Venkatesan, C.; Ramamurti, V.

    1990-12-01

    In the treatment of the structural dynamic problem of composite materials, two alternate types of formulations, based on the elastic modulus and compliance quantities, exist in the literature. The definitions of the various rigidities are observed to differ in these two approaches. Following these two types of formulation, the structural dynamic characteristics of a composite beam are analyzed. The results of the analysis are compared with those available in the literature. Based on the comparison, the influence of the warping function in defining the coupling terms in the modulus approach and also on the natural frequencies of the beam has been identified. It is found from the analysis that, in certain cases, the difference between the results of the two approaches is appreciable. These differences may be attributed to the constraints imposed on the deformation and flexibility of the beam by the choice of the description of the warping behaviour. Finally, the influence of material properties on the structural dynamic characteristics of the beam is studied for different composites for various angles of orthotropy.

  15. Electron Beam Dynamics in 4GLS

    CERN Document Server

    Williams, P H; Muratori, B D; Owen, H L; Smith, S L

    2007-01-01

    Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA High Average Current branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of the injector designs, electron transport, and energy recovery is given, including ongoing studies of coherent synchrotron radiation, beam break-up and wakefields. This work is being pursued for the forthcoming Technical Design Report due in 2008.

  16. RIA Beam Dynamics Comparing TRACK to IMPACT

    CERN Document Server

    Mustapha, Brahim; Ostroumov, Peter; Qiang, Ji; Ryne, Robert D

    2005-01-01

    In order to benchmark the newly developed beam dynamics code TRACK we have performed comparisons with well established existing codes. During code development, codes like TRANSPORT, COSY, GIOS and RAYTRACE were used to check TRACK's implementation of the different beam line elements. To benchmark the end-to-end simulation of the RIA driver linac, the simulation of the low-energy part (from the ion source to the entrance of the SC linac) was compared with PARMTEQ and found to agree well. For the simulation of the SC linac the code IMPACT is used. Prior to these simulations, the code IMPACT had to be updated to meet the special requirements of the RIA driver linac. Features such as multiple charge state acceleration, stripper simulation and beam collimation were added to the code. IMPACT was also modified to support new types of rf cavities and to include fringe fields for all the elements. This paper will present a comparison of the beam dynamics simulation in the RIA driver linac between the codes TRACK and I...

  17. Modal Perturbation Method for the Dynamic Characteristics of Timoshenko Beams

    OpenAIRE

    2005-01-01

    Timoshenko beams have been widely used in structural and mechanical systems. Under dynamic loading, the analytical solution of a Timoshenko beam is often difficult to obtain due to the complexity involved in the equation of motion. In this paper, a modal perturbation method is introduced to approximately determine the dynamic characteristics of a Timoshenko beam. In this approach, the differential equation of motion describing the dynamic behavior of the Timoshenko beam can be transformed int...

  18. Beam dynamics issues in the FCC

    CERN Document Server

    AUTHOR|(CDS)2067437; Benedikt, Michael; Besana, Maria Ilaria; Bruce, Roderik; Bruning, Oliver; Buffat, Xavier; Burkart, Florian; Burkhardt, Helmut; Calatroni, Sergio; Cerutti, Francesco; Fartoukh, Stephane; Fiascaris, Maria; Garion, Cedric; Goddard, Brennan; Hofle, Wolfgang; Holzer, Bernhard; Jowett, John; Kersevan, Roberto; Martin, Roman; Mether, Lotta Maria; Milanese, Attilio; Pieloni, Tatiana; Redaelli, Stefano; Rumolo, Giovanni; Salvant, Benoit; Schaumann, Michaela; Schulte, Daniel; Chapochnikova, Elena; Stoel, Linda; Tambasco, Claudia; Tomas Garcia, Rogelio; Tommasini, Davide; Zimmermann, Frank; Guillermo Canton, Gerardo; Kornilov, Vladimir; Boine-Frankenheim, Oliver; Niedermayer, Uwe; Mitsuhashi, Toshiyuki; Ohmi, Kazuhito; Chance, Antoine; Dalena, Barbara; Payet, Jacques; Bambade, Philip; Faus-Golfe, Angeles; Molson, James; Biarrotte, Jean-Luc; Lachaize, Antoine; Fox, John D; Stupakov, Gennady; Abelleira, Jose; Cruz Alaniz, Emilia; Seryi, Andrei; Appleby, Robert Barrie; Boscolo, Manuela; Collamati, Francesco; Drago, Alessandro; Barranco Garcia, Javier; Khan, Shaukat; Riemann, Bernhard

    2016-01-01

    The international Future Circular Collider (FCC) study is designing hadron, lepton and lepton-hadron colliders based on a new 100 km tunnel in the Geneva region. The main focus and ultimate goal of the study are high luminosity proton-proton collisions at a centre-of-mass energy of 100 TeV, using 16 T Nb3Sn dipole magnets. Specific FCC beam dynamics issues are related to the large circumference, the high brightness—made available by radiation damping —, the small geometric emittance, unprecedented collision energy and luminosity, the huge amount of energy stored in the beam, large synchrotron radiation power, plus the injection scenarios. In addition to the FCC-hh proper, also a High-Energy LHC (HE-LHC) is being explored, using the FCC-hh magnet technology in the existing LHC tunnel, which can yield a centre-of-mass energy around 25 TeV.

  19. Photorefractive dynamic holography using self-pumped phase conjugate beam

    Indian Academy of Sciences (India)

    Arun Anand; C S Narayanamurthy

    2006-03-01

    Dynamic holography in photorefractive materials using self-pumped phase conjugate beam of the object beam itself as the other writing beam is proposed. Our detailed theoretical analysis shows four-fold increase in the diffraction efficiency of dynamic holograms if recorded using this geometry even in photorefractive crystal like BTO (having low optical activity) without applying external field. Detailed theoretical analysis is given.

  20. Beam stability & nonlinear dynamics. Formal report

    Energy Technology Data Exchange (ETDEWEB)

    Parsa, Z. [ed.

    1996-12-31

    his Report includes copies of transparencies and notes from the presentations made at the Symposium on Beam Stability and Nonlinear Dynamics, December 3-5, 1996 at the Institute for Theoretical Physics, University of California, Santa Barbara California, that was made available by the authors. Editing, reduction and changes to the authors contributions were made only to fulfill the printing and publication requirements. We would like to take this opportunity and thank the speakers for their informative presentations and for providing copies of their transparencies and notes for inclusion in this Report.

  1. Nonlinear dynamic characteristic analysis of jointed beam with clearance

    Science.gov (United States)

    Zhang, Jing; Guo, Hong-Wei; Liu, Rong-Qiang; Wu, Juan; Kou, Zi-Ming; Deng, Zong-Quan

    2016-12-01

    The impact and elasticity of discontinuous beams with clearance frequently affect the dynamic response of structures used in space missions. This study investigates the dynamic response of jointed beams which are the periodic units of deployable structures. The vibration process of jointed beams includes free-play and impact stages. A method for the dynamic analysis of jointed beams with clearance is proposed based on mode superposition and instantaneous static deformation. Transfer matrix, which expresses the relationship of the responses before and after the impact of jointed beams, is derived to calculate the response of the jointed beams after a critical position. The dynamic responses of jointed beams are then simulated. The effects of various parameters on the displacement and velocity of beams are investigated.

  2. Beam dynamics analysis in pulse compression using electron beam compact simulator for Heavy Ion Fusion

    Directory of Open Access Journals (Sweden)

    Kikuchi Takashi

    2013-11-01

    Full Text Available In a final stage of an accelerator system for heavy ion inertial fusion (HIF, pulse shaping and beam current increase by bunch compression are required for effective pellet implosion. A compact simulator with an electron beam was constructed to understand the beam dynamics. In this study, we investigate theoretically and numerically the beam dynamics for the extreme bunch compression in the final stage of HIF accelerator complex. The theoretical and numerical results implied that the compact experimental device simulates the beam dynamics around the stagnation point for initial low temperature condition.

  3. Impact of Dynamic Magnetic fields on the CLIC Main Beam

    CERN Document Server

    Snuverink, J; Jach, C; Jeanneret, JB; Schulte, D; Stulle, F

    2010-01-01

    The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.

  4. Doublet vs. FODO structure: beam dynamics and layout

    CERN Document Server

    Eshraqi, M; CERN. Geneva. BE Department

    2010-01-01

    A FoDo (singlet) structure is designed for the CERN Superconducting Proton LINAC. This architecture is compared to the baseline (doublet) architecture of SPL on the basis of its beam dynamics performance and the required investment. The sensitivity of both layouts to quadrupole gradient errors and misalignment is checked and a correction scheme for beam steering is proposed. Finally a single quad beam dilution scheme is studied and designed for the pilot beam dump.

  5. Molecular beam studies of reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.T. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  6. Advanced Beam-Dynamics Simulation Tools for RIA

    CERN Document Server

    Garnett, Robert; Crandall, Kenneth; Ostroumov, Peter; Qiang, Ji; Ryne, Robert D; Wangler, Thomas; York, Richard; Zhao, Qiang

    2005-01-01

    Understanding beam losses is important for the high-intensity RIA driver linac. Small fractional beam losses can produce radioactivation of the beamline components that can prevent or hinder hands-on maintenance, reducing facility availability. Operational and alignment errors in the RIA driver linac can lead to beam losses caused by irreversible beam-emittance growth and halo formation. We are developing multiparticle beam-dynamics simulation codes for RIA driver-linac simulations extending from the low-energy beam transport (LEBT) line to the end of the linac. These codes run on the NERSC parallel supercomputing platforms at LBNL, which allow us to run simulations with large numbers of macroparticles for the beam-loss calculations. The codes have the physics capabilities needed for RIA, including transport and acceleration of multiple-charge-state beams, and beam-line elements such as high-voltage platforms within the linac, interdigital accelerating structures, charge-stripper foils, and capabilities for h...

  7. Dynamic Stability of Euler Beams under Axial Unsteady Wind Force

    Directory of Open Access Journals (Sweden)

    You-Qin Huang

    2014-01-01

    Full Text Available Dynamic instability of beams in complex structures caused by unsteady wind load has occurred more frequently. However, studies on the parametric resonance of beams are generally limited to harmonic loads, while arbitrary dynamic load is rarely involved. The critical frequency equation for simply supported Euler beams with uniform section under arbitrary axial dynamic forces is firstly derived in this paper based on the Mathieu-Hill equation. Dynamic instability regions with high precision are then calculated by a presented eigenvalue method. Further, the dynamically unstable state of beams under the wind force with any mean or fluctuating component is determined by load normalization, and the wind-induced parametric resonant response is computed by the Runge-Kutta approach. Finally, a measured wind load time-history is input into the dynamic system to indicate that the proposed methods are effective. This study presents a new method to determine the wind-induced dynamic stability of Euler beams. The beam would become dynamically unstable provided that the parametric point, denoting the relation between load properties and structural frequency, is located in the instability region, no matter whether the wind load component is large or not.

  8. Dynamic stiffness matrix of partial-interaction composite beams

    Directory of Open Access Journals (Sweden)

    Guangjian Bao

    2015-03-01

    Full Text Available Composite beams have a wide application in building and bridge engineering because of their advantages of mechanical properties, constructability and economic performance. Unlike static characteristics, the methods of studying the dynamic characteristics of partial-interaction composite beams were limited, especially dynamic stiffness matrix method. In this article, the dynamic stiffness matrix of partial-interaction composite beams was derived based on the assumption of the Euler–Bernoulli beam theory, and then it was used to predict the frequencies of the free vibration of the single-span composite beams with various boundary conditions or different axial forces. The corresponding vibration modes and buckling loads were also obtained. From the comparison with the existing results, the numerical results obtained by the proposed method agreed reasonably with those in the literatures. The dynamic stiffness matrix method is an accurate method which can determine natural vibration frequencies and vibration mode shapes in any precision theoretically. As a result, when the higher precision or natural frequencies of higher order are required, the dynamic stiffness matrix method is superior when compared to other approximate and numerical methods. The dynamic stiffness matrix method can also be combined with the finite-element method to calculate the free vibration frequencies and natural mode shapes of composite beams in complex conditions.

  9. Beam Dynamics Studies in Recirculating Machines

    CERN Document Server

    Pellegrini, Dario; Latina, A

    The LHeC and the CLIC Drive Beam share not only the high-current beams that make them prone to show instabilities, but also unconventional lattice topologies and operational schemes in which the time sequence of the bunches varies along the machine. In order to asses the feasibility of these projects, realistic simulations taking into account the most worrisome effects and their interplays, are crucial. These include linear and non-linear optics with time dependent elements, incoherent and coherent synchrotron radiation, short and long-range wakefields, beam-beam effect and ion cloud. In order to investigate multi-bunch effects in recirculating machines, a new version of the tracking code PLACET has been developed from scratch. PLACET2, already integrates most of the effects mentioned before and can easily receive additional physics. Its innovative design allows to describe complex lattices and track one or more bunches accordingly to the machine operation, reproducing the bunch train splitting and recombinat...

  10. Dynamic behaviour of a rotating cracked beam

    Science.gov (United States)

    Yashar, Ahmed; Ghandchi-Tehrani, Maryam; Ferguson, Neil

    2016-09-01

    This paper presents a new approach to investigate and analyse the vibrational behaviour of cracked rotating cantilever beams, which can for example represent helicopter or wind turbine blades. The analytical Hamiltonian method is used in modelling the rotating beam and two numerical methods, the Rayleigh-Ritz and FEM, are used to study the natural frequencies and the mode shapes of the intact rotating beams. Subsequently, a crack is introduced into the FE model and simulations are performed to identify the modal characteristics for an open cracked rotating beam. The effect of various parameters such as non-dimensional rotating speed, hub ratio and slenderness ratio are investigated for both the intact and the cracked rotating beam, and in both directions of chordwise and flapwise motion. The veering phenomena in the natural frequencies as a function of the rotational speed and the buckling speed are considered with respect to the slenderness ratio. In addition, the mode shapes obtained for the flapwise vibration are compared using the modal assurance criterion (MAC). Finally, a new three dimensional design chart is produced, showing the effect of crack location and depth on the natural frequencies of the rotating beam. This chart will be subsequently important in identifying crack defects in rotating blades.

  11. Screw theoretic view on dynamics of spatially compliant beam

    Institute of Scientific and Technical Information of China (English)

    Xi-lun DING; J.M.SELIG

    2010-01-01

    Beams with spatial compliance can be deformed as bending in a plane,twisting,and extending.In terms of the screw theory on rigid body motions,the concept of"deflection screw"is introduced,a spatial compliant beam theory via the deflection screw is proposed,and the spatial compliance of such a beam system is presented and analysed based on the material theory and fundamental kinematic assumptions.To study the dynamics of the spatially compliant beam,the potential energy and the kinetic energy of the beam are discussed by using the screw theory to obtain the Lagrangian.The Rayleigh-Ritz method is used to compute the vibrational frequencies based on discussions of boundary conditions and shape functions.The eigenfrequencies of the beam with spatial compliance are compared with those of individual deformation cases,pure bending,extension,or torsion.Finally,dynamics of a robot with two spatial compliant links and perpendicular joints is studied using the spatial compliant beam theory.Coupling between the joint rigid body motions and the deformations of spatial compliant links can easily be found in dynamic simulation.The study shows the effectiveness of using the screw theory to deal with the problems of dynamic modeling and analysis of mechanisms with spatially compliant links.

  12. A piecewise continuous Timoshenko beam model for the dynamic analysis of tapered beam-like structures

    Science.gov (United States)

    Shen, Ji Yao; Abu-Saba, Elias G.; Mcginley, William M.; Sharpe, Lonnie, Jr.; Taylor, Lawrence W., Jr.

    1992-01-01

    Distributed parameter modeling offers a viable alternative to the finite element approach for modeling large flexible space structures. The introduction of the transfer matrix method into the continuum modeling process provides a very useful tool to facilitate the distributed parameter model applied to some more complex configurations. A uniform Timoshenko beam model for the estimation of the dynamic properties of beam-like structures has given comparable results. But many aeronautical and aerospace structures are comprised of non-uniform sections or sectional properties, such as aircraft wings and satellite antennas. This paper proposes a piecewise continuous Timoshenko beam model which is used for the dynamic analysis of tapered beam-like structures. A tapered beam is divided into several segments of uniform beam elements. Instead of arbitrarily assumed shape functions used in finite element analysis, the closed-form solution of the Timoshenko beam equation is used. Application of the transfer matrix method relates all the elements as a whole. By corresponding boundary conditions and compatible conditions a characteristic equation for the global tapered beam has been developed, from which natural frequencies can be derived. A computer simulation is shown in this paper, and compared with the results obtained from the finite element analysis. While piecewise continuous Timoshenko beam model decreases the number of elements significantly; comparable results to the finite element method are obtained.

  13. Beam dynamics design studies of a superconducting radioactive ion beam postaccelerator

    CERN Document Server

    Fraser, M A; Jones, R M

    2011-01-01

    The HIE-ISOLDE project at CERN proposes a superconducting upgrade to increase the energy range and quality of the radioactive ion beams produced at ISOLDE, which are currently postaccelerated by the normal conducting radioactive ion beam experiment linac. The specification and design choices for the HIE-ISOLDE linac are outlined along with a comprehensive beam dynamics study undertaken to understand and mitigate the sources of beam emittance dilution. The dominant cause of transverse emittance growth was attributed to the coupling between the transverse and longitudinal motions through the phase dependence of the rf defocusing force in the accelerating cavities. A parametric resonance induced by the coupling was observed and its excitation surveyed as a function of transverse phase advance using numerical simulations and analytic models to understand and avoid the regions of transverse beam instability. Other sources of emittance growth were studied and where necessary ameliorated, including the beam steering...

  14. Propagation dynamics of vortices in Helico-Conical optical beams

    CERN Document Server

    Bareza, Nestor

    2015-01-01

    We present the dynamics of optical vortices (OVs) that came from the propagation of helico-conical optical beam. This dynamics is investigated numerically by tracking the OVs at several distances using rigorous scalar diffraction theory. To ensure that our numerical calculations are correct, we compare the intensity profiles and their corresponding interferograms taken at different propagation distances between simulations and experiments. We observe that the peripheral isopolar vortices transport radially inward, toward the optical axis along the transverse spatial space as the beam propagates. When the beam has a central vortex, these vortices have significant induced angular rates of motion about the optical axis. These propagation dynamics of vortices influence the internal energy flow and the wave profile reconstruction of the beam, which can be important when deciding their applications.

  15. Beam manipulation techniques, nonlinear beam dynamics, and space charge effect in high energy high power accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S. Y.

    2014-04-07

    We had carried out a design of an ultimate storage ring with beam emittance less than 10 picometer for the feasibility of coherent light source at X-ray wavelength. The accelerator has an inherent small dynamic aperture. We study method to improve the dynamic aperture and collective instability for an ultimate storage ring. Beam measurement and accelerator modeling are an integral part of accelerator physics. We develop the independent component analysis (ICA) and the orbit response matrix method for improving accelerator reliability and performance. In collaboration with scientists in National Laboratories, we also carry out experimental and theoretical studies on beam dynamics. Our proposed research topics are relevant to nuclear and particle physics using high brightness particle and photon beams.

  16. Beam Dynamics Challenges for FCC-ee

    CERN Document Server

    AUTHOR|(SzGeCERN)442987; Benedikt, Michael; Oide, Katsunobu; Bogomyagkov, Anton; Levichev, Evgeny; Migliorati, Mauro; Wienands, Uli

    2015-01-01

    The goals of FCC-ee include reaching luminosities of up to a few 1036 cm-2s-1 per interaction point at the Z pole or some 1034 cm-2s-1 at the ZH production peak, and pushing the beam energy up to ≥175 GeV, in a ring of 100 km circumference, with a total synchrotron-radiation power not exceeding 100 MW. A parameter baseline as well as high-luminosity crab-waist options were described in [1] and [2], respectively. The extremely high luminosity and resulting short beam lifetime (due to radiative Bhabha scattering) are sustained by top-up injection. The FCC-ee design status and typical beam parameters for different modes of operation are reported in [3]. One distinct feature of the FCC-ee design is its conception as a double ring, with separate beam pipes for the two counter-rotating (electron and positron) beams, resembling, in this aspect, the high-luminosity B factories PEP-II, KEKB and SuperKEKB as well as the LHC. The two separate rings do not only permit operation with a large number of bunches, up to a f...

  17. Overview on production and dynamics of high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Serafini, L. [INFN-Milano and UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, California 90095-1547 (United States)

    1997-02-01

    The advent of laser driven RF Photoinjectors has raised the interest in the beam dynamics associated with intense, quasi-laminar, space charge dominated electron beams: the relevant phenomena observed in such a new regime of beam physics are presented and discussed in this paper. Most of the emphasis is focused on the analysis of the so called emittance correction technique, which is applied in the operation of RF guns in order to enhance the performances of these devices in terms of the attainable beam brightness, i.e., minimizing the beam emittance. A fully analytical description of this process is presented, based on an envelope equation treatment which leads to the concept of {ital invariant envelope}. The implications of such a concept are discussed and specific examples are given to compare the analytical predictions to the results of numerical simulations. {copyright} {ital 1997 American Institute of Physics.}

  18. Beam Dynamics Design Studies of a Superconducting Radioactive Ion Beam Post-accelerator

    CERN Document Server

    Fraser, MA; Pasini, M

    2011-01-01

    The HIE-ISOLDE project at CERN proposes a superconducting upgrade to increase the energy range and quality of the radioactive ion beams produced at ISOLDE, which are currently post- accelerated by the normal conducting REX linac. The specification and design choices for the HIE-ISOLDE linac are outlined along with a comprehensive beam dynamics study undertaken to understand and mitigate the sources of beam emittance dilution. The dominant cause of transverse emittance growth was attributed to the coupling between the transverse and longitudinal motions through the phase dependence of the rf defocusing force in the accelerating cavities. A parametric resonance induced by the coupling was observed and its excitation surveyed as a function of trans- verse phase advance using numerical simulations and analytic models to understand and avoid the regions of transverse beam instability. Other sources of emittance growth were studied and where necessary ameliorated, including the beam steering force in the quarter-wa...

  19. Dynamic response of a viscoelastic Timoshenko beam

    Science.gov (United States)

    Kalyanasundaram, S.; Allen, D. H.; Schapery, R. A.

    1987-01-01

    The analysis presented in this study deals with the vibratory response of viscoelastic Timoshenko (1955) beams under the assumption of small material loss tangents. The appropriate method of analysis employed here may be applied to more complex structures. This study compares the damping ratios obtained from the Timoshenko and Euler-Bernoulli theories for a given viscoelastic material system. From this study the effect of shear deformation and rotary inertia on damping ratios can be identified.

  20. Dynamic Stiffness Matrix for a Beam Element with Shear Deformation

    Directory of Open Access Journals (Sweden)

    Walter D. Pilkey

    1995-01-01

    Full Text Available A method for calculating the dynamic transfer and stiffness matrices for a straight Timoshenko shear beam is presented. The method is applicable to beams with arbitrarily shaped cross sections and places no restrictions on the orientation of the element coordinate system axes in the plane of the cross section. These new matrices are needed because, for a Timoshenko beam with an arbitrarily shaped cross section, deflections due to shear in the two perpendicular planes are coupled even when the coordinate axes are chosen to be parallel to the principal axes of inertia.

  1. Dynamic analysis for planar beam with clearance joint

    Science.gov (United States)

    Yao, XiaoGuang; Guo, XiaoSong; Feng, YongBao; Yu, ChuanQiang; Ma, Changlin

    2015-03-01

    An analytical model was presented in this study to describe the dynamic characteristics of a planar rotation beam with clearance joint. The spherical contact model was introduced to calculate the collision forces for the planar revolute joint. Unlike previous research, to acquire an accurate and convergent solution, the second-order coupling term of the beam axial deformation is taken into account. Then, the flexible beam was divided into discrete elements via the finite element method. The dynamic equations of the model were deduced via the Hamilton's principle. Further, the dynamic responses were obtained and analyzed in the non-inertial and inertial coordinates. To prove the validity of the presented methodology, a virtual prototype model with identical conditions was created in ADAMS. A numerical example was simultaneously calculated by the two different approaches. Comparison of the results shows that the two approaches match quite well. Finally, some valuable conclusions describing the inner-joint collision process are extracted and summarized.

  2. High Dynamic Range Beam Imaging with Two Simultaneously Sampling CCDs

    Energy Technology Data Exchange (ETDEWEB)

    Evtushenko, Pavel [JLAB; Douglas, David R. [JLAB; Legg, Robert A. [JLAB; Tennant, Christopher D. [JLAB

    2013-05-01

    Transverse beam profile measurement with sufficiently high dynamic range (HDR) is a key diagnostic to measure the beam halo, understand its sources and evolution. In this contribution we describe our initial experience with the HDR imaging of the electron beam at the JLab FEL. On contrary to HDR measurements made with wire scanners in counting mode, which provide only two or three 1D projections of transverse beam distribution, imaging allows to measure the distribution itself. That is especially important for non-equilibrium beams in the LINACs. The measurements were made by means of simultaneous imaging with two CCD sensors with different exposure time. Two images are combined then numerically in to one HDR image. The system works as an online tool providing HDR images at 4 Hz. An optically polished YAG:Ce crystal with the thickness of 100 {micro}m was used for the measurements. When tested with a laser beam images with the DR of about 10{sup 5} were obtained. With the electron beam the DR was somewhat smaller due to the limitations in the time structure of the tune-up beam macro pulse.

  3. High Dynamic Range Beam Imaging with Two Simultaneously Sampling CCDs

    Energy Technology Data Exchange (ETDEWEB)

    Evtushenko, Pavel E. [JLAB; Douglas, David R. [JLAB

    2013-06-01

    Transverse beam profile measurement with sufficiently high dynamic range (HDR) is a key diagnostic to measure the beam halo, understand its sources and evolution. In this contribution we describe our initial experience with the HDR imaging of the electron beam at the JLab FEL. On contrary to HDR measurements made with wire scanners in counting mode, which provide only two or three 1D projections of transverse beam distribution, imaging allows to measure the distribution itself. That is especially important for non-equilibrium beams in the LINACs. The measurements were made by means of simultaneous imaging with two CCD sensors with different exposure time. Two images are combined then numerically in to one HDR image. The system works as an online tool providing HDR images at 4 Hz. An optically polished YAG:Ce crystal with the thickness of 100 {micro}m was used for the measurements. When tested with a laser beam images with the DR of about 10{sup 5} were obtained. With the electron beam the DR was somewhat smaller due to the limitations in the time structure of the tune-up beam macro pulse.

  4. Intense ion-beam dynamics in the NICA collider

    Science.gov (United States)

    Kozlov, O. S.; Meshkov, I. N.; Sidorin, A. O.; Trubnikov, G. V.

    2016-12-01

    The problems of intense ion-beam dynamics in the developed and optimized optical structure of the NICA collider are considered. Conditions for beam collisions and obtaining the required parameters of luminosity in the operation energy range are discussed. The restriction on collider luminosity is related to effects of the domination of the space charge and intrabeam scattering. Applying methods of cooling, electron and stochastic ones, will permit one to suppress these effects and reach design luminosity. The work also deals with systems of magnetic field correction and problems of calculating the dynamic aperture of the collider.

  5. DARHT-II Long-Pulse Beam-Dynamics Experiments

    CERN Document Server

    Ekdahl, Carl; Bartsch, Richard; Bender, Howard; Briggs, Richard J; Broste, William; Carlson, Carl; Caudill, Larry; Chan, Kwok-Chi D; Chen Yu Jiuan; Dalmas, Dale; Durtschi, Grant; Eversole, Steven; Eylon, Shmuel; Fawley, William M; Frayer, Daniel; Gallegos, Robert J; Harrison, James; Henestroza, Enrique; Holzscheiter, M H; Houck, Timothy L; Hughes, Thomas P; Jacquez, Edward; Johnson, Douglas; Johnson, Jeffrey; Jones, Kenneth; McCuistian, Brian T; Meidinger, Alfred; Montoya, Nicholas; Mostrom, Chris; Moy, Kenneth; Nath, Subrata; Nielsen, Kurt; Oro, David; Rodriguez, Leroy; Rodriguez, Patrick; Rowton, Larry J; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin; Schulze, Martin E; Simmons, David; Studebaker, Jan; Sturgess, Ronald; Sullivan, Gary; Swinney, Charles; Tang, Yan; Temple, Rodney; Tipton, Angela; Tom, C Y; Vernon Smith, H; Yu, Simon

    2005-01-01

    When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam.

  6. Dynamically loaded beam failure under corroded conditions

    NARCIS (Netherlands)

    Veerman, R.P.; Koenders, E.A.B.

    2014-01-01

    De-icing salts, used on roads in heavy winters, may enter reinforced concrete (RC) structures via its capillary pore system or via cracks, initiating reinforcement corrosion and reducing its remaining service-life. Vehicles passing real bridges exert a dynamic impact action that might activate a fat

  7. Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Mastoridis, Themistoklis [Stanford Univ., CA (United States)

    2010-08-01

    The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC

  8. Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

    Science.gov (United States)

    Semenova, V. A.; Kulya, M. S.; Bespalov, V. G.

    2016-08-01

    The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm.

  9. SciDAC Advances and Applications in Computational Beam Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ryne, R.; Abell, D.; Adelmann, A.; Amundson, J.; Bohn, C.; Cary, J.; Colella, P.; Dechow, D.; Decyk, V.; Dragt, A.; Gerber, R.; Habib, S.; Higdon, D.; Katsouleas, T.; Ma, K.-L.; McCorquodale, P.; Mihalcea, D.; Mitchell, C.; Mori, W.; Mottershead, C.T.; Neri, F.; Pogorelov, I.; Qiang, J.; Samulyak, R.; Serafini, D.; Shalf, J.; Siegerist, C.; Spentzouris, P.; Stoltz, P.; Terzic, B.; Venturini, M.; Walstrom, P.

    2005-06-26

    SciDAC has had a major impact on computational beam dynamics and the design of particle accelerators. Particle accelerators--which account for half of the facilities in the DOE Office of Science Facilities for the Future of Science 20 Year Outlook--are crucial for US scientific, industrial, and economic competitiveness. Thanks to SciDAC, accelerator design calculations that were once thought impossible are now carried routinely, and new challenging and important calculations are within reach. SciDAC accelerator modeling codes are being used to get the most science out of existing facilities, to produce optimal designs for future facilities, and to explore advanced accelerator concepts that may hold the key to qualitatively new ways of accelerating charged particle beams. In this poster we present highlights from the SciDAC Accelerator Science and Technology (AST) project Beam Dynamics focus area in regard to algorithm development, software development, and applications.

  10. SciDAC advances and applications in computational beam dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ryne, R [Lawrence Berkeley National Laboratory (United States); Abell, D [Tech-X Corporation (United States); Adelmann, A [Paul Scherrer Institute, (Switzerland); Amundson, J [Fermi National Accelerator Laboratory (United States); Bohn, C [Fermi National Accelerator Laboratory (United States); Cary, J [Tech-X Corporation (United States); Colella, P [Lawrence Berkeley National Laboratory (United States); Dechow, D [Tech-X Corporation (United States); Decyk, V [University of California at Los Angeles (United States); Dragt, A [University of Maryland (United States); Gerber, R [Lawrence Berkeley National Laboratory (United States); Habib, S [Los Alamos National Laboratory (United States); Higdon, D [Los Alamos National Laboratory (United States); Katsouleas, T [University of Southern California (United States); Ma, K-L [University of California at Davis (United States); McCorquodale, P [Lawrence Berkeley National Laboratory (United States); Mihalcea, D [Northern Illinois University (United States); Mitchell, C [University of Maryland (United States); Mori, W [University of California at Los Angeles (United States); Mottershead, C T [Los Alamos National Laboratory (United States); Neri, F [Los Alamos National Laboratory (United States); Pogorelov, I [Lawrence Berkeley National Laboratory (United States); Qiang, J [Lawrence Berkeley National Laboratory (United States); Samulyak, R [Brookhaven National Laboratory (United States); Serafini, D [Lawrence Berkeley National Laboratory (United States); Shalf, J [Lawrence Berkeley National Laboratory (United States); Siegerist, C [Lawrence Berkeley National Laboratory (United States); Spentzouris, P [Fermi National Accelerator Laboratory (United States); Stoltz, P [Tech-X Corporation (United States); Terzic, B [Northern Illinois University (United States); Venturini, M [Lawrence Berkeley National Laboratory (United States); Walstrom, P [Los Alamos National Laboratory (United States)

    2005-01-01

    SciDAC has had a major impact on computational beam dynamics and the design of particle accelerators. Particle accelerators-which account for half of the facilities in the DOE Office of Science Facilities for the Future of Science 20 Year Outlook-are crucial for US scientific, industrial, and economic competitiveness. Thanks to SciDAC, accelerator design calculations that were once thought impossible are now carried routinely, and new challenging and important calculations are within reach. SciDAC accelerator modeling codes are being used to get the most science out of existing facilities, to produce optimal designs for future facilities, and to explore advanced accelerator concepts that may hold the key to qualitatively new ways of accelerating charged particle beams. In this paper we present highlights from the SciDAC Accelerator Science and Technology (AST) project Beam Dynamics focus area in regard to algorithm development, software development, and applications.

  11. Helical tractor beam: analytical solution of Rayleigh particle dynamics.

    Science.gov (United States)

    Carretero, Luis; Acebal, Pablo; Garcia, Celia; Blaya, Salvador

    2015-08-10

    We analyze particle dynamics in an optical force field generated by helical tractor beams obtained by the interference of a cylindrical beam with a topological charge and a co-propagating temporally de-phased plane wave. We show that, for standard experimental conditions, it is possible to obtain analytical solutions for the trajectories of particles in such force field by using of some approximations. These solutions show that, in contrast to other tractor beams described before, the intensity becomes a key parameter for the control of particle trajectories. Therefore, by tuning the intensity value the particle can describe helical trajectories upstream and downstream, a circular trajectory in a fixed plane, or a linear displacement in the propagation direction. The approximated analytical solutions show good agreement to the corresponding numerical solutions of the exact dynamical differential equations.

  12. Cold atom dynamics in crossed laser beam waveguides

    CERN Document Server

    Torrontegui, E; Ruschhaupt, A; Guéry-Odelin, D; Muga, J G

    2010-01-01

    We study the dynamics of neutral cold atoms in an $L$-shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detuned laser at the corner. Complemented with a vibrational cooling process this setting works as a one-way device or "atom diode".

  13. Parallel Beam Dynamics Code Development for High Intensity Cyclotron

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>1 Parallel PIC algorithm Self field solver is the key part of a high intensity beam dynamic PIC code which usually adopts the P-M (Particle-Mesh) method to solve the space charge. The P-M method is composed of four major

  14. Studies of beam dynamics in relativistic klystron two-beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka band (~ 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional experimental efforts are also

  15. Quantitative high dynamic range beam profiling for fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, T. J., E-mail: t.j.mitchell@dur.ac.uk; Saunter, C. D.; O’Nions, W.; Girkin, J. M.; Love, G. D. [Centre for Advanced Instrumentation and Biophysical Sciences Institute, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

    2014-10-15

    Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly within the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.

  16. Dual-Beam Atom Laser Driven by Spinor Dynamics

    Science.gov (United States)

    Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

    2007-01-01

    An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

  17. Temporal nonlinear beam dynamics in infiltrated photonic crystal fibers

    DEFF Research Database (Denmark)

    Bennet, Francis; Rosberg, Christian Romer; Neshev, Dragomir N.

    of nonlinear beam reshaping occurring on a short time scale before the establishment of a steady state regime. In experiment, a 532nm laser beam can be injected into a single hole of an infiltrated PCF cladding structure, and the temporal dynamics of the nonlinear response is measured by monitoring......Liquid-infiltrated photonic crystal fibers (PCFs) offer a new way of studying light propagation in periodic and discrete systems. A wide range of available fiber structures combined with the ease of infiltration opens up a range of novel experimental opportunities for optical detection and bio......-sensing as well as active devices for all-optical switching at low (mW) laser powers. Commercially available PCFs infiltrated with liquids also provide a versatile and compact tool for exploration of the fundamentals of nonlinear beam propagation in periodic photonic structures. To explore the full scientific...

  18. Beam dynamics design for uranium drift tube linear accelerator

    Science.gov (United States)

    Dou, Wei-Ping; He, Yuan; Lu, Yuan-Rong

    2014-07-01

    KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0 emA, is accelerated from injection energy of 0.35 MeV/u to output energy of 1.30 MeV/u by IH-DTL operated at 81.25 MHz in HIAF project at IMP of CAS. It achieves a transmission efficiency of 94.95% with a cavity length of 267.8 cm. The optimization aims are the reduction of emittance growth, beam loss and project costs. Because of the requirements of CW mode operation, the designed average acceleration gradient is about 2.48 MV/m. The maximum axial field is 10.2 MV/m, meanwhile the Kilpatrick breakdown field is 10.56 MV/m at 81.25 MHz.

  19. KONUS Beam Dynamics Design of Uranium DTL for HIAF

    CERN Document Server

    Dou, W P; Lu, Y R

    2013-01-01

    KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0emA, is accelerated from injection energy of 0.35MeV/u to output energy of 1.3MeV/u by IH-DTL operated at 81.25MHz in HIAF project at IMP of CAS. It achieves transmission efficiency of 94.95% with the cavity length 267.8cm. Optimization aims are the reduction of emittance growth, of beam loss and of project costs. Because of the requirements of CW mode operation,the designed average acceleration gradient is about 2.48MV/m. Maximum axial filed is 10.2MV/m, meanwhile Kilpatrick breakdown field is 10.56MV/m at 81.25MHz.

  20. Beam dynamics in rf guns and emittance correction techniques

    Science.gov (United States)

    Serafini, Luca

    1994-02-01

    In this paper we present a general review of beam dynamics in a laser-driven rf gun. The peculiarity of such an accelerating structure versus other conventional multi-cell linac structures is underlined on the basis of the Panofsky-Wenzel theorem, which is found to give a theoretical background for the well known Kim's model. A basic explanation for some proposed methods to correct rf induced emittance growth is also derived from the theorem. We also present three emittance correction techniques for the recovery of space-charge induced emittance growth, namely the optimum distributed disk-like bunch technique, the use of rf spatial harmonics to correct spherical aberration induced by space charge forces and the technique of emittance filtering by clipping the electron beam. The expected performances regarding the beam quality achievable with different techniques, as predicted by scaling laws and simulations, are analyzed, and, where available, compared to experimental results.

  1. Study of longitudinal dynamics in space-charge dominated beams

    Science.gov (United States)

    Tian, Kai

    Modern accelerator applications, such as heavy ion fusion drivers, pulsed neutron sources, electron injectors for high-energy linear colliders, and X-ray Free Electron Lasers, demand beams with high intensity, low emittance and small energy spread. At low (non-relativistic) energies, the "electrostatic", collective interactions from space-charge forces existing in such intense beams play the dominant role; we characterize these beams as space-charge dominated beams. This dissertation presents numerous new findings on the longitudinal dynamics of a space-charge dominated beam, particularly on the propagation of density perturbations. In order to fully understand the complex physics of longitudinal space-charge waves, we combine the results of theory, computer simulation, and experiment. In the Long Solenoid Experimental system (LSE), with numerous diagnostic tools and techniques, we have, for the first time, experimentally measured the detailed energy profiles of longitudinal space-charge waves at different locations, both near the beam source and at the end of the transport system. Along with the current profiles, we have a complete set of experimental data for the propagation of space-charge waves. We compare these measured results to a 1-D theory and find better agreement for beams with perturbations in the linear regime, where the perturbation strength is less than 10%, than those with nonlinear perturbations. Using fast imaging techniques that we newly developed, we have, for the first time, obtained the progressive time-resolved images of longitudinal slices of a space-charge dominated beam. These images not only provide us time-resolved transverse density distribution of the beam, but also enable us to take time-resolved transverse phase space measurement using computerized tomography. By combining this information with the longitudinal energy measurement, we have, for the first time, experimentally constructed the full 6-D phase space. Part of the results

  2. Space-charge dynamics of polymethylmethacrylate under electron beam irradiation

    CERN Document Server

    Gong, H; Ong, C K

    1997-01-01

    Space-charge dynamics of polymethylmethacrylate (PMMA) under electron beam irradiation has been investigated employing a scanning electron microscope. Assuming a Gaussian space-charge distribution, the distribution range (sigma) has been determined using a time-resolved current method in conjunction with a mirror image method. sigma is found to increase with irradiation time and eventually attain a stationary value. These observations have been discussed by taking into account radiation-induced conductivity and charge mobility. (author)

  3. Nonlinear Dynamical analysis of an AFM tapping mode microcantilever beam

    Directory of Open Access Journals (Sweden)

    Choura S.

    2012-07-01

    Full Text Available We focus in this paper on the modeling and dynamical analysis of a tapping mode atomic force microscopy (AFM microcantilever beam. This latter is subjected to a harmonic excitation of its base displacement and to Van der Waals and DMT contact forces at its free end. For AFM design purposes, we derive a mathematical model for accurate description of the AFM microbeam dynamics. We solve the resulting equations of motions and associated boundary conditions using the Galerkin method. We find that using one-mode approximation in tapping mode operating in the neighborhood of the contact region one-mode approximation may lead to erroneous results.

  4. Chaotic dynamics of flexible Euler-Bernoulli beams.

    Science.gov (United States)

    Awrejcewicz, J; Krysko, A V; Kutepov, I E; Zagniboroda, N A; Dobriyan, V; Krysko, V A

    2013-12-01

    Mathematical modeling and analysis of spatio-temporal chaotic dynamics of flexible simple and curved Euler-Bernoulli beams are carried out. The Kármán-type geometric non-linearity is considered. Algorithms reducing partial differential equations which govern the dynamics of studied objects and associated boundary value problems are reduced to the Cauchy problem through both Finite Difference Method with the approximation of O(c(2)) and Finite Element Method. The obtained Cauchy problem is solved via the fourth and sixth-order Runge-Kutta methods. Validity and reliability of the results are rigorously discussed. Analysis of the chaotic dynamics of flexible Euler-Bernoulli beams for a series of boundary conditions is carried out with the help of the qualitative theory of differential equations. We analyze time histories, phase and modal portraits, autocorrelation functions, the Poincaré and pseudo-Poincaré maps, signs of the first four Lyapunov exponents, as well as the compression factor of the phase volume of an attractor. A novel scenario of transition from periodicity to chaos is obtained, and a transition from chaos to hyper-chaos is illustrated. In particular, we study and explain the phenomenon of transition from symmetric to asymmetric vibrations. Vibration-type charts are given regarding two control parameters: amplitude q(0) and frequency ω(p) of the uniformly distributed periodic excitation. Furthermore, we detected and illustrated how the so called temporal-space chaos is developed following the transition from regular to chaotic system dynamics.

  5. Beam dynamics simulations for linacs driving short-wavelength FELs

    Energy Technology Data Exchange (ETDEWEB)

    Ferrario, M.; Tazzioli, F. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori nazionali di Frascati; Serafini, L. [Milan Univ., Milan (Italy); Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1999-07-01

    The fast code HOMDYN has been recently developed, in the framework of the TTF (Tesla test facility) collaboration, in order to study the beam dynamics of linacs delivering high brightness beams as those needed for short wavelength Fel experiments. These linacs are typically driven by radio-frequency photo-injectors, where correlated time dependent space charge effects are of great relevance: these effects cannot be studied by standard beam optics codes (TRACE3D, etc.) and they have been modeled so far by means of multi-particle (Pic or quasistatic) codes requiring heavy cpu time and memory allocations. HOMDYN is able to describe the beam generation at the photo-cathode and the emittance compensation process in the injector even running on a laptop with very modest running rimes (less than a minute). In this paper it is showed how this capability of the code is exploited so to model a whole linac up to the point where the space charge dominated regime is of relevance (200 MeV).

  6. Lie Algebraic Treatment of Linear and Nonlinear Beam Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Alex J. Dragt; Filippo Neri; Govindan Rangarajan; David Douglas; Liam M. Healy; Robert D. Ryne

    1988-12-01

    The purpose of this paper is to present a summary of new methods, employing Lie algebraic tools, for characterizing beam dynamics in charged-particle optical systems. These methods are applicable to accelerator design, charged-particle beam transport, electron microscopes, and also light optics. The new methods represent the action of each separate element of a compound optical system, including all departures from paraxial optics, by a certain operator. The operators for the various elements can then be concatenated, following well-defined rules, to obtain a resultant operator that characterizes the entire system. This paper deals mostly with accelerator design and charged-particle beam transport. The application of Lie algebraic methods to light optics and electron microscopes is described elsewhere (1, see also 44). To keep its scope within reasonable bounds, they restrict their treatment of accelerator design and charged-particle beam transport primarily to the use of Lie algebraic methods for the description of particle orbits in terms of transfer maps. There are other Lie algebraic or related approaches to accelerator problems that the reader may find of interest (2). For a general discussion of linear and nonlinear problems in accelerator physics see (3).

  7. Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

    OpenAIRE

    Cai, Weixing; zhao,binghui; Conover, David; Liu, Jiangkun; Ning, Ruola

    2012-01-01

    Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan.

  8. Dynamic bowtie filter for cone-beam/multi-slice CT.

    Directory of Open Access Journals (Sweden)

    Fenglin Liu

    Full Text Available A pre-patient attenuator ("bowtie filter" or "bowtie" is used to modulate an incoming x-ray beam as a function of the angle of the x-ray with respect to a patient to balance the photon flux on a detector array. While the current dynamic bowtie design is focused on fan-beam geometry, in this study we propose a methodology for dynamic bowtie design in multi-slice/cone-beam geometry. The proposed 3D dynamic bowtie is an extension of the 2D prior art. The 3D bowtie consists of a highly attenuating bowtie (HB filled in with heavy liquid and a weakly attenuating bowtie (WB immersed in the liquid of the HB. The HB targets a balanced flux distribution on a detector array when no object is in the field of view (FOV. The WB compensates for an object in the FOV, and hence is a scaled-down version of the object. The WB is rotated and translated in synchrony with the source rotation and patient translation so that the overall flux balance is maintained on the detector array. First, the mathematical models of different scanning modes are established for an elliptical water phantom. Then, a numerical simulation study is performed to compare the performance of the scanning modes in the cases of the water phantom and a patient cross-section without any bowtie and with a dynamic bowtie. The dynamic bowtie can equalize the numbers of detected photons in the case of the water phantom. In practical cases, the dynamic bowtie can effectively reduce the dynamic range of detected signals inside the FOV. Furthermore, the WB can be individualized using a 3D printing technique as the gold standard. We have extended the dynamic bowtie concept from 2D to 3D by using highly attenuating liquid and moving a scale-reduced negative copy of an object being scanned. Our methodology can be applied to reduce radiation dose and facilitate photon-counting detection.

  9. Crossed-beam studies of the dynamics of radical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, K. [Argonne National Laboratory, IL (United States)

    1993-12-01

    The objective of this program is to characterize the detailed dynamics of elementary radical reactions and to provide a better understanding of radical reactivity in general. The radical beam is typically generated by a laser photolysis method. After colliding with the reacting molecule in a crossed-beam apparatus, the reaction product state distribution is interrogated by laser spectroscopic techniques. Several radicals of combustion significance, such as O, CH, OH, CN and NCO have been successfully generated and their collisional behavior at the state-to-state integral cross section level of detail has been studied in this manner. During the past year, the detection system has been converted from LIF to REMPI schemes, and the emphasis of this program shifted to investigate the product angular distributions. Both inelastic and reactive processes have been studied.

  10. Dynamic steering beams for efficient force measurement in optical manipulation

    Institute of Scientific and Technical Information of China (English)

    Xiaocong Yuan; Yuquan Zhang; Rui Cao; Xing Zhao; Jing Bu; Siwei Zhu

    2011-01-01

    @@ An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported.Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium.The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force.The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead.The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.%An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported. Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium. The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force. The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead. The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.

  11. Beam Dynamics for the CTF3 Preliminary Phase

    CERN Document Server

    Corsini, R; Rinolfi, Louis; Risselada, Thys; Royer, P; Tecker, F A

    2001-01-01

    In the framework of the CLIC RF power source studies, the new scheme of electron pulse compression and bunch frequency multiplication, using injection by RF deflectors into an isochronous ring, will be tested at CERN during the CTF3 preliminary phase. The present LPI complex will be modified in order to allow a test of this scheme at low charge. The design of the new front-end, of the modified linac, of the matched transfer line, and of the isochronous ring lattice is presented here.The results of the related beam dynamics studies are also discussed.

  12. Dynamics of 3D Timoshenko gyroelastic beams with large attitude changes for the gyros

    Science.gov (United States)

    Hassanpour, Soroosh; Heppler, G. R.

    2016-01-01

    This work is concerned with the theoretical development of dynamic equations for undamped gyroelastic beams which are dynamic systems with continuous inertia, elasticity, and gyricity. Assuming unrestricted or large attitude changes for the axes of the gyros and utilizing generalized Hooke's law, Duleau torsion theory, and Timoshenko bending theory, the energy expressions and equations of motion for the gyroelastic beams in three-dimensional space are derived. The so-obtained comprehensive gyroelastic beam model is compared against earlier gyroelastic beam models developed using Euler-Bernoulli beam models and is used to study the dynamics of gyroelastic beams through numerical examples. It is shown that there are significant differences between the developed unrestricted Timoshenko gyroelastic beam model and the previously derived zero-order restricted Euler-Bernoulli gyroelastic beam models. These differences are more pronounced in the short beam and transverse gyricity cases.

  13. Photon counting spectroscopic CT with dynamic beam attenuator

    CERN Document Server

    Atak, Haluk

    2016-01-01

    Purpose: Photon counting (PC) computed tomography (CT) can provide material selective CT imaging at lowest patient dose but it suffers from suboptimal count rate. A dynamic beam attenuator (DBA) can help with count rate by modulating x-ray beam intensity such that the low attenuating areas of the patient receive lower exposure, and detector behind these areas is not overexposed. However, DBA may harden the beam and cause artifacts and errors. This work investigates positive and negative effects of using DBA in PCCT. Methods: A simple PCCT with single energy bin, spectroscopic PCCT with 2 and 5 energy bins, and conventional energy integrating CT with and without DBA were simulated and investigated using 120kVp tube voltage and 14mGy air dose. The DBAs were modeled as made from soft tissue (ST) equivalent material, iron (Fe), and holmium (Ho) K-edge material. A cylindrical CT phantom and chest phantom with iodine and CaCO3 contrast elements were used. Image artifacts and quantification errors in general and mat...

  14. Self-modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, T.; Fedele, R. [Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli Federico II and INFN Sezione di Napoli, Napoli (Italy); Nicola, S. De [CNR-SPIN and INFN Sezione di Napoli, Napoli (Italy); Tanjia, F. [Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli Federico II and INFN Sezione di Napoli, Napoli (Italy); Jovanović, D. [Institute of Physics, University of Belgrade, Belgrade (Serbia); Mannan, A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)

    2016-09-01

    The self-modulated dynamics of a relativistic charged particle beam is provided within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.

  15. Chaotic dynamics of flexible Euler-Bernoulli beams

    Energy Technology Data Exchange (ETDEWEB)

    Awrejcewicz, J., E-mail: awrejcew@p.lodz.pl [Department of Automation, Biomechanics and Mechatronics, Lodz University of Technology, 1/15 Stefanowski St., 90-924 Lodz, Poland and Department of Vehicles, Warsaw University of Technology, 84 Narbutta St., 02-524 Warsaw (Poland); Krysko, A. V., E-mail: anton.krysko@gmail.com [Department of Applied Mathematics and Systems Analysis, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation); Kutepov, I. E., E-mail: iekutepov@gmail.com; Zagniboroda, N. A., E-mail: tssrat@mail.ru; Dobriyan, V., E-mail: Dobriy88@yandex.ru; Krysko, V. A., E-mail: tak@san.ru [Department of Mathematics and Modeling, Saratov State Technical University, Politehnicheskaya 77, 410054 Saratov (Russian Federation)

    2013-12-15

    Mathematical modeling and analysis of spatio-temporal chaotic dynamics of flexible simple and curved Euler-Bernoulli beams are carried out. The Kármán-type geometric non-linearity is considered. Algorithms reducing partial differential equations which govern the dynamics of studied objects and associated boundary value problems are reduced to the Cauchy problem through both Finite Difference Method with the approximation of O(c{sup 2}) and Finite Element Method. The obtained Cauchy problem is solved via the fourth and sixth-order Runge-Kutta methods. Validity and reliability of the results are rigorously discussed. Analysis of the chaotic dynamics of flexible Euler-Bernoulli beams for a series of boundary conditions is carried out with the help of the qualitative theory of differential equations. We analyze time histories, phase and modal portraits, autocorrelation functions, the Poincaré and pseudo-Poincaré maps, signs of the first four Lyapunov exponents, as well as the compression factor of the phase volume of an attractor. A novel scenario of transition from periodicity to chaos is obtained, and a transition from chaos to hyper-chaos is illustrated. In particular, we study and explain the phenomenon of transition from symmetric to asymmetric vibrations. Vibration-type charts are given regarding two control parameters: amplitude q{sub 0} and frequency ω{sub p} of the uniformly distributed periodic excitation. Furthermore, we detected and illustrated how the so called temporal-space chaos is developed following the transition from regular to chaotic system dynamics.

  16. Study of Effect of Ion Source Energy Spread on RFQ Beam Dynamics at REX-ISOLDE

    CERN Document Server

    Fraser, M A

    2013-01-01

    With an upgrade to the Electron Beam Ion Source (EBIS) at REX under consideration a study was launched in order to understand the effect of an increased energy spread from the ion source on the beam dynamics of the RFQ. Due to the increased electron beam potential needed to achieve the upgrade’s charge breeding specification it is expected that the energy spread of the beam will increase from today’s estimated value of approximately +-0.1%. It is shown through beam dynamics simulations that the energy spread can be increased to +-1% without significant degradation of the beam quality output by the RFQ.

  17. Beam Dynamics Studies for a Laser Acceleration Experiment

    CERN Document Server

    Spencer, James; Noble, Robert; Palmer, Dennis T; Siemann, Robert

    2005-01-01

    The NLC Test Accelerator at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun, originally proposed for the NLCTA, is being installed together with a large-angle extraction line at 60 MeV. This is followed by a matching section, final focus and buncher for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. The RF gun is discussed in another paper. We discuss only the beam dynamics and high resolution analysis system at 6 MeV based on using Parmela and high-order Transport for bunch charges from 50 pC to 1 nC. Beyond the diagnostics, this system uses the emittance compensating solenoids and a low energy, high resolution spectrometer (LES) to help tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5° extraction line provide 1:1 phase space transfer without linear dispersion or use of sextu...

  18. The thermal-wave model: A Schroedinger-like equation for charged particle beam dynamics

    Science.gov (United States)

    Fedele, Renato; Miele, G.

    1994-01-01

    We review some results on longitudinal beam dynamics obtained in the framework of the Thermal Wave Model (TWM). In this model, which has recently shown the capability to describe both longitudinal and transverse dynamics of charged particle beams, the beam dynamics is ruled by Schroedinger-like equations for the beam wave functions, whose squared modulus is proportional to the beam density profile. Remarkably, the role of the Planck constant is played by a diffractive constant epsilon, the emittance, which has a thermal nature.

  19. Beam dynamics and error study of the medium energy beam transport line in the Korea Heavy-Ion Medical Accelerator

    Science.gov (United States)

    Kim, Chanmi; Kim, Eun-San; Hahn, Garam

    2016-11-01

    The Korea Heavy Ion Medical Accelerator consists of an injector and a synchrotron for an ion medical accelerator that is the first carbon-ion therapy system in Korea. The medium energy beam transport(MEBT) line connects the interdigital H-mode drift tube linac and the synchrotron. We investigated the beam conditions after the charge stripper by using the LISE++ and the SRIM codes. The beam was stripped from C4+ into C6+ by using the charge stripper. We investigated the performance of a de-buncher in optimizing the energy spread and the beam distribution in z-dW/W (direction of beam progress-beam and energy) phase. We obtained the results of the tracking simulation and the error analysis by using the TRACK code. Possible misalignments and rotations of the magnets were considered in the simulations. States of the beam were examined when errors occurred in the magnets by the applying analytic fringe field model in TRACK code. The condition for the beam orbit was optimized by using correctors and profile monitors to correct the orbit. In this paper, we focus on the beam dynamics and the error studies dedicated to the MEBT beam line and show the optimized beam parameters for the MEBT.

  20. Electron-beam dynamics for an advanced flash-radiography accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August Jr. [Los Alamos National Laboratory

    2015-06-22

    Beam dynamics issues were assessed for a new linear induction electron accelerator. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Beam physics issues were examined through theoretical analysis and computer simulations, including particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos will result if the same engineering standards and construction details are upheld.

  1. Effects of Structural Parameters on the Dynamics of a Beam Structure with a Beam-Type Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Mothanna Y. Abd

    2012-01-01

    Full Text Available A beam-type absorber has been known as one of the dynamic vibration absorbers used to suppress excessive vibration of an engineering structure. This paper studies an absorbing beam which is attached through a visco-elastic layer on a primary beam structure. Solutions of the dynamic response are presented at the midspan of the primary and absorbing beams in simply supported edges subjected to a stationary harmonic load. The effect of structural parameters, namely, rigidity ratio, mass ratio, and damping of the layer and the structure as well as the layer stiffness on the response is investigated to reduce the vibration amplitude at the fundamental frequency of the original single primary beam. It is found that this can considerably reduce the amplitude at the corresponding troublesome frequency, but compromised situation should be noted by controlling the structural parameters. The model is also validated with measured data with reasonable agreement.

  2. Analytical estimation of the beam-beam interaction limited dynamic apertures and lifetimes in e{sup +}e{sup -} circular colliders

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J

    2000-12-01

    Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. [1], in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between the beam-beam limited beam lifetimes and the beam-beam tune shifts are established, which show clearly why experimentally one has always a maximum beam-beam tune shift, {zeta}{sub y,max}, around 0.045 for e{sup +}e{sup -} circular colliders, and why one can use round beams to double this value approximately. Comparisons with some machine parameters are given. Finally, we discuss the mechanism of the luminosity reduction due to a definite collision crossing angle. (author)

  3. Wavefront aberrations of x-ray dynamical diffraction beams.

    Science.gov (United States)

    Liao, Keliang; Hong, Youli; Sheng, Weifan

    2014-10-01

    The effects of dynamical diffraction in x-ray diffractive optics with large numerical aperture render the wavefront aberrations difficult to describe using the aberration polynomials, yet knowledge of them plays an important role in a vast variety of scientific problems ranging from optical testing to adaptive optics. Although the diffraction theory of optical aberrations was established decades ago, its application in the area of x-ray dynamical diffraction theory (DDT) is still lacking. Here, we conduct a theoretical study on the aberration properties of x-ray dynamical diffraction beams. By treating the modulus of the complex envelope as the amplitude weight function in the orthogonalization procedure, we generalize the nonrecursive matrix method for the determination of orthonormal aberration polynomials, wherein Zernike DDT and Legendre DDT polynomials are proposed. As an example, we investigate the aberration evolution inside a tilted multilayer Laue lens. The corresponding Legendre DDT polynomials are obtained numerically, which represent balanced aberrations yielding minimum variance of the classical aberrations of an anamorphic optical system. The balancing of classical aberrations and their standard deviations are discussed. We also present the Strehl ratio of the primary and secondary balanced aberrations.

  4. Optimal Design of Proposed 800 MeV Proton Cyclotron Beam Dynamics

    Institute of Scientific and Technical Information of China (English)

    YANG; Jian-jun; LI; Ming; ZHANG; Tian-jue; SONG; Guo-fang; AN; Shi-zhong

    2015-01-01

    The high intensity beam dynamic simulation shows that the theoretic beam current limit of the original design version of the 800 MeV proton cyclotron CYCIEA-800is 1mA.In order to further improve the current limit and reduce beam losses in the cyclotron,the layout of the cyclotron

  5. Dynamic simulation and efficiency analysis of beam pumping system

    Institute of Scientific and Technical Information of China (English)

    邢明明; 董世民; 童志雄; 田然凤; 陈慧玲

    2015-01-01

    An improved whole model of beam pumping system was built. In the detail, for surface transmission system (STS), a new mathematical model was established considering the influence of some factors on the STS’s torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string (SRS), an improved mathematical model was built considering the influence of some parameters on the SRS’s longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system.

  6. Particle-in-cell mode beam dynamics simulation of the low energy beam transport for the SSC-linac injector

    Institute of Scientific and Technical Information of China (English)

    XIAO Chen; HE Yuan; YUAN You-Jin; YAO Qing-Gao; WANG Zhi-Jun; CHANG Wei; LIU Yong; XIA Jia-Wen

    2011-01-01

    A new SSC-linac system (injector into separated sector cyclotron) is being designed in the HIRFL (heavy ion research facility of Lanzhou). As part of SSC-Linac, the LEBT (low energy beam transport) consists of seven solenoids, four quadrupoles, a bending magnet and an extra multi-harmonic buncher. The total length of this segment is about 7 meters. The beam dynamics in this LEBT has been studied using three-dimensional PIC (particle-in-cell) code BEAMPATH. The simulation results show that the continuous beam from the ion source is first well analyzed by a charge-to-mass selection system, and the beam of the selected charge-to-mass ratio is then efficiently pre-bunched by a multi-harmonic buncher and optimally matched into the RFQ (radio frequency quadrupole) for further acceleration. The principles and effects of the solenoid collimation channel are discussed, and it could limit the beam emittance by changing the aperture size.

  7. Chaotic dynamics of flexible beams driven by external white noise

    Science.gov (United States)

    Awrejcewicz, J.; Krysko, A. V.; Papkova, I. V.; Zakharov, V. M.; Erofeev, N. P.; Krylova, E. Yu.; Mrozowski, J.; Krysko, V. A.

    2016-10-01

    Mathematical models of continuous structural members (beams, plates and shells) subjected to an external additive white noise are studied. The structural members are considered as systems with infinite number of degrees of freedom. We show that in mechanical structural systems external noise can not only lead to quantitative changes in the system dynamics (that is obvious), but also cause the qualitative, and sometimes surprising changes in the vibration regimes. Furthermore, we show that scenarios of the transition from regular to chaotic regimes quantified by Fast Fourier Transform (FFT) can lead to erroneous conclusions, and a support of the wavelet analysis is needed. We have detected and illustrated the modifications of classical three scenarios of transition from regular vibrations to deterministic chaos. The carried out numerical experiment shows that the white noise lowers the threshold for transition into spatio-temporal chaotic dynamics. A transition into chaos via the proposed modified scenarios developed in this work is sensitive to small noise and significantly reduces occurrence of periodic vibrations. Increase of noise intensity yields decrease of the duration of the laminar signal range, i.e., time between two successive turbulent bursts decreases. Scenario of transition into chaos of the studied mechanical structures essentially depends on the control parameters, and it can be different in different zones of the constructed charts (control parameter planes). Furthermore, we found an interesting phenomenon, when increase of the noise intensity yields surprisingly the vibrational characteristics with a lack of noisy effect (chaos is destroyed by noise and windows of periodicity appear).

  8. Low energy ion beam dynamics of NANOGAN ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sarvesh, E-mail: sarvesh@iuac.res.in; Mandal, A.

    2016-04-01

    A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

  9. Contact dynamics of elasto-plastic thin beams simulated via absolute nodal coordinate formulation

    Institute of Scientific and Technical Information of China (English)

    Qing-Tao Wang; Qiang Tian; Hai-Yan Hu

    2016-01-01

    Under the frame of multibody dynamics, the contact dynamics of elasto-plastic spatial thin beams is numerically studied by using the spatial thin beam elements of absolute nodal coordinate formulation (ANCF). The inter-nal force of the elasto-plastic spatial thin beam element is derived under the assumption that the plastic strain of the beam element depends only on its longitudinal deformation. A new body-fixed local coordinate system is introduced into the spatial thin beam element of ANCF for efficient con-tact detection in the contact dynamics simulation. The linear isotropic hardening constitutive law is used to describe the elasto-plastic deformation of beam material, and the classical return mapping algorithm is adopted to evaluate the plastic strains. A multi-zone contact approach of thin beams previ-ously proposed by the authors is also introduced to detect the multiple contact zones of beams accurately, and the penalty method is used to compute the normal contact force of thin beams in contact. Four numerical examples are given to demonstrate the applicability and effectiveness of the pro-posed elasto-plastic spatial thin beam element of ANCF for flexible multibody system dynamics.

  10. Beam dynamics at the main LEBT of RAON accelerator

    CERN Document Server

    Jin, Hyunchang

    2015-01-01

    The high-intensity rare-isotope accelerator (RAON) of the Rare Isotope Science Project (RISP) in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams. The ion beams, which are generated by Electron Cyclotron Resonance Ion Source (ECR-IS), will be transported through the main Low Energy Beam Transport (LEBT) system to the Radio Frequency Quadrupole (RFQ). While passing the beams through LEBT, we should keep the transverse beam size and longitudinal emittance small. Furthermore, the matching of required twiss parameter at the RFQ entrance will be performed by using electro-static quadrupoles at the main LEBT matching section which is from the multi-harmonic buncher (MHB) to the entrance of RFQ. We will briefly review the new aspects of main LEBT lattice and the beam matching at the main LEBT matching section will be presented. In addition, the effects of various errors on the beam orbit and the correction of distorted orbit will be discussed.

  11. QUASI-STATIC AND DYNAMICAL ANALYSIS FOR VISCOELASTIC TIMOSHENKO BEAM WITH FRACTIONAL DERIVATIVE CONSTITUTIVE RELATION

    Institute of Scientific and Technical Information of China (English)

    朱正佑; 李根国; 程昌钧

    2002-01-01

    The equations of motion governing the quasi-static and dynamical behavior of a viscoelastic Timoshenko beam are derived. The viscoelastic material is assumed to obey a three-dimensional fractional derivative constitutive relation. The quasi-static behavior of the viscoelastic Timoshenko beam under step loading is analyzed and the analytical solution is obtained. The influence of material parameters on the deflection is investigated. The dynamical response of the viscoelastic Timoshenko beam subjected to a periodic excitation is studied by means of mode shape functions. And the effect of both transverse shear and rotational inertia on the vibration of the beam is discussed.

  12. Dynamic Euler-Bernoulli Beam Equation: Classification and Reductions

    Directory of Open Access Journals (Sweden)

    R. Naz

    2015-01-01

    Full Text Available We study a dynamic fourth-order Euler-Bernoulli partial differential equation having a constant elastic modulus and area moment of inertia, a variable lineal mass density g(x, and the applied load denoted by f(u, a function of transverse displacement u(t,x. The complete Lie group classification is obtained for different forms of the variable lineal mass density g(x and applied load f(u. The equivalence transformations are constructed to simplify the determining equations for the symmetries. The principal algebra is one-dimensional and it extends to two- and three-dimensional algebras for an arbitrary applied load, general power-law, exponential, and log type of applied loads for different forms of g(x. For the linear applied load case, we obtain an infinite-dimensional Lie algebra. We recover the Lie symmetry classification results discussed in the literature when g(x is constant with variable applied load f(u. For the general power-law and exponential case the group invariant solutions are derived. The similarity transformations reduce the fourth-order partial differential equation to a fourth-order ordinary differential equation. For the power-law applied load case a compatible initial-boundary value problem for the clamped and free end beam cases is formulated. We deduce the fourth-order ordinary differential equation with appropriate initial and boundary conditions.

  13. Dynamics of the off axis intense beam propagation in a spiral inflector

    Science.gov (United States)

    Goswami, A.; Sing Babu, P.; Pandit, V. S.

    2017-01-01

    In this paper the dynamics of space charge dominated beam in a spiral inflector is discussed by developing equations of motion for centroid and beam envelope for the off axis beam propagation. Evolution of the beam centroid and beam envelope is studied as a function of the beam current for various input beam parameters. The transmission of beam through the inflector is also estimated as a function of the beam current for an on axis and off axis beam by tracking a large number of particles. Simulation studies show that shift of the centroid from the axis at the inflector entrance affects the centroid location at the exit of the inflector and causes reduction in the beam transmission. The centroid shift at the entrance in the horizontal plane (h plane) is more critical as it affects the centroid shift in the vertical plane (u plane) by a large amount near the inflector exit where the available aperture is small. The beam transmission is found to reduce with increase in the centroid shift as well as with the beam current.

  14. A stochastic model for the semiclassical collective dynamics of charged beams in particle accelerators

    CERN Document Server

    De Martino, S; Illuminati, F; Martino, Salvatore De; Siena, Silvio De; Illuminati, Fabrizio

    1999-01-01

    A recent proposal (see quant-ph/9803068) to simulate semiclassical corrections to classical dynamics by suitable classical stochastic fluctuations is applied to the specific instance of charged beam dynamics in particle accelerators. The resulting picture is that the collective beam dynamics, at the leading semiclassical order in Planck constant can be described by a particular diffusion process, the Nelson process, which is time-reversal invariant. Its diffusion coefficient $\\sqrt{N}\\lambda_{c}$ represents a semiclassical unit of emittance (here $N$ is the number of particles in the beam, and $\\lambda_{c}$ is the Compton wavelength). The stochastic dynamics of the Nelson type can be easily recast in the form of a Schroedinger equation, with the semiclassical unit of emittance replacing Planck constant. Therefore we provide a physical foundation to the several quantum-like models of beam dynamics proposed in recent years. We also briefly touch upon applications of the Nelson and Schroedinger formalisms to inc...

  15. Dynamic Analysis of Kineto-Elastic Beam System with Second-order Effect

    Institute of Scientific and Technical Information of China (English)

    LU Nian-li; LUO Bing; XIA Yong-jun

    2009-01-01

    Dynamic equations of motional flexible beam elements were derived considering second-order effect. Non-linear finite element method and three-node Euler-Bernoulli beam elements were used. Because accuracy is higher in non-linear structural analysis, three-node beam elements are used to deduce shape functions and stiffness matrices in dynamic equations of flexible elements. Static condensation method was used to obtain the finial dynamic equations of three-node beam elements. According to geometrical relations of nodal displacements in concomitant and global coordinate system, dynamic equations of elements can be transformed to global coordinate system by concomitant coordinate method in order to build the global dynamic equations. Analyzed amplitude condition of flexible arm support of a port crane, the results show that second-order effect should be considered in kinetic-elastic analysis for heavy load machinery of big flexibility.

  16. Stochastic collective dynamics of charged-particle beams in the stability regime.

    Science.gov (United States)

    Petroni, N C; De Martino, S; De Siena, S; Illuminati, F

    2001-01-01

    We introduce a description of the collective transverse dynamics of charged (proton) beams in the stability regime by suitable classical stochastic fluctuations. In this scheme, the collective beam dynamics is described by time-reversal invariant diffusion processes deduced by stochastic variational principles (Nelson processes). By general arguments, we show that the diffusion coefficient, expressed in units of length, is given by lambda(c)sqrt[N], where N is the number of particles in the beam and lambda(c) the Compton wavelength of a single constituent. This diffusion coefficient represents an effective unit of beam emittance. The hydrodynamic equations of the stochastic dynamics can be easily recast in the form of a Schrödinger equation, with the unit of emittance replacing the Planck action constant. This fact provides a natural connection to the so-called "quantum-like approaches" to beam dynamics. The transition probabilities associated to Nelson processes can be exploited to model evolutions suitable to control the transverse beam dynamics. In particular we show how to control, in the quadrupole approximation to the beam-field interaction, both the focusing and the transverse oscillations of the beam, either together or independently.

  17. An optical Hamiltonian experiment and the beam dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bazzani, A. [Department of Physics and CIG, University of Bologna, INFN sezione di Bologna (Italy)]. E-mail: bazzani@bo.infn.it; Freguglia, P. [Department of Pure and Applied Mathematics, University of L' Aquila (Italy); Fronzoni, L. [Department of Physics and CISC, University of Pisa (Italy); Turchetti, G. [Department of Physics and CIG, University of Bologna, INFN sezione di Bologna (Italy)

    2006-06-01

    The analogy between geometric optics and Hamiltonian mechanics is used to propose an experiment that simulates the beam propagation in a focusing magnetic lattice of a particle accelerator. A laser beam is reflected several times by a parabolic mirror and the resulting pattern is registered by a photo camera. This experiment allows to illustrate some aspects of nonlinear beam transport in presence of nonlinearities and stochastic perturbations. The experimental results are discussed and compared with computer simulations.

  18. On the way to high dynamic range beam profile measurements

    Energy Technology Data Exchange (ETDEWEB)

    Egberts, Jan; Artikova, Sayyora [Max-Planck-Institut fuer Kernphysik (Germany); Welsch, Carsten [University of Liverpool (United Kingdom); Cockcroft Institute of Accelerator Science and Technology (United Kingdom)

    2009-07-01

    A thorough understanding of halo formation and its possible control is highly desirable for essentially all particle accelerators. Particles outside the beam core are not only lost for further experiments, they are also likely to hit the drift chamber and thereby activate the beam pipe, which makes work on the accelerator costly and time consuming. A well-established technique for transverse beam profile measurements is synchrotron radiation (SR) for high energy and high luminosity accelerators like the LHC or CTF3. At much lower beam energies, an alternative for transverse beam profile measurements based on the direct measurement of light is optical transition radiation (OTR) or the insertion of a luminescent screen. What applies for essentially all these light generation processes, is that the light intensity is over a wide range proportional to the particle density, which makes the optical analysis of such light an ideal tool for beam profile measurements. A particular challenge, however, is to distinguish the particles in the tail regions of the beam distribution from the much more intense beam core. In this contribution, we present results from laboratory measurements on two different devices that might form the technical base of a future beam halo monitor: the novel SpectraCam XDR camera system and a flexible masking technique based on a DMD micro mirror array.

  19. Sonar beam dynamics in leaf-nosed bats.

    Science.gov (United States)

    Linnenschmidt, Meike; Wiegrebe, Lutz

    2016-07-07

    Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to object distance. First, we show that the height and width of the bats sonar beam, as imprinted on a parabolic 45 channel microphone array, varies even within each animal and this variation is unrelated to changes in call level or spectral content. Second, we show that these animals are able to systematically decrease height and width of their sonar beam while focusing on the approaching object. Thus it appears that sonar beam sharpening is a further, facultative means of reducing search volume, likely to be employed by stationary animals when the object position is close and unambiguous. As only half of our individuals sharpened their beam onto the approaching object we suggest that this strategy is facultative, under voluntary control, and that beam formation is likely mediated by muscular control of the acoustic aperture of the bats' nose leaf.

  20. Quasi-static and dynamical bending of a cantilever poroelastic beam

    Institute of Scientific and Technical Information of China (English)

    YANG Yi; LI Li; YANG Xiao

    2009-01-01

    Based on the theory of porous media, the quasi-static and dynamical bending of a cantilever poroelastic beam subjected to a step load at its free end is investigated, and the influences of its permeability on bending deformation is examined.The initial boundary value problems for dynamical and quasi-static responses are solved with the Laplace transform technique,and the deflections, the bending moments of the solid skeleton and the equivalent couples of the pore fluid pressure are shown in figures. It is shown that the dynamical and quasi-static behavior of the saturated poroelastic beam depends closely on the permeability conditions at the beam ends. Under the different permeability conditions, the deflections of the beam may oscillate or not. The Mandel-Cryer effect also exists in liquid-saturated poroelastic beams.

  1. End to End Beam Dynamics of the ESS Linac

    DEFF Research Database (Denmark)

    Thomsen, Heine Dølrath

    2012-01-01

    The European Spallation Source, ESS, uses a linear accelerator to deliver a high intensity proton beam to the target station. The nominal beam power on target will be 5 MW at an energy of 2.5 GeV. We briefly describe the individual accelerating structures and transport lines through which we have...

  2. Beam dynamics studies to develop LHC luminosity model

    CERN Document Server

    Campogiani, Giovanna; Papaphilippou, Ioannis

    The thesis project aims at studying the different physical processes that are impacting luminosity, one of the key figures of merit of a collider operation. In particular the project focuses on extracting the most relevant parameters for the high-energy part of the model, which is mostly dominated by the beam-beam effect. LHC luminosity is degraded by parasitic collisions that reduce the beam lifetime and the particles stability in the collider. This instability is due to the non-linear effects of one beam electromagnetic field on another in the interaction region. Such parasitic encounters can be as many as 16 per interaction region, piling up to around 180 000 per second. Our goal is to study the evolution of charge density distribution in the beam, by tracking particles through a symplectic integrator that includes the beam-beam effect. In particular we want to obtain data on the halo particles, which are more sensible to instability, to better characterise the beam lifetime and monitor the luminosity evol...

  3. Experimental validation of flexible multibody dynamics beam formulations

    Energy Technology Data Exchange (ETDEWEB)

    Bauchau, Olivier A., E-mail: olivier.bauchau@sjtu.edu.cn; Han, Shilei [University of Michigan-Shanghai Jiao Tong University Joint Institute (China); Mikkola, Aki; Matikainen, Marko K. [Lappeenranta University of Technology, Department of Mechanical Engineering (Finland); Gruber, Peter [Austrian Center of Competence in Mechatronics GmbH (Austria)

    2015-08-15

    In this paper, the accuracies of the geometrically exact beam and absolute nodal coordinate formulations are studied by comparing their predictions against an experimental data set referred to as the “Princeton beam experiment.” The experiment deals with a cantilevered beam experiencing coupled flap, lag, and twist deformations. In the absolute nodal coordinate formulation, two different beam elements are used. The first is based on a shear deformable approach in which the element kinematics is described using two nodes. The second is based on a recently proposed approach featuring three nodes. The numerical results for the geometrically exact beam formulation and the recently proposed three-node absolute nodal coordinate formulation agree well with the experimental data. The two-node beam element predictions are similar to those of linear beam theory. This study suggests that a careful and thorough evaluation of beam elements must be carried out to assess their ability to deal with the three-dimensional deformations typically found in flexible multibody systems.

  4. Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

    NARCIS (Netherlands)

    Man, Z.; Du, L.; Min, C.; Zhang, Y.; Zhang, C.; Zhu, S.; Urbach, H.P.; Yuan, X.C.

    2014-01-01

    Vector beams, which have space-variant state of polarization (SOP) comparing with scalar beams with spatially homogeneous SOP, are used to manipulate surface plasmon polarizations (SPPs). We find that the excitation, orientation, and distribution of the focused SPPs excited in a high numerical apert

  5. Radiative damping and electron beam dynamics in plasma-based accelerators.

    Science.gov (United States)

    Michel, P; Schroeder, C B; Shadwick, B A; Esarey, E; Leemans, W P

    2006-08-01

    The effects of radiation reaction on electron beam dynamics are studied in the context of plasma-based accelerators. Electrons accelerated in a plasma channel undergo transverse betatron oscillations due to strong focusing forces. These oscillations lead to emission by the electrons of synchrotron radiation, with a corresponding energy loss that affects the beam properties. An analytical model for the single particle orbits and beam moments including the classical radiation reaction force is derived and compared to the results of a particle transport code. Since the betatron amplitude depends on the initial transverse position of the electron, the resulting radiation can increase the relative energy spread of the beam to significant levels (e.g., several percent). This effect can be diminished by matching the beam into the channel, which could require micron sized beam radii for typical values of the beam emittance and plasma density.

  6. Radiative damping and electron beam dynamics in plasma-based accelerators

    Science.gov (United States)

    Michel, P.; Schroeder, C. B.; Shadwick, B. A.; Esarey, E.; Leemans, W. P.

    2006-08-01

    The effects of radiation reaction on electron beam dynamics are studied in the context of plasma-based accelerators. Electrons accelerated in a plasma channel undergo transverse betatron oscillations due to strong focusing forces. These oscillations lead to emission by the electrons of synchrotron radiation, with a corresponding energy loss that affects the beam properties. An analytical model for the single particle orbits and beam moments including the classical radiation reaction force is derived and compared to the results of a particle transport code. Since the betatron amplitude depends on the initial transverse position of the electron, the resulting radiation can increase the relative energy spread of the beam to significant levels (e.g., several percent). This effect can be diminished by matching the beam into the channel, which could require micron sized beam radii for typical values of the beam emittance and plasma density.

  7. Beam Dynamics Observations of the 2015 High Intensity Scrubbing Runs at the Cern Sps

    CERN Document Server

    Bartosik, Hannes; Li, Kevin; Mether, Lotta; Romano, Annalisa; Rumolo, Giovanni; Schenk, Michael

    2016-01-01

    Beam quality degradation caused by e-cloud effects has been identified as one of the main performance limitations for high intensity LHC beams with 25 ns bunch spacing in the SPS. In view of the beam parameters targeted with the LHC injectors upgrade (LIU) project, about two weeks of SPS machine time in 2015 were devoted to dedicated scrubbing runs with high intensity LHC 25 ns and dedicated 'doublet' beams in order to study the achievable reduction of e-cloud effects and quantify the consequent beam performance improvements. This paper describes the main observations concerning the coherent instabilities and beam dynamics limitations encountered as well as a detailed characterisation of the performance reach with the highest beam intensity presently available from the pre-injectors.

  8. Beam dynamics in a long-pulse linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mc Cuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rose, Chris R [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Trainham, C [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Scarpetti, Raymond [LLNL; Genoni, Thomas [VOSS; Hughes, Thomas [VOSS; Toma, Carsten [VOSS

    2010-01-01

    The second axis of the Dual Axis Radiography of Hydrodynamic Testing (DARHT) facility produces up to four radiographs within an interval of 1.6 microseconds. It accomplishes this by slicing four micro-pulses out of a long 1.8-kA, 16.5-MeV electron beam pulse and focusing them onto a bremsstrahlung converter target. The long beam pulse is created by a dispenser cathode diode and accelerated by the unique DARHT Axis-II linear induction accelerator (LIA). Beam motion in the accelerator would be a problem for radiography. High frequency motion, such as from beam breakup instability, would blur the individual spots. Low frequency motion, such as produced by pulsed power variation, would produce spot to spot differences. In this article, we describe these sources of beam motion, and the measures we have taken to minimize it.

  9. Dynamic spatial structure of spontaneous beams in photorefractive bismuth sillicon oxide

    DEFF Research Database (Denmark)

    Buchhave, Preben; Lyuksyutov, S.; Vasnetsov, M.

    1996-01-01

    We report the domain structure of spontaneously occurring beams (subharmonics) in photorefractive bismuth silicon oxide with an applied electric field from 1 to 6 kV/cm and a running grating. The subharmonic beams are generated in a pattern of domains that evolve dynamically as they move through...

  10. Beam dynamics studies in the driver LINAC pre-stripper section of the RIA facility

    Indian Academy of Sciences (India)

    E S Lessner; P N Ostroumov

    2002-12-01

    The RIA facility driver LINAC consists of about 400 superconducting (SC) independently phased rf cavities. The LINAC is designed to accelerate simultaneously several charge-state beams to generate as much as 400 kW of uranium beam power. The LINAC beam dynamics is most sensitive to the focusing and accelerating structure parameters of the pre-stripper section, where the uranium beam is accelerated from 0.17 keV/u to 9.4 MeV/u. This section is designed to accept and accelerate two charge states (28 and 29) of uranium beam from an ECR ion source. The pre-stripper section must be designed to minimize the beam emittance distortion of this two-charge-state beam. In particular, the inter-cryostat spaces must be minimized and beam parameters near transitions of the accelerating and focusing lattices must be matched carefully. Several sources of possible effective emittance growth are considered in the design of the pre-stripper section and a tolerance budget is established. Numerical beam dynamics studies include realistic electric and magnetic three-dimensional field distributions in the SC rf cavities and SC solenoids. Error effects in the longitudinal beam parameters are studied.

  11. Dynamic stiffness matrix development and free vibration analysis of a moving beam

    Science.gov (United States)

    Banerjee, J. R.; Gunawardana, W. D.

    2007-06-01

    The dynamic stiffness matrix of a moving Bernoulli-Euler beam is developed and used to investigate its free flexural vibration characteristics. In order to develop the dynamic stiffness matrix, it is necessary to derive and solve the governing differential equation of motion of the moving beam in closed analytical form. The solution is then used to obtain the general expressions for both responses and loads. Boundary conditions are applied to determine the constants in the general solution, leading to the formation of the frequency dependent dynamic stiffness matrix of the moving beam, relating the amplitudes of the harmonically varying loads to those of the corresponding responses. The application of the resulting dynamic stiffness matrix using the Wittrick-Williams algorithm is demonstrated by some illustrative examples. Numerical results for both simply supported and fixed-fixed end conditions of the beam are discussed, and wherever possible, some are compared with those available in the literature.

  12. Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

    Energy Technology Data Exchange (ETDEWEB)

    Cai Weixing; Zhao Binghui; Conover, David; Liu Jiangkun; Ning Ruola [Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Radiology, Shanghai 6th People' s Hospital, 600 Yishan Road, Xuhui, Shanghai (China); Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States) and Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States)

    2012-01-15

    Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan. Methods: A dynamic cone beam CT scan acquired projections over four revolutions within a time window of 40 s after contrast agent injection through a femoral vein to cover the entire wash-in and wash-out phases. A dynamic cone beam CT reconstruction algorithm was utilized and a novel recovery method was developed to correct the time-enhancement curve of contrast flow. From the same data set, both projection-based subtraction and reconstruction-based subtraction approaches were utilized and compared to remove the background tissues and visualize the 3D vascular structure to provide the dynamic anatomic information. Results: Through computer simulations, the new recovery algorithm for dynamic time-enhancement curves was optimized and showed excellent accuracy to recover the actual contrast flow. Canine model experiments also indicated that the recovered time-enhancement curves from dynamic cone beam CT imaging agreed well with that of an IV-digital subtraction angiography (DSA) study. The dynamic vascular structures reconstructed using both projection-based subtraction and reconstruction-based subtraction were almost identical as the differences between them were comparable to the background noise level. At the enhancement peak, all the major carotid and cerebral arteries and the Circle of Willis could be clearly observed. Conclusions: The proposed dynamic cone beam CT approach can accurately recover the actual contrast flow, and dynamic anatomic imaging can be obtained with high isotropic 3D resolution. This approach is promising for diagnosis and treatment planning of vascular diseases and strokes.

  13. Analysis of Static and Dynamic Behavior of T-shape Beam Reinforced by External Prestressing Tendon

    Directory of Open Access Journals (Sweden)

    Dinghai Li

    2013-01-01

    Full Text Available External prestressing has become a primary method for strengthening existing concrete beam and has been increasingly used in the construction of newly erected ones, particularly railroad bridges in recent years. In order to evaluate the effect of this method, the static and dynamic behavior of a T-frame beam reinforced by external prestressed strengthened concrete beam was analyzed by 3D finite element method, and the field test study was also made. The study was carried out to further investigate the simply supported reinforced prestressed concrete beam strengthened by external prestressing through theory analysis and experiment.

  14. Report of the working group on production and dynamics of high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, R.L. [MS H851I, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bisognano, J.; Brau, C.; Hogan, M.; Kim, K.; Milton, S.; Nuhn, H.; Pagani, C.; Pierini, P.; Reiser, M.; Schmerge, J.; Serafini, L.; Teng, L.; Winick, H.; Cornacchia, M.

    1997-02-01

    This paper summarizes the main discussions of the Working Group on the Production and Dynamics of High Brightness Beams. The following topics are covered in this paper: proposed new electron sources and needed research on existing sources, discussions on issues relating to the description of phase space on non-thermalized electron beam distributions and the theoretical modeling on non-thermalized electron beam distributions, and the present status of the theoretical modeling of beam transport in bends. {copyright} {ital 1997 American Institute of Physics.}

  15. Control of beam dynamics in high energy induction linacs

    Science.gov (United States)

    Caporaso, G. J.

    1986-07-01

    The Advent of laser-ion-guiding in the Advanced test Accelerator along with the development of accelerator cavities optimized with respect to beam breakup coupling impedence now make it possible to consider a new class of high current, high emergy linear induction accelerators. The control of the beam breakup and other instabilities by laser guiding and by various magnetic focusing schemes will be discussed along with the scaling laws for the design of such machines to minimize the growth of the beam breakup instability. Many linacs, particularly induction linacs are limited in performance by the beam breakup (BBU) instability. The instability is found in two forms. In the first form the accelerating cavities communicate with one another through interaction with the beam and through propagation of cavity fields through the accelerator structure. In the second form which is the more virulent of the two, the cavities couple to each other only through their interactions with the beam. It is this second form of PPU that will be discussed in this paper.

  16. Beam dynamics and commissioning of low and medium energy H- beam at Linac4

    CERN Document Server

    Satri, Masoomeh Yarmohammadi; Lamehi-Rachti , Mohammad

    The First step of the CERN Large Hadron Collider injectors upgrade (LIU) project is Linac4. It accelerates H- ions to 160 MeV in an 80 m long accelerator housed in a tunnel 12 m underground, presently under construction. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex to increase the LHC luminosity. It consists of a 45 keV RF volume source, a twosolenoid Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) accelerating the beam to 3 MeV, a Medium Energy Beam Transport (MEBT) line. The MEBT houses a fast chopper to selectively remove unwanted micro-bunches in the 352 MHz sequence and avoid losses at capture in the CERN PSB (1 MHz). After chopping, the beam acceleration continues by a 50 MeV Drift Tube Linac (DTL), a 100 MeV Cell-Coupled Drift Tube Linac and a Pi-Mode Structure bringing the beam to the final energy of 160 MeV. Linac4 has been commissioned with a temporary source up to 12 MeV. The beam commissioning stages of Linac4 in LEBT...

  17. Injector Beam Dynamics for a High-Repetition Rate 4th-Generation Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, C. F.; Corlett, J.; Emma, P.; Filippetto, D.; Penn, G.; Qiang, J.; Reinsch, M.; Sannibale, F.; Steier, C.; Venturini, M.; Wells, R.

    2013-05-20

    We report on the beam dynamics studies and optimization methods for a high repetition rate (1 MHz) photoinjector based on a VHF normal conducting electron source. The simultaneous goals of beamcompression and reservation of 6-dimensional beam brightness have to be achieved in the injector, in order to accommodate a linac driven FEL light source. For this, a parallel, multiobjective optimization algorithm is used. We discuss the relative merits of different injector design points, as well as the constraints imposed on the beam dynamics by technical considerations such as the high repetition rate.

  18. Beam dynamics studies on BEPC-Ⅱstorage rings at the commissioning stage

    Institute of Scientific and Technical Information of China (English)

    QIN Qing; HUANG Nan; LIU Wei-Bin; LIU Yu-Dong; PENG Yue-Mei; QIU Jing; WANG Dou; WANG Xin-Hao; WANG Na; WANG Jiu-Qing; WEI Yuan-Yuan; WEN Xue-Mei; XING Jun; XU Gang; Yu Cheng-Hui; ZHANG Chuang; ZHANG Yuan; ZHAO Zheng; ZHOU De-Min

    2009-01-01

    During the 1st and 2nd stages of the commissioning of the upgrade project of the Beijing Electron Positron Collider(BEPC Ⅱ),which started on Nov.12,2006 and Oct.24,2007,respectively,we got the luminosity one tenth of its design value,provided beams to synchrotron radiation users for about 4 months,and studied beam dynamics as well.In this paper,some beam dynamics studies on the storage rings and their preliminary results are given.

  19. Dynamics and Control of Articulated Anisotropic Timoshenko Beams

    Science.gov (United States)

    Balakrishnan, A. V.

    1996-01-01

    The paper illustrates the use of continuum models in control design for stabilizing flexible structures. A 6-DOF anisotropic Timoshenko beam with discrete nodes where lumped masses or actuators are located provides a sufficiently rich model to be of interest for mathematical theory as well as practical application. We develop concepts and tools to help answer engineering questions without having to resort to ad hoc heuristic ("physical") arguments or faith. In this sense the paper is more mathematically oriented than engineering papers and vice versa at the same time. For instance we make precise time-domain solutions using the theory of semigroups of operators rather than formal "inverse Laplace transforms." We show that the modes arise as eigenvalues of the generator of the semigroup, which are then related to the eigenvalues of the stiffness operator. With the feedback control, the modes are no longer orthogonal and the question naturally arises as to whether there is still a modal expansion. Here we prove that the eigenfunctions yield a biorthogonal Riesz basis and indicate the corresponding expansion. We prove mathematically that the number of eigenvalues is nonfinite, based on the theory of zeros of entire functions. We make precise the notion of asymptotic modes and indicate how to calculate them. Although limited by space, we do consider the root locus problem and show for instance that the damping at first increases as the control gain increases but starts to decrease at a critical value, and goes to zero as the gain increases without bound. The undamped oscillatory modes remain oscillatory and the rigid-body modes go over into deadbeat modes. The Timoshenko model dynamics are translated into a canonical wave equation in a Hilbert space. The solution is shown to require the use of an "energy" norm which is no more than the total energy: potential plus kinetic. We show that, under an appropriate extension of the notion of controllability, rate feedback with

  20. A New Dynamic Model for a Flexible Hub-Beam System

    Institute of Scientific and Technical Information of China (English)

    LIU Zhu-yong; HONG Jia-zhen; CAI Guo-ping

    2009-01-01

    In this paper, a new dynamic model for the flexible hub-beam system is proposed by using the principle of continuum medium mechanics and the finite element discretization method. In the proposed model, the coupling deformation of any element of the beam is only related with the nodal coordinates of this element. So this model is suitable to the rotating beam in an arbitrary shape. Numerical examples of slender beams in straight and irregular shapes are carried out to demonstrate the validation of the proposed model. Simulation results indicate that the proposed model can be used valid for dynamic description of flexible rotating beam in irregular shape, and for both low and high rotation speeds.

  1. A particle-in-cell mode beam dynamics simulation of medium energy beam transport for the SSC-Linac

    Institute of Scientific and Technical Information of China (English)

    XIAO Chen; XU Meng-Xin; HE Shou-Bo; XIA Jia-Wen; HE Yuan; YUAN You-Jin; LU Yuan-Rong; LIU Yong; WANG Zhi-Jun; DU Xiao-Nan; YAO Qing-Gao; LIU Ge

    2012-01-01

    A new linear accelerator system,called the SSC-Linac injector,is being designed at HIRFL (the heavy ion research facility of Lanzhou).As part of the SSC-Linac,the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles,a re-buncher and a diagnose box.The total length of this segment is about 1.75 m.The beam dynamics simulation in MEBT has been studied using the TRACK 3D particlein-cell code,and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces,and that most of the particles can be captured by the final sector focusing cyclotronfor further acceleration.The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail,and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.

  2. A particle-in-cell mode beam dynamics simulation of medium energy beam transport for the SSC-Linac

    Science.gov (United States)

    Xiao, Chen; He, Yuan; Yuan, You-Jin; Lu, Yuan-Rong; Liu, Yong; Wang, Zhi-Jun; Du, Xiao-Nan; Yao, Qing-Gao; Liu, Ge; Xu, Meng-Xin; He, Shou-Bo; Xia, Jia-Wen

    2012-01-01

    A new linear accelerator system, called the SSC-Linac injector, is being designed at HIRFL (the heavy ion research facility of Lanzhou). As part of the SSC-Linac, the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles, a re-buncher and a diagnose box. The total length of this segment is about 1.75 m. The beam dynamics simulation in MEBT has been studied using the TRACK 3D particle-in-cell code, and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces, and that most of the particles can be captured by the final sector focusing cyclotron for further acceleration. The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail, and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.

  3. Modeled and Measured Dynamics of a Composite Beam with Periodically Varying Foam Core

    Science.gov (United States)

    Cabell, Randolph H.; Cano, Roberto J.; Schiller, Noah H.; Roberts Gary D.

    2012-01-01

    The dynamics of a sandwich beam with carbon fiber composite facesheets and foam core with periodic variations in material properties are studied. The purpose of the study is to compare finite element predictions with experimental measurements on fabricated beam specimens. For the study, three beams were fabricated: one with a compliant foam core, a second with a stiffer core, and a third with the two cores alternating down the length of the beam to create a periodic variation in properties. This periodic variation produces a bandgap in the frequency domain where vibrational energy does not readily propagate down the length of the beam. Mode shapes and natural frequencies are compared, as well as frequency responses from point force input to velocity response at the opposite end of the beam.

  4. Gas dynamics considerations in a non-invasive profile monitor for charged particle beams

    CERN Document Server

    Tzoganis, Vasilis; Welsch, Carsten P

    2014-01-01

    A non-invasive, gas jet-based, beam profile monitor has been developed in the QUASAR Group at the Cockcroft Institute, UK. This allows on-line measurement of the 2-dimensional transverse profile of particle beams with negligible disturbance to either primary beam or accelerator vacuum. The monitor is suitable for use with beams across a wide range of energies and intensities. In this setup a nozzle-skimmer system shapes a thin supersonic gas jet into a curtain. However, the small dimensions of the gas inlet nozzle and subsequent skimmers were shown to be the cause of many operational problems. In this paper, the dynamics of gas jet formation transport and shaping is discussed before an image-processing based alignment technique is introduced. Furthermore, experimental results obtained with a 5 keV electron beam are discussed and the effects of gas stagnation pressure on the acquired beam are presented.

  5. Cold phase fluid model of the longitudinal dynamics ofspace-charged dominated beams

    Energy Technology Data Exchange (ETDEWEB)

    de Hoon, Michiel J.L.; Lee, Edward P.; Barnard, John J.; Friedman, Alex

    2002-03-01

    The dynamics of a longitudinally cold, charged-particle beam can be simulated by dividing the beam into slices and calculating the motion of the slice boundaries due to the longitudinal electric field generated by the beam. On each time step, the beam charge is deposited onto an (r, z) grid, and an existing (r, z) electrostatic field solver is used to find the longitudinal electric field. Transversely, the beam envelope equation is used for each slice boundary separately. In contrast to the g-factor model, it can be shown analytically that the repulsive electric field of a slice compressed to zero length is bounded. Consequently, this model allows slices to overtake their neighbors, effectively incorporating mixing. The model then effectively describes a cold fluid in longitudinal z, v{sub z} phase space. Longitudinal beam compression calculations based on this cold phase fluid model showed that slice overtaking reflects local mixing, while the global phase space structure is preserved.

  6. Propagation dynamics of a light beam in fractional Schr\\"odinger equation

    CERN Document Server

    Zhang, Yiqi; Belić, Milivoj R; Zhong, Weiping; Zhang, Yanpeng; Xiao, Min

    2015-01-01

    Dynamics of wavepackets in fractional Schrodinger equation is still an open problem. The difficulty stems from the fact that the fractional Laplacian derivative is essentially a nonlocal operator. We investigate analytically and numerically the propagation of optical beams in fractional Schr\\"odinger equation with a harmonic potential. We find that the propagation of one- and two-dimensional (1D, 2D) input chirped Gaussian beams is not harmonic. In 1D, the beam propagates along a zigzag trajectory in the real space, which corresponds to a modulated anharmonic oscillation in the momentum space. In 2D, the input Gaussian beam evolves into a breathing ring structure in both real and momentum spaces, which forms a filamented funnel-like aperiodic structure. The beams remain localized in propagation, but with increasing distance display increasingly irregular behavior, unless both the linear chirp and the transverse displacement of the incident beam are zero.

  7. DTL cavity design and beam dynamics for a TAC linear proton accelerator

    Science.gov (United States)

    Caliskan, A.; Yılmaz, M.

    2012-02-01

    A 30 mA drift tube linac (DTL) accelerator has been designed using SUPERFISH code in the energy range of 3-55 MeV in the framework of the Turkish Accelerator Center (TAC) project. Optimization criteria in cavity design are effective shunt impedance (ZTT), transit-time factor and electrical breakdown limit. In geometrical optimization we have aimed to increase the energy gain in each RF gap of the DTL cells by maximizing the effective shunt impedance (ZTT) and the transit-time factor. Beam dynamics studies of the DTL accelerator have been performed using beam dynamics simulation codes of PATH and PARMILA. The results of both codes have been compared. In the beam dynamical studies, the rms values of beam emittance have been taken into account and a low emittance growth in both x and y directions has been attempted.

  8. DTL cavity design and beam dynamics for a TAC linear proton accelerator

    Institute of Scientific and Technical Information of China (English)

    A. Caliskan; M. Yi1maz

    2012-01-01

    A 30 mA drift tube linac (DTL) accelerator has been designed using SUPERFISH code in the energy range of 3-55 MeV in the framework of the Turkish Accelerator Center (TAC) project.Optimization criteria in cavity design are effective shunt impedance (ZTT),transit-time factor and electrical breakdown limit.In geometrical optimization we have aimed to increase the energy gain in each RF gap of the DTL cells by maximizing the effective shunt impedance (ZTT) and the transit-time factor.Beam dynamics studies of the DTL accelerator have been performed using beam dynamics simulation codes of PATH and PARMILA.The results of both codes have been compared.In the beam dynamical studies,the rms values of beam emittance have been taken into account and a low emittance growth in both x and y directions has been attempted.

  9. Dynamics and transport of laser-accelerated particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Stefan

    2010-04-19

    The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

  10. Beam dynamics simulation of the Spallation Neutron Source linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, H.; Billen, J.H.; Bhatia, T.S.

    1998-12-31

    The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H{sup {minus}} pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from 402.5 MHz DTL with a 4 {beta}{lambda} structure to a CCDTL operated at 805 MHz with a 12 {beta}{lambda} structure. After a discussion of overall feature of the linac, they present an end-to-end particle simulation using the new version of the PARMILA code for a beam starting from the RFQ entrance through the rest of the linac. At 1000 MeV, the beam is transported to a storage ring. The storage ring requires a large ({+-}500-keV) energy spread. This is accomplished by operating the rf-phase in the last section of the linac so the particles are at the unstable fixed point of the separatrix. They present zero-current phase advance, beam size, and beam emittance along the entire linac.

  11. Beam dynamics and optics studies for the LHC injectors upgrade

    CERN Document Server

    Bartosik, Hannes; Benedikt, Michael

    The Large Hadron Collider (LHC) upgrade, which aims at reaching significantly higher luminosities at the experiment sites, requires the existing injector chain to provide proton beams with unprecedented beam intensity and brightness. The required beam parameters are out of reach for the CERN accelerator complex in its present state. Therefore, upgrade possibilities of the existing injectors for mitigating their performance limitations or their partial replacement by new machines have been studied. The transition energy plays a central role for the performance of synchrotrons. Designing a lattice with negative momentum compaction (NMC), i.e. imaginary transition energy, allows avoiding transition crossing and thus the associated performance limitations. In the first part of this thesis, the properties of an NMC cell are studied. The limits of betatron stability are evaluated by a combination of analytical and numerical calculations. The NMC cell is then used for the design study of a new synchrotron called P...

  12. Melt pool dynamics during selective electron beam melting

    Science.gov (United States)

    Scharowsky, T.; Osmanlic, F.; Singer, R. F.; Körner, C.

    2014-03-01

    Electron beam melting is a promising additive manufacturing technique for metal parts. Nevertheless, the process is still poorly understood making further investigations indispensable to allow a prediction of the part's quality. To improve the understanding of the process especially the beam powder interaction, process observation at the relevant time scale is necessary. Due to the difficult accessibility of the building area, the high temperatures, radiation and the very high scanning speeds during the melting process the observation requires an augmented effort in the observation equipment. A high speed camera in combination with an illumination laser, band pass filter and mirror system is suitable for the observation of the electron beam melting process. The equipment allows to observe the melting process with a high spatial and temporal resolution. In this paper the adjustment of the equipment and results of the lifetime and the oscillation frequencies of the melt pool for a simple geometry are presented.

  13. Beam Dynamics Studies for High-Intensity Beams in the CERN Proton Synchrotron

    CERN Document Server

    AUTHOR|(CDS)2082016; Benedikt, Michael

    With the discovery of the Higgs boson, the existence of the last missing piece of the Standard Model of particle physics (SM) was confirmed. However, even though very elegant, this theory is unable to explain, for example, the generation of neutrino masses, nor does it account for dark energy or dark matter. To shed light on some of these open questions, research in fundamental particle physics pursues two complimentary approaches. On the one hand, particle colliders working at the high-energy frontier, such as the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), located in Geneva, Switzerland, are utilized to investigate the fundamental laws of nature. Alternatively, fixed target facilities require high-intensity beams to create a large flux of secondary particles to investigate, for example, rare particle decay processes, or to create neutrino beams. This thesis investigates limitations arising during the acceleration of high-intensity beams at the CERN Proton Synchrotro...

  14. Generation and dynamics of optical beams with polarization singularities.

    Science.gov (United States)

    Cardano, Filippo; Karimi, Ebrahim; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2013-04-08

    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as "lemon", "star", and "spiral". Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  15. Generation and dynamics of optical beams with polarization singularities

    CERN Document Server

    Cardano, Filippo; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2013-01-01

    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as \\qo{lemon}, \\qo{star}, and \\qo{vortex}. Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  16. Chaotic ray dynamics in an optical cavity with a beam splitter

    CERN Document Server

    Puentes, G; Woerdman, J P

    2003-01-01

    We investigate the ray dynamics in an optical cavity when a ray splitting mechanism is present. The cavity is a conventional two-mirror stable resonator and the ray splitting is achieved by inserting an optical beam splitter perpendicular to the cavity axis. Using Hamiltonian optics, we show that such a simple device presents a surprisingly rich chaotic ray dynamics.

  17. Measuring radiation damage dynamics by pulsed ion beam irradiation: 2016 project annual report

    Energy Technology Data Exchange (ETDEWEB)

    Kucheyev, Sergei O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-04

    The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 3, this project had the following two major milestones: (i) the demonstration of the measurement of thermally activated defect-interaction processes by pulsed ion beam techniques and (ii) the demonstration of alternative characterization techniques to study defect dynamics. As we describe below, both of these milestones have been met.

  18. Time series analysis of Coulomb collisions in a beam dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Vivoli, A. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy)]. E-mail: vivoli@bo.infn.it; Benedetti, C. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy); Turchetti, G. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy)

    2006-06-01

    In this paper, a time series analysis of collisional effects in a numerical simulation of a coasting beam transverse dynamics is presented. The simulation performs a numerical integration of the Hamilton's equations of a two-dimensional system of particles, describing the transverse dynamics of the beam. Then, an analysis of the time series generated has been applied in order to describe the dynamics of the system by means of the mean field equations, with the addition of a stochastic process in order to model Coulomb collisions.

  19. Beam-dynamics driven design of the LHeC energy-recovery linac

    Science.gov (United States)

    Pellegrini, Dario; Latina, Andrea; Schulte, Daniel; Bogacz, S. Alex

    2015-12-01

    The LHeC is envisioned as a natural upgrade of the LHC that aims at delivering an electron beam for collisions with the existing hadronic beams. The current baseline design for the electron facility consists of a multipass superconducting energy-recovery linac (ERL) operating in a continuous wave mode. The unprecedently high energy of the multipass ERL combined with a stringent emittance dilution budget poses new challenges for the beam optics. Here, we investigate the performances of a novel arc architecture based on a flexible momentum compaction lattice that mitigates the effects of synchrotron radiation while containing the bunch lengthening. Extensive beam-dynamics investigations have been performed with placet2, a recently developed tracking code for recirculating machines. They include the first end-to-end tracking and a simulation of the machine operation with a continuous beam. This paper briefly describes the Conceptual Design Report lattice, with an emphasis on possible and proposed improvements that emerged from the beam-dynamics studies. The detector bypass section has been integrated in the lattice, and its design choices are presented here. The stable operation of the ERL with a current up to ˜150 mA in the linacs has been validated in the presence of single- and multibunch wakefields, synchrotron radiation, and beam-beam effects.

  20. Dynamic modeling and analysis of the PZT-bonded composite Timoshenko beams: Spectral element method

    Science.gov (United States)

    Lee, Usik; Kim, Daehwan; Park, Ilwook

    2013-03-01

    The health of thin laminated composite beams is often monitored using the ultrasonic guided waves excited by wafer-type piezoelectric transducers (PZTs). Thus, for the smart composite beams which consist of a laminated composite base beam and PZT layers, it is very important to develop a very reliable mathematical model and to use a very accurate computational method to predict accurate dynamic characteristics at very high ultrasonic frequency. In this paper, the axial-bending-shear-lateral contraction coupled differential equations of motion are derived first by the Hamilton's principle with Lagrange multipliers. The smart composite beam is represented by a Timoshenko beam model by adopting the first-order shear deformation theory (FSDT) for the laminated composite base beam. The axial deformation of smart composite beam is improved by taking into account the effects of lateral contraction by adopting the concept of Mindlin-Herrmann rod theory. The spectral element model is then formulated by the variation approach from coupled differential equations of motion transformed into the frequency domain via the discrete Fourier transform. The high accuracy of the present spectral element model is verified by comparing with other solution methods: the finite element model developed in this paper and the commercial FEA package ANSYS. Finally the dynamics and wave characteristics of some example smart composite beams are investigated through the numerical studies.

  1. Static and dynamic testing of a damaged post tensioned concrete beam

    Directory of Open Access Journals (Sweden)

    Limongelli M.P.

    2015-01-01

    Full Text Available In this paper are reported the results of an experimental campaign carried out on a post tensioned concrete beam with the aim of investigating the possibility to detect early warning signs of deterioration basing on static and/or dynamic tests. The beam was tested in several configurations aimed to reproduce several different phases of the ‘life’ of the beam: the original undamaged state, increasing loss of tension in the post tensioning cables, a strengthening intervention carried out by means of a second tension cable, formation of further cracks on the strengthened beam. Responses of the beam were measured by an extensive set of instruments consisting of accelerometers, inclinometers, displacement transducers, strain gauges and optical fibres. The paper discusses the tests program and the dynamic characterization of the beam in the different damage scenarios. The modal properties of the beam in the different phases were recovered basing on the responses recorded on the beam during sine-sweep and impact hammer tests. The variation of the first modal frequency was studied to investigate the sensitivity of this parameter to both the cracking of the concrete section and the tension in the cables and also to compare results given by different types of experimental tests.

  2. Pseudo Slice Energy Spread in Dynamics of Electron Beams Moving through Magnetic Bends

    CERN Document Server

    Li, Rui

    2014-01-01

    In the previous canonical formulation of beam dynamics for an electron bunch moving ultrarelativistically through magnetic bending systems, we have shown that the transverse dynamics equation for a particle in the bunch has a driving term which behaves as the centrifugal force caused by the particle's initial potential energy due to collective particle interactions within the bunch. As a result, the initial potential energy at the entrance of a bending system, which we call pseudo (kinetic) energy, is indistinguishable from the usual kinetic energy offset from the design energy in its perturbation to particle optics through dispersion and momentum compaction. In this paper, in identifying this centrifugal force on particles as the remnant of the CSR cancellation effect in transverse particle dynamics, we show how the dynamics equation in terms of the canonical momentum for beam motion on a curved orbit is related to the Panofsky-Wenzel theorem for wakefields for beam motion on a straight path. It is shown tha...

  3. Dynamics of Rigid Bodies and Flexible Beam Structures

    DEFF Research Database (Denmark)

    Nielsen, Martin Bjerre

    of rigid bodies and flexible beam structures with emphasis on the rotational motion. The first part deals with motion in a rotating frame of reference. A novel approach where the equations of motion are formulated in a hybrid state-space in terms of local displacements and global velocities is presented...

  4. Dynamics of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    Science.gov (United States)

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.; Ji, Qing; Persaud, Arun; Seidl, Peter A.; Schenkel, Thomas

    2016-10-01

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams. Here we present experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a FEPS plasma. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Near-complete charge neutralization is established 5 μs after the driving pulse is applied to the FEPS, and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub- μs surface discharge. Measurements of current flow in the driving circuit of the FEPS suggest that plasma can be generated for tens of μs after the high voltage pulse is applied. This is confirmed by fast photography of the plasma in the 1-meter long FEPS on NDCX-II, where effective charge neutralization of the beam was achieved with the optimized FEPS timing. This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0209CH11466 (PPPL) and DE-AC0205CH11231 (LBNL).

  5. Electromagnetic and beam dynamics studies of a high current drift tube linac for LEHIPA

    Science.gov (United States)

    Roy, S.; Rao, S. V. L. S.; Pande, R.; Krishnagopal, S.; Singh, P.

    2014-06-01

    We have performed detailed electromagnetic and beam dynamics studies of a 352.21 MHz drift-tube linac (DTL) that will accelerate a 30 mA CW proton beam from 3 to 20 MeV. At such high currents space charge effects are important, and therefore the effect of linear as well as non-linear space charge has been studied (corresponding to uniform and Gaussian initial beam distributions), in order to avoid space charge instabilities. To validate the electromagnetic simulations, a 1.2 m long prototype of the DTL was fabricated. RF measurements performed on the prototype were in good agreement with the simulations. A detailed simulation study of beam halos was also performed, which showed that beyond a current of 10 mA, significant longitudinal beam halos are excited even for a perfectly matched beam, whereas for a mis-matched beam transverse beam halos are also excited. However, these do not lead to any beam loss within the DTL.

  6. An exact dynamic stiffness matrix for axially loaded double-beam systems

    Indian Academy of Sciences (India)

    Li Xiaobin; Xu Shuangxi; Wu Weiguo; Li Jun

    2014-06-01

    An exact dynamic stiffness method is presented in this paper to determine the natural frequencies and mode shapes of the axially loaded double-beam systems,which consist of two homogeneous and prismatic beams with a distributed spring in parallel between them.The effects of the axial force, shear deformation and rotary inertia are considered, as shown in the theoretical formulation. The dynamic stiffness influence coefficients are formulated from the governing differential equations of the axially loaded double-beam system in free vibration by using the Laplace transform method. An example is given to demonstrate the effectiveness of this method, in which ten boundary conditions are investigated and the effect of the axial force on the natural frequencies and mode shapes of the double-beam system are further discussed.

  7. Beam Dynamics Based Design of Solenoid Channel for TAC Proton Linac

    CERN Document Server

    Kisoglu, H F

    2014-01-01

    Today a linear particle accelerator (linac), in which electric and magnetic fields are of vital importance, is one of the popular energy generation sources like Accelerator Driven System (ADS). A multipurpose, including primarily ADS, proton linac with energy of ~2 GeV is planned to constitute within the Turkish Accelerator Center (TAC) project collaborated by more than 10 Turkish universities. A Low Energy Beam Transport (LEBT) channel with two solenoids is a subcomponent of this linac. It transports the proton beam ejected by an ion source, and matches it with the Radio Frequency Quadrupole (RFQ) that is an important part of the linac. The LEBT channel would be consisted of two focusing solenoids and some diagnostic elements such as faraday cup, BC transformers, etc. This paper includes a beam dynamical design and optimization study of LEBT channel for TAC proton linac done by using a beam dynamics simulation code PATH MANAGER and comparing of the simulation results with the theoretical expectations.

  8. Dynamic Nonlinear Focal Shift in Amplitude Modulated Moderately Focused Acoustic Beams

    CERN Document Server

    Jiménez, Noé; González-Salido, Nuria

    2016-01-01

    The phenomenon of the displacement of the position of the pressure, intensity and acoustic radiation force maxima along the axis of focused acoustic beams under increasing driving amplitudes (nonlinear focal shift) is studied for the case of a moderately focused beam excited with continuous and 25 kHz amplitude modulated signals, both in water and tissue. We prove that in amplitude modulated beams the linear and nonlinear propagation effects coexist in a semi-period of modulation, giving place to a complex dynamic behaviour, where the singular points of the beam (peak pressure, rarefaction, intensity and acoustic radiation force) locate at different points on axis as a function of time. These entire phenomena are explained in terms of harmonic generation and absorption during the propagation in a lossy nonlinear medium both, for a continuous and an amplitude modulated beam. One of the possible applications of the acoustic radiation force displacement is the generation of shear waves at different locations by ...

  9. Non-Gaussian beam dynamics in low energy antiproton storage rings

    Science.gov (United States)

    Resta-López, J.; Hunt, J. R.; Welsch, C. P.

    2016-10-01

    In low energy antiproton facilities, where electron cooling is fundamental, the cooling forces together with heating phenomena causing emittance blow-up, such as Intra Beam Scattering (IBS), result in highly non-Gaussian beam distributions. In these cases, a precise simulation of IBS effects is essential to realistically evaluate the long term beam evolution, taking into account the non-Gaussian characteristics of the beam. Here, we analyse the beam dynamics in the Extra Low ENergy Antiproton ring (ELENA), which is a new small synchrotron currently being constructed at CERN to decelerate antiprotons to energies as low as 100 keV. Simulations are performed using the code BETACOOL, comparing different models of IBS.

  10. Dynamic Stresses in the LHC TCDS Diluter from 7 TeV Beam Loading

    CERN Document Server

    Goddard, B; Presland, A; Weterings, W

    2006-01-01

    In the event of an unsynchronised beam abort, the MSD extraction septum of the LHC beam dumping system is protected from damage by the TCDS diluter. The simultaneous constraints of obtaining sufficient beam dilution while ensuring the survival of the TCDS make the design difficult, with high thermally induced dynamic stresses occurring in the material needed to attenuate the particle showers induced by the primary beam impact. In this paper, full 3D simulations are described where the worst-case beam loading has been used to generate the local temperature rise and to follow the resulting time evolution of the mechanical stresses. The results and the accompanying design changes for the TCDS, to provide an adequate performance margin, are detailed.

  11. Experimental Dynamic Analysis of Nonlinear Beams under Moving Loads

    Directory of Open Access Journals (Sweden)

    A. Bellino

    2012-01-01

    Full Text Available It is well known that nonlinear systems, as well as linear time-varying systems, are characterized by non-stationary response signals. In this sense, they both show natural frequencies that are not constant over time; this variation has however different origins: for a time-varying system the mass, and possibly the stiffness distributions, are changing over time, while for a nonlinear system the natural frequencies are amplitude-dependent. An interesting case of time-varying system occurs when analyzing the transit of a train over a railway bridge, easily simulated by the crossing of a moving load over a beam. In this case, the presence of a nonlinearity in the beam behaviour can cause a significant alteration of the modal parameters extracted from the linearized model, such that the contributions of the two effects are no more distinguishable.

  12. A computational procedure for multibody systems including flexible beam dynamics

    Science.gov (United States)

    Downer, J. D.; Park, K. C.; Chiou, J. C.

    1990-01-01

    A computational procedure suitable for the solution of equations of motions for flexible multibody systems has been developed. The flexible beams are modeled using a fully nonlinear theory which accounts for both finite rotations and large deformations. The present formulation incorporates physical measures of conjugate Cauchy stress and covariant strain increments. As a consequence, the beam model can easily be interfaced with real-time strain measurements and feedback control systems. A distinct feature of the present work is the computational preservation of total energy for undamped systems; this is obtained via an objective strain increment/stress update procedure combined with an energy-conserving time integration algorithm which contains an accurate update of angular orientations. The procedure is demonstrated via several example problems.

  13. Dynamic Response of Inextensible Beams by Improved Energy Balance Method

    DEFF Research Database (Denmark)

    Sfahani, M. G.; Barari, Amin; Omidvar, M.

    2011-01-01

    An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam with a rotationa......An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam...... procedure for a particular value of the initial condition is then used to estimate the constants. This semi-analytical representation gives excellent approximations to the exact solutions for the whole range of the oscillation amplitude, reducing the respective error of angular frequency in comparison...

  14. Dynamic Response of Axially Loaded Euler-Bernoulli Beams

    DEFF Research Database (Denmark)

    Bayat, M.; Barari, Amin; Shahidi, M.

    2011-01-01

    The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibration behavior of Euler-Bernoulli beams subjected to axial loads. Analytical expr...... to the conventional methods, only one iteration leads to high accuracy of the solutions which are valid for a wide range of vibration amplitudes....

  15. Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR

    OpenAIRE

    Ruprecht, M.; Goslawski, P.; Jankowiak, A.; Neumann, A.; Ries, M; Wüstefeld, G.; Weis, T.

    2015-01-01

    BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches rms can be stored simultaneously in the BESSY II storage ring has recently been proposed [1]. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern...

  16. Design of a superconducting beam transport channel and beam dynamics for a strong-focusing cyclotron

    Science.gov (United States)

    Badgley, Karie Elizabeth

    There is an increasing interest in high power proton accelerators for use as neutron and muon sources, accelerator driven systems (ADS) for nuclear waste transmutation, high energy physics, medical physics, nuclear physics, and medical isotope production. Accelerating high current beams has a number of challenges; including avoiding harmful resonance crossing, space charge effects and, specific to cyclotrons, sufficient turn separation at injection and extraction. The Accelerator Research Laboratory at Texas A&M University is developing a high-power strong-focusing cyclotron with two main technologies to overcome these challenges. The first is a superconducting RF cavity to provide the energy gain required for fully separated turns. The second is the use of superconducting beam transport channels within the sectors of the cyclotron to provide strong-focusing with alternating focusing and defocusing quadrupoles. A method has been developed to find the equilibrium spiral orbit through the cyclotron which maintains isochronicity. The isochronous spiral orbit was then used to perform full linear optics calculations. The strengths of the quadrupoles were adjusted to hold the horizontal and vertical betatron tunes constant per turn to avoid resonance crossing. Particle tracking was performed with a modified MAD-X-PTC code and Synergia to provide a framework for future space charge studies. Magnetic modeling was performed on a 2D cross section of the beam transport channel. The wire locations were adjusted to reduce the higher order multipoles and a good field region was obtained at 70% of the beam pipe aperture with multipoles less than 10-4 . The 2D model was also used to determine the required current density needed to produce the quadrupole gradients. MgB2 superconducting wire was chosen as it meets all the field and current requirements and can operate at a reduced cryogenic cost. A winding mandrel was also designed and fabricated which minimized the bend radius for

  17. Simulation of Electron Beam Dynamics in a Nonmagnetized High-Current Vacuum Diode

    CERN Document Server

    Anishchenko, Sergey

    2016-01-01

    The electron beam dynamics in a nonmagnetized high-current vacuum diode is analyzed for different cathode-anode gap geometries. The conditions enabling to achieve the minimal {initial} momentum spread in the electron beam are found out. A drastic rise of current density in a vacuum diode with a ring-type cathode is described. The effect is shown to be caused by electrostatic repulsion.

  18. Control of Dynamic Response of Thin-Walled Composite Beams using Structural Tailoring and Piezoelectric Actuation

    OpenAIRE

    Na, Sungsoo

    1997-01-01

    A dual approach integrating structural tailoring and adaptive materials technology and designed to control the dynamic response of cantilever beams subjected to external excitations is addressed. The cantilevered structure is modeled as a thin-walled beam of arbitrary cross-section and incorporates a number of non-classical effects such as transverse shear, warping restraint, anisotropy of constituent materials and heterogeneity of the construction. Whereas structura...

  19. Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit

    DEFF Research Database (Denmark)

    Jakobsen, Lasse; Surlykke, Annemarie

    2010-01-01

    Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases...... of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals....

  20. Comparison of Standard Issue and ANCRA International MILVAN Restraint Beams in Static and Dynamic Environments

    Science.gov (United States)

    1990-04-01

    BEAMS IN STATIC AND DYNAMIC ENVIRONMENTS 93-10168 Prepared fo r: 1 8Distribution unlimited U.S. Army Troop Support Command ATTN: AMSTR-PLBM St. Louis ...ACCESSION NO St. Louis , MO 63120-1798 N 11 TITLE (Include Security Classification) Comparison of Standard Issue and ANCRA International MILVAN Restraint Beams...j * .** 4 ...*.**.*.* ... .* ***.***..***..*** 4-q14 drax @TO 31 aDlu \\t-I ur ne 4-1 r! S.......... .. •o

  1. LHeC ERL Design and Beam-dynamics Issues

    Energy Technology Data Exchange (ETDEWEB)

    S.A. Bogacz, I. Shin, D. Schulte, F. Zimmermann

    2011-09-01

    We discuss machine and beam parameter choices for a Linac-Ring option of the Large Hadron electron Collider (LHeC) based on the LHC. With the total wall-plug power limited to 100 MW and a target current of about 6 mA the desired luminosity of 1033 cm-2 s-1 can be reached, providing one exploits unique features of the Energy Recovery Linac (ERL). Here, we describe the overall layout of such ERL complex located on the LHC site. We present an optimized multi-pass linac optics enabling operation of the proposed 3-pass Recirculating Linear Accelerator (RLA) in the Energy Recovery mode. We also describe emittance preserving return arc optics architecture; including layout and optics of the arc switch-yard. Furthermore, we discuss importance of collective effects such as: beam breakup in the RLA, as well as ion accumulation, with design-integrated mitigation measures, and the electron-beam disruption in collision. Finally, a few open questions are highlighted.

  2. Nonlinear Dynamics of High-Brightness Electron Beams and Beam-Plasma Interactions: Theories, Simulations, and Experiments

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Bohn (deceased), P. Piot and B. Erdelyi

    2008-05-31

    According to its original Statement of Work (SOW), the overarching objective of this project is: 'To enhance substantially the understanding of the fundamental dynamics of nonequilibrium high-brightness beams with space charge.' Our work and results over the past three and half years have been both intense and fruitful. Inasmuch as this project is inextricably linked to a larger, growing research program - that of the Beam Physics and Astrophysics Group (BPAG) - the progress that it has made possible cannot easily be separated from the global picture. Thus, this summary report includes major sections on 'global' developments and on those that can be regarded as specific to this project.

  3. Thermal effect on the dynamic response of axially functionally graded beam subjected to a moving harmonic load

    Science.gov (United States)

    Wang, Yuewu; Wu, Dafang

    2016-10-01

    Dynamic response of an axially functionally graded (AFG) beam under thermal environment subjected to a moving harmonic load is investigated within the frameworks of classical beam theory (CBT) and Timoshenko beam theory (TBT). The Lagrange method is employed to derive the equations of thermal buckling for AFG beam, and then with the critical buckling temperature as a parameter the Newmark-β method is adopted to evaluate the dynamic response of AFG beam under thermal environments. Admissible functions denoting transverse displacement are expressed in simple algebraic polynomial forms. Temperature-dependency of material constituent is considered. The rule of mixture (Voigt model) and Mori-Tanaka (MT) scheme are used to evaluate the beam's effective material properties. A ceramic-metal AFG beam with immovable boundary condition is considered as numerical illustration to show the thermal effects on the dynamic behaviors of the beam subjected to a moving harmonic load.

  4. Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, A.; El Hdiy, A.; Troyon, M. [Laboratoire de Recherche en Nanosciences, Bat. 6, case no 15, UFR Sciences, Universite de Reims Champagne Ardenne, 51687 Reims Cedex 2 (France); Amiard, G.; Ronda, A.; Berbezier, I. [IM2NP, Faculte des Sciences et Techniques, Campus de Saint Jerome - Case 142, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France)

    2012-04-16

    Dynamics of hole storage in spherical Ge nanocrystals (NCs) formed by a two step dewetting/nucleation process on an oxide layer grown on an n-doped <001> silicon substrate is studied using a nano-electron beam induced current technique. Carrier generation is produced by an electron beam irradiation. The generated current is collected by an atomic force microscope--tip in contact mode at a fixed position away from the beam spot of about 0.5 {mu}m. This distance represents the effective diffusion length of holes. The time constants of holes charging are determined and the effect of the NC size is underlined.

  5. Beam dynamics studies and parametric characterization of a standing wave electron linac

    Science.gov (United States)

    Dash, R.; Mondal, J.; Sharma, A.; Mittal, K. C.

    2013-07-01

    This paper presents the results of electron beam tracking simulations for a 30 MeV standing wave electron linac at Electron Beam Centre Kharghar, Navi Mumbai, India. For the pulsed mode operation of the present linac preferential operation parameters have been determined from the results of beam dynamics studies. This electron accelerator is a general purpose facility for generation of Bremsstrahlung X-rays and neutron scattering experiments. This electron accelerator-based experimental neutron facility will be used for measurement of neutron cross-section (n,γ), (n, xn) and (n, f) reactions at different energies for various materials and material irradiation studies.

  6. Beams dynamics optimisation of LINAC4 structures for increased operational flexibility

    CERN Document Server

    Bellodi, G; Garcia Tudela, M; Hein, L M; Lallement, J B; Lombardi, A M; Posocco, P A; Sargsyan, E; Stovall, J

    2010-01-01

    Linac4 is a new 160 MeV, 40 mA pulsed beam current H- accelerator which will be the source of particles for all proton accelerators at CERN. Construction started in October 2008, and beam commissioning of the 3 MeV front-end is scheduled for early next year. A baseline design of the linac beam dynamics was completed 2 years ago and validated by a systematic campaign of transverse and longitudinal error studies to assess tolerance limits and machine activation levels. Recent studies have been mainly focused on optimising this design to achieve both a smoother performance for nominal beam conditions and to gain operational flexibility for non-nominal scenarios. These include a review of the chopper beam dynamics design, a re-definition of the DTL and CCDTL inter-tank regions and a study of operational schemes for reduced beam currents (either permanent or in pulse-to-pulse mode). These studies have been carried out in parallel to first specifications for a beam commissioning strategy of the linac and its low-en...

  7. Fast range switching of passively scattered proton beams using a modulation wheel and dynamic beam current modulation.

    Science.gov (United States)

    Sánchez-Parcerisa, D; Pourbaix, J C; Ainsley, C G; Dolney, D; Carabe, A

    2014-04-01

    In proton radiotherapy, the range of particles in the patient body is determined by the energy of the protons. For most systems, the energy selection time is on the order of a few seconds, which becomes a serious obstacle for continuous dose delivery techniques requiring adaptive range modulation. This work analyses the feasibility of using the range modulation wheel, an element in the beamline used to form the spread-out Bragg peak (SOBP), to produce near-instantaneous changes not only in the modulation, but also in the range of the beam. While delivering proton beams in double scattering mode, the beam current can be synchronized with the range modulation wheel rotation by defining a current modulation pattern. Different current modulation patterns were computed from Monte Carlo simulations of our double scattering nozzle to range shift an SOBP of initial range 15 cm by varying degrees of up to ∼9 cm. These patterns were passed to the treatment control system at our institution and the resulting measured depth-dose distributions were analysed in terms of flatness, distal penumbra and relative irradiation time per unit mid-SOBP dose. Suitable SOBPs were obtained in all cases, with the maximum range shift being limited only by the maximum thickness of the wheel. The distal dose fall-off (80% to 20%) of the shifted peaks was broadened to about 1 cm, from the original 0.5 cm, and the predicted overhead in delivery time showed a linear increase with the amount of the shift. By modulating the beam current in clinical scattered proton beams equipped with a modulation wheel, it is possible to dynamically modify the in-patient range of the SOBP without adding any specific hardware or compensators to the beamline. A compromise between sharper distal dose fall-off and lower delivery time can be achieved and is subject to optimization.

  8. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  9. Nonlinear dynamic analysis of damaged Reddy-Bickford beams supported on an elastic Pasternak foundation

    Science.gov (United States)

    Stojanović, Vladimir; Petković, Marko D.

    2016-12-01

    Geometrically nonlinear free and forced vibrations of damaged high order shear deformable beams resting on a nonlinear Pasternak foundation are investigated in this paper. Equations of motion are derived for the beam which is under subjected combined action of arbitrarily distributed or concentrated transverse loading as well as axial loading. To account for shear deformations, the concept of high order shear deformation is used in comparison with the concept of first order shear deformation theory. Analyses are performed to investigate the effects of the specific stiffness of the foundation on the damaged beam frequencies and displacements with the aim of equalising the response of a damaged and an intact beam. According to that, functions of the foundation stiffness are determined depending on the location and size of the damage as a result of the possibility for the damaged beam to behave like one that is intact. An advanced p-version of the finite element method is developed for geometrically nonlinear vibrations of damaged Reddy-Bickford beams. The present study gives a clear view of the nonlinear dynamical behaviour of four types of beams according to high order shear deformation theory - an intact beam, a damaged beam, a damaged beam on an elastic foundation and intact beam on elastic foundation. The paper also presents the derivation of a new set of two nonlinear partial differential equations where only the transverse and axial displacements figure. The forced nonlinear vibrations problem is solved in the time domain using the Newmark integration method. Free vibration analysis carried out by harmonic balance and the use of continuation methods and backbone curves are constructed.

  10. DYNAMIC STABILITY OF AXIALLY MOVING VISCOELASTIC BEAMS WITH PULSATING SPEED

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-dong; CHEN Li-qun

    2005-01-01

    Parametric vibration of an axially moving, elastic, tensioned beam with pulsating speed was investigated in the vicinity of subharmonic and combination resonance. The method of averaging was used to yield a set of autonomous equations when the parametric excitation frequency is twice or the combination of the natural frequencies. Instability boundaries were presented in the plane of parametric frequency and amplitude. The analytical results were numerically verified. The effects of the viscoelastic damping, steady speed and tension on the instability boundaries were numerically demonstrated. It is found that the viscoelastic damping decreases the instability regions and the steady speed and the tension make the instability region drift along the frequency axis.

  11. Nonlinear dynamics of a sliding beam on two supports under sinusoidal excitation

    Indian Academy of Sciences (India)

    R J Somnay; R A Ibrahim

    2006-08-01

    This study deals with the nonlinear dynamics associated with large deformation of a beam sliding on two-knife edge supports under external excitation. The beam is referred to as a Gospodnetic–Frisch-Fay beam, after the researchers who reported its static deformation in closed form. The freedom of the beam to slide on its supports imparts a nonlinear characteristic to the force-deflection response. The restoring elastic force of the beam possesses characteristics similar to those of the roll-restoring moment of ships. The Gospodnetic–Frisch-Fay exact solution is given in terms of elliptic functions. A curve fit of the exact solution up to eleventh-order is constructed to establish the governing equation of motion under external excitation. The dynamic stability of the unperturbed beam is examined for the damped and undamped cases. The undamped case reveals periodic orbits and one homoclinic orbit depending on the value of the initial conditions. The response to a sinusoidal excitation at a frequency below the linear natural frequency is numerically estimated for different excitation amplitude and different values of initial conditions covered by the area of the homoclinic orbit. The safe basins of attraction are plotted for different values of excitation amplitude. It is found that the safe region of operation is reduced as the excitation amplitude increases.

  12. Beam dynamics in a rebunching CH cavity with high space charge

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Malte; Heilmann, Manuel; Meusel, Oliver; Noll, Daniel; Podlech, Holger; Ratzinger, Ulrich; Seibel, Anja [Institute for Applied Physics, Goethe-University, Frankfurt am Main (Germany)

    2013-07-01

    The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is under construction with expected first beam in 2013. It will allow research on nucleosynthesis of elements in stars by the s-process as well as on neutron capture cross sections for activation experiments providing knowledge gain on transmutation of radioactive waste and fusion reactor materials. The 5-gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination and completes the LINAC section. It will be used for varying the output energy between 1.8 and 2.2 MeV as well as for focusing the proton beam bunch longitudinally to compensate the huge space charge forces at high currents up to 200 mA. Therefore beam dynamics and beam transport performance research on this CH cavity is under progress. It includes benchmarking of different beam dynamic codes like LORASR, TraceWin and a new particle-in-cell tracking code for non-relativistic beams currently under development at IAP as well as validation of the results by measurements. Furthermore, this CH rebuncher serves as prototype for CH cavity operation at MYRRHA (Mol, Belgium), an Accelerator Driven System (ADS) for transmutation of high level nuclear waste.

  13. IH-DTL design with KONUS beam dynamics for KHIMA project

    Science.gov (United States)

    Lee, Yumi; Kim, Eun-San; Li, Zhihui; Hahn, Garam

    2015-11-01

    The Kombinierte Null Grad Struktur (KONUS) beam dynamics design of the interdigit H-mode drift tube linac (IH-DTL) for the Korea Heavy Ion Medical Accelerator (KHIMA) project is presented. We performed a KONUS beam dynamics simulation for a carbon beam (12C4+) with the LORASR code. The 12C4+ beam was accelerated from an input energy of 0.4 MeV/u to an output energy of 7 MeV/u by the IH-DTL operated at 200 MHz. The optimization aims were to increase the transmission efficiency and to minimize the beam emittance growth, beam loss, and project costs. The buncher with two gaps and two quadrupole doublets were placed between the RFQ and the IH-DTL. The whole IH-DTL consists of two tanks, 56 acceleration gaps, and four quadrupole triplets. It achieves a transmission efficiency of 100%. The total length from the exit of the RFQ to the exit of the IH-DTL is approximately 507.7 cm.

  14. Many-beam dynamical simulation of electron backscatter diffraction patterns

    Energy Technology Data Exchange (ETDEWEB)

    Winkelmann, Aimo [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)], E-mail: winkelm@mpi-halle.mpg.de; Trager-Cowan, Carol; Sweeney, Francis [Department of Physics, University of Strathclyde, Glasgow G4 ONG, Scotland (United Kingdom); Day, Austin P. [Aunt Daisy Scientific Ltd., Dixton Rd., Monmouth, Gwent, NP25 3PP (United Kingdom); Parbrook, Peter [EPSRC National Centre for III-V Technologies, University of Sheffield (United Kingdom)

    2007-04-15

    We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{l_brace}0001{r_brace} at 20 kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment.

  15. DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE

    Institute of Scientific and Technical Information of China (English)

    Sung-Gaun Kim; Ilhyun Kim; Amkee Kim; Seung-Joon Kim; Junhong Park

    2008-01-01

    The permanent residual strain in aluminum (Al) alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles.Consequently,the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam.In this paper,the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied.The beam specimens with various residual strains were made by cyclic compression-compression stress.The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method.As a result,the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam.The loss factor shows a manifest dependence on the fatigue residual strain.

  16. Modeling Gun Dynamics with Three-Dimensional Beam Elements

    Science.gov (United States)

    1990-11-01

    34 Sixth U.S. Army Symposium on Gun Dynamics, 14-17 May, 1990. Shames, Irving, and Clive Dym. Energy and Finite Element Methods in Structural Mechanics. New...Group ATIN: Mr. G. Barker Mr. A. E. Chambers Mr. J. Hoyle Mr. N. D. Manners Mr. S. E. Powell Dr. D. N. Bulman Shrivenham, Swindon, Wilts SN6 8LA

  17. Comprehensive proton dose algorithm using pencil beam redefinition and recursive dynamic splitting

    CERN Document Server

    Gottschalk, Bernard

    2016-01-01

    We compute, from first principles, the absolute dose or fluence distribution per incident proton charge in a known heterogeneous terrain exposed to known proton beams. The algorithm is equally amenable to scattered or scanned beams. All objects in the terrain (including collimators) are sliced into slabs, of any convenient thickness, perpendicular to the nominal beam direction. Transport is by standard Fermi-Eyges theory. Transverse heterogeneities are handled by breaking up pencil beams (PBs) either by conventional redefinition or a new form of 2D recursive dynamic splitting: the mother PB is replaced, conserving emittance and charge, by seven daughters of equal transverse size. One has 1/4 the charge and travels in the mother's direction and six have 1/8 the charge, are arranged hexagonally and radiate from the mother's virtual point source. The longitudinal (energy-like) variable is pv (proton momentum times speed). Each material encountered is treated on its own merits, not referenced to water. Slowing do...

  18. The properties of low energy neutral particles in a neutral beam source: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung-hoon, E-mail: physh@kaist.ac.k [Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Yoo, Suk Jae [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Chang, Choong-Seock [Department of Physics, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Courant Institute of Mathematical Sciences, New York University, Mercer Street, New York, NY 10012 (United States)

    2010-09-01

    Application of a hyperthermal neutral beam source is one of the candidate methods of reducing plasma induced damage problems. The neutral beam is generated by vertical collisions between energetic ions and a reflector composed of metal. However, it is difficult to measure the neutral angle and energy distribution experimentally. We simulate the hyperthermal neutral beam (HNB) generation using a molecular dynamics algorithm. In order to obtain a low energy neutral beam, ions with various energies are vertically projected onto the reflector surface. A rough surface structure that has been experimentally measured is used for a realistic simulation. The energy distributions are obtained and the ratio of energy of reflected neutral particles agrees with experimental data.

  19. Flexible core masking technique for beam halo measurements with high dynamic range

    Energy Technology Data Exchange (ETDEWEB)

    Egberts, J [Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Welsch, C P, E-mail: Carsten.Welsch@quasar-group.co [Cockcroft Institute, Daresbury Science and Innovation Campus, WA4 4AD Warrington (United Kingdom)

    2010-04-15

    A thorough understanding of halo formation and its possible control is highly desirable for essentially all particle accelerators. Particles outside the beam core are not only lost for further experiments, they are also likely to hit the beam pipe, and activate this, as well as accelerator and experimental components in close proximity, which makes work on the accelerator costly and time consuming. Well established techniques for transverse beam profile measurements of electron or high energy hadron beams are the observation of synchrotron radiation, optical transition radiation or the like. A particular challenge, however, is the detection of particles in the tail regions of the beam distribution in close proximity of the very intense beam core. Results from laboratory measurements on two different devices are presented that might form the technical base of a future beam halo monitor: the novel SpectraCam XDR camera system which has an intrinsically high dynamic range due to its unique pixel design, and a flexible masking technique based on a DMD micro mirror array which allows for a fast mask generation to blank out the central core.

  20. Simulation of high energy photoelectron diffraction using many-beam dynamical Kikuchi-band theory

    Science.gov (United States)

    Winkelmann, Aimo; Schröter, Bernd; Richter, Wolfgang

    2004-06-01

    We use the many-beam dynamical theory of electron diffraction for the calculation of x-ray photoelectron diffraction (XPD) patterns of the substrate emission. The reciprocity principle is used to apply a Bloch wave model for the diffraction of an incoming plane wave by a three-dimensional crystal. In this way, many-beam dynamical simulations of XPD in the context of Kikuchi-band theory can be carried out. This extends the results of the two-beam theory used so far and leads to quantitative descriptions of XPD patterns in the picture of photoelectrons reflected by lattice planes. The effects of forward scattering directions, substrate polarity, circular structures due to onedimensional diffraction, and emitter specific extinction of Kikuchi lines can be reproduced by Kikuchi-band theory. The results are compared with single scattering cluster calculations. In this way, the equivalence of the cluster approach and the Kikuchi-band picture can be demonstrated completely in both directions

  1. ANALYSIS OF DYNAMICAL BUCKLING AND POST BUCKLING FOR BEAMS BY FINITE SEGMENT METHOD

    Institute of Scientific and Technical Information of China (English)

    YIN Xue-gang; DU Si-yi; HU Ji-yun; DING Jian-ping

    2005-01-01

    Based on the multi-rigid body discretization model, namely, finite segment model,a chain multi-rigid-body-hinge-spring system model of a beam was presented,then a nonlinear parametrically exacted vibration equation of multi-degrees of freedom system was established using the coordination transformation method, and its resonance fields were derived by the restriction parameter method, that is, the dynamical buckling analysis of the beam. Because the deformation of a beam is not restricted by the discrete model and dynamic equation, the post buckling analysis can be done in above math model. The numerical solutions of a few examples were obtained by direct integrated method, which shows that the mechanical and math model gotten is correct.

  2. Coherent and dynamic beam splitting based on light storage in cold atoms

    Science.gov (United States)

    Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

    2016-01-01

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing. PMID:27677457

  3. Influence of the flexibility of beams and slabs in static response and dynamic properties

    Directory of Open Access Journals (Sweden)

    J. R. BUENO

    Full Text Available Abstract This article examines numerically the flexibility influence of support beams in static response and dynamic properties of a symmetric plate formed by massive slabs of reinforced concrete in elastic linear regime, using the Finite Element Method. In the static response the variation of bending mo-ments and displacements are evaluated, which depend on the relationship between the flexibility of the slab and the beam. The evaluation of dynamic properties is held in undamped free vibration, through which the vibration modes and the values of the natural frequencies is obtained, which are compared with the limits of the Brazilian standard code for design of concrete structures. Results show that the response may show great variation due to the change in the relationship between bending stiffness of the slabs and the beams.

  4. Dynamics analysis of microsphere in a dual-beam fiber-optic trap with transverse offset.

    Science.gov (United States)

    Chen, Xinlin; Xiao, Guangzong; Luo, Hui; Xiong, Wei; Yang, Kaiyong

    2016-04-04

    A comprehensive dynamics analysis of microsphere has been presented in a dual-beam fiber-optic trap with transverse offset. As the offset distance between two counterpropagating beams increases, the motion type of the microsphere starts with capture, then spiral motion, then orbital rotation, and ends with escape. We analyze the transformation process and mechanism of the four motion types based on ray optics approximation. Dynamic simulations show that the existence of critical offset distances at which different motion types transform. The result is an important step toward explaining physical phenomena in a dual-beam fiber-optic trap with transverse offset, and is generally applicable to achieving controllable motions of microspheres in integrated systems, such as microfluidic systems and lab-on-a-chip systems.

  5. Precision beam pointing control with jitter attenuation by optical deflector exhibiting dynamic hysteresis in COIL

    Science.gov (United States)

    Ma, Yan-Hua; Zhang, Zeng-Bao; Zhang, Zhi-Guo; Liu, Qin; He, Xin; Shi, Wen-Bo; Mao, Jian-Qin; Jin, Yu-Qi

    2015-02-01

    Due to the existence of various disturbances during the lasing process of the chemical oxygen iodine laser (COIL), the optical beam pointing performance is severely degraded. In this paper, an adaptive control methodology is proposed for the precise pointing control of the optical beam with active beam jitter rejection using a giant magnetostrictive optical deflector (GMOD) which exhibits severe dynamic hysteresis nonlinearity. In particular, a least square support vector machine (LS-SVM) based fast compensator is employed to eliminate the dynamic hysteresis without the inverse model construction. Then an improved feedforward adaptive filter is developed to deal with jitter attenuation when the full-coherent reference signal is unavailable. To improve the stability and overall robustness of the controller, especially when a large initial bias exists, a PI controller is placed in parallel with the adaptive filter. Experimental results validate the precise pointing ability of the proposed control method.

  6. Propagation dynamics of super-Gaussian beams in fractional Schrödinger equation: from linear to nonlinear regimes.

    Science.gov (United States)

    Zhang, Lifu; Li, Chuxin; Zhong, Haizhe; Xu, Changwen; Lei, Dajun; Li, Ying; Fan, Dianyuan

    2016-06-27

    We have investigated the propagation dynamics of super-Gaussian optical beams in fractional Schrödinger equation. We have identified the difference between the propagation dynamics of super-Gaussian beams and that of Gaussian beams. We show that, the linear propagation dynamics of the super-Gaussian beams with order m > 1 undergo an initial compression phase before they split into two sub-beams. The sub-beams with saddle shape separate each other and their interval increases linearly with propagation distance. In the nonlinear regime, the super-Gaussian beams evolve to become a single soliton, breathing soliton or soliton pair depending on the order of super-Gaussian beams, nonlinearity, as well as the Lévy index. In two dimensions, the linear evolution of super-Gaussian beams is similar to that for one dimension case, but the initial compression of the input super-Gaussian beams and the diffraction of the splitting beams are much stronger than that for one dimension case. While the nonlinear propagation of the super-Gaussian beams becomes much more unstable compared with that for the case of one dimension. Our results show the nonlinear effects can be tuned by varying the Lévy index in the fractional Schrödinger equation for a fixed input power.

  7. Non-linear beam dynamics tests in the LHC: LHC dynamic aperture MD on Beam 2 (24th of June 2012)

    CERN Document Server

    Maclean, E H; Persson, T H B; Redaelli, S; Schmidt, F; Tomas, R; Uythoven, J

    2013-01-01

    This MD note summarizes measurements performed on LHC Beam 2 during the non-linear machine development (MD) of 24 June 2012. The aim of the measurement was to observe the dynamic aperture of LHC Beam 2, and obtain turn-by-turn (TbT) betatron oscillation data, enabling the study of amplitude detuning and resonance driving terms (RDTs). The regular injections required by the MD also represented an opportunity to test a new coupling feedback routine based on the analysis of injection oscillation data. Initial measurements were performed on the nominal state of the LHC at injection. On completion of this study the Landau octupoles were turned off and corrections for higher-order chromaticities were implemented to reduce the non-linearity of the machine as far as possible. A second set of measurements were then performed. All studies were performed using the LHC aperture kicker (MKA).

  8. Dynamic scattering of electron vortex beams – A Bloch wave analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mendis, B.G., E-mail: b.g.mendis@durham.ac.uk

    2015-02-15

    Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum () transfer between the vortex beam and the specimen due to dynamic scattering is critical. In general the pendellösung consists of short and long wavelength oscillations. The former is due to interference between the tightly bound 1s and more dispersive non-1s Bloch states, while the latter is due to interference between the non-1s states. For EMCD experiments with ±ħ angular momentum beams, momentum transfer can be minimised by selecting the appropriate aperture size, so that the probe wavefunction approximately matches that of the 2p-type Bloch states. For manipulating nanoparticles with large angular momentum beams small apertures are required to excite the 1s state and thereby enhance the short wavelength oscillations in . This enables efficient momentum transfer to the specimen, provided the nanoparticle dimension corresponds to a minimum in the pendellösung. - Highlights: • Dynamic scattering of vortex beams is analysed using Bloch waves. • Fundamental origins of pendellösung oscillations are identified. • Effect on magnetic dichroism measurements and nanoparticle manipulation is discussed.

  9. Dynamics and guided waves in a smart Timoshenko beam with lateral contraction

    Science.gov (United States)

    Park, I.; Kim, S.; Lee, U.

    2013-07-01

    Surface-bonded wafer-type piezoelectric transducers (PZTs) have been widely used to excite or measure ultrasonic guided waves for the structural health monitoring of thin-walled structures. For successful prediction of the dynamics and ultrasonic guided waves, it is essential to use very reliable computational models for the PZT-bonded multi-layer smart structures. In this paper, the spectral element model is developed for two-layer smart beams which consist of a metallic base beam layer and a PZT layer. Axial-bending-shear-contraction coupled equations of motion and boundary conditions are derived by using Hamilton’s principle with Lagrange multipliers based on the Timoshenko beam theory and Mindlin-Herrmann rod theory. The high accuracy of this spectral element model is verified in due course and the effects of a lateral contraction on the dynamics and guided wave characteristics of the example smart beams are investigated by using this spectral element model. In addition, the constraint forces at the interface between the base beam and the PZT layer are also investigated via Lagrange multipliers.

  10. Comparison of Parmela and MAFIA Simulations of Beam Dynamics in High Current Photoinjector

    CERN Document Server

    Kurennoy, Sergey S

    2004-01-01

    A high-current RF photoinjector producing low-emittance electron beam is an important technology for high-power CW FEL. LANL-AES team designed a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector with magnetic emittance compensation. With the electric field gradients of 7, 7, and 5 MV/m in the three subsequent cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and the transverse rms emittance 7 mm-mrad. Beam dynamics in the photoinjector has been modeled in details. In addition to the usual approach, with fields calculated by Superfish-Poisson and beam simulations performed by Parmela, we also used MAFIA group of codes, both to calculate cavity fields and to model beam dynamics with its particle-in-cell module TS. The second way naturally includes wake-field effects into consideration. The simulation results and comparison between two approaches will be presented.

  11. On the dynamic stability of shear deformable beams under a tensile load

    Science.gov (United States)

    Caddemi, S.; Caliò, I.; Cannizzaro, F.

    2016-07-01

    Loss of stability of beams in a linear static context due to the action of tensile loads has been disclosed only recently in the scientific literature. However, tensile instability in the dynamic regime has been only marginally covered. Several aspects concerning the role of shear deformation on the tensile dynamic instability on continuous and discontinuous beams are still to be addressed. It may appear as a paradox, but also for the case of the universally studied Timoshenko beam model, despite its old origin, frequency-axial load diagrams in the range of negative values of the load (i.e. tensile load) has never been brought to light. In this paper, for the first time, the influence of a conservative tensile axial loads on the dynamic behaviour of the Timoshenko model, according to the Haringx theory, is assessed. It is shown that, under increasing tensile loads, regions of positive/negative fundamental frequency variations can be distinguished. In addition, the beam undergoes eigen-mode changes, from symmetric to anti-symmetric shapes, until tensile instability of divergence type is reached. As a further original contribution on the subject, taking advantage of a new closed form solution, it is shown that the same peculiarities are recovered for an axially loaded Euler-Bernoulli vibrating beam with multiple elastic sliders. This latter model can be considered as the discrete counterpart of the Timoshenko beam-column in which the internal sliders concentrate the shear deformation that in the Timoshenko model is continuously distributed. Original aspects regarding the evolution of the vibration frequencies and the relevant mode shapes with the tensile load value are highlighted.

  12. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.

    Science.gov (United States)

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-06-30

    In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation.

  13. Three-dimensional dynamic photonic crystal creation by four laser beams interference in colloidal quantum dots

    Science.gov (United States)

    Smirnov, A. M.; Mantsevich, V. N.; Ezhova, K. V.; Tikhonov, I. V.; Dneprovskii, V. S.

    2016-04-01

    We investigate a simple way to create dynamic photonic crystals with different lattice symmetry by interference of four non-coplanar laser beams in colloidal solution of CdSe/ZnS quantum dots (QDs). The formation of dynamic photonic crystal was confirmed by the observed diffraction of the beams that have excited photonic crystal at the angles equal to that calculated for the corresponding three-dimensional lattice (self-diffraction regime). Self-diffraction from an induced 3D transient photonic crystal has been discovered in the case of resonant excitation of the excitons (electron - hole transitions) in CdSe/ZnS QDs (highly absorbing colloidal solution) by powerful beams of mode-locked laser with picosecond pulse duration. Self-diffraction arises for four laser beams intersecting in the cell with colloidal CdSe/ZnS QDs due to the induced 3D dynamic photonic crystal. The physical processes that arise in CdSe/ZnS QDs and are responsible for the observed self-action effects are discussed.

  14. Beam dynamics with the Hamilton-Jacobi equation

    Energy Technology Data Exchange (ETDEWEB)

    Gabella, W.E.; Ruth, R.D.; Warnock, R.L.

    1989-03-01

    We describe a non-perturbative method to solve the Hamilton-Jacobi equation for invariant surfaces in phase space. The problem is formulated in action-angle variables with a general nonlinear perturbation. The solution of the Hamilton-Jacobi equation is regarded as the fixed point of a map on the Fourier coefficients of the generating function. Periodicity of the generator in the independent variable is enforced with a shooting method. We present two methods for finding the fixed point and hence the invariant surface. A solution by plain iteration is economical but has a restricted domain of convergence. The Newton iteration is costly but yields solutions up to the dynamic aperture. Examples of lattices with sextupoles for chromatic correction are discussed. 10 refs., 5 figs., 1 tab.

  15. Nonlinear dynamics and chaos in an optomechanical beam

    CERN Document Server

    Navarro-Urrios, D; Colombano, M F; Garcia, P D; Sledzinska, M; Alzina, F; Griol, A; Martinez, A; Sotomayor-Torres, C M

    2016-01-01

    Optical non-linearities, such as thermo-optic effects and free-carrier-dispersion, are often considered as undesired effects in silicon-based resonators and, more specifically, optomechanical (OM) cavities, affecting the relative detuning between an optical resonance and the excitation laser. However, the interplay between such mechanisms could also enable unexpected physical phenomena to be used in new applications. In the present work, we exploit those non-linearities and their intercoupling with the mechanical degrees of freedom of a silicon OM nanobeam to unveil a rich set of fundamentally different complex dynamics. By smoothly changing the parameters of the excitation laser, namely its power and wavelength, we demonstrate accurate control for activating bi-dimensional and tetra-dimensional limit-cycles, a period doubling route and chaos. In addition, by scanning the laser parameters in opposite senses we demonstrate bistability and hysteresis between bi-dimensional and tetra-dimensional limit-cycles, be...

  16. Progress on optimization of the nonlinear beam dynamics in the MEIC collider rings

    Energy Technology Data Exchange (ETDEWEB)

    Nosochkov, Y. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Cai, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sullivan, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, M-H [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wienands, U. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Morozov, V. S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Ya. S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lin, F. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Pilat, F. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Y. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-07-13

    One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 1034 cm-2s-1. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.

  17. Progress on Optimization of the Nonlinear Beam Dynamics in the MEIC Collider Rings

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Vasiliy S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Lin, Fanglei [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Pilat, Fulvia [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cai, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Nosochkov, Y. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sullivan, Michael [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, M.-H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wienands, Uli [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-09-01

    One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 1034 cm-2s-1. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.

  18. Studies on the Dynamic Buckling of Circular Plate Irradiated by Laser Beam

    Institute of Scientific and Technical Information of China (English)

    黄晨光; 段祝平

    2002-01-01

    The dynamic buckling of thin copper plate induced by laser beam, was analyzed with the numerical integration and disturbance methods of controlling equation. The buckling and post-buckling of thin plate were shown, with the consideration of the temperature distribution, inertia effect and initial deflection. At last, the buckling criterion about the circular plate was obtained and used to investigate the relation between the critical laser intensity and the ratio of thickness and diameter of the plate. The results fit the experimental observation and the FEM simulation very well, and benefit to the understanding of failure phenomenon of structures irradiated by laser beam.

  19. Beam Dynamics for the Preliminary Phase of the New CLIC Test Facility (CTF3)

    CERN Document Server

    Corsini, R; Rinolfi, Louis; Risselada, Thys; Royer, P; Tecker, F A

    2001-01-01

    In the framework of the CLIC (Compact Linear Collider) RF power source studies, the scheme of electron pulse compression and bunch frequency mulitiplication, using injection by RF deflectors into an isochronous ring, will be tested, at low charge, during the preliminary phase of the new CLIC Test Facility (CTF3) at CERN. In this paper, we describe the beam dynamics studies made in order to assess the feasibility of the bunch combination experiment, as well as the related beam measurements performed on the LEP Pre-Injector complex (LPI) before its transformation into CTF3

  20. Beam dynamics design of the main accelerating section with KONUS in the CSR-LINAC

    CERN Document Server

    Xiao-Hu, Zhang; Jia-Wen, Xia; Xue-Jun, Yin; Heng, Du

    2013-01-01

    The CSR-LINAC injector has been proposed in Heavy Ion Research Facility in Lanzhou (HIRFL). The linac mainly consists of two parts, the RFQ and the IH-DTL. The KONUS (Kombinierte Null Grad Struktur) concept has been introduced into the DTL section. In this paper, the re-matching of the main accelerating section will be finished in the 3.7 MeV/u scheme and the new beam dynamics design up to 7 MeV/u will be also shown. Through the beam re-matching, the relative emittance growth has been suppressed greatly along the linac.

  1. ELASTIC-PLASTIC DYNAMIC RESPONSE OF A CANTILEVER BEAM SUBJECTED TO OBLIQUE IMPACT AT ITS TIP

    Institute of Scientific and Technical Information of China (English)

    Xi Feng; Liu Feng

    2005-01-01

    By employing large deformation governing equations expressed in the form of finite difference, the dynamic responses of an elastic, perfectly plastic cantilever subjected to an oblique impact at its tip was numerically studied. Through analyzing the instantaneous distribution of the yield function (ψ= |M/Mo|+ (N/No)2), bending moment and axial force during the early stage of the response, the elastic-plastic deformation mechanism and the influence of axial component of an oblique impact on the dynamic response of a cantilever beam were discussed. The present analysis shows that the deformation mechanism of an elastic-plastic cantilever subjected to an obtained by using the rigid, perfectly plastic approach, the mode of shrinking plastic region that occurred instantly after the oblique impact and the mode of stationary hinge were both confirmed.The primary features of the deformation mechanism are captured by both analysis methods. It has also been found that the beam's deformation is mainly controlled by the axial component of the oblique impact in the early phase of the dynamic response, the deformation mechanism is obviously different from the case of a transverse impact. With further development of the response,the axial component attenuates rapidly and gives negligible contribution to the yielding of the beam cross-section. At the same time, the bending moments along the cantilever develop gradually and dominate the beam's deformation. The numerical results indicate that the mass, impact speed and oblique angle are the important factors that influence the elastic-plastic dynamic response of a cantilever beam.

  2. Statistical signal processing techniques for coherent transversal beam dynamics in synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Alhumaidi, Mouhammad

    2015-03-04

    identifying and analyzing the betatron oscillation sourced from the kick based on its mixing and temporal patterns. The accelerator magnets can generate unwanted spurious linear and non-linear fields due to fabrication errors or aging. These error fields in the magnets can excite undesired resonances leading together with the space charge tune spread to long term beam losses and reducing dynamic aperture. Therefore, the knowledge of the linear and non-linear magnets errors in circular accelerator optics is very crucial for controlling and compensating resonances and their consequent beam losses and beam quality deterioration. This is indispensable, especially for high beam intensity machines. Fortunately, the relationship between the beam offset oscillation signals recorded at the BPMs is a manifestation of the accelerator optics, and can therefore be exploited in the determination of the optics linear and non-linear components. Thus, beam transversal oscillations can be excited deliberately for purposes of diagnostics operation of particle accelerators. In this thesis, we propose a novel method for detecting and estimating the optics lattice non-linear components located in-between the locations of two BPMs by analyzing the beam offset oscillation signals of a BPMs-triple containing these two BPMs. Depending on the non-linear components in-between the locations of the BPMs-triple, the relationship between the beam offsets follows a multivariate polynomial accordingly. After calculating the covariance matrix of the polynomial terms, the Generalized Total Least Squares method is used to find the model parameters, and thus the non-linear components. A bootstrap technique is used to detect the existing polynomial model orders by means of multiple hypothesis testing, and determine confidence intervals for the model parameters.

  3. Cluster beam steering onto silicon surfaces studied by molecular dynamics

    CERN Document Server

    Mazzone, A M

    2002-01-01

    The purpose of this study is to investigate the effects of the impact conditions on cluster deposition in silicon and is motivated by recent results obtained using a variable incidence angle during deposition of metallic clusters and atoms. Therefore deposition of silicon clusters with a kinetic energy in the range from 0.5 to 10 eV/atom directed at normal and grazing incidence onto crystalline silicon has been studied using a molecular dynamics simulation method. The influence of other relevant parameters, such as the interatomic forces and the cluster size and shape, has also been investigated. This study shows that the physics of deposition is almost entirely dictated by the nature of the interatomic forces. When using potentials with the four-fold coordination typical of bulk a clear dependence on the size N is observed and the spreading index eta decreases with the increase of N for all incidence conditions. The cluster binding strength is perceptibly increased when using a potential accounting for the c...

  4. Observation of dynamic wavelength shifts of a four-beam laser diode and study of its adaptability to optical heads.

    Science.gov (United States)

    Shinoda, M; Kime, K

    1995-04-01

    Dynamic wavelength shifts for a four-beam laser diode were observed with a streak camera system. The wavelength shift does not exceed 2 nm for pulsed laser beam operation at a bottom power of 5 mW and a peak power of 40 mW. For a 5-mW continuous operation laser beam, the induced wavelength shift in the presence of another laser beam under the above pulse condition does not exceed 1 nm. The observed wavelength shifts are small enough for practical use, and this four-beam laser diode can be successfully applied to multibeam optical heads for parallel data processing.

  5. Dynamics of Finite Energy Airy Beams Carrying Orbital Angular Momentum in Multilevel Atomic Vapors

    Science.gov (United States)

    Wu, Zhenkun; Wang, Shun; Hu, Weifei; Gu, Yuzong

    2016-10-01

    We numerically investigate the dynamics of inward circular finite-energy Airy beams carrying different orbital angular momentum (OAM) numbers in a close-Λ three-level atomic vapor with the electromagnetically induced transparency (EIT) window. We report that due to the EIT induced by the microwave field, the transverse intensity distribution properties of Airy beam can be feasibly manipulated and modulated through adjusting OAM numbers l and the frequency detuning, as well as the propagation distance, in the multi-level atomic systems. What's more, the rotation of the beam also can be observed with different positions in atomic ensembles. The investigation may provide a useful tool for studying particle manipulation, signal processing and propagation in graded-index (GRIN) fibers.

  6. Dynamic Tuning of Transmission Wavelength of MEMS-Based Ge Waveguides on a Si Beam

    Directory of Open Access Journals (Sweden)

    Masashi Hirase

    2016-03-01

    Full Text Available Three-dimensional structures of microelectro-mechanical systems (MEMS-based Ge waveguide on a Si beam were fabricated for dynamic tuning of the fundamental absorption edge of Ge by external stressing. The application of various amounts of external forces up to 1 GPa onto the Si beam shows clear red-shifts in the absorption edge of Ge waveguides on the Si beam by ~40 nm. This shift was reproduced by the deformation potential theory, considering that mode of propagation in the Ge waveguide. The wavelength tuning range obtained makes it possible to cover the whole C-band of optical communication, indicating it to be a promising approach to electro-absorption Ge modulators to get them to work with a broader wavelength range than previously reported.

  7. Dynamic modeling of double-helical gear with Timoshenko beam theory and experiment verification

    Directory of Open Access Journals (Sweden)

    Jincheng Dong

    2016-05-01

    Full Text Available In the dynamic study of the double-helical gear transmission, the coupling shaft in the middle of the two helical gears is difficult to be handled accurately. In this article, the coupling shaft is treated as the Timoshenko beam elements and is synthesized with the lumped-mass method of the two helical gear pairs. Then, the numerical integration method is used to solve the amplitude–frequency responses and dynamic factors under diverse operating conditions. A gear vibration test rig of closed power circuit is developed for in-depth experimental measurements and model validation. After comparing the theoretical data with the practical results, the following conclusions are drawn: (1 the dynamic model with the Timoshenko beam element is quite appropriate and reliable in the dynamic analysis of double-helical gear transmission and is of great theoretical value in the accurate dynamic research of the double-helical gear transmission. (2 In both theoretical analysis and experimental measurements, the dynamic factors of gear pair diminish with the increase in the input torque and augment with the increase in the input speed. (3 The deviation ratio of the theoretical data and the experimental results decrease with the increase in the input torque, reaching the minimum at the highest input speed.

  8. Slip-stacking Dynamics for High-Power Proton Beams at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, Jeffrey Scott [Indiana Univ., Bloomington, IN (United States)

    2015-12-01

    Slip-stacking is a particle accelerator configuration used to store two particle beams with different momenta in the same ring. The two beams are longitudinally focused by two radiofrequency (RF) cavities with a small frequency difference between them. Each beam is synchronized to one RF cavity and perturbed by the other RF cavity. Fermilab uses slip-stacking in the Recycler so as to double the power of the 120 GeV proton beam in the Main Injector. This dissertation investigates the dynamics of slip-stacking beams analytically, numerically and experimentally. In the analytic analysis, I find the general trajectory of stable slip-stacking particles and identify the slip-stacking parametric resonances. In the numerical analysis, I characterize the stable phase-space area and model the particle losses. In particular, I evaluate the impact of upgrading the Fermilab Booster cycle-rate from 15 Hz to 20 Hz as part of the Proton Improvement Plan II (PIP-II). The experimental analysis is used to verify my approach to simulating slip-stacking loss. I design a study for measuring losses from the longitudinal single-particle dynamics of slip-stacking as a function of RF cavity voltage and RF frequency separation. I further propose the installation of a harmonic RF cavity and study the dynamics of this novel slip-stacking configuration. I show the harmonic RF cavity cancels out parametric resonances in slip-stacking, reduces emittance growth during slip-stacking, and dramatically enhances the stable phase-space area. The harmonic cavity is expected to reduce slip-stacking losses to far exceed PIP-II requirements. These results raise the possibility of extending slip-stacking beyond the PIP-II era.

  9. Beam dynamics aspects of crab cavities in the CERN Large Hadron Collider

    CERN Document Server

    Sun, Y P; Barranco, J; Tomás, R; Weiler, T; Zimmermann, F; Calaga, R; Morita, A

    2009-01-01

    Modern colliders bring into collision a large number of bunches to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. Such crab cavities have been proposed for both linear and circular colliders. The crab cavities are rf cavities operated in a transverse dipole mode, which imparts on the beam particles a transverse kick that varies with the longitudinal position along the bunch. The use of crab cavities in the Large Hadron Collider (LHC) may not only raise the luminosity, but it could also complicate the beam dynamics, e.g., crab cavities might not only cancel synchrobetatron resonances excited by the crossing angle but they could also excite new ones, they could reduce the dynamic aperture for off-momentum particles, they could influence the aperture and orbit...

  10. Dynamic stiffness matrix of thin-walled composite I-beam with symmetric and arbitrary laminations

    Science.gov (United States)

    Kim, Nam-Il; Shin, Dong Ku; Park, Young-Suk

    2008-11-01

    For the spatially coupled free vibration analysis of thin-walled composite I-beam with symmetric and arbitrary laminations, the exact dynamic stiffness matrix based on the solution of the simultaneous ordinary differential equations is presented. For this, a general theory for the vibration analysis of composite beam with arbitrary lamination including the restrained warping torsion is developed by introducing Vlasov's assumption. Next, the equations of motion and force-displacement relationships are derived from the energy principle and the first order of transformed simultaneous differential equations are constructed by using the displacement state vector consisting of 14 displacement parameters. Then explicit expressions for displacement parameters are derived and the exact dynamic stiffness matrix is determined using force-displacement relationships. In addition, the finite-element (FE) procedure based on Hermitian interpolation polynomials is developed. To verify the validity and the accuracy of this study, the numerical solutions are presented and compared with analytical solutions, the results from available references and the FE analysis using the thin-walled Hermitian beam elements. Particular emphasis is given in showing the phenomenon of vibrational mode change, the effects of increase of the modulus and the bending-twisting coupling stiffness for beams with various boundary conditions.

  11. Nonlinear and long-term beam dynamics in low energy storage rings

    Science.gov (United States)

    Papash, A. I.; Smirnov, A. V.; Welsch, C. P.

    2013-06-01

    Electrostatic storage rings operate at very low energies in the keV range and have proven to be invaluable tools for atomic and molecular physics. Because of the mass independence of electric rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged biomolecules, opening up unique research opportunities. However, earlier measurements have shown strong limitations in maximum beam intensity, fast decay of the stored ion current, and reduced beam lifetime. The nature of these effects has not been fully understood and an improved understanding of the physical processes influencing beam motion and stability in such rings is needed. In this paper, a comprehensive study into nonlinear and long-term beam dynamics studies is presented on the examples of a number of existing and planned electrostatic storage rings using the BETACOOL, OPERA-3D, and MAD-X simulation software. A detailed investigation into ion kinetics, under consideration of effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target, is carried out and yields a consistent explanation of the physical effects in a whole class of storage rings. The lifetime, equilibrium momentum spread, and equilibrium lateral spread during collisions with the target are estimated. In addition, the results from experiments at the Test Storage Ring, where a low-intensity beam of CF+ ions at 93keV/u has been shrunk to extremely small dimensions, are reproduced. Based on these simulations, the conditions for stable ring operation with an extremely low-emittance beam are presented. Finally, results from studies into the interaction of 3-30 keV ions with a gas jet target are summarized.

  12. Dynamic nonlinear focal shift in amplitude modulated moderately focused acoustic beams.

    Science.gov (United States)

    Jiménez, Noé; Camarena, Francisco; González-Salido, Nuria

    2017-03-01

    The phenomenon of the displacement of the position of the pressure, intensity and acoustic radiation force maxima along the axis of focused acoustic beams under increasing driving amplitudes (nonlinear focal shift) is studied for the case of a moderately focused beam excited with continuous and 25kHz amplitude modulated signals, both in water and tissue. We prove that in amplitude modulated beams the linear and nonlinear propagation effects coexist in a semi-period of modulation, giving place to a complex dynamic behavior, where the singular points of the beam (peak pressure, rarefaction, intensity and acoustic radiation force) locate at different points on axis as a function of time. These entire phenomena are explained in terms of harmonic generation and absorption during the propagation in a lossy nonlinear medium both for a continuous and an amplitude modulated beam. One of the possible applications of the acoustic radiation force displacement is the generation of shear waves at different locations by using a focused mono-element transducer excited by an amplitude modulated signal.

  13. End-to-End Beam Dynamics Simulations for the ANL-RIA Driver Linac

    CERN Document Server

    Ostroumov, P N

    2004-01-01

    The proposed Rare Isotope Accelerator (RIA) Facility consists of a superconducting (SC) 1.4 GV driver linac capable of producing 400 kW beams of any ion from hydrogen to uranium. The driver is configured as an array of ~350 SC cavities, each with independently controllable rf phase. For the end-to-end beam dynamics design and simulation we use a dedicated code, TRACK. The code integrates ion motion through the three-dimensional fields of all elements of the driver linac beginning from the exit of the electron cyclotron resonance (ECR) ion source to the production targets. TRACK has been parallelized and is able to track large number of particles in randomly seeded accelerators with misalignments and a comprehensive set of errors. The simulation starts with multi-component dc ion beams extracted from the ECR. Beam losses are obtained by tracking up to million particles in hundreds of randomly seeded accelerators. To control beam losses a set of collimators is applied in designated areas. The end-to-end simulat...

  14. High performance computation on beam dynamics problems in high intensity compact cyclotrons

    Institute of Scientific and Technical Information of China (English)

    ADELMANN; Andreas

    2011-01-01

    This paper presents the research progress in the beam dynamics problems for future high intensity compact cyclotrons by utilizing the state-of-the-art high performance computation technology. A "Start-to-Stop" model, which includes both the interaction of the internal particles of a single bunch and the mutual interaction of neighboring multiple bunches in the radial direction, is established for compact cyclotrons with multi-turn extraction. This model is then implemented in OPAL-CYCL, which is a 3D object-oriented parallel code for large scale particle simulations in cyclotrons. In addition, to meet the running requirement of parallel computation, we have constructed a small scale HPC cluster system and tested its performance. Finally, the high intensity beam dynamics problems in the 100 MeV compact cyclotron, which is being constructed at CIAE, are studied using this code and some conclusions are drawn.

  15. Diffraction control in PT-symmetric photonic lattices: from beam rectification to dynamic localization

    CERN Document Server

    Kartashov, Yaroslav V; Konotop, Vladimir V; Torner, Lluis

    2016-01-01

    We address the propagation of light beams in longitudinally modulated PT-symmetric lattices, built as arrays of couplers with periodically varying separation between their channels, and show a number of possibilities for efficient diffraction control available in such non-conservative structures. The dynamics of light in such lattices crucially depends on the ratio of the switching length for the straight segments of each coupler and the longitudinal lattice period. Depending on the longitudinal period, one can achieve either beam rectification, when the input light propagates at a fixed angle across the structure without diffractive broadening, or dynamic localization, when the initial intensity distribution is periodically restored after each longitudinal period. Importantly, the transition between these two different propagation regimes can be achieved by tuning only gain and losses acting in the system, provided that the PT-symmetry remains unbroken. The impact of Kerr nonlinearity is also discussed.

  16. Optical beam dynamics in a gas repetitively heated by femtosecond filaments

    CERN Document Server

    Jhajj, N; Wahlstrand, J K; Milchberg, H M

    2013-01-01

    We investigate beam pointing dynamics in filamentation in gases driven by high repetition rate femtosecond laser pulses. Upon suddenly exposing a gas to a kilohertz train of filamenting pulses, the filament is steered from its original direction to a new stable direction whose equilibrium is determined by a balance among buoyant, viscous, and diffusive processes in the gas. Results are shown for Xe and air, but are broadly applicable to all configurations employing high repetition rate femtosecond laser propagation in gases.

  17. A High Dynamic-Range Beam Position Measurement System for ELSA-2

    CERN Document Server

    Balleyguier, P; Guimbal, P; Borrion, H

    2003-01-01

    New beamlines are presently under construction for ELSA, a 20 MeV electron linac located at Bruyères-le-Châtel. These lines need a beam position measurement system filling the following requirements: small footprint, wide dynamic range, single-bunch/multi-bunch capability, simple design. We designed a compact 4-stripline sensor and an electronic treatment chain based on logarithmic amplifiers. This paper presents the design, cold and hot test results.

  18. DYNAMICS OF IONIZATION-ENHANCED SPECTRAL EXPANSION IN WATER INDUCED BY AN INTENSE FEMTOSECOND LASER BEAM

    Institute of Scientific and Technical Information of China (English)

    WANG SHU-FENG; QIN YUAN-DONG; YANG HONG; WANG DAN-LING; ZHU CHANG-JUN; GONG QI-HUANG

    2001-01-01

    The dynamic process of white-continuum generation in water was investigated by the pump-probe technique with a femtosecond intense laser at 805nm. The spectrum width of the probe beam was broadened at the blue side and varied with different delay times. This blueshift was attributed to the ionization-enhanced optical nonlinearity, in which both the multi-photon ionization and avalanche ionization had an effect.

  19. Dynamic modeling of double-helical gear with Timoshenko beam theory and experiment verification

    OpenAIRE

    Jincheng Dong; Sanmin Wang; He Lin; Ying Wang

    2016-01-01

    In the dynamic study of the double-helical gear transmission, the coupling shaft in the middle of the two helical gears is difficult to be handled accurately. In this article, the coupling shaft is treated as the Timoshenko beam elements and is synthesized with the lumped-mass method of the two helical gear pairs. Then, the numerical integration method is used to solve the amplitude–frequency responses and dynamic factors under diverse operating conditions. A gear vibration test rig of closed...

  20. Dynamic Characteristics of Growing Modes of Raman Instability from Intense Laser Beam Propagating Through Plasma

    Institute of Scientific and Technical Information of China (English)

    LIU Shi-Bing; CHEN Tao; CHEN Shi-Gang

    2004-01-01

    An essential dispersion relation,which can describe the dynamic properties of stimulated Raman scattering instability as a laser beam propagates through plasmas,is derived analytically.The development of growth mode,angle distribution,and temperature dependence of the instabilities are presented by solving this dispersion relation numerically.A significant dynamic characteristic has been revealed that the temperature increasing of the electron would result in redshift of scattered spectrum at high laser intensities.Furthermore,a novel modulational instability with double-peak temporal structure appears in a limited density region because of the coupling of scattered upshift and downshift waves.

  1. Production of Dynamic Frozen Waves: Controlling shape, location (and speed) of diffraction-resistant beams

    CERN Document Server

    Vieira, Tárcio A; Zamboni-Rached, Michel; Recami, Erasmo

    2015-01-01

    In recent times, we experimentally realized a quite efficient modeling of the shape of diffraction-resistant optical beams; thus generating for the first time the so-called Frozen Waves (FW), whose longitudinal intensity pattern can be arbitrarily chosen, within a prefixed space interval of the propagation axis. Such waves possess a host of potential applications: in medicine, biomedical optics, optical tweezers, atom guiding, remote sensing, tractor beams, optical communications or metrology, and other topics in photonic areas. In this work, we extend our theory of FWs -- which led to beams endowed with a static envelope -- through a dynamic modeling of the FWs, whose shape is now allowed to evolve in time in a predetermined way. And we experimentally create such dynamic FWs in Optics, via a computational holographic technique and a spatial light modulator. Experimental results are here presented for two cases of dynamic FWs, one of the zeroth and the other of higher order, the last one being the most intere...

  2. Radiation defect dynamics in Si at room temperature studied by pulsed ion beams

    Science.gov (United States)

    Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Myers, M. T.; Shao, L.; Kucheyev, S. O.

    2015-10-01

    The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ˜4-13 ms and a diffusion length of ˜15-50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.

  3. Discrete time transfer matrix method for dynamics of multibody system with flexible beams moving in space

    Institute of Scientific and Technical Information of China (English)

    Xiao-Ting Rui; Edwin Kreuzer; Bao Rong; Bin He

    2012-01-01

    In this paper,by defining new state vectors and developing new transfer matrices of various elements moving in space,the discrete time transfer matrix method of multi-rigid-flexible-body system is expanded to study the dynamics of muhibody system with flexible beams moving in space.Formulations and numerical example of a rigidflexible-body three pendulums system moving in space are given to validate the method. Using the new method to study the dynamics of multi-rigid-flexible-body system mov ing in space,the global dynamics equations of system are not needed,the orders of involved matrices of the system are very low and the computational speed is high,irrespective of the size of the system.The new method is simple,straightforward,practical,and provides a powerful tool for multi-rigid-flexible-body system dynamics.

  4. A computational procedure for the dynamics of flexible beams within multibody systems. Ph.D. Thesis Final Technical Report

    Science.gov (United States)

    Downer, Janice Diane

    1990-01-01

    The dynamic analysis of three dimensional elastic beams which experience large rotational and large deformational motions are examined. The beam motion is modeled using an inertial reference for the translational displacements and a body-fixed reference for the rotational quantities. Finite strain rod theories are then defined in conjunction with the beam kinematic description which accounts for the effects of stretching, bending, torsion, and transverse shear deformations. A convected coordinate representation of the Cauchy stress tensor and a conjugate strain definition is introduced to model the beam deformation. To treat the beam dynamics, a two-stage modification of the central difference algorithm is presented to integrate the translational coordinates and the angular velocity vector. The angular orientation is then obtained from the application of an implicit integration algorithm to the Euler parameter/angular velocity kinematical relation. The combined developments of the objective internal force computation with the dynamic solution procedures result in the computational preservation of total energy for undamped systems. The present methodology is also extended to model the dynamics of deployment/retrieval of the flexible members. A moving spatial grid corresponding to the configuration of a deployed rigid beam is employed as a reference for the dynamic variables. A transient integration scheme which accurately accounts for the deforming spatial grid is derived from a space-time finite element discretization of a Hamiltonian variational statement. The computational results of this general deforming finite element beam formulation are compared to reported results for a planar inverse-spaghetti problem.

  5. The dynamic flexibility method in structural dynamics: Application to nonuniform beams and plates and to cavity-backed plates

    Science.gov (United States)

    Lee, Jinkyo

    1993-01-01

    Efficient and accurate analytical or semi-analytical solutions have been developed for the dynamics of one and two dimensional linear structures employing elemental dynamic flexibility formulation. This dissertation is divided into three parts. In the first, the elemental flexibility formulation is developed for Euler-Bernoulli beams having discontinuous section properties, which can be viewed as the synthesis of uniform beams, and the exactness of the solution is established. In the second, the elemental flexibility formulation is extended to thin rectangular plates having Levy boundary conditions, and conditions under which the exact solution can be achieved are presented. In the third, the structural-acoustic problem of Helmholtz fluid enclosed by a partially flexible cavity is posed and solved. Here, a concise analytical representation of the structural dynamics is used in conjunction with a boundary element approach for the fluid medium to give an efficient and accurate semi-analytical solution. All three sections are organized along similar lines. Following an introduction and review of the pertinent literature, the governing equations are derived and solved, a series of example problems is presented, the results from the examples are compared with similar results from the literature, and efficacy of the method when compared with other methods is discussed. This is followed by a general conclusions section and a series of appendices.

  6. Dynamical Model for an Interharmonic Property of a Piezoelectric Bimorph Cantilever Beam with Self-Sensing Function

    OpenAIRE

    Ting Zhang; Ying Pan; Lijie Cao

    2016-01-01

    A piezoelectric bimorph cantilevered beam is analyzed dynamically by a longitudinal and transverse coupling theory. When a sinusoidal voltage is applied on the actuating layer of the bimorph, the output voltage of the sensing layer appears as interharmonic component signal. The interharmonic frequency is noninteger harmonic frequency of the applied voltage. A dynamic model is proposed to describe the interharmonic property of the piezoelectric bimorph beam. Through some simulations and experi...

  7. High Dynamic Magnetic Beam Current Measurements by Means of Optimised Magneto-Resistance (MR) Sensor Engineering

    CERN Document Server

    Hape, M; Ricken, W

    2005-01-01

    The GSI-FAIR project (facility for antiprotons and ion research) will comprehend DC currents up to around 5 A in the SIS 100 synchrotron and after bunch compression down to 50 ns pulse length the peak currents will reach up to 100 A. To meet these higher demands of beam current measurements new sensor techniques are foreseen. The measurement device itself will be designed in form of a clip-on ampere-meter. The air gap of the flux concentrator is assumed to be around 5 mm and thus, the estimated maximum field therein is around 30 mT for a beam current of 100 A peak. The resolution of this device is aimed to be 1 mA in beam current, corresponding to a system dynamic of around 105. This high demands of beam current measurement require more sophisticated sensor types than just using a Hall probe. The characteristics of AMR (anisotropic magneto-resistance), GMR (giant magneto-resistance) and GMI (giant magneto-impedance) sensors like hysteresis, linearity and sensitivity have been measured within the magnetic fiel...

  8. Dynamic scattering of electron vortex beams--a Bloch wave analysis.

    Science.gov (United States)

    Mendis, B G

    2015-02-01

    Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum (〈Lz〉) transfer between the vortex beam and the specimen due to dynamic scattering is critical. In general the 〈Lz〉 pendellösung consists of short and long wavelength oscillations. The former is due to interference between the tightly bound 1s and more dispersive non-1s Bloch states, while the latter is due to interference between the non-1s states. For EMCD experiments with ±ħ angular momentum beams, momentum transfer can be minimised by selecting the appropriate aperture size, so that the probe wavefunction approximately matches that of the 2p-type Bloch states. For manipulating nanoparticles with large angular momentum beams small apertures are required to excite the 1s state and thereby enhance the short wavelength oscillations in 〈Lz〉. This enables efficient momentum transfer to the specimen, provided the nanoparticle dimension corresponds to a minimum in the 〈Lz〉 pendellösung.

  9. Static and Dynamic Experimental Analysis of the Galloping Stability of Porous H-Section Beams

    Directory of Open Access Journals (Sweden)

    F. Gandia

    2014-01-01

    Full Text Available The phenomenon of self-induced vibrations of prismatic beams in a cross-flow has been studied for decades, but it is still of great interest due to their important effects in many different industrial applications. This paper presents the experimental study developed on a prismatic beam with H-section. The aim of this analysis is to add some additional insight into the behaviour of the flow around this type of bodies, in order to reduce galloping and even to avoid it. The influence of some relevant geometrical parameters that define the H-section on the translational galloping behaviour of these beams has been analysed. Wind loads coefficients have been measured through static wind tunnel tests and the Den Hartog criterion applied to elucidate the influence of geometrical parameters on the galloping properties of the bodies under consideration. These results have been completed with surface pressure distribution measurements and, besides, dynamic tests have been also performed to verify the static criterion. Finally, the morphology of the flow past the tested bodies has been visualised by using smoke visualization techniques. Since the rectangular section beam is a limiting case of the H-section configuration, the results here obtained are compared with the ones published in the literature concerning rectangular configurations; the agreement is satisfactory.

  10. Nonlinear dynamic response of beam and its application in nanomechanical resonator

    Institute of Scientific and Technical Information of China (English)

    Yin Zhang; Yun Liu; Kevin D. Murphy

    2012-01-01

    Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application.Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed.The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach.The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity,its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects.However,for the nanomechanical resonator of the curvature-dominant nonlinearity,its dynamic nonlinearity is only dependent on axial loading.Compared with the tension-dominant nonlinearity,the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity can result in both hardening and softening effects.The analysis on the dynamic nonlinearity can be very helpful to the tuning application of the nanomechanical resonator.

  11. Beam Dynamics Studies and Design Optimisation of New Low Energy Antiproton Facilities

    CERN Document Server

    Resta-Lopez, Javier; Welsch, Carsten P

    2016-01-01

    Antiprotons, stored and cooled at low energies in a storage ring or at rest in traps, are highly desirable for the investigation of a large number of basic questions on fundamental interactions. This includes the static structure of antiprotonic atomic systems and the time-dependent quantum dynamics of correlated systems. The Antiproton Decelerator (AD) at CERN is currently the worlds only low energy antiproton factory dedicated to antimatter experiments. New antiproton facilities, such as the Extra Low ENergy Antiproton ring (ELENA) at CERN and the Ultra-low energy Storage Ring (USR) at FLAIR, will open unique possibilities. They will provide cooled, high quality beams of extra-low energy antiprotons at intensities exceeding those achieved presently at the AD by factors of ten to one hundred. These facilities, operating in the energy regime between 100 keV down to 20 keV, face several design and beam dynamics challenges, for example nonlinearities, space charge and scattering effects limiting beam life time....

  12. Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams

    Directory of Open Access Journals (Sweden)

    Zhenyu Wang

    2013-01-01

    Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.

  13. Three-dimensional ordering of cold ion beams in a storage ring: A molecular-dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Yuri, Yosuke, E-mail: yuri.yosuke@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi Takasaki, Gunma 370-1292 Japan (Japan)

    2015-06-29

    Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.

  14. An Analysis of Beamed Wireless Power Transfer in the Fresnel Zone Using a Dynamic, Metasurface Aperture

    CERN Document Server

    Smith, David R; Yurduseven, Okan; Larouche, Stephane; Lipworth, Guy; Urzhumov, Yaroslav; Reynolds, Matthew S

    2016-01-01

    Wireless power transfer (WPT) has been an active topic of research, with a number of WPT schemes implemented in the near-field (coupling) and far-field (radiation) regimes. Here, we consider a beamed WPT scheme based on a dynamically reconfigurable source aperture transferring power to receiving devices within the Fresnel (near-zone) region. In this context, the dynamic aperture resembles a reconfigurable lens capable of focusing power to a well-defined spot, whose dimension can be related to a point spread function (PSF). Near-zone focusing can be achieved by generating different amplitude or phase profiles over the aperture, which can be realized using traditional architectures, such as phased arrays. Alternatively, metasurface guided-wave apertures can achieve dynamic focusing, with potentially lower cost implementations. We present an initial tradeoff analysis of the near-zone WPT concept, relating key parameters such as spot size, aperture size, wavelength, focal distance, and availability of sources. We...

  15. Combined dynamic stiffness matrix and precise time integration method for transient forced vibration response analysis of beams

    Science.gov (United States)

    Tang, Bin

    2008-01-01

    A method has been developed for determining the transient response of a beam. The beam is divided into several continuous Timoshenko beam elements. The overall dynamic stiffness matrix is assembled in turn. Using Leung's equation, we derive the overall mass and stiffness matrices which are more suitable for response analysis than the overall dynamic stiffness matrix. The forced vibration of the beam is computed by the precise time integration method. Three illustrative beams are discussed to evaluate the performance of the current method. Solutions calculated by the finite element method and theoretical analysis are also enumerated for comparison. In these examples, we have found that the current method can solve the forced vibration of structures with a higher precision.

  16. Vertical dynamic deflection measurement in concrete beams with the Microsoft Kinect.

    Science.gov (United States)

    Qi, Xiaojuan; Lichti, Derek; El-Badry, Mamdouh; Chow, Jacky; Ang, Kathleen

    2014-02-19

    The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate using a single sensor. This paper presents the results of an investigation into the development of a Microsoft Kinect-based system for measuring the deflection of reinforced concrete beams subjected to cyclic loads. New segmentation methods for object extraction from the Kinect's depth imagery and vertical displacement reconstruction algorithms have been developed and implemented to reconstruct the time-dependent displacement of concrete beams tested in laboratory conditions. The results demonstrate that the amplitude and frequency of the vertical displacements can be reconstructed with submillimetre and milliHz-level precision and accuracy, respectively.

  17. ARTICLE Crossed Beams Study on the Dynamics of F Atom Reaction with 1,2-Butadiene

    Science.gov (United States)

    Xiao, Chong-fa; Shen, Guan-lin; Wang, Xiu-yan; Yang, Xue-ming

    2010-12-01

    We have investigated the dynamics of the F+C4H6 reaction using the universal crossed molecular beam method. The C4H5F+H reaction channel was observed in this experiment. Angular resolved time-of-flight spectra have been measured for the C4H5F product. Product angular distributions as well as kinetic energy distributions were determined for this product channel. Experimental results show that the C4H5F product is largely backward scattered with considerable forward scattering signal, relative to the F atom beam direction. This suggests that the reaction channel mainly proceeds via a long-lived complex formation mechanism, with possible contribution from a direct SN2 type mechanism.

  18. Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy

    Science.gov (United States)

    Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J.

    2014-01-01

    Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content. PMID:24689588

  19. Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J., E-mail: gsimpson@purdue.edu [Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907 (United States)

    2014-03-15

    Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content.

  20. REX-ISOLDE RFQ Beam Dynamics Studies using CST EM Studio

    CERN Document Server

    Fraser, M A

    2014-01-01

    The original CNC milling files used to machine the electrodes of the REX-ISOLDE RFQ were acquired in late 2012 and electrostatic simulations were carried out using CST EM Studio in order to attain a 3D field map of the electric fields in the region around the beam axis. The objective was to construct a beam dynamics simulation tool that frees us from the constraints of the PARMTEQM code, which was used to design the RFQ, and that will afford us more flexibility in the studies needed for pre-bunching into the RFQ with an external multi-harmonic buncher. This note details the geometry of the electrodes and their simulation in CST EM Studio, the implementation of particle tracking in the computed field map using TRACK and benchmarking studies with PARMTEQM v3.09.

  1. BEAM DYNAMICS ANALYSIS FOR THE ULTRA-FAST KICKER IN CIRCULAR COOLER RING OF JLEIC

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yulu [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Inst. Modern Phys., Chinese Academy of Sciences, Lanzhou, China; Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    An ultra-fast kicker system consisting of four quarter wavelength resonator based deflecting cavities was developed that simultaneously resonates at 10 subharmonic modes of the 476.3MHz bunch repetition frequency. Thus every 10th bunch in the bunch train will experience a transverse kick while all the other bunches are undisturbed. This fast kicker is being developed for the Energy Recovery Linac (ERL) based electron Circular Cooler Ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously MEIC). The electron bunches can be reused 10-30 turns thus the beam current in the ERL can be reduced to 1/10 - 1/30 (150mA - 50mA) of the cooling bunch current (1.5A). In this paper, several methods to synthesize such a kicker waveform and the comparison made by the beam dynamics tracking in Elegant will be discussed.

  2. Crossed molecular beam studies of unimolecular reaction dynamics. [Angular and velocity distributions

    Energy Technology Data Exchange (ETDEWEB)

    Buss, R.J.

    1979-04-01

    The study of seven radical-molecule reactions using the crossed molecular beam technique with supersonic nozzle beams is reported. Product angular and velocity distributions were obtained and compared with statistical calculations in order to identify dynamical features of the reactions. In the reaction of chlorine and fluorine atoms with vinyl bromide, the product energy distributions are found to deviate from predictions of the statistical model. A similar effect is observed in the reaction of chlorine atoms with 1, 2 and 3-bromopropene. The reaction of oxygen atoms with ICl and CF/sub 3/I has been used to obtain an improved value of the IO bond energy, 55.0 +- 2.0 kcal mol/sup -1/. In all reactions studied, the product energy and angular distributions are found to be coupled, and this is attributed to a kinematic effect of the conservation of angular momentum.

  3. Evolutionary genetic optimization of the injector beam dynamics for the ERL test facility at IHEP

    CERN Document Server

    Yi, Jiao

    2013-01-01

    The energy recovery linac test facility (ERL-TF), a compact ERL-FEL (free electron laser) two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector started with a photocathode direct-current gun was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1~1.2 mm, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization for the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future constructing and commissioning of the ERL-TF injector.

  4. Neutron transport study of a beam port based dynamic neutron radiography facility

    Science.gov (United States)

    Khaial, Anas M.

    Neutron radiography has the ability to differentiate between gas and liquid in two-phase flow due both to the density difference and the high neutron scattering probability of hydrogen. Previous studies have used dynamic neutron radiography -- in both real-time and high-speed -- for air-water, steam-water and gas-liquid metal two-phase flow measurements. Radiography with thermal neutrons is straightforward and efficient as thermal neutrons are easier to detect with relatively higher efficiency and can be easily extracted from nuclear reactor beam ports. The quality of images obtained using neutron radiography and the imaging speed depend on the neutron beam intensity at the imaging plane. A high quality neutron beam, with thermal neutron intensity greater than 3.0x 10 6 n/cm2-s and a collimation ratio greater than 100 at the imaging plane, is required for effective dynamic neutron radiography up to 2000 frames per second. The primary objectives of this work are: (1) to optimize a neutron radiography facility for dynamic neutron radiography applications and (2) to investigate a new technique for three-dimensional neutron radiography using information obtained from neutron scattering. In this work, neutron transport analysis and experimental validation of a dynamic neutron radiography facility is studied with consideration of real-time and high-speed neutron radiography requirements. A beam port based dynamic neutron radiography facility, for a target thermal neutron flux of 1.0x107 n/cm2-s, has been analyzed, constructed and experimentally verified at the McMaster Nuclear Reactor. The neutron source strength at the beam tube entrance is evaluated experimentally by measuring the thermal and fast neutron fluxes using copper activation flux-mapping technique. The development of different facility components, such as beam tube liner, gamma ray filter, beam shutter and biological shield, is achieved analytically using neutron attenuation and divergence theories. Monte

  5. Numerical Simulations of Nonlinear Dynamics of Electron Cyclotron Maser with a Straight Beam

    Institute of Scientific and Technical Information of China (English)

    KONG Ling-Bao; HOU Zhi-Ling

    2011-01-01

    An electron cyclotron maser based on anomalous Doppler effect (ADECM) with an initially axial beam velocity is considered,and the nonlinear equation of beam-wave interaction is presented.With the numerical methods,the nonlinear dynamics of the ADECM is investigated.It is shown that the saturated interaction efficiency of the ADECM approaches 90% and the interaction length for the saturated efficiency spans about 5-20cm.The results may be of importance for designing a compact device in applications in microwave generations or microwave heating of ceramic laminates.In the late 1950s,the theoretical studies on the instability of electron cyclotron maser based on normal Doppler effect (NDECM) were performed almost simultaneously by Gaponov,[1] Twiss,[2] and Schneider.[3] Their discoveries have resulted in the most successful fast-wave devices such as the gyrotron and variants.[4,5] The possible applications of microwaves span a wide range of technologies such as in thermonuclear fusion energy,charged particle accelerations,radar systems,and processing of advanced ceramics.[6-16]%An electron cyclotron maser based on anomalous Doppler effect (ADECM) with an initially axial beam velocity is considered, and the nonlinear equation of beam-wave interaction is presented. With the numerical methods, the nonlinear dynamics of the ADECM is investigated. It is shown that the saturated interaction efficiency of the ADECM approaches 90% and the interaction length for the saturated efficiency spans about 5-20 cm. The results may be of importance for designing a compact device in applications in microwave generations or microwave heating of ceramic laminates.

  6. Non-linear Dynamics in ETG Mode Saturation and Beam-Plasma Instabilities

    Science.gov (United States)

    Tokluoglu, Erinc K.

    Non-linear mechanisms arise frequently in plasmas and beam-plasma systems resulting in dynamics not predicted by linear theory. The non-linear mechanisms can influence the time evolution of plasma instabilities and can be used to describe their saturation. Furthermore time and space averaged non-linear fields generated by instabilities can lead to collisionless transport and plasma heating. In the case of beam-plasma systems counter-intuitive beam defocusing and scaling behavior which are interesting areas of study for both Low-Temperature and High Energy Density physics. The non-linear mode interactions in form of phase coupling can describe energy transfer to other modes and can be used to describe the saturation of plasma instabilities. In the first part of this thesis, a theoretical model was formulated to explain the saturation mechanism of Slab Electron Temperature Gradient (ETG) mode observed in the Columbia Linear Machine (CLM), based on experimental time-series data collected through probe diagnostics [1]. ETG modes are considered to be a major player in the unexplained high levels of electron transport observed in tokamak fusion experiments and the saturation mechanism of these modes is still an active area of investigation. The data in the frequency space indicated phase coupling between 3 modes, through a higher order spectral correlation coefficient known as bicoherence. The resulting model is similar to [2], which was a treatment for ITG modes observed in the CLM and correctly predicts the observed saturation level of the ETG turbulence. The scenario is further supported by the fact that the observed mode frequencies are in close alignment with those predicted theoretical dispersion relations. Non-linear effects arise frequently in beam-plasma systems and can be important for both low temperature plasma devices commonly used for material processing as well as High Energy Density applications relevant to inertial fusion. The non-linear time averaged

  7. Lattice design and beam dynamics studies of the high energy beam transport line in the RAON heavy ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hyunchang, E-mail: hcjin@ibs.re.kr; Jang, Ji-Ho; Jang, Hyojae; Jeon, Dong-O

    2015-12-01

    In RAON heavy ion accelerator, beams generated by superconducting electron cyclotron resonance ion source (ECR-IS) or Isotope Separation On-Line (ISOL) system are accelerated by lower energy superconducting linac and high energy superconducting linac. The accelerated beams are used in the high energy experimental hall which includes bio-medical and muon-SR facilities, after passing through the high energy beam transport lines. At the targets of those two facilities, the stable and small beams meeting the requirements rigorously are required in the transverse plane. Therefore the beams must be safely sent to the targets and simultaneously satisfy the two requirements, the achromatic condition and the mid-plane symmetric condition, of the targets. For this reason, the lattice design of the high energy beam transport lines in which the long deflecting sections are included is considered as a significant issue in the RAON accelerator. In this paper, we will describe the calculated beam optics satisfying the conditions and present the result of particle tracking simulations with the designed lattice of the high energy beam transport lines in the RAON accelerator. Also, the orbit distortion caused by the machine imperfections and the orbit correction with correctors will be discussed.

  8. FAST TRACK COMMUNICATION: Relativistic echo dynamics and the stability of a beam of Landau electrons

    Science.gov (United States)

    Sadurní, E.; Seligman, T. H.

    2008-03-01

    We extend the concepts of echo dynamics and fidelity decay to relativistic quantum mechanics, specifically in the context of Klein-Gordon and Dirac equations under external electromagnetic fields. In both cases, we define similar expressions for the fidelity amplitude under perturbations of these fields and a covariant version of the echo operator. Transformation properties under the Lorentz group are established. An alternate expression for fidelity is given in the Dirac case in terms of a 4-current. As an application, we study a beam of Landau electrons perturbed by field inhomogeneities.

  9. Relativistic echo dynamics and the stability of a beam of Landau electrons

    Energy Technology Data Exchange (ETDEWEB)

    SadurnI, E; Seligman, T H [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)], E-mail: sadurni@fis.unam.mx, E-mail: seligman@fis.unam.mx

    2008-03-14

    We extend the concepts of echo dynamics and fidelity decay to relativistic quantum mechanics, specifically in the context of Klein-Gordon and Dirac equations under external electromagnetic fields. In both cases, we define similar expressions for the fidelity amplitude under perturbations of these fields and a covariant version of the echo operator. Transformation properties under the Lorentz group are established. An alternate expression for fidelity is given in the Dirac case in terms of a 4-current. As an application, we study a beam of Landau electrons perturbed by field inhomogeneities. (fast track communication)

  10. Effects of Structural Damage on Dynamic Behavior at Sandwich Composite Beams - Part I-Theoretical Approach

    Directory of Open Access Journals (Sweden)

    Tufoi Marius

    2014-07-01

    Full Text Available This paper series presents an analysis regarding the dynamics of sandwich composite beams, embedded at one end, in order to highlight the effect of geometrical and material discontinuities upon the natural frequencies. In first part (Part I, analysis was performed with EulerBernoulli analytical method for determining the vibration modes and in second part (Part II, analysis was performed with numerical simulation in SolidWorks software for a five-layer composite. In the last section of the paper, an example is shown regarding how to interpret the obtained results.

  11. Experimental investigation of the longitudinal beam dynamics in a photoinjector using a two-macroparticle bunch

    Energy Technology Data Exchange (ETDEWEB)

    Piot, P.; /Northern Illinois U. /Fermilab; Tikhoplav, R.; /Rochester U.; Mihalcea, D.; Barov, N.; /Northern Illinois U.

    2006-03-01

    We have developed a two-macroparticle bunch to explore the longitudinal beam dynamics through various components of the Fermilab/NICADD photoinjector. Such a two-macroparticle bunch is generated by splitting the ultraviolet pulse from the photocathode drive laser. The presented method allows the exploration of radiofrequency-induced compression in the 1.625 cell rf-gun and the booster cavity. It also allows a direct measurement of the momentum compaction of the magnetic bunch compressor. The measurements are compared with analytical and numerical models.

  12. Long-time dynamics of two classes of beam and plate equations

    OpenAIRE

    2016-01-01

    In this thesis we will discuss the well-posedness and long-time dynamics of curved beam and thermoelastic plates. First, we considered the Bresse system with nonlinear damping and forcing terms. For this model we show the Timoshenko system as a singular limit of the Bresse system as the arch curvature l goes to 0 and under suitable assumptions on the nonlinearity we prove the existence of a smooth global attractor with finite fractal dimension and exponential attractors as well. We also compa...

  13. Measuring radiation damage dynamics by pulsed ion beam irradiation. 2015 Annual Progress Report for DOE/NE/NEET

    Energy Technology Data Exchange (ETDEWEB)

    Kucheyev, S. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-07

    The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation processes in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 2, this project had the following two major milestones: (i) measurement of the temperature dependence of defect dynamics in SiC and (ii) the evaluation of the robustness of the pulsed beam method from studies of the defect generation rate. As we describe below, both of these milestones have been met.

  14. Analysis of regular and chaotic dynamics of the Euler-Bernoulli beams using finite difference and finite element methods

    Institute of Scientific and Technical Information of China (English)

    J. Awrejcewicz; A.V. Krysko; J. Mrozowski; O.A. Saltykova; M.V. Zhigalov

    2011-01-01

    Chaotic vibrations of flexible non-linear EulerBernoulli beams subjected to harmonic load and with various boundary conditions (symmetric and non-symmetric) are studied in this work. Reliability of the obtained results is verified by the finite difference method (FDM) and the finite element method (FEM) with the Bubnov-Galerkin approximation for various boundary conditions and various dynamic regimes (regular and non-regular). The influence of boundary conditions on the Euler-Bernoulli beams dynamics is studied mainly, dynamic behavior vs. control parameters {ωp, q0} is reported, and scenarios of the system transition into chaos are illustrated.

  15. Chaotic dynamics in charged-particle beams: Possible analogs of galactic evolution

    Energy Technology Data Exchange (ETDEWEB)

    Bohn, Courtlandt L.; /Northern Illinois U. /Fermilab

    2004-12-01

    During the last couple of years of his life, Henry Kandrup became intensely interested in using charged-particle beams as a tool for exploring the dynamics of evolving galaxies. He and I recognized that both galaxies and charged-particle beams can exhibit collisionless relaxation on surprisingly short time scales, and that this circumstance can be attributed to phase mixing of chaotic orbits. The chaos is often triggered by resonances caused by time dependence in the bulk potential, which acts almost identically for attractive gravitational forces as for repulsive electrostatic forces superposed on external focusing forces. Together we published several papers concerning evolving beams and galaxies, papers that relate to diverse topics such as the physics of chaotic mixing, the applicability of the Vlasov-Poisson formalism, and the production of diffuse halos. We also teamed with people from the University of Maryland to begin designing controlled experiments to be done at the University of Maryland Electron Ring. This paper highlights our collaborative findings as well as plans for future investigations that the findings have motivated.

  16. Dynamics of submicron aerosol droplets in a robust optical trap formed by multiple Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Thanopulos, Ioannis [Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, ETH Zurich, CH-8093 Zurich (Switzerland); Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens 11635 (Greece); Luckhaus, David; Signorell, Ruth, E-mail: rsignorell@ethz.ch [Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, ETH Zurich, CH-8093 Zurich (Switzerland); Preston, Thomas C. [School of Chemistry, University of Bristol, Cantock' s Close, Clifton, Bristol BS8 1TS (United Kingdom)

    2014-04-21

    In this paper, we model the three-dimensional escape dynamics of single submicron-sized aerosol droplets in optical multiple Bessel beam traps. Trapping in counter-propagating Bessel beams (CPBBs) is compared with a newly proposed quadruple Bessel beam (QBB) trap, which consists of two perpendicularly arranged CPBB traps. Calculations are performed for perfectly and imperfectly aligned traps. Mie-theory and finite-difference time-domain methods are used to calculate the optical forces. The droplet escape kinetics are obtained from the solution of the Langevin equation using a Verlet algorithm. Provided the traps are perfectly aligned, the calculations indicate very long lifetimes for droplets trapped either in the CPBB or in the QBB trap. However, minor misalignments that are hard to control experimentally already severely diminish the stability of the CPBB trap. By contrast, such minor misalignments hardly affect the extended droplet lifetimes in a QBB trap. The QBB trap is found to be a stable, robust optical trap, which should enable the experimental investigation of submicron droplets with radii down to 100 nm. Optical binding between two droplets and its potential role in preventing coagulation when loading a CPBB trap is briefly addressed.

  17. BEAM DYNAMICS SIMULATIONS OF SARAF ACCELERATOR INCLUDING ERROR PROPAGATION AND IMPLICATIONS FOR THE EURISOL DRIVER

    CERN Document Server

    J. Rodnizki, D. Berkovits, K. Lavie, I. Mardor, A. Shor and Y. Yanay (Soreq NRC, Yavne), K. Dunkel, C. Piel (ACCEL, Bergisch Gladbach), A. Facco (INFN/LNL, Legnaro, Padova), V. Zviagintsev (TRIUMF, Vancouver)

    AbstractBeam dynamics simulations of SARAF (Soreq Applied Research Accelerator Facility) superconducting RF linear accelerator have been performed in order to establish the accelerator design. The multi-particle simulation includes 3D realistic electromagnetic field distributions, space charge forces and fabrication, misalignment and operation errors. A 4 mA proton or deuteron beam is accelerated up to 40 MeV with a moderated rms emittance growth and a high real-estate gradient of 2 MeV/m. An envelope of 40,000 macro-particles is kept under a radius of 1.1 cm, well below the beam pipe bore radius. The accelerator design of SARAF is proposed as an injector for the EURISOL driver accelerator. The Accel 176 MHZ β0=0.09 and β0=0.15 HWR lattice was extended to 90 MeV based on the LNL 352 MHZ β0=0.31 HWR. The matching between both lattices ensures smooth transition and the possibility to extend the accelerator to the required EURISOL ion energy.

  18. Fine-tuning the etch depth profile via dynamic shielding of ion beam

    CERN Document Server

    Wu, Lixiang; Fu, Shaojun

    2016-01-01

    We introduce a method for finely adjusting the etch depth profile by dynamic shielding in the course of ion beam etching (IBE), which is crucial for the ultra-precision fabrication of large optics. We study the physical process of dynamic shielding and propose a parametric modeling method to quantitatively analyze the shielding effect on etch depths, or rather the shielding rate, where a piecewise Gaussian model is adopted to fit the shielding rate profile. We have conducted two experiments. In the experiment on parametric modeling of shielding rate profiles, its result shows that the shielding rate profile is significantly influenced by the rotary angle of the leaf. And the experimental result of fine-tuning the etch depth profile shows good agreement with the simulated result, which preliminarily verifies the feasibility of our method.

  19. Dynamical Dipole mode in heavy-ion fusion reactions by using stable and radioactive beams

    Directory of Open Access Journals (Sweden)

    Molini P.

    2011-10-01

    Full Text Available The existence of the dynamical dipole mode in the 192Pb composite system was investigated through the study of its prompt γ decay employing the 40Ca + 152Sm and 48Ca + 144Sm reactions at Elab =11 and 10.1 MeV/u, respectively. The γ-rays and light charged particles were detected in coincidence with evaporation residues and fission fragments. First results of this experiment show that the dynamical dipole mode survives in collisions involving heavier mass reaction partners than those studied previously. As a fast cooling mechanism on the fusion path, the prompt dipole γ radiation could be of interest for the synthesis of super-heavy elements through ”hot” fusion reactions. Furthermore, by using radioactive beams and the prompt γ radiation as a probe we could get information on the symmetry energy at sub-saturation densities.

  20. A feasibility study of Dynamic Phantom scanner for quality assurance of photon beam profiles at various gantry angles.

    Science.gov (United States)

    Zhang, Yunkai; Hsi, Wen C; Chu, James C H; Bernard, Damian B; Abrams, Ross A

    2005-01-01

    The effect of gantry rotation on beam profiles of photon and electron beams is an important issue in quality assurance for radiotherapy. To address variations in the profiles of photon and electron beams at different gantry angles, a Dynamic Phantom scanner composed of a 20 x 12 x 6 cm3 scanning Lucite block was designed as a cross-beam-profile scanner. To our knowledge, differences between scanned profiles acquired at different gantry angles with a small size Lucite block and those acquired a full-size (60 x 60 x 50 cm3) water phantom have not been previously investigated. We therefore performed a feasibility study for a first prototype Dynamic Phantom scanner without a gantry attachment mount. Radiation beams from a Varian LINAC 21EX and 2100C were used. Photon beams (6 MV and 18 MV) were shaped by either collimator jaws or a Varian 120 Multileaf (MLC) collimator, and electron beams (6 MeV, 12 MeV, and 20 MeV) were shaped by a treatment cone. To investigate the effect on profiles by using a Lucite block, a quantitative comparison of scanned profiles with the Dynamic Phantom and a full-size water phantom was first performed at a 0 degrees gantry angle for both photon and electron beams. For photon beam profiles defined by jaws at 1.0 cm and 5.0 cm depths of Lucite (i.e., at 1.1 cm and 5.7 cm depth of water), a good agreement (less than 1% variation) inside the field edge was observed between profiles scanned with the Dynamic Phantom and with a water phantom. The use of Lucite in the Dynamic Phantom resulted in reduced penumbra width (about 0.5 mm out of 5 mm to 8mm) and reduced (1% to 2%) scatter dose beyond the field edges for both 6 MV and 18 MV beams, compared with the water phantom scanner. For profiles of the MLC-shaped 6 MV photon beam, a similar agreement was observed. For profiles of electron beams scanned at 2.9 cm depth of Lucite (i.e., at 3.3 cm depth of water), larger disagreements in profiles (3% to 4%) and penumbra width (3 mm to 4 mm out of 12 mm

  1. Myocardial physiology measurements using contrast enhanced dynamic computed tomography: simulation of beam hardening effect

    Science.gov (United States)

    Cao, Minsong; Stantz, Keith M.; Liang, Yun

    2006-03-01

    Initial animal study for quantifying myocardial physiology through contrast-enhanced dynamic x-ray CT suggested that beam hardening is one of the limiting factors for accurate regional physiology measurement. In this study, a series of simulations were performed to investigate its deterioration effects and two correction algorithms were adapted to evaluate for their efficiency in improving the measurements. The simulation tool consists of a module simulating data acquisition of a real polyenergetic scanner system and a heart phantom consisting of simple geometric objects representing ventricles and myocardium. Each phantom component was modeled with time-varying attenuation coefficients determined by ideal iodine contrast dynamic curves obtained from experimental data or simulation. A compartment model was used to generate the ideal myocardium contrast curve using physiological parameters consistent with measured values. Projection data of the phantom were simulated and reconstructed to produce a sequence of simulated CT images. Simulated contrast dynamic curves were fitted to the compartmental model and the resultant physiological parameters were compared with ideal values to estimate the errors induced by beam hardening artifacts. The simulations yielded similar deterioration patterns of contrast dynamic curves as observed in the initial study. Significant underestimation of left ventricle curves and corruption of regional myocardium curves result in systematic errors of regional perfusion up to approximately 24% and overestimates of fractional blood volume (f iv) up to 13%. The correction algorithms lead to significant improvement with errors of perfusion reduced to 7% and errors of f iv within 2% which shows promise for more robust myocardial physiology measurement.

  2. The CERN antiproton target: hydrocode analysis of its core material dynamic response under proton beam impact

    CERN Document Server

    Martin, Claudio Torregrosa; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-01-01

    Antiprotons are produced at CERN by colliding a 26 GeV/c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 {\\deg}C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of...

  3. CERN antiproton target: Hydrocode analysis of its core material dynamic response under proton beam impact

    Science.gov (United States)

    Martin, Claudio Torregrosa; Perillo-Marcone, Antonio; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-07-01

    Antiprotons are produced at CERN by colliding a 26 GeV /c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 °C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 44% in tensile pressure could be obtained by the use of a high density tantalum cladding.

  4. Studying wedge factors and beam profiles for physical and enhanced dynamic wedges

    Directory of Open Access Journals (Sweden)

    Ahmad Misbah

    2010-01-01

    Full Text Available This study was designed to investigate variation in Varian′s Physical and Enhanced Dynamic Wedge Factors (WF as a function of depth and field size. The profiles for physical wedges (PWs and enhanced dynamic wedges (EDWs were also measured using LDA-99 array and compared for confirmation of EDW angles at different depths and field sizes. WF measurements were performed in water phantom using cylindrical 0.66 cc ionization chamber. WF was measured by taking the ratio of wedge and open field ionization data. A normalized wedge factor (NWF was introduced to circumvent large differences between wedge factors for different wedge angles. A strong linear dependence of PW Factor (PWF with depth was observed. Maximum variation of 8.9% and 4.1% was observed for 60° PW with depth at 6 and 15 MV beams respectively. The variation in EDW Factor (EDWF with depth was almost negligible and less than two per cent. The highest variation in PWF as a function of field size was 4.1% and 3.4% for thicker wedge (60° at 6 and 15 MV beams respectively and decreases with decreasing wedge angle. EDWF shows strong field size dependence and significant variation was observed for all wedges at both photon energies. Differences in profiles between PW and EDW were observed on toe and heel sides. These differences were dominant for larger fields, shallow depths, thicker wedges and low energy beam. The study indicated that ignoring depth and field size dependence of WF may result in under/over dose to the patient especially doing manual point dose calculation.

  5. Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, Oleksandr

    2015-06-24

    The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U{sup 90+} beam at the existing storage ring ESR, GSI.

  6. Beam Dynamics Investigation of the 101.28 MHz IH Structure as Injector for the HIE-ISOLDE SC Linac

    CERN Document Server

    Fraser, M A; Jones, R M; Voulot, D

    2010-01-01

    The first phase of the HIE-ISOLDE project at CERN consists of a superconducting (SC) linac upgrade in order to increase the energy of post-accelerated radioactive ion beams from 2.8 MeV/u to over 10 MeV/u (for A/q = 4.5). In preparation for the upgrade, we present beam dynamics studies of the booster section of the normal conducting (NC) REX-ISOLDE linac, focused on the longitudinal development of the beam in the 101.28 MHz Interdigital H-mode Structure (IHS), employing a Combined Zero Degree Structure (KONUS), pulsing at a high gradient of over 3 MV/m. The evolution of the transverse emittance in the SC linac depends critically on the injected longitudinal phase space distribution of particles from the existing linac and, with a better understanding of the beam dynamics upstream, the performance of the upgrade can be optimised. Data taken during the commissioning phase of the REX-ISOLDE linac is analysed to understand the properties of the beam in the booster and combined with beam dynamics simulations which...

  7. A dynamic model of a cantilever beam with a closed, embedded horizontal crack including local flexibilities at crack tips

    Science.gov (United States)

    Liu, J.; Zhu, W. D.; Charalambides, P. G.; Shao, Y. M.; Xu, Y. F.; Fang, X. M.

    2016-11-01

    As one of major failure modes of mechanical structures subjected to periodic loads, embedded cracks due to fatigue can cause catastrophic failure of machineries. Understanding the dynamic characteristics of a structure with an embedded crack is helpful for early crack detection and diagnosis. In this work, a new three-segment beam model with local flexibilities at crack tips is developed to investigate the vibration of a cantilever beam with a closed, fully embedded horizontal crack, which is assumed to be not located at its clamped or free end or distributed near its top or bottom side. The three-segment beam model is assumed to be a linear elastic system, and it does not account for the nonlinear crack closure effect; the top and bottom segments always stay in contact at their interface during the beam vibration. It can model the effects of local deformations in the vicinity of the crack tips, which cannot be captured by previous methods in the literature. The middle segment of the beam containing the crack is modeled by a mechanically consistent, reduced bending moment. Each beam segment is assumed to be an Euler-Bernoulli beam, and the compliances at the crack tips are analytically determined using a J-integral approach and verified using commercial finite element software. Using compatibility conditions at the crack tips and the transfer matrix method, the nature frequencies and mode shapes of the cracked cantilever beam are obtained. The three-segment beam model is used to investigate the effects of local flexibilities at crack tips on the first three natural frequencies and mode shapes of the cracked cantilever beam. A stationary wavelet transform (SWT) method is used to process the mode shapes of the cracked cantilever beam; jumps in single-level SWT decomposition detail coefficients can be used to identify the length and location of an embedded horizontal crack.

  8. Dynamical Model for an Interharmonic Property of a Piezoelectric Bimorph Cantilever Beam with Self-Sensing Function

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    2016-01-01

    Full Text Available A piezoelectric bimorph cantilevered beam is analyzed dynamically by a longitudinal and transverse coupling theory. When a sinusoidal voltage is applied on the actuating layer of the bimorph, the output voltage of the sensing layer appears as interharmonic component signal. The interharmonic frequency is noninteger harmonic frequency of the applied voltage. A dynamic model is proposed to describe the interharmonic property of the piezoelectric bimorph beam. Through some simulations and experiments, the theoretical model is verified effectively to express the nonlinear characteristic. Furthermore, when the piezoelectric bimorph resonance happens, some interharmonic response at low frequency will modulate with the resonance response.

  9. Transverse beam dynamics in non-linear Fixed Field Alternating Gradient accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Haj, Tahar M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-02

    In this paper, we present some aspects of the transverse beam dynamics in Fixed Field Ring Accelerators (FFRA): we start from the basic principles in order to derive the linearized transverse particle equations of motion for FFRA, essentially FFAGs and cyclotrons are considered here. This is a simple extension of a previous work valid for linear lattices that we generalized by including the bending terms to ensure its correctness for FFAG lattice. The space charge term (contribution of the internal coulombian forces of the beam) is contained as well, although it is not discussed here. The emphasis is on the scaling FFAG type: a collaboration work is undertaken in view of better understanding the properties of the 150 MeV scaling FFAG at KURRI in Japan, and progress towards high intensity operation. Some results of the benchmarking work between different codes are presented. Analysis of certain type of field imperfections revealed some interesting features about this machine that explain some of the experimental results and generalize the concept of a scaling FFAG to a non-scaling one for which the tune variations obey a well-defined law.

  10. Reaction dynamics of Cl + butanol isomers by crossed-beam sliced ion imaging.

    Science.gov (United States)

    Estillore, Armando D; Visger-Kiefer, Laura M; Suits, Arthur G

    2012-01-01

    Butanol is now prominent among the prototype renewable biofuels. We have studied oxidation of a variety of butanol isomers under single collision conditions using chlorine atom as the oxidizing agent to gain detailed insight into the energetics and dynamics of these reactions. The interaction of chlorine atom radicals with butanol isomers: n-butanol, iso-butanol, sec-butanol, and tert-butanol have been studied by crossed-beam dc slice ion imaging techniques. The hydroxybutyl radicals generated from the H-abstraction processes were probed by single photon ionization using an F2 excimer laser. After background subtraction and density-to-flux correction of the raw images, translational energy distribution and product angular distributions were generated. At low collision energy, the hydroxyalkyl products are backscattered with respect to the alcohol beam and the scattering shifts to the forward direction as the collision energy is increased. The translational energy distributions are reminiscent to that of Cl + pentane reactions we studied earlier, i.e. a sharp forward peak -80% of the collision energy appears at the high collision energy. Isomer-specific details of the reactions will be discussed.

  11. Noether Symmetry Analysis of the Dynamic Euler-Bernoulli Beam Equation

    Science.gov (United States)

    Johnpillai, A. G.; Mahomed, K. S.; Harley, C.; Mahomed, F. M.

    2016-05-01

    We study the fourth-order dynamic Euler-Bernoulli beam equation from the Noether symmetry viewpoint. This was earlier considered for the Lie symmetry classification. We obtain the Noether symmetry classification of the equation with respect to the applied load, which is a function of the dependent variable of the underlying equation. We find that the principal Noether symmetry algebra is two-dimensional when the load function is arbitrary and extends for linear and power law cases. For all cases, for each of the Noether symmetries associated with the usual Lagrangian, we construct conservation laws for the equation via the Noether theorem. We also provide a basis of conservation laws by using the adjoint algebra. The Noether symmetries pick out the special value of the power law, which is -7. We consider the Noether symmetry reduction for this special case, which gives rise to a first integral that is used for our numerical code. For this, we then find numerical solutions using an in-built function in MATLAB called bvp4c, which is a boundary value solver for differential equations that are depicted in five figures. The physical solutions obtained are for the deflection of the beam with an increase in displacement. These are given in four figures and discussed.

  12. Beam dynamics in resonant plasma wakefield acceleration at SPARC_LAB

    Science.gov (United States)

    Romeo, S.; Anania, M. P.; Chiadroni, E.; Croia, M.; Ferrario, M.; Marocchino, A.; Pompili, R.; Vaccarezza, C.

    2016-09-01

    Strategies to mitigate the increase of witness emittance and energy spread in beam driven plasma wakefield acceleration are investigated. Starting from the proposed resonant wakefield acceleration scheme in quasi-non-linear regime that is going to be carried out at SPARC_LAB, we performed systematic scans of the parameters to be used for drivers. The analysis will show that one of the main requirements to preserve witness quality during the acceleration is to have accelerating and focusing fields that are very stable during all the accelerating length. The difference between the dynamics of the leading bunch and the trailing bunch is pointed out. The classical condition on bunch length kpσz =√{ 2 } seems to be an ideal condition for the first driver within long accelerating lengths. The other drivers show to follow different longitudinal matching conditions. In the end a new method for the investigation of the matching for the first driver is introduced.

  13. Beam dynamics simulations in laser electron storage rings and optical stochastic cooling

    Science.gov (United States)

    Duru, Alper

    Laser-electron storage rings are potential compact X-ray sources. Longitudinal dynamics in laser-electron storage rings is studied including the effects of both laser interaction and synchrotron radiation. It is shown that the steady state energy spread can reach as high as a few percent. The main reason is the wide spread in the energy loss by electrons to laser photons. Optical stochastic cooling has been studied numerically. The effects of the finite bandwidth of the amplifier are mixing and signal distortion. Both are included in the simulations and the results are compared to theoretical results. It is shown that the beam can be cooled both in transverse and longitudinal phase phase spaces simultaneously.

  14. Single-particle And Collective Effects Of Cubic Nonlinearity In The Beam Dynamics Of Proton Synchrotrons

    CERN Document Server

    Tran Hy, J

    1998-01-01

    This thesis describes some new studies of the effects of cubic nonlinearities arising from image-charge forces and octupole magnets on the transverse beam dynamics of proton synchrotrons and storage rings, and also a study of the damping of coherent oscillations using a feed-back damper. In the latter case, various corrective algorithms were modeled using linear one-turn maps. Kicks of fixed amplitude but appropriate sign were shown to provide linear damping and no coherent tune shift, though the rate predicted analytically was somewhat higher than that observed in simulations. This algorithm gave much faster damping (for equal power) than conventional proportional kicks, which damp exponentially. Two single-particle effects of the image-change force were investigated: distortion of the momentum dispersion function and amplitude dependence of the betatron tunes (resulting in tune spread). The former is calculated using transfer maps and the method of undetermined coefficients, the latter by solving the cubic ...

  15. Entrance channel effect with stable and radioactive beams using dynamical cluster decay model

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Raj, E-mail: rajkumarfzr@gmail.com [Dipartimento di Fisica “Galileo Galilei” and INFN, University of Padova, Padova-35131 (Italy); Jain, Deepika [School of Physics and Material Science, Thapar University, Patiala-147004 (India)

    2014-09-15

    The decay of hot and rotating {sup 172}Yb*, formed in two entrance channels {sup 124}Sn + {sup 48}Ca and {sup 132}Sn + {sup 40}Ca, is studied using the dynamical cluster-decay model. The effect of entrance channel, deformations (up to β{sub 2}), barrier modification and fusion enhancement are addressed. The decay pattern of compound system, formed in different channels at comparable energy around the barrier, shows change in magnitude with structure remains almost same. There is an increase in the fusion probability with decrease in barrier modification, which leads to fusion enhancement at low energies. The higher ℓ values are contributing for {sup 132}Sn + {sup 40}Ca channel at lower energies as compare to {sup 124}Sn + {sup 48}Ca. It is inferred that with the use of stable and radioactive beam, forming same compound nucleus, the entrance channel dependence changes with the excitation energy.

  16. Non-Linear Beam Dynamics Studies of the Diamond Storage Ring

    CERN Document Server

    Bartolini, Riccardo; Belgroune, Mahdia; Henry Rowland, James; Jones, James; Martin, Ian; Singh, Beni

    2005-01-01

    The non-linear beam dynamics have been investigated for the non-zero dispersion lattice of the Diamond storage ring. Effects in realistic lattice configurations such as the introduction of coupling errors, beta beating, closed orbit correction, quadrupole fringe field and in-vacuum and helical insertion devices have been studied in the presence of realistic physical aperture limitations. Frequency map analysis together with 6D tracking allows identification of the limiting resonances as well as the loss locations and calculation of the influence of non-linear longitudinal motion on the Touschek lifetime. The sensitivity of the lattice to some of these effects leads to the identification of a better working point for the machine.

  17. A Multimedia Tutorial for Charged-Particle Beam Dynamics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Silbar, Richard R.

    1999-07-26

    In September 1995 WhistleSoft, Inc., began developing a computer-based multimedia tutorial for charged-particle beam dynamics under Phase II of a Small Business Innovative Research grant from the U.S. Department of Energy. In Phase I of this project (see its Final Report) we had developed several prototype multimedia modules using an authoring system on NeXTStep computers. Such a platform was never our intended target, and when we began Phase II we decided to make the change immediately to develop our tutorial modules for the Windows and Macintosh microcomputer market. This Report details our progress and accomplishments. It also gives a flavor of the look and feel of the presently available and upcoming modules.

  18. Exact dynamic stiffness matrix for flexural vibration of three-layered sandwich beams

    Science.gov (United States)

    Howson, W. P.; Zare, A.

    2005-04-01

    An exact dynamic member stiffness matrix (exact finite element), which defines the flexural motion of a three-layered sandwich beam with unequal faceplates, is developed from the closed form solution of the governing differential equation. This enables the powerful modelling features associated with the finite element technique to be utilised, including the ability to account for nodal masses, spring support stiffnesses and non-classical boundary conditions. However, such a formulation necessitates the solution of a transcendental eigenvalue problem. This is accomplished using the Wittrick-Williams algorithm, which enables the required natural frequencies to be converged upon to any required accuracy with the certain knowledge that none have been missed. The accuracy of the method is confirmed by comparison with three sets of published results and a final example indicates its range of application.

  19. Stability of graphene edges under electron beam: equilibrium energetics versus dynamic effects.

    Science.gov (United States)

    Kotakoski, Jani; Santos-Cottin, David; Krasheninnikov, Arkady V

    2012-01-24

    Electron beam of a transmission electron microscope can be used to alter the morphology of graphene nanoribbons and create atomically sharp edges required for applications of graphene in nanoelectronics. Using density-functional-theory-based simulations, we study the radiation hardness of graphene edges and show that the response of the ribbons to irradiation is not determined by the equilibrium energetics as assumed in previous experiments, but by kinetic effects associated with the dynamics of the edge atoms after impacts of energetic electrons. We report an unexpectedly high stability of armchair edges, comparable to that of pristine graphene, and demonstrate that the electron energy should be below ~50 keV to minimize the knock-on damage.

  20. Particle-in-cell mode beam dynamics simulation of the low energy beam transport for the SSC-linac injector

    Institute of Scientific and Technical Information of China (English)

    XIAO Chen; HE Yuan; YUAN You-Jin; YAO Qing-Gao; WANG Zhi-Jun; CHANG Wei; LIU Yong; XIA Jia-Wen

    2011-01-01

    A new SSC-linac system (injector into separated sector cyclotron) is being designed in the HIRFL (heavy ion research facility of Lanzhou). As part of SSC-Linac, the LEBT (low energy beam transport) consists of seven solenoids, four quadrupoles, a bending

  1. Development of RFQ particle dynamics simulation tools and validation with beam tests

    Energy Technology Data Exchange (ETDEWEB)

    Maus, Johannes M.

    2010-07-01

    Two different strategies of designing RFQs have been introduced. The analytic description of the electric fields inside the quadrupole channel has been derived and the two term simplification was shown as well as the limitation of these approaches. The main work of this thesis was the implementation and analysis of a multigrid Poisson solver to describe the potential and electric field of RFQs which are needed to simulate the particle dynamics accurately. The main two ingredients of a multigrid Poisson solver are the ability of a Gauss-Seidel iteration method to smooth the error of an approximation within a few iteration steps and the coarse grid principle. The smoothing corresponds to a damping of the high frequency components of the error. After the smoothing, the error term can well be approximated on a coarser grid in which the low frequency components of the error on the fine grid are converted to high frequency errors on the coarse grid which can be damped further with the same Gauss-Seidel method. After implementation, the multigrid Poisson solver was analyzed using two different type of test problems: with and without a charge density. As a charge density, a homogeneously charged ball and cylinder were used to represent the bunched and unbunched beam and placed inside a quadruple channel. The solver showed a good performance. Next, the performance of the solver to calculate the external potentials (and fields) of RFQs was analyzed. Closing the analysis of the external field, the transmission and fraction of accelerated particles of the set of 12 RFQs for the two different methods were shown. In the last chapter of this thesis some experimental work on the MAFF (Munich Accelerator for Fission Fragments) IH-RFQ is described. The MAFF RFQ was designed to accelerate very neutron-rich fission fragments for various experiments. The machine was assembled in Frankfurt and a beam test stand was built. As a part of this thesis the shunt impedance of the structure was

  2. Snap-through and pull-in analysis of an electro-dynamically actuated curved micro-beam using a nonlinear beam model

    Science.gov (United States)

    Hu, Y. J.; Yang, J.; Kitipornchai, S.

    2013-07-01

    This paper presents a geometrically nonlinear micro-beam model for the electro-dynamic analysis of an initially curved micro-beam under an applied voltage, with an emphasis on its snap-through and pull-in behaviors. The governing equations of motion and the associated boundary conditions are derived in an arc coordinate system without involving any assumptions on the nonlinear deformation. Differential quadrature method (DQM) and Petzold-Gear Backward Differentiation Formulas (BDF) are employed to solve the governing equations in the space and time domains respectively to obtain the nonlinear fundamental frequency, snap-through voltage, pull-in voltage and the corresponding mode shapes of a micro-beam clamped at both ends. The present analysis is validated through a direct comparison with the published experimental and numerical results. A parametric study is conducted to investigate the influences of the initial gap, base length, arc rise, and initial curved configuration on the snap-through and pull-in behaviors of the micro-beam.

  3. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  4. Physical simulation of the long-term dynamic action of a plasma beam on a space debris object

    Science.gov (United States)

    Shuvalov, Valentin A.; Gorev, Nikolai. B.; Tokmak, Nikolai A.; Kochubei, Galina S.

    2017-03-01

    A methodology is developed for physical (laboratory) simulation of the long-term dynamic action of plasma beam high-energy ions on a space debris object with the aim of removing it to a lower orbit followed by its burning in the Earth's atmosphere. The methodology is based on the use of a criterion for the equivalence of two plasma beam exposure regimes (in the Earth' ionosphere and in laboratory conditions) and an accelerated test procedure in what concerns space debris object material sputtering and space debris object erosion by a plasma beam in the Earth's ionosphere. The space debris coating material (blanket thermal insulation) sputtering yield and normal and tangential momentum transfer coefficients are determined experimentally as a function of the ion energy and the ion beam incidence angle.

  5. Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-03-12

    Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused

  6. Dynamic behavior of pre- and post-instability of an axisymmetric elastic beam subjected to axial leakage flow

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, K.; Morikazu, H.; Shintani, A. [Osaka Prefectural Univ., Mechanical Systems Engineering, Graduate School of Engineering (Japan)

    2004-07-01

    The dynamic behavior of an axisymmetric elastic beam subjected to axial leakage flow is investigated numerically and experimentally. The coupled equations of motion for a fluid and a beam structure are derived using the Navier-Stokes equation for an axial leakage flow-path and the Euler-Bernoulli beam theory. The variation in the dynamic behavior during pre- and post-instability is investigated with respect to increasing axial leakage flow velocity. The experiment was performed to determine the critical velocity of the unstable dynamic behavior of an axisymmetric elastic beam confined in a concentric cylinder subjected to axial leakage flow through a small annulus, and to measure the variation of the dynamic behavior during pre- and post-instability when the unstable phenomenon with the lower predominant frequency is shifted to the higher. The relationships between the axial flow velocities and the unstable phenomena are clarified for the transition from the lower mode to the higher mode by comparing the numerical simulation results with experimental observations. (authors)

  7. Beam Dynamics in an Electron Lens with the Warp Particle-in-cell Code

    CERN Document Server

    Stancari, Giulio; Redaelli, Stefano

    2014-01-01

    Electron lenses are a mature technique for beam manipulation in colliders and storage rings. In an electron lens, a pulsed, magnetically confined electron beam with a given current-density profile interacts with the circulating beam to obtain the desired effect. Electron lenses were used in the Fermilab Tevatron collider for beam-beam compensation, for abort-gap clearing, and for halo scraping. They will be used in RHIC at BNL for head-on beam-beam compensation, and their application to the Large Hadron Collider for halo control is under development. At Fermilab, electron lenses will be implemented as lattice elements for nonlinear integrable optics. The design of electron lenses requires tools to calculate the kicks and wakefields experienced by the circulating beam. We use the Warp particle-in-cell code to study generation, transport, and evolution of the electron beam. For the first time, a fully 3-dimensional code is used for this purpose.

  8. Dynamic Responses of Supported Beams with Intermediate Supports Under Moving Loads

    Directory of Open Access Journals (Sweden)

    Biaobiao Zhang

    2012-01-01

    Full Text Available In this paper, a new beam shape function configuration method for determining transient responses of a finite Euler-Bernoulli beam with two intermediate supports excited by moving pressure wave loads is developed. To clarify this method, this beam structure is excited by the moving sinusoidal loads as an example. Transient responses of this beam structure are investigated and verified by the traditional finite element method. This method can be used to solve transient response problems of moving pressure loads exciting the beam structure with intermediate support. Actually it can be extended to solve other complicated beam structure problems.

  9. A transport model and numerical simulation of the high-frequency dynamics of three-dimensional beam trusses.

    Science.gov (United States)

    Le Guennec, Yves; Savin, Éric

    2011-12-01

    The theory of microlocal analysis shows that the energy density associated with the high-frequency vibrations of a three-dimensional Timoshenko beam satisfies a Liouville-type transport equation. In the present application, the material of the beam is assumed to be isotropic. Its parameters are allowed to vary along the beam axis at length scales much larger than the wavelength of the high-frequency waves traveling in it. Moreover, the curvature and torsion of the beam are accounted for. The first part of the paper focuses on the derivation of the transport model for a single three-dimensional beam. In order to extend this model to beam trusses, the reflection/transmission phenomena of the energy fluxes at junctions of beams are described by power flow reflection/transmission operators in a subsequent part. For numerical simulations, a discontinuous Galerkin finite element method is used on account of the discontinuities of the energy density field at the junctions. Thus, a complete mechanical-numerical modeling of the linear transient dynamics of beam trusses is proposed. It is illustrated by numerical examples highlighting some remarkable features of high-frequency vibrations: The onset of a diffusive regime characterized by energy equipartition rules at late times. Energy diffusion is prompted by the multiple reflection/transmission of waves at the junctions, with possible mode (polarization) conversions. This is the regime applicable to the statistical energy analysis of structural acoustics systems. The main purpose of this research is to develop an effective strategy to simulate and predict the transient response of beam trusses impacted by acoustic or mechanical shocks.

  10. Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-03-12

    Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused

  11. Nonlinear dynamics for charges particle beams with a curved axis in the matrix - recursive model

    Energy Technology Data Exchange (ETDEWEB)

    Dymnikov, A.D. [University of St Petersburg, (Russian Federation). Institute of Computational Mathematics and Control Process

    1993-12-31

    In this paper a new matrix and recursive approach has been outlined for treating nonlinear optics of charged particle beams. This approach is a new analytical and computational tool for designers of optimal beam control systems. 9 refs.

  12. Fast computation of statistical uncertainty for spatiotemporal distributions estimated directly from dynamic cone beam SPECT projections

    Energy Technology Data Exchange (ETDEWEB)

    Reutter, Bryan W.; Gullberg, Grant T.; Huesman, Ronald H.

    2001-04-09

    The estimation of time-activity curves and kinetic model parameters directly from projection data is potentially useful for clinical dynamic single photon emission computed tomography (SPECT) studies, particularly in those clinics that have only single-detector systems and thus are not able to perform rapid tomographic acquisitions. Because the radiopharmaceutical distribution changes while the SPECT gantry rotates, projections at different angles come from different tracer distributions. A dynamic image sequence reconstructed from the inconsistent projections acquired by a slowly rotating gantry can contain artifacts that lead to biases in kinetic parameters estimated from time-activity curves generated by overlaying regions of interest on the images. If cone beam collimators are used and the focal point of the collimators always remains in a particular transaxial plane, additional artifacts can arise in other planes reconstructed using insufficient projection samples [1]. If the projection samples truncate the patient's body, this can result in additional image artifacts. To overcome these sources of bias in conventional image based dynamic data analysis, we and others have been investigating the estimation of time-activity curves and kinetic model parameters directly from dynamic SPECT projection data by modeling the spatial and temporal distribution of the radiopharmaceutical throughout the projected field of view [2-8]. In our previous work we developed a computationally efficient method for fully four-dimensional (4-D) direct estimation of spatiotemporal distributions from dynamic SPECT projection data [5], which extended Formiconi's least squares algorithm for reconstructing temporally static distributions [9]. In addition, we studied the biases that result from modeling various orders temporal continuity and using various time samplings [5]. the present work, we address computational issues associated with evaluating the statistical uncertainty of

  13. Comparison of three different concepts of high dynamic range and dependability optimised current measurement digitisers for beam loss systems

    CERN Document Server

    Viganò, W; Effinger, E; Venturini, G G; Zamantzas, C

    2012-01-01

    Three Different Concepts of High Dynamic Range and Dependability Optimised Current Measurement Digitisers for Beam Loss Systems will be compared on this paper. The first concept is based on Current to Frequency Conversion, enhanced with an ADC for extending the dynamic range and decreasing the response time. A summary of 3 years’ worth of operational experience with such a system for LHC beam loss monitoring will be given. The second principle is based on an Adaptive Current to Frequency Converter implemented in an ASIC. The basic parameters of the circuit are discussed and compared with measurements. Several measures are taken to harden both circuits against single event effects and to make them tolerant for operation in radioactive environments. The third circuit is based on a Fully Differential Integrator for enhanced dynamic range, where laboratory and test installation measurements will be presented. All circuits are designed to avoid any dead time in the acquisition and have reliability and fail safe...

  14. Dynamic characterization, monitoring and control of rotating flexible beam-mass structures via piezo-embedded techniques

    Science.gov (United States)

    Lai, Steven H.-Y.

    1992-01-01

    A variational principle and a finite element discretization technique were used to derive the dynamic equations for a high speed rotating flexible beam-mass system embedded with piezo-electric materials. The dynamic equation thus obtained allows the development of finite element models which accommodate both the original structural element and the piezoelectric element. The solutions of finite element models provide system dynamics needed to design a sensing system. The characterization of gyroscopic effect and damping capacity of smart rotating devices are addressed. Several simulation examples are presented to validate the analytical solution.

  15. Numerical Simulation of Dynamic Response of Fiber Reinforced Ceramic Matrix Composite Beam with Matrix Cracks Using Multiscale Modeling

    Institute of Scientific and Technical Information of China (English)

    Gao Xiguang; Song Yingdong; Sun Zhigang; Hu Xuteng

    2010-01-01

    A multiscale method for simulating the dynamic response of ceramic matrix composite (CMC) with matrix cracks is developed.At the global level,the finite element method is employed to simulate the dynamic response ofa CMC beam.While at the local level,the multiscale mechanical method is used to estimate the stress/strain response of the material.A distributed computing system is developed to speed up the simulation.The simulation of dynamic response of a Nicalon/CAS-Ⅱ beam being subjected to harmonic loading is performed as a numerical example.The results show that both the stress/strain responses under tension and compressive loading are nonlinear.These conditions result in a different response compared with that of elastic beam,such as:1) the displacement response is not symmetric about the axis of time;2) in the condition of small external load,the response at first order natural frequency is limited within a finite range;3) decreasing the matrix crack space will increase the displacement response of the beam.

  16. Reaction dynamics induced by the radioactive ion beam 7Be on medium-mass and heavy targets

    Science.gov (United States)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Stefanini, C.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Keeley, N.; Lay, J. A.; Marquinez-Duran, G.; Martel, I.; Mazzocchi, C.; Molini, P.; Nicoletto, M.; Pakou, A.; Parkar, V. V.; Rusek, K.; Sánchez-Benítez, A. M.; Sandoli, M.; Sava, T.; Sgouros, O.; Signorini, C.; Silvestri, R.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Toniolo, N.; Zerva, K.

    2015-10-01

    We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam 7Be (Sα = 1.586 MeV) on medium-mass (58Ni) and heavy (208Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×105 pps 7Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.

  17. Investigation and optimization of transverse non-linear beam dynamics in the high-energy storage ring HESR

    Energy Technology Data Exchange (ETDEWEB)

    Welsch, Dominic Markus

    2010-03-10

    The High-Energy Storage Ring (HESR) is part of the upcoming Facility for Antiproton and Ion Research (FAIR) which is planned as a major extension to the present facility of the Helmholtzzentrum fuer Schwerionenforschung (GSI) in Darmstadt. The HESR will provide antiprotons in the momentum range from 1.5 to 15 GeV/c for the internal target experiment PANDA. The demanding requirements of PANDA in terms of beam quality and luminosity together with a limited production rate of antiprotons call for a long beam life time and a minimum of beam loss. Therefore, an effective closed orbit correction and a sufficiently large dynamic aperture of the HESR are crucial. With this thesis I present my work on both of these topics. The expected misalignments of beam guiding magnets have been estimated and used to simulate the closed orbit in the HESR. A closed orbit correction scheme has been developed for different ion optical settings of the HESR and numerical simulations have been performed to validate the scheme. The proposed closed orbit correction method which uses the orbit response matrix has been benchmarked at the Cooler Synchrotron COSY of the Forschungszentrum Juelich. A chromaticity correction scheme for the HESR consisting of sextupole magnets has been developed to reduce tune spread and thus to minimize the emittance growth caused by betatron resonances. The chromaticity correction scheme has been optimized through dynamic aperture calculations. The estimated field errors of the HESR dipole and quadrupole magnets have been included in the non-linear beam dynamics studies. Investigations concerning their optimization have been carried out. The ion optical settings of the HESR have been improved using dynamic aperture calculations and the technique of frequency map analysis. The related diffusion coefficient was also used to predict long-term stability based on short-term particle tracking. With a reasonable reduction of the quadrupole magnets field errors and a

  18. The exact explicit dynamic stiffness matrix of multi-cracked Euler-Bernoulli beam and applications to damaged frame structures

    Science.gov (United States)

    Caddemi, S.; Caliò, I.

    2013-06-01

    In this paper the closed form expression of the exact dynamic stiffness matrix of an Euler-Bernoulli beam in the presence of an arbitrary number of concentrated cracks is derived. The procedure adopted for the evaluation of the dynamic stiffness matrix is based on the availability of the exact closed form solution of the vibration modes of the multi-cracked beam, derived by the same authors in a previous paper. The knowledge of the exact explicit dynamic stiffness matrix of the multi-cracked beam makes the direct evaluation of the exact global dynamic stiffness matrix of damaged frame structures possible. Furthermore, it allows the exact evaluation of the frequencies and the corresponding vibration modes, consistent with the distributed parameter model, through the application of the well-known Wittrick-Williams algorithm. Some numerical applications, relative to the evaluation of frequencies and the corresponding mode shapes of multi-cracked framed structure, are reported. Furthermore, the closed-form solution has been validated by comparing with some exact results available in the literature, for a simple single cracked frame. Finally, further new results for a multi-cracked frame have been compared with those obtained by a finite element simulation.

  19. aSi EPIDs for the in-vivo dosimetry of static and dynamic beams

    Energy Technology Data Exchange (ETDEWEB)

    Piermattei, A. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Cilla, S. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); U.O. di Fisica Sanitaria, Fondazione per la Ricerca e Cura ‘Giovanni Paolo II’, 86100 Campobasso (Italy); Azario, L.; Greco, F. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Russo, M. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); U.O. di Fisica Sanitaria, Ospedale Belcolle, 01100 Viterbo (Italy); Grusio, M. [Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy); Orlandini, L. [U.O. di Fisica Medica, Centro Oncologico Fiorentino, 50121 Firenze (Italy); Fidanzio, A., E-mail: andrea.fidanzio@rm.unicatt.it [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, 00146 Roma (Italy); Istituto di Fisica e U.O.C. di Fisica Sanitaria, Università Cattolica del S. Cuore, 00168 Roma (Italy)

    2015-10-01

    Portal imaging by amorphous silicon (aSi) photodiode is currently the most applied technology for in-vivo dosimetry (IVD) of static and dynamic radiotherapy beams. The strategy, adopted in this work to perform the IVD procedure by aSi EPID, is based on: in patient reconstruction of the isocenter dose and day to day comparison between 2D-portal images to verify the reproducibility of treatment delivery. About 20.000 tests have been carried out in this last 3 years in 8 radiotherapy centers using the SOFTDISO program. The IVD results show that: (i) the procedure can be implemented for linacs of different manufacturer, (ii) the IVD analysis can be obtained on a computer screen, in quasi real time (about 2 min after the treatment delivery) and (iii) once the causes of the discrepancies were eliminated, all the global IVD tests for single patient were within the acceptance criteria defined by: ±5% for the isocenter dose, and P{sub γ<1}≥90% of the checked points for the 2D portal image γ-analysis. This work is the result of a project supported by the Istituto Nazionale di Fisica Nucleare (INFN) and Università Cattolica del S.Cuore (UCSC)

  20. A CLIC Damping Wiggler Prototype at ANKA: Commissioning and Preparations for a Beam Dynamics Experimental Program

    CERN Document Server

    Bernhard, Axel; Casalbuoni, Sara; Ferracin, Paolo; Garcia Fajardo, Laura; Gerstl, Stefan; Gethmann, Julian; Grau, Andreas; Huttel, Erhard; Khrushchev, Sergey; Mezentsev, Nikolai; Müller, Anke-Susanne; Papaphilippou, Yannis; Saez de Jauregui, David; Schmickler, Hermann; Schoerling, Daniel; Shkaruba, Vitaliy; Smale, Nigel; Tsukanov, Valery; Zisopoulos, Panagiotis; Zolotarev, Konstantin

    2016-01-01

    In a collaboration between CERN, BINP and KIT a prototype of a superconducting damping wiggler for the CLIC damping rings has been installed at the ANKA synchrotron light source. On the one hand, the foreseen experimental program aims at validating the technical design of the wiggler, particularly the conduction cooling concept applied in its cryostat design, in a long-term study. On the other hand, the wiggler's influence on the beam dynamics particularly in the presence of collective effects is planned to be investigated. ANKA's low-alpha short-bunch operation mode will serve as a model system for these studies on collective effects. To simulate these effects and to make verifiable predictions an accurate model of the ANKA storage ring in low-alpha mode, including the insertion devices is under parallel development. This contribution reports on the first operational experience with the CLIC damping wiggler prototype in the ANKA storage ring and steps towards the planned advanced experimental program with th...

  1. Dynamic layer rearrangement during growth of layered oxide films by molecular beam epitaxy.

    Science.gov (United States)

    Lee, J H; Luo, G; Tung, I C; Chang, S H; Luo, Z; Malshe, M; Gadre, M; Bhattacharya, A; Nakhmanson, S M; Eastman, J A; Hong, H; Jellinek, J; Morgan, D; Fong, D D; Freeland, J W

    2014-09-01

    The A(n+1)B(n)O(3n+1) Ruddlesden-Popper homologous series offers a wide variety of functionalities including dielectric, ferroelectric, magnetic and catalytic properties. Unfortunately, the synthesis of such layered oxides has been a major challenge owing to the occurrence of growth defects that result in poor materials behaviour in the higher-order members. To understand the fundamental physics of layered oxide growth, we have developed an oxide molecular beam epitaxy system with in situ synchrotron X-ray scattering capability. We present results demonstrating that layered oxide films can dynamically rearrange during growth, leading to structures that are highly unexpected on the basis of the intended layer sequencing. Theoretical calculations indicate that rearrangement can occur in many layered oxide systems and suggest a general approach that may be essential for the construction of metastable Ruddlesden-Popper phases. We demonstrate the utility of the new-found growth strategy by performing the first atomically controlled synthesis of single-crystalline La3Ni2O7.

  2. aSi EPIDs for the in-vivo dosimetry of static and dynamic beams

    Science.gov (United States)

    Piermattei, A.; Cilla, S.; Azario, L.; Greco, F.; Russo, M.; Grusio, M.; Orlandini, L.; Fidanzio, A.

    2015-10-01

    Portal imaging by amorphous silicon (aSi) photodiode is currently the most applied technology for in-vivo dosimetry (IVD) of static and dynamic radiotherapy beams. The strategy, adopted in this work to perform the IVD procedure by aSi EPID, is based on: in patient reconstruction of the isocenter dose and day to day comparison between 2D-portal images to verify the reproducibility of treatment delivery. About 20.000 tests have been carried out in this last 3 years in 8 radiotherapy centers using the SOFTDISO program. The IVD results show that: (i) the procedure can be implemented for linacs of different manufacturer, (ii) the IVD analysis can be obtained on a computer screen, in quasi real time (about 2 min after the treatment delivery) and (iii) once the causes of the discrepancies were eliminated, all the global IVD tests for single patient were within the acceptance criteria defined by: ±5% for the isocenter dose, and PγFisica Nucleare (INFN) and Università Cattolica del S.Cuore (UCSC).

  3. Dual beam Doppler FD-OCT system with integrated Dynamic Vessel Analyzer and rotatable beams to measure total retinal blood flow

    Science.gov (United States)

    Doblhoff-Dier, Veronika; Werkmeister, René M.; Gröschl, Martin; Schmetterer, Leopold

    2014-03-01

    We present a method capable of measuring the total retinal blood flow in arteries and veins based on dual beam Fourierdomain Doppler optical coherence tomography (OCT) in combination with a fundus camera based Dynamic Vessel Analyzer. Incorporating a Dynamic vessel analyzer into the system not only gives a live image of the fundus - it also allows determining the vessels' diameter precisely during the OCT measurement, which is necessary for the determination of the blood flow. While dual beam systems with fixed detection plane allow only vessels with certain orientations to be measured, the detection plane of our system can be rotated by 90°. This ensures that the blood's velocity can be measured in all vessels around the optic nerve head. The results of the total blood flow measurements are in the same range as previously published data. Additionally, the high degree of conformity between the measured venous and arterial flow corroborated the system's validity. For larger vessels, the logarithmic values of vessel diameter and blood flow were found to be related linearly with a regression coefficient of around 3, which is in accordance with Murray's law. For smaller vessels (diameter below 60 μm), the values diverge from the linear dependence. The high sensitivity and the good agreement with published data suggest a high potential for examining the retinal blood flow in patients with ocular diseases.

  4. Timoshenko beam-column with generalized end conditions on elastic foundation: Dynamic-stiffness matrix and load vector

    Science.gov (United States)

    Arboleda-Monsalve, Luis G.; Zapata-Medina, David G.; Aristizabal-Ochoa, J. Darío

    2008-03-01

    The dynamic-stiffness matrix and load vector of a Timoshenko beam-column resting on a two-parameter elastic foundation with generalized end conditions are presented. The proposed model includes the frequency effects on the stiffness matrix and load vector as well as the coupling effects of: (1) bending and shear deformations along the member; (2) translational and rotational lumped masses at both ends; (3) translational and rotational masses uniformly distributed along its span; (3) axial load (tension or compression) applied at both ends; and (4) shear forces along the span induced by the applied axial load as the beam deforms according to the "modified shear equation" proposed by Timoshenko. The dynamic analyses of framed structures can be performed by including the effects of the imposed frequency ( ω>0) on the dynamic-stiffness matrix and load vector while the static and stability analyses can be carried out by making the frequency ω=0. The proposed model and corresponding dynamic-stiffness matrix and load vector represent a general solution capable to solve, just by using a single segment per element, the static, dynamic and stability analyses of any elastic framed structure made of prismatic beam-columns with semi-rigid connections resting on two-parameter elastic foundations. Analytical results indicate that the elastic behavior of framed structures made of beam-columns is frequency dependent and highly sensitive to the coupling effects just mentioned. Three comprehensive examples are presented to show the capacities and validity of the proposed method and the obtained results are compared with the finite element method and other analytical approaches.

  5. Dynamics of laser-driven proton beam focusing and transport into solid density matter

    Science.gov (United States)

    Kim, J.; McGuffey, C.; Beg, F.; Wei, M.; Mariscal, D.; Chen, S.; Fuchs, J.

    2016-10-01

    Isochoric heating and local energy deposition capabilities make intense proton beams appealing for studying high energy density physics and the Fast Ignition of inertial confinement fusion. To study proton beam focusing that results in high beam density, experiments have been conducted using different target geometries irradiated by a kilojoule, 10 ps pulse of the OMEGA EP laser. The beam focus was measured by imaging beam-induced Cu K-alpha emission on a Cu foil that was positioned at a fixed distance. Compared to a free target, structured targets having shapes of wedge and cone show a brighter and narrower K-alpha radiation emission spot on a Cu foil indicating higher beam focusability. Experimentally observed images with proton radiography demonstrate the existence of transverse fields on the structures. Full-scale simulations including the contribution of a long pulse duration of the laser confirm that such fields can be caused by hot electrons moving through the structures. The simulated fields are strong enough to reflect the diverging main proton beam and pinch a transverse probe beam. Detailed simulation results including the beam focusing and transport of the focused intense proton beam in Cu foil will be presented. This work was supported by the National Laser User Facility Program through Award DE-NA0002034.

  6. Physical aspects of dynamic stereotactic radiosurgery with very small photon beams (1.5 and 3 mm in diameter).

    Science.gov (United States)

    Paskalev, Kamen A; Seuntjens, Jan P; Patrocinio, Horacio J; Podgorsak, Ervin B

    2003-02-01

    Stereotactic radiosurgery is often used for treating functional disorders. For some of these disorders, the size of the target can be on the order of a millimeter and the radiation dose required for treatment on the order of 80 Gy. The very small radiation field and high prescribed dose present a difficult challenge in beam calibration, dose distribution calculation, and dose delivery. In this work the dose distribution for dynamic stereotactic radiosurgery, carried out with 1.5 and 3 mm circular fields, was studied. A 10 MV beam from a Clinac-18 linac (Varian, Palo Alto, CA) was used as the radiation source. The BEAM/EGS4 Monte Carlo code was used to model the treatment head of the machine along with the small-field collimators. The models were validated with the EGSnrc code, first through a calculation of percent depth doses (PDD) and dose profiles in a water phantom for the two small stationary circular beams and then through a comparison of the calculated with measured PDD and profile data. The three-dimensional (3-D) dose distributions for the dynamic rotation with the two small radiosurgical fields were calculated in a spherical water phantom using a modified version of the fast XVMC Monte Carlo code and the validated models of the machine. The dose distributions in a horizontal plane at the isocenter of the linac were measured with low-speed radiographic film. The maximum sizes of the Monte Carlo-calculated 50% isodose surfaces in this horizontal plane were 2.3 mm for the 1.5 mm diameter beam and 3.8 mm for the 3 mm diameter beam. The maximum discrepancies between the 50% isodose surface on the film and the 50% Monte Carlo-calculated isodose surfaces were 0.3 mm for both the 1.5 and 3 mm beams. In addition, the displacement of the delivered dose distributions with respect to the laser-defined isocenter of the machine was studied. The results showed that dynamic radiosurgery with very small beams has a potential for clinical use.

  7. Thermoelastic and Pyroelectric Couplings Effects on Dynamics and Active Control of Smart Piezolaminated Beam Modeled by Finite Element Method

    Directory of Open Access Journals (Sweden)

    M. Sanbi

    2014-01-01

    Full Text Available Smart structures with integrated sensors, actuators, and control electronics are of importance to the next generation high-performance structural systems. In this study, thermopiezoelastic characteristics of piezoelectric beam continua are studied and applications of the theory to active structures in sensing and optimal control are discussed. Using linear thermopiezoelastic theory and Timoshenko assumptions, a generic thermopiezoelastic theory for piezolaminated composite beam is derived. Finite element equations for the thermopiezoelastic media are obtained by using the linear constitutive equations in Hamilton's principle together with the finite element approximations. The structure consists of a modeling of cantilevered piezolaminated Timoshenko beam with integrated thermopiezoelectric elements between two aluminium layers. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG accompanied by the Kalman filter is applied. The effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. We show that the control procedure cannot be perturbed by applying a thermal gradient and the control can be applied at any time during the period of vibration of the beam.

  8. Dynamics and stability of an extending beam attached to an axially moving base immersed in dense fluid

    Science.gov (United States)

    Yan, H.; Ni, Q.; Dai, H. L.; Wang, L.; Li, M.; Wang, Y.; Luo, Y.

    2016-11-01

    In the present study, we construct a theoretical model for investigating the dynamics and stability of a flexible slender cantilever which is attached to an axially moving base fully immersed in an incompressible fluid. Meanwhile, the cantilevered beam is subjected to a time dependent axial extension. The coordinate transformation is utilized to derive the governing equations with consideration of an axial added mass coefficient and realistic initial conditions. Based on the Galerkin approach and Runge-Kutta technique, the numerical results for the dynamical behavior of the system under conditions of steady rate of extension and speed of the moving base are displayed. It is demonstrated that there is a critical value of extension rate at which the beam loses stability in the case when the base is fixed. As the base moves beyond a certain speed, however, the beam returns to be stable even if the extension rate is above the critical value. Furthermore, the beam system can exhibit peak response as the base moving speed is much higher than the extension rate.

  9. Testing of the stability of intensity modulated beams generated with dynamic multileaf collimation, applied to the MM50 racetrack microtron.

    Science.gov (United States)

    Dirkx, M L; Heijmen, B J

    2000-12-01

    Recently, we have published a method for the calculation of required leaf trajectories to generate optimized intensity modulated x-ray beams by means of dynamic multileaf collimation [Phys. Med. Biol. 43, 1171-1184 (1998)]. For the MM50 Racetrack Microtron it has been demonstrated that the dosimetric accuracy of this method, in combination with the dose calculation algorithm of the Cadplan 3D treatment planning system, is adequate for a clinical application (within 2% or 0.2 cm). Prior to initiating patient treatment with dynamic multileaf collimation (DMLC), tests have been performed to investigate the stability of DMLC fields generated at the MM50, (i) in time, (ii) subject to gantry rotation and (iii) in case of treatment interrupts, e.g., caused by an error detected by the treatment machine. The stability of relative dose profiles, normalized to a reference point in a relatively flat part of the modulated beam profile, was assessed from measurements with an electronic portal imaging device (EPID), with a linear diode array attached to the collimator and with film. The dose in the reference point was monitored using an ionization chamber. Tests were performed for several intensity modulated fields using 10 and 25 MV photon beams. Based on film measurements for sweeping 0.1 cm leaf gaps it was concluded that in an 80 days period the variation in leaf positioning was within 0.05 cm, without requiring any recalibration. For a uniform 10x10 cm2 field, realized dynamically by a scanning 0.4x10 cm2 slit beam, a maximum variation in slit width of 0.01 cm was derived from ionization chamber measurements, both in time and for gantry rotation. For a clinical example, the dose in the reference point reproduced within 0.2% (1 SD) over a period of 100 days. Apart from regions with very large dose gradients, variations in the relative beam profiles measured with the EPID were generally less than 1% (1 SD). For different gantry angles the dose profiles also reproduced within 1

  10. Beam dynamics and expected RHIC performance with 56MHz RF upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Fedotov,A.V.; Ben-Zvi, I.

    2009-05-04

    An upgrade of the RHIC storage RF system with a superconducting 56 MHz cavity was recently proposed. This upgrade will provide a significant increase in the acceptance of the RHIC 197 MHz storage RF bucket. This paper summarizes simulations of beam evolution due to intra-beam scattering (IBS) for beam parameters expected with the 56 MHz SRF cavity upgrade. Expected luminosity improvements are shown for Au ions at 100 GeV/nucleon and protons at 250 GeV.

  11. Nonstationary plasma-thermo-fluid dynamics and transition in processes of deep penetration laser beam-matter interaction

    Science.gov (United States)

    Golubev, Vladimir S.; Banishev, Alexander F.; Azharonok, V. V.; Zabelin, Alexandre M.

    1994-09-01

    A qualitative analysis of the role of some hydrodynamic flows and instabilities by the process of laser beam-metal sample deep penetration interaction is presented. The forces of vapor pressure, melt surface tension and thermocapillary forces can determined a number of oscillatory and nonstationary phenomena in keyhole and weld pool. Dynamics of keyhole formation in metal plates has been studied under laser beam pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined at 0.5 X 105 - 106 W/cm2 laser power densities. Oscillatory regime of plate break- down has been found out. Small-dimensional structures with d-(lambda) period was found on the frozen cavity walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure on the frozen pattern being a helix-shaped modulation of the keyhole walls and bottom relief has been revealed. Temperature oscillations related to capillary oscillations in the melt layer were discovered in the cavity. Interaction of the CW CO2 laser beam and the matter by beam penetration into a moving metal sample has been studied. The pulsed and thermodynamic parameters of the surface plasma were investigated by optical and spectroscopic methods. The frequencies of plasma jets pulsations (in 10 - 105 Hz range) are related to possible melt surface instabilities of the keyhole.

  12. Investigating the performances of a 1 MV high pulsed power linear transformer driver: from beam dynamics to x radiation

    Science.gov (United States)

    Maisonny, R.; Ribière, M.; Toury, M.; Plewa, J. M.; Caron, M.; Auriel, G.; d'Almeida, T.

    2016-12-01

    The performance of a 1 MV pulsed high-power linear transformer driver accelerator were extensively investigated based on a numerical approach which utilizes both electromagnetic and Monte Carlo simulations. Particle-in-cell calculations were employed to examine the beam dynamics throughout the magnetically insulated transmission line which governs the coupling between the generator and the electron diode. Based on the information provided by the study of the beam dynamics, and using Monte Carlo methods, the main properties of the resulting x radiation were predicted. Good agreement was found between these simulations and experimental results. This work provides a detailed understanding of mechanisms affecting the performances of this type of high current, high-voltage pulsed accelerator, which are very promising for a growing number of applications.

  13. Convergence of Galerkin truncation for dynamic response of finite beams on nonlinear foundations under a moving load

    Science.gov (United States)

    Ding, Hu; Chen, Li-Qun; Yang, Shao-Pu

    2012-05-01

    The present paper investigates the convergence of the Galerkin method for the dynamic response of an elastic beam resting on a nonlinear foundation with viscous damping subjected to a moving concentrated load. It also studies the effect of different boundary conditions and span length on the convergence and dynamic response. A train-track or vehicle-pavement system is modeled as a force moving along a finite length Euler-Bernoulli beam on a nonlinear foundation. Nonlinear foundation is assumed to be cubic. The Galerkin method is utilized in order to discretize the nonlinear partial differential governing equation of the forced vibration. The dynamic response of the beam is obtained via the fourth-order Runge-Kutta method. Three types of the conventional boundary conditions are investigated. The railway tracks on stiff soil foundation running the train and the asphalt pavement on soft soil foundation moving the vehicle are treated as examples. The dependence of the convergence of the Galerkin method on boundary conditions, span length and other system parameters are studied.

  14. Statistical signal processing techniques for coherent transversal beam dynamics in synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Alhumaidi, Mouhammad

    2015-03-04

    Transversal coherent beam oscillations can occur in synchrotrons directly after injection due to errors in position and angle, which stem from inaccurate injection kicker reactions. Furthermore, the demand for higher beam intensities is always increasing in particle accelerators. The wake fields generated by the traveling particles will be increased by increasing the beam intensity. This leads to a stronger interaction between the beam and the different accelerator components, which increases the potential of coherent instabilities. Thus, undesired beam oscillations will occur when the natural damping is not enough to attenuate the oscillations generated by the coherent beam-accelerator interactions. The instabilities and oscillations can be either in transversal or longitudinal direction. In this work we are concerned with transversal beam oscillations only. In normal operation, transversal beam oscillations are undesired since they lead to beam quality deterioration and emittance blow up caused by the decoherence of the oscillating beam. This decoherence is caused by the tune spread of the beam particles. The emittance blow up reduces the luminosity of the beam, and thus the collision quality. Therefore, beam oscillations must be suppressed in order to maintain high beam quality during acceleration. A powerful way to mitigate coherent instabilities is to employ a feedback system. A Transversal Feedback System (TFS) senses instabilities of the beam by means of Pickups (PUs), and acts back on the beam through actuators, called kickers. In this thesis, a novel concept to use multiple PUs for estimating the beam displacement at the position with 90 phase advance before the kicker is proposed. The estimated values should be the driving feedback signal. The signals from the different PUs are delayed such that they correspond to the same bunch. Subsequently, a weighted sum of the delayed signals is suggested as an estimator of the feedback correction signal. The

  15. DYNAMIC RESPONSE OF A RIGID,PERFECTLY PLASTIC FREE-FREE BEAM STRUCK BY A PROJECTILE ATANY CROSS-SECTION ALONG ITS SPAN

    Institute of Scientific and Technical Information of China (English)

    YangJialing; LiuXuhong

    2004-01-01

    The rigid, perfectly plastic dynamic response of a free-free beam subjected to impact by a projectile at any cross-section is studied. The instantaneous deformations of the beam are given through an analysis of the complete solution for rigid plastic structures. The influence of some parameters such as the input energy and mass ratio on the plastic deformation, travelling plastic hinge position and energy partitioning of the beam are discussed.

  16. Diode Dynamics, Beam Generation and Transport and Plasma Erosion Opening Switch Development.

    Science.gov (United States)

    1983-05-17

    provide standoff protecti.on for the ion diode~s) b) allow close packing of multipla generators saround a coamion target :IiaT.Lr and c) facili- tate tim...beam and plasma parame:ers in w1hich the very intense ion bea= ms behave like weak beams in prescribed electromagnetic fields. As a result, concepts of

  17. Nonlinear Dynamic Analysis of Functionally Graded Timoshenko Beam fixed to a Rotating Hub

    Science.gov (United States)

    Panigrahi, B.; Pohit, G.

    2016-08-01

    The present work accounts centrifugal stiffening effect on the nonlinear vibration response of an FGM Timoshenko beam. Analysis is carried out for a cantilever beam fixed with a rotating hub. Material is assumed to have a gradation relation along the depth of the beam. Centrifugal force and axial displacement raised due to the rotating hub is incorporated in the strain energy equations. Subsequent to this, an iterative technique is employed to obtain amplitude dependent vibration response of a rotating Timoshenko beam while material follows a gradation relation along the beam depth. Main objective of the work is to obtain the effects of rotational speeds, hub radius, and different gradation relations on the linear as well as nonlinear frequencies and mode shapes.

  18. 用Timoshenko梁修正理论研究功能梯度材料梁的动力响应%Dynamic responses of a beam with functionally graded materials with Timoshenko beam correction theory

    Institute of Scientific and Technical Information of China (English)

    吴晓; 罗佑新

    2011-01-01

    The dynamic response of a beam with functionally graded materials was studied with Timoshenko beam correction theory. The neutral plane site of the beam with functionally graded materials was determined with the static equilibrium equations, and the vibration equations of the beam with functionally graded materials were established with Timoshenko beam correction theory, the expression for the natural frequencies of the beam with functionally graded materials and the analytical solution to forced vibration of the beam under the action of harmonic load were obtained. The effect of neutral plane site and gradient index on the dynamic responses of the beam were discussed, and Timoshenko beam correction theory was verified with finite element method. Analysis of examples indicated that the neutral plane site has larger influence on the dynamic responses of the beam with functionally graded materials.%采用Timoshenko梁修正理论研究了功能梯度材料梁的动力响应问题,利用静力方程确定了功能梯度材料梁的中性轴位置,在此基础上应用Timoshenko梁修正理论建立了功能梯度材料梁的振动方程,求得其自振频率表达式及其在简谐荷载作用下强迫振动的解析解.分析了中性面位置、梯度指数等因素对功能梯度材料梁的动力响应的影响,并用有限元法验证Timoshenko梁修正理论.通过实例计算,得到了中性轴位置对功能梯度材料梁动力响应有较大影响.

  19. Molecular beam studies of unimolecular and bimolecular chemical reaction dynamics using VUV synchrotron radiation as a product probe

    Energy Technology Data Exchange (ETDEWEB)

    Blank, David Andrew [Univ. of California, Berkeley, CA (United States)

    1997-08-01

    This dissertation describes the use of a new molecular beam apparatus designed to use tunable VUV synchrotron radiation for photoionization of the products from scattering experiments. The apparatus was built at the recently constructed Advanced Light Source at Lawrence Berkeley National Laboratory, a third generation 1-2 GeV synchrotron radiation source. The new apparatus is applied to investigations of the dynamics of unimolecular reactions, photodissociation experiments, and bimolecular reactions, crossed molecular beam experiments. The first chapter describes the new apparatus and the VUV radiation used for photoionization. This is followed by a number of examples of the many advantages provided by using VUV photoionization in comparison with the traditional technique of electron bombardment ionization. At the end of the chapter there is a discussion of the data analysis employed in these scattering experiments. The remaining four chapters are complete investigations of the dynamics of four chemical systems using the new apparatus and provide numerous additional examples of the advantages provided by VUV photoionizaiton of the products. Chapters 2-4 are photofragment translational spectroscopy studies of the photodissociation dynamics of dimethyl sulfoxide, acrylonitrile, and vinyl chloride following absorption at 193 mn. All of these systems have multiple dissociation channels and provide good examples of the ability of the new apparatus to unravel the complex UV photodissociation dynamics that can arise in small polyatomic molecules.

  20. Exact dynamic stiffness matrix of non-symmetric thin-walled curved beams subjected to initial axial force

    Science.gov (United States)

    Nam-Il, Kim; Moon-Young, Kim

    2005-06-01

    An improved numerical method to exactly evaluate the dynamic element stiffness matrix is proposed for the spatially coupled free vibration analysis of non-symmetric thin-walled curved beams subjected to uniform axial force. For this purpose, firstly equations of motion, boundary conditions and force-deformation relations are rigorously derived from the total potential energy for a curved beam element. Next systems of linear algebraic equations with non-symmetric matrices are constructed by introducing 14 displacement parameters and transforming the fourth-order simultaneous differential equations into the first-order simultaneous equations. And then explicit expressions for displacement parameters are numerically evaluated via eigensolutions and the exact 14×14 element stiffness matrix is determined using force-deformation relations. In order to demonstrate the validity and the accuracy of this study, the spatially coupled natural frequencies of non-symmetric thin-walled curved beams subjected to uniform compressive and tensile forces are evaluated and compared with analytical and finite element solutions using Hermitian curved beam elements or ABAQUS's shell element. In addition, some results by the parametric study are reported.

  1. Study of Acquisition Electronics with a High Dynamic Range for a Beam Loss Measurement System

    CERN Document Server

    Venturini, G; Dehning, B; Effinger, E

    2010-01-01

    The particles accelerated in CERN accelerator chain reach high energies, topped by the particle energy at collision in the LHC, 7 GeV. During the operation, an amount of particles is inevitably lost from the beam. Depending on the extent of the losses, physical damage to machine components may be caused and the shower of secondary emission particles deposits energy in the surrounding equipment constituting the accelerator. The hadronic cascade also activates their materials, representing a hazard to the workers at CERN. In the LHC, the superconducting magnets that constitute the synchrotron lattice are kept at an operating temperature of 1:9K through a cryogenic facility employing superliquid helium, the increase in their temperature potentially initiates a quench. In the SPS, the damage due to a lost beam is also visible. The Beam Loss Monitoring (BLM) system has been developed to reliably protect the machines composing CERN’s accelerator chain and additionally provide information about the beam status: th...

  2. Dynamic axial stabilization of counterpropagating beam-traps with feedback control

    DEFF Research Database (Denmark)

    Tauro, Sandeep; Bañas, Andrew Rafael; Palima, Darwin;

    2010-01-01

    Optical trapping in a counter-propagating (CP) beam-geometry provides unique advantages in terms of working distance, aberration requirements and intensity hotspots. However, its axial performance is governed by the wave propagation of the opposing beams, which can limit the practical geometries....... Advanced implementation of this feedback-driven approach can help make CP-trapping resistant to a host of perturbations such as laser fluctuations, mechanical vibrations and other distortions emphasizing its experimental versatility....

  3. Beam dynamic simulations of the CLIC crab cavity and implications on the BDS

    Energy Technology Data Exchange (ETDEWEB)

    Shinton, I.R.R., E-mail: ian.shinton@stfc.ac.uk [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Cockcroft Institute of Accelerator Science and Technology, Daresbury (United Kingdom); Burt, G. [Engineering Department, Lancaster University, Lancaster (United Kingdom); Cockcroft Institute of Accelerator Science and Technology, Daresbury (United Kingdom); Glasman, C.J.; Jones, R.M. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Cockcroft Institute of Accelerator Science and Technology, Daresbury (United Kingdom); Wolski, A. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Cockcroft Institute of Accelerator Science and Technology, Daresbury (United Kingdom)

    2011-11-21

    The Compact Linear Collider (CLIC) is a proposed electron positron linear collider design aiming to achieve a centre of mass energy of up to 3 TeV. The main accelerating structures in CLIC operate at an X-band frequency of 11.994 GHz with an accelerating gradient of 100 MV/m. The present design requires the beams to collide at a small crossing angle of 10 mrad per line giving a resultant overall crossing angle of 20 mrad. Transverse deflecting cavities, referred to as 'Crab cavities', are installed in the beam delivery system (BDS) of linear collider designs in order to ensure the final luminosity at the interaction point (IP) is comparable to that in a head on collision. We utilise the beam tracking code PLACET combined with the beam-beam code GUINEA-PIG to calculate the resulting luminosity at the IP. We follow a similar tuning procedure to that used for the design of the ILC crab cavities and anitcrab cavities. However an unexpected loss in luminosity of 10% was observed for the 20 mrad design was observed. It was discovered that the action of the crab cavities can affect the geometric aberrations resulting from the sextupoles used to correct chromatic effects in the beam delivery system. This has direct consequences regarding the design of the present CLIC BDS.

  4. Characterization of a wide dynamic-range, radiation-tolerant charge-digitizer asic for monitoring of Beam losses

    CERN Document Server

    Guido Venturini, G G; Dehning, B; Kayal, M

    2012-01-01

    An Application Specific Integrated Circuit (ASIC) has been designed and fabricated to provide a compact solution to digitize current signals from ionization chambers and diamond detectors, employed as beam loss monitors at CERN and several other high energy physics facilities. The circuit topology has been devised to accept positive and negative currents, to have a wide dynamic range (above 120 dB), withstand radiation levels over 10 Mrad and offer different modes of operation, covering a broad range of applications. Furthermore, an internal conversion reference is employed in the digitization, to provide an accurate absolute measurement. This paper discusses the detailed characterization of the first prototype: linearity, radiation tolerance and temperature dependence of the conversion, as well as implications and system-level considerations regarding its use for beam instrumentation applications in a high energy physics facility.

  5. Reaction dynamics induced by the radioactive ion beam {sup 7}Be on medium-mass and heavy targets

    Energy Technology Data Exchange (ETDEWEB)

    Mazzocco, M., E-mail: marco.mazzocco@pd.infn.it; Stefanini, C.; Strano, E.; Torresi, D.; Lay, J. A.; Molini, P.; Soramel, F. [Dipartimento di Fisica e Astronomia, Università di Padova, via F. Marzolo 8, I-35131 Padova (Italy); INFN-Sezione di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Boiano, A.; Parascandolo, C.; Pierroutsakou, D.; Di Meo, P. [INFN-Sezione di Napoli, via Cintia, I-80126, Napoli (Italy); Boiano, C. [INFN-Sezione di Milano, via Celoria 16, I-20133, Napoli (Italy); La Commara, M.; Sandoli, M.; Silvestri, R. [INFN-Sezione di Napoli, via Cintia, I-80126, Napoli (Italy); Dipartimento di Fisica, Università di Napoli “Federico II”, via Cintia, I-80126, Napoli (Italy); Manea, C.; Nicoletto, M. [INFN-Sezione di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Acosta, L. [Departamento de Fìsica Aplicada, Universidad de Huelva, Campus de El Carmen, E-21071 Huelva (Spain); INFN-Sezione di Catania, via Santa Sofia 64, I-95123, Catania (Italy); Fernandez-Garcia, J. P. [INFN-Sezione di Catania, via Santa Sofia 64, I-95123, Catania (Italy); Glodariu, T. [National Institute for Physics and Nuclear Engineering (NIPNE), 30 Reactorului St., 077125 Magurele (Romania); and others

    2015-10-15

    We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam {sup 7}Be (S{sub α} = 1.586 MeV) on medium-mass ({sup 58}Ni) and heavy ({sup 208}Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×10{sup 5} pps {sup 7}Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.

  6. Instrumentation and Beam Dynamics Study of Advanced Electron-Photon Facility in Indiana University

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Tianhuan [Indiana Univ., Bloomington, IN (United States)

    2011-08-01

    The Advanced eLectron-PHoton fAcility (ALPHA) is a compact electron accelerator under construction and being commissioned at the Indiana University Center for Exploration of Energy and Matter (CEEM). In this thesis, we have studied the refurbished Cooler Injector Synchrotron (CIS) RF cavity using both the transmission line model and SUPERFISH simulation. Both low power and high power RF measurements have been carried out to characterize the cavity. Considering the performance limit of ferrite, we have designed a new ferrite loaded, co-axial quarter wave like cavity with similar structure but a more suitable ferrite material. We have also designed a traveling wave stripline kicker for fast extraction by POISSON and Microwave Studio. The strips geometry is trimmed to maximize the uniformity of the kicking field and match the impedance of the power cables. The time response simulation shows the kicker is fast enough for machine operation. The pulsed power supply requirement has also been specified. For the beam diagnosis in the longitudinal direction, we use a wideband Wall Gap Monitor (WGM) served in CIS. With proper shielding and amplification to get good WGM signal, we have characterized the injected and extracted beam signal in single pass commissioning, and also verified the debunching effect of the ALPHA storage ring. A modulation-demodulation signal processing method is developed to measure the current and longitudinal profile of injected beam. By scanning the dipole strength in the injection line, we have reconstructed the tomography of the longitudinal phase space of the LINAC beam. In the accumulation mode, ALPHA will be operated under a low energy and high current condition, where intra beam scattering (IBS) becomes a dominant effect on the beam emittance. A self consistent simulation, including IBS effect, gas scattering and linear coupling, has been carried out to calculate the emittance of the stored beam.

  7. Simulation of crystalline beams in storage rings using molecular dynamics technique

    Science.gov (United States)

    Meshkov, I.; Katayama, T.; Sidorin, A.; Smirnov, A.; Syresin, E.; Trubnikov, G.; Tsutsui, H.

    2006-03-01

    Achieving very low temperatures in the beam rest frame can present new possibilities in accelerator physics. Increasing luminosity in the collider and in experiments with targets is a very important asset for investigating rare radioactive isotopes. The ordered state of circulating ion beams was observed at several storage rings: NAP-M [Budker, et al., in: Proceedings of the 4th All-Union Conference on Charged-Particle Accelerators [in Russian], vol. 2, Nauka, Moscow, 1975, p. 309; Budker et al., Part. Accel. 7 (1976) 197; Budker et al., At. Energ. 40 (1976) 49. E. Dementev, N. Dykansky, A. Medvedko et al., Prep. CERN/PS/AA 79-41, Geneva, 1979] (Novosibirsk), ESR [M. Steck et al., Phys. Rev. Lett. 77 (1996) 3803] and SIS [Hasse and Steck, Ordered ion beams, in: Proceeding of EPAC '2000] (Darmstadt), CRYRING [Danared et al., Observation of ordered ion beams in CRYRING, in: Proceeding of PAC '2001] (Stockholm) and PALLAS [Schramm et al., in: J.L. Duggan (Eds.), Proceedings of the Conference on Appl. of Acc. in Research and Industry AIP Conference Proceedings, p. 576 (to be published)] (Munich). In this report, the simulation of 1D crystalline beams with BETACOOL code is presented. The sudden reduction of momentum spread in the ESR experiment is described with this code. Simulation shows good agreement with experimental results and also with the intrabeam scattering (IBS) theory [Martini, Intrabeam scattering in the ACOOL-AA machines, CERN PS/84-9 AA, Geneva, 1984]. The code was used to calculate characteristics of the ordered state of ion beams for the TARN-II [Katayama, TARN II project, in: Proceedings of the IUCF workshop on nuclear physics with stored cooled beams, Spencer, IN, USA, 1984].

  8. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Chu, P.M.Y.

    1991-10-01

    The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V{yields}T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH{sub 3} production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  9. Speckle dynamics for dual-beam optical illumination of a rotating structure

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Yura, Harold; Hanson, Steen Grüner

    2009-01-01

    An out-of-plane rotating object is illuminated with two spatially separated coherent beams, giving rise to fully developed speckles, which will translate and gradually decorrelate in the observation plane, located in the far field. The speckle pattern is a compound structure, consisting of random...... speckles modulated by a smaller and repetitive structure. Generally, these two components of the compound speckle structure will move as rigid structures with individual velocities determined by the characteristics of the two illuminating beams. Closed-form analytical expressions are found for the space......- and time-lagged covariance of irradiance and the corresponding power spectrum for the two spatially separated illuminating beams. The present analysis is valid for propagation through an arbitrary ABCD system, though the focus for the experimental evaluation is far-field observations using an optical...

  10. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  11. Beam dynamics in the final focus section of the future linear collider

    CERN Document Server

    AUTHOR|(SzGeCERN)739431; TOMAS, Rogelio

    The exploration of new physics in the ``Tera electron-Volt''~(TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction~Point~(IP).\\par In addition to several effects affecting the luminosity, three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.\\par This thesis considers two important aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3~TeV, and the instrumentation and experimental work on beam stabilization in a test facility.\\par The current linear collider projects, CLIC~\\cite{CLICdes} and ILC~\\cite{ILCdes}, have lattices designed using...

  12. Beam dynamics in an initial part of a high Brightness electron linac

    CERN Document Server

    Ayzatsky, M I; Dovbnya-Kushnir, V A

    2001-01-01

    The paper is focused on problems of obtained a bright electron beam in a system that includes a grid-controlled electron gun,a klystron type type subharmonical buncher, a standing wave fundamental buncher with increasing accelerating field and a short travelling wave accelerating section. Beam focusing is provided by a longitudinal solenoidal magnetic field.It was shown that the proposed system can provide electron bunches with a peak current more than 100 A and normalized r.m.s. emittance no more than phi centre dot mm centre dot mrad.

  13. Instability and dynamics of two nonlinearly coupled laser beams in a plasma

    CERN Document Server

    Shukla, P K; Marklund, M; Stenflo, L; Kourakis, I; Parviainen, M; Dieckmann, M E

    2006-01-01

    We investigate the nonlinear interaction between two laser beams in a plasma in the weakly nonlinear and relativistic regime. The evolution of the laser beams is governed by two nonlinear Schroedinger equations that are coupled with the slow plasma density response. We study the growth rates of the Raman forward and backward scattering instabilities as well of the Brillouin and self-focusing/modulational instabilities. The nonlinear evolution of the instabilities is investigated by means of direct simulations of the time-dependent system of nonlinear equations.

  14. Extending the Nonlinear-Beam-Dynamics Concept of 1D Fixed Points to 2D Fixed Lines

    CERN Document Server

    Franchetti, G.

    2015-01-01

    The origin of nonlinear dynamics traces back to the study of the dynamics of planets with the seminal work of Poincaré at the end of the nineteenth century: Les Méthodes Nouvelles de la Mécanique Céleste, Vols. 1–3 (Gauthier Villars, Paris, 1899). In his work he introduced a methodology fruitful for investigating the dynamical properties of complex systems, which led to the so-called “Poincaré surface of section,” which allows one to capture the global dynamical properties of a system, characterized by fixed points and separatrices with respect to regular and chaotic motion. For two-dimensional phase space (one degree of freedom) this approach has been extremely useful and applied to particle accelerators for controlling their beam dynamics as of the second half of the twentieth century.We describe here an extension of the concept of 1D fixed points to fixed lines in two dimensions. These structures become the fundamental entities for characterizing the nonlinear motion in the four-dimensional phas...

  15. Static and dynamic testing of concrete beams reinforced with fibres and continuous bars

    NARCIS (Netherlands)

    Körmeling, H.A.; Reinhardt, H.W.; Shah, S.P.

    1979-01-01

    The main purpose of the testing program was to get an idea about the influence of steel fibres on the fatigue performance of conventionally reinforced concrete beams. The influence of three types of steel fibres with three various percentages on the failure load, the cycles to failure, the crack wid

  16. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats

    DEFF Research Database (Denmark)

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-01-01

    " than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final...

  17. Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature.

    Science.gov (United States)

    Taioli, Simone; Garberoglio, Giovanni; Simonucci, Stefano; a Beccara, Silvio; Aversa, Lucrezia; Nardi, Marco; Verucchi, Roberto; Iannotta, Salvatore; Dapor, Maurizio; Alfè, Dario

    2013-01-28

    In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C(60) collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C(60) impact on the Si surface is in good agreement with our experimental findings.

  18. Electron-beam dynamics in a strong laser field including quantum radiation reaction

    CERN Document Server

    Neitz, Norman

    2014-01-01

    The evolution of an electron beam colliding head-on with a strong plane-wave field is investigated in the framework of strong-field QED including radiation-reaction effects due to photon emission. Employing a kinetic approach to describe the electron and the photon distribution it is shown that at a given total laser fluence the final electron distribution depends on the shape of the laser envelope and on the pulse duration, in contrast to the classical predictions of radiation reaction based on the Landau-Lifshitz equation. Finally, it is investigated how the pair-creation process leads to a nonlinear coupled evolution of the electrons in the beam, of the produced charged particles, and of the emitted photons.

  19. Electron-beam dynamics in a strong laser field including quantum radiation reaction

    Science.gov (United States)

    Neitz, N.; Di Piazza, A.

    2014-08-01

    The evolution of an electron beam colliding head on with a strong plane-wave field is investigated in the framework of strong-field QED including radiation-reaction effects due to photon emission. Employing a kinetic approach to describe the electron and the photon distribution it is shown that at a given total laser fluence the final electron distribution depends on the shape of the laser envelope and on the pulse duration, in contrast to the classical predictions of radiation reaction based on the Landau-Lifshitz equation. Finally, it is investigated how the pair-creation process leads to a nonlinear coupled evolution of the electrons in the beam, of the produced charged particles, and of the emitted photons.

  20. Dynamic response of an accelerator driven system to accelerator beam interruptions for criticality

    Energy Technology Data Exchange (ETDEWEB)

    Lafuente, A.; Abanades, A.; Leon, P.T.; Sordo, F. [E.T.S. Ingenieros Industriales, J. Gutierrez Abascal, 2-28006 Madrid (Spain); Martinez-Val, J.M. [E.T.S. Ingenieros Industriales, J. Gutierrez Abascal, 2-28006 Madrid (Spain)], E-mail: mval@etsii.upm.es

    2008-06-21

    Subcritical nuclear reactors driven by intense neutron sources can be very suitable tools for nuclear waste transmutation, particularly in the case of minor actinides with very low fractions of delayed neutrons. A proper control of these systems needs to know at every time the absolute value of the reactor subcriticality (negative reactivity), which must be measured by fully reliable methods, usually conveying a short interruption of the accelerator beam in order to assess the neutron flux reduction. Those interruptions should be very short in time, for not disturbing too much the thermal magnitudes of the reactor. Otherwise, the cladding and the fuel would suffer from thermal fatigue produced by those perturbations, and the mechanical integrity of the reactor would be jeopardized. It is shown in this paper that beam interruptions of the order of 400 {mu}s repeated every second would not disturb significantly the reactor thermal features, while enabling for an adequate measurement of the negative reactivity.

  1. Dynamic response of an accelerator driven system to accelerator beam interruptions for criticality

    Science.gov (United States)

    Lafuente, A.; Abanades, A.; Leon, P. T.; Sordo, F.; Martinez-Val, J. M.

    2008-06-01

    Subcritical nuclear reactors driven by intense neutron sources can be very suitable tools for nuclear waste transmutation, particularly in the case of minor actinides with very low fractions of delayed neutrons. A proper control of these systems needs to know at every time the absolute value of the reactor subcriticality (negative reactivity), which must be measured by fully reliable methods, usually conveying a short interruption of the accelerator beam in order to assess the neutron flux reduction. Those interruptions should be very short in time, for not disturbing too much the thermal magnitudes of the reactor. Otherwise, the cladding and the fuel would suffer from thermal fatigue produced by those perturbations, and the mechanical integrity of the reactor would be jeopardized. It is shown in this paper that beam interruptions of the order of 400 μs repeated every second would not disturb significantly the reactor thermal features, while enabling for an adequate measurement of the negative reactivity.

  2. MEASUREMENT OF THE TRANSVERSE BEAM DYNAMICS IN A TESLA-TYPE SUPERCONDUCTING CAVITY

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [NICADD, DeKalb; Eddy, N. [Fermilab; Edstrom, D. [Fermilab; Lunin, A. [Fermilab; Piot, P. [NICADD, DeKalb; Ruan, J. [Fermilab; Solyak, N. [Fermilab

    2016-09-26

    Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.

  3. Effects of Structural Damage on Dynamic Behavior at Sandwich Composite Beams – Part II- FEM Analysis

    Directory of Open Access Journals (Sweden)

    Marius Tufoi

    2014-07-01

    Full Text Available This paper presents results obtained by modal analysis on composite beam like structures in healthy and damaged state. The aim is to obtain damage “signatures” for all possible damage scenarios and to use these data to assess transversal cracks based on vibration techniques, by involving natural frequency shifts. The analysis was performed in SolidWorks software for a five-layer composite, 20 vibration modes being obtained by numerical simulation.

  4. Timoshenko Beam Theory based Dynamic Modeling of Lightweight Flexible Link Robotic Manipulators

    OpenAIRE

    Loudini, Malik

    2010-01-01

    An investigation into the development of flexible link robot manipulators mathematical models, with a high modeling accuracy, using Timoshenko beam theory concepts has been presented. The emphasis has been, essentially, set on obtaining accurate and complete equations of motion that display the most relevant aspects of structural properties inherent to the modeled lightweight flexible robotic structure. In particular, two important damping mechanisms: internal structural viscoelasticity effec...

  5. Off-axis beam dynamics in rf-gun-based electron photoinjectors

    Science.gov (United States)

    Huang, R.; Mitchell, C.; Papadopoulos, C.; Qian, H.; Venturini, M.; Qiang, J.; Filippetto, D.; Staples, J.; Jia, Q.; Sannibale, F.

    2016-11-01

    The need to operate an rf-gun-based electron photoinjector with a beam emitted away from the cathode center can occur under various circumstances. First, in some cases the cathode can be affected by ion back-bombardment that progressively reduces the quantum efficiency (QE) in its center, making off-axis operation mandatory; second, in some cases the drive laser intensity can be sufficiently high to generate QE depletion in the cathode area illuminated by the laser, forcing off-axis operation; last, in cathodes with nonuniform QE distribution it could be convenient to operate off axis to exploit a better QE. However, operation in this mode may lead to growth of the projected transverse beam emittances due to correlations between the transverse and longitudinal degrees of freedom that are introduced within the gun and downstream rf cavities. A strategy is described to mitigate this emittance growth by allowing the beam to propagate along a carefully tuned off-axis trajectory in downstream rf cavities to remove the time-dependent rf kicks introduced in the gun. Along this trajectory, short range wakefields do not degrade the emittance, and long range wakefields degrade the emittance for very high repetition rate only.

  6. Particle simulation of collision dynamics for ion beam injection into a rarefied gas

    Energy Technology Data Exchange (ETDEWEB)

    Giuliano, Paul N.; Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2013-03-15

    This study details a comparison of ion beam simulations with experimental data from a simplified plasma test cell in order to study and validate numerical models and environments representative of electric propulsion devices and their plumes. The simulations employ a combination of the direct simulation Monte Carlo and particle-in-cell methods representing xenon ions and atoms as macroparticles. An anisotropic collision model is implemented for momentum exchange and charge exchange interactions between atoms and ions in order to validate the post-collision scattering behaviors of dominant collision mechanisms. Cases are simulated in which the environment is either collisionless or non-electrostatic in order to prove that the collision models are the dominant source of low- and high-angle particle scattering and current collection within this environment. Additionally, isotropic cases are run in order to show the importance of anisotropy in these collision models. An analysis of beam divergence leads to better characterization of the ion beam, a parameter that requires careful analysis. Finally, suggestions based on numerical results are made to help guide the experimental design in order to better characterize the ion environment.

  7. Beam dynamics simulation of HEBT for the SSC-linac injector

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Ni; YUAN You-Jin; XIAO Chen; HE Yuan; WANG Zhi-Jun; SHENG Li-Na

    2012-01-01

    The SSC-linac (a new injector for the Separated Sector Cyclotron) is being designed in the HIRFL (Heavy Ion Research Facility in Lanzhou) system to accelerate 238U34+ from 3.72 keV/u to 1.008 MeV/u.As a part of the SSC-linac injector,the HEBT (high energy beam transport) has been designed by using the TRACE-3D code and simulated by the 3D PIC (particle-in-cell) Track code.The total length of the HEBT is about 12 meters and a beam line of about 6 meters are shared with the exiting beam line of the HIRFL system.The simulation results show that the particles can be delivered efficiently in the HEBT and the particles at the exit of the HEBT well match the acceptance of the SSC for further acceleration.The dispersion is eliminated absolutely in the HEBT.The space-charge effect calculated by the Track code is inconspicuous.According to the simulation,more than 60 percent of the particles from the ion source can be transported into the acceptance of the SSC.

  8. A new cantilever beam-rigid-body MEMS gyroscope: mathematical model and linear dynamics

    CERN Document Server

    Lajimi, Seyed Amir Mousavi; Abdel-Rahman, Eihab

    2014-01-01

    A new microbeam-rigid-body gyroscope is introduced and its static and dynamic behaviours are studied. The main structure includes a microbeam and an eccentric end-rigid-body influencing the dynamic and static characteristics of the sensor. The sensitivity of the device and the effect of system parameters on the microsystem's response are investigated.

  9. Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics

    Science.gov (United States)

    Stenzel, R. L.

    1978-01-01

    Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.

  10. Nonlinear Dynamic Analysis of an Inclined Timoshenko Beam Subjected to a Moving Mass/Force with Beam’s Weight Included

    Directory of Open Access Journals (Sweden)

    Ahmad Mamandi

    2011-01-01

    Full Text Available In this study, the nonlinear vibrations analysis of an inclined pinned-pinned self-weight Timoshenko beam made of linear, homogenous and isotropic material with a constant cross section and finite length subjected to a traveling mass/force with constant velocity is investigated. The nonlinear coupled partial differential equations of motion for the rotation of warped cross section, longitudinal and transverse displacements are derived using the Hamilton's principle. These nonlinear coupled PDEs are solved by applying the Galerkin's method to obtain dynamic responses of the beam. The dynamic magnification factor and normalized time histories of mid-point of the beam are obtained for various load velocity ratios and the outcome results have been compared to the results with those obtained from linear solution. The influence of the large deflections caused by a stretching effect due to the beam's fixed ends is captured. It was seen that existence of quadratic-cubic nonlinear terms in the nonlinear governing coupled PDEs of motion causes stiffening (hardening behavior of the dynamic responses of the self-weight beam under the act of a traveling mass as well as equivalent concentrated moving force. Furthermore, in a case where the object leaves the beam, its planar motion path is derived and the targeting accuracy is investigated and compared with those from the rigid solution assumption.

  11. STUDY OF THE REACTION DYNAMICS OF Li + HF, HCl BY THE CROSSED MOLECULAR BEAMS METHOD

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Christopher H.; Casavecchia, Piergiorgio; Tiedemann, Peter W.; Valentini, James J.; Lee, Yuan T.

    1980-05-01

    The reactions of (I) Li + HF {yields} LiF + H and (II) Li + HCl {yields} LiCl + H have been studied by the crossed molecular beams method. Angular distributions [N({theta})] of product molecules have been measured at 4 collision energies (E{sub c}) ranging from about 2 to 9 kcal/mole and time-of-flight (TOF) measurements of product velocity distribution were made at approximately E{sub c} = 3 and 9 kcal/mole for both reactions (I) and (II). The combined N({theta}) and TOF results were used to generate contour maps of lithium-halide product flux in angle and recoil velocity in the center-of-mass (c.m.) frame. For reaction (I) at E{sub c} = 3 kcal/mole the c.m. angular distribution [T({theta})] shows evidence of complex formation with near forward-backward symmetry; slightly favored backward peaking is observed. The shape of this T({theta}) indicates there is significant parallel or antiparallel spatial orientation of initial and final orbital angular momentum {rvec L} and {rvec L}', even though with H departing L' must be rather small and {rvec L} = {rvec J}', where {rvec J}' is the final rotational angular momentum vector. It is deduced that coplanar reaction geometries are strongly favored. At E{sub c} = 8.7 kcal/mole the T({theta}) of reaction (I) becomes strongly forward peaked. The product translational energy distributions P(E{sub T}') at both these collision energies give an average E{sub T}' of ~55% of the total available energy; this appears consistent with a theoretically calculated late exit barrier to reaction. The T({theta}) at E{sub c} = 2.9 and 9.2 kcal/mole for reaction (II) are forward-sideways peaked. Most of the available energy (~70%) goes into recoil velocity at both E{sub c} for LiCl formation. This suggests a late energy release for this 11 kcal/mole exoergic reaction. Both reactions (I) and (II) show evidence of no more than a minor partitioning of energy into product vibrational excitation. Integral reactive cross sections ({sigma}{sub R

  12. 用Timoshenko梁修正理论研究泡沫金属铝合金梁的动力响应%Dynamic responses of a foam metal aluminum alloy beam with timoshenko beam theory

    Institute of Scientific and Technical Information of China (English)

    吴晓; 孙晋; 黄翀; 罗佑新

    2011-01-01

    采用Timoshenko梁修正理论研究了泡沫金属铝合金梁的动力响应问题.应用Timoshenko梁修正理论建立了泡沫金属铝合金梁的振动方程,求得了其自振频率表达式及其在简谐荷载作用下强迫振动的解析解.通过实例计算,把球形泡沫铝合金梁与其它泡沫铝合金梁进行了对比分析,得出了球形泡沫金属铝合金梁的动力性能优于其它泡沫铝合金梁的动力性能.%The dynamic response of a foam metal aluminum alloy beam was studied with Timoshenko beam theory.Its vibration equation was established with Timoshenko beam theory, the expression of its natural frequency and the analytical solution of its forced vibration under the action of harmonic load were obtained.The comparative analysis of a spherical foam aluminum alloy beam and the another foam aluminum alloy ones was carried out with practical calculation.It was summarized that the spherical foam metal aluminum alloy beam has better dynamic performances than others.

  13. Dynamic control of coherent orbital-angular-momentum beams in turbid environments

    Science.gov (United States)

    Morgan, K. S.; Miller, J. K.; Cochenour, B. M.; Johnson, E. G.

    2016-05-01

    This work examines the propagation properties of two superimposed coherent orbital angular momentum (OAM) modes for use in underwater systems as an alternative to amplitude modulation. An OAM mode of l=+2 is interfered with OAM mode l=-1 from a λ = 540 nm laser source. These OAM modes are superimposed using a Mach-Zehnder (MZ) interferometer combined with diffractive optical elements. By manipulating the optical path length of one of the MZ legs, the interference of these beams can be temporally controlled. The spatial profile is maintained in a turbid environment up through 4.9 attenuation lengths for both cases.

  14. Parallelisation of PyHEADTAIL, a Collective Beam Dynamics Code for Particle Accelerator Physics

    CERN Document Server

    Oeftiger, Adrian

    2016-01-01

    The longitudinal tracking engine of the particle accelerator simulation application PyHEADTAIL shows a heavy potential for parallelisation. For basic beam circulation, the tracking functionality with the leap-frog algorithm is extracted and compared between a sequential C and a concurrent CUDA C API implementation for 1 million revolutions. Including the sequential data I/O in both versions, a pure speedup of up to S = 100 is observed which is in the order of magnitude of what is expected from Amdahl's law. From O(100) macro-particles on the overhead of initialising the GPU CUDA device appears outweighed by the concurrent computations on the 448 available CUDA cores.

  15. Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review

    CERN Document Server

    Hum, Sean Victor

    2013-01-01

    Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas.

  16. Field calculations, single-particle tracking, and beam dynamics with space charge in the electron lens for the Fermilab Integrable Optics Test Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Noll, Daniel [Goethe Univ., Frankfurt (Germany); Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-11-17

    An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Singleparticle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize the main findings and list directions for further work.

  17. ION BEAM POLARIZATION DYNAMICS IN THE 8 GEV BOOSTER OF THE JLEIC PROJECT AT JLAB

    Energy Technology Data Exchange (ETDEWEB)

    Kondratenko, A. M. [GOO Zaryad, Russkaya st., 41, Novosibirsk, 630058, Russia; Kondratenko, M. A. [GOO Zaryad, Russkaya st., 41, Novosibirsk, 630058, Russia; Morozov, Vasiliy [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lin, Fanglei; Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Filatov, Yuri [MIPT, Dolgoprudniy, Moscow Region, Russia

    2016-05-01

    In the Jefferson Lab’s Electron-Ion Collider (JLEIC) project, an injector of polarized ions into the collider ring is a superconducting 8 GeV booster. Both figure-8 and racetrack booster versions were considered. Our analysis showed that the figure-8 ring configuration allows one to preserve the polarization of any ion species during beam acceleration using only small longitudinal field with an integral less than 0.5 Tm. In the racetrack booster, to pre-serve the polarization of ions with the exception of deu-terons, it suffices to use a solenoidal Siberian snake with a maximum field integral of 30 Tm. To preserve deuteron polarization, we propose to use arc magnets for the race-track booster structure with a field ramp rate of the order of 1 T/s. We calculate deuteron and proton beam polari-zations in both the figure-8 and racetrack boosters includ-ing alignment errors of their magnetic elements using the Zgoubi code.

  18. Beam dynamic design of a high intensity injector for proton linac

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Wei-Ping, E-mail: douweiping@impcas.ac.cn [Institute of Modern Physics, The Chinese Academy of Sciences, Lanzhou 73000 (China); Wang, Zhi-Jun [Institute of Modern Physics, The Chinese Academy of Sciences, Lanzhou 73000 (China); Jia, Fang-Jian [State Key Lab of Nuclear Physics and Technology, Peking University, Beijing 100847 (China); He, Yuan, E-mail: hey@impcas.ac.cn [Institute of Modern Physics, The Chinese Academy of Sciences, Lanzhou 73000 (China); Wang, Zhi; Lu, Yuan-Rong [State Key Lab of Nuclear Physics and Technology, Peking University, Beijing 100847 (China)

    2016-08-11

    A compact room-temperature injector is designed to accelerate 100 mA proton beam from 45 keV to 4.06 MeV for the proposed high intensity proton linac at State Key Lab of Nuclear Physics and Technology in Peking university. The main feature is that the Radio Frequency Quadruple (RFQ) and the Drift Tube linac (DTL) sections are merged in one piece at the total length of 276 cm. The beam is matched in transverse directions with an compact internal doublet instead of an external matching section in between. The design has reached a high average accelerating gradient up to 1.55 MV/m with transmission efficiency of 95.9% at the consideration of high duty factor operation. The operation frequency is chose to be 200 MHz due to the already available RF power source. The injector combines a 150 cm long 4-vanes RFQ internal section from 45 keV to 618 keV with a 126 cm long H-type DTL section to 4.06 MeV. In general the design satisfy the challenges of the project requirements. And the details are presented in this paper.

  19. Beam dynamic design of a high intensity injector for proton linac

    Science.gov (United States)

    Dou, Wei-Ping; Wang, Zhi-Jun; Jia, Fang-Jian; He, Yuan; Wang, Zhi; Lu, Yuan-Rong

    2016-08-01

    A compact room-temperature injector is designed to accelerate 100 mA proton beam from 45 keV to 4.06 MeV for the proposed high intensity proton linac at State Key Lab of Nuclear Physics and Technology in Peking university. The main feature is that the Radio Frequency Quadruple (RFQ) and the Drift Tube linac (DTL) sections are merged in one piece at the total length of 276 cm. The beam is matched in transverse directions with an compact internal doublet instead of an external matching section in between. The design has reached a high average accelerating gradient up to 1.55 MV/m with transmission efficiency of 95.9% at the consideration of high duty factor operation. The operation frequency is chose to be 200 MHz due to the already available RF power source. The injector combines a 150 cm long 4-vanes RFQ internal section from 45 keV to 618 keV with a 126 cm long H-type DTL section to 4.06 MeV. In general the design satisfy the challenges of the project requirements. And the details are presented in this paper.

  20. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    Science.gov (United States)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik

    2014-02-01

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 1011 n/cm2/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  1. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik, E-mail: hskang@postech.ac.kr [Pohang Accelerator Laboratory, San31, Hyoja-dong, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

    2014-02-14

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E < 12.47% for 99% particles). The whole linac comprises mainly E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 10{sup 11} n/cm{sup 2}/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  2. Dynamic Analysis of Three-Layer Sandwich Beams with Thick Viscoelastic Damping Core for Finite Element Applications

    Directory of Open Access Journals (Sweden)

    Fernando Cortés

    2015-01-01

    Full Text Available This paper presents an analysis of the dynamic behaviour of constrained layer damping (CLD beams with thick viscoelastic layer. A homogenised model for the flexural stiffness is formulated using Reddy-Bickford’s quadratic shear in each layer, and it is compared with Ross-Kerwin-Ungar (RKU classical model, which considers a uniform shear deformation for the viscoelastic core. In order to analyse the efficiency of both models, a numerical application is accomplished and the provided results are compared with those of a 2D model using finite elements, which considers extensional and shear stress and longitudinal, transverse, and rotational inertias. The intermediate viscoelastic material is characterised by a fractional derivative model, with a frequency dependent complex modulus. Eigenvalues and eigenvectors are obtained from an iterative method avoiding the computational problems derived from the frequency dependence of the stiffness matrices. Also, frequency response functions are calculated. The results show that the new model provides better accuracy than the RKU one as the thickness of the core layer increases. In conclusion, a new model has been developed, being able to reproduce the mechanical behaviour of thick CLD beams, reducing storage needs and computational time compared with a 2D model, and improving the results from the RKU model.

  3. The dynamic behavior of a cantilever beam coupled to a non-ideal unbalanced motor through numerical and experimental analysis

    Science.gov (United States)

    Gonçalves, P. J. P.; Silveira, M.; Pontes Junior, B. R.; Balthazar, J. M.

    2014-09-01

    An excitation force that is not influenced by the system state is said to be an ideal energy source. In real situations, a direct and feedback coupling between the excitation source and the system must always exist at a certain level. This manifestation of the law of conservation of energy is known as the Sommerfeld effect. In the case of obtaining a mathematical model for such a system, additional equations are usually necessary to describe the vibration sources with limited power and its coupling with the mechanical system. In this work, a cantilever beam and a non-ideal DC motor fixed to its free end are analyzed. The motor has an unbalanced mass that provides excitation to the system which is proportional to the current applied to the motor. During the coast up operation of the motor, if the drive power is increased slowly, making the excitation frequency pass through the first natural frequency of the beam, the DC motor speed will remain the same until it suddenly jumps to a much higher value (simultaneously its amplitude jumps to a much lower value) upon exceeding a critical input power. It was found that the Sommerfeld effect depends on some system parameters and the motor operational procedures. These parameters are explored to avoid the resonance capture in the Sommerfeld effect. Numerical simulations and experimental tests are used to help gather insight of this dynamic behavior.

  4. Growth of CdTe on Si(100) surface by ionized cluster beam technique: Experimental and molecular dynamics simulation

    Science.gov (United States)

    Araghi, Houshang; Zabihi, Zabiholah; Nayebi, Payman; Ehsani, Mohammad Mahdi

    2016-10-01

    II-VI semiconductor CdTe was grown on the Si(100) substrate surface by the ionized cluster beam (ICB) technique. In the ICB method, when vapors of solid materials such as CdTe were ejected through a nozzle of a heated crucible into a vacuum region, nanoclusters were created by an adiabatic expansion phenomenon. The clusters thus obtained were partially ionized by electron bombardment and then accelerated onto the silicon substrate at 473 K by high potentials. The cluster size was determined using a retarding field energy analyzer. The results of X-ray diffraction measurements indicate the cubic zinc blende (ZB) crystalline structure of the CdTe thin film on the silicon substrate. The CdTe thin film prepared by the ICB method had high crystalline quality. The microscopic processes involved in the ICB deposition technique, such as impact and coalescence processes, have been studied in detail by molecular dynamics (MD) simulation.

  5. Exact dynamic stiffness matrix of a three-dimensional shear beam with doubly asymmetric cross-section

    Science.gov (United States)

    Rafezy, B.; Howson, W. P.

    2006-02-01

    The dynamic member stiffness matrix of a three-dimensional shear beam with doubly asymmetric cross-section is derived exactly from the governing, sixth-order differential equation of motion. Such a formulation accounts for the uniform distribution of mass in the member and necessitates the solution of a transcendental eigenvalue problem. This is achieved using the Wittrick-Williams algorithm, where the necessary parameters are developed using a generalised procedure. An example is given to clarify the theory, together with a small parametric study that indicates when lateral-torsional coupling may safely be ignored. The work also holds considerable potential in its application to the approximate analysis of asymmetric, multi-storey, three-dimensional frame structures.

  6. New method for oblique impact dynamics research of a flexible beam with large overall motion considering impact friction force

    Institute of Scientific and Technical Information of China (English)

    W Yuan; L Li; D G Zhang; J Z Hong

    2016-01-01

    A flexible beam with large overall rotating motion impacting with a rigid slope is studied in this paper. The tangential friction force caused by the oblique impact is analyzed. The tangential motion of the system is divided into a stick state and a slip state. The contact constraint model and Coulomb friction model are used respectively to deal with the two states. Based on this hybrid mod-eling method, dynamic equations of the system, which include all states (before, during, and after the collision) are obtained. Simulation results of a concrete example are compared with the results obtained from two other models: a nontangential friction model and a modified Coulomb model. Differences in the results from the three models are discussed. The tangential friction force cannot be ignored when an oblique impact occurs. In addition, the results obtained from the model proposed in this paper are more consistent with real movement.

  7. The Dynamic Response of an Euler-Bernoulli Beam on an Elastic Foundation by Finite Element Analysis using the Exact Stiffness Matrix

    Science.gov (United States)

    Kim, Jeong Soo; Kyum Kim, Moon

    2012-08-01

    In this study, finite element analysis of beam on elastic foundation, which received great attention of researchers due to its wide applications in engineering, is performed for estimating dynamic responses of shallow foundation using exact stiffness matrix. First, element stiffness matrix based on the closed solution of beam on elastic foundation is derived. Then, we performed static finite element analysis included exact stiffness matrix numerically, comparing results from the analysis with some exact analysis solutions well known for verification. Finally, dynamic finite element analysis is performed for a shallow foundation structure under rectangular pulse loading using trapezoidal method. The dynamic analysis results exist in the reasonable range comparing solution of single degree of freedom problem under a similar condition. The results show that finite element analysis using exact stiffness matrix is evaluated as a good tool of estimating the dynamic response of structures on elastic foundation.

  8. R&D ERL: Beam dynamics, parameters, and physics to be learned

    Energy Technology Data Exchange (ETDEWEB)

    Kayran, D.

    2010-02-01

    The R&D ERL facility at BNL aims to demonstrate CW operation of ERL with average beam current in the range of 0.1-1 ampere, combined with very high efficiency of energy recovery. The ERL is being installed in one of the spacious bays in Bldg. 912 of the RHIC/AGS complex (Fig. 1). The bay is equipped with an overhead crane. The facility has a control room, two service rooms and a shielded ERL cave. The control room is located outside of the bay in a separate building. The single story house is used for a high voltage power supply for 1 MW klystron. The two-story unit houses a laser room, the CW 1 MW klystron with its accessories, most of the power supplies and electronics. The ERL R&D program has been started by the Collider Accelerator Department (C-AD) at BNL as an important stepping-stone for 10-fold increase of the luminosity of the Relativistic Heavy Ion Collider (RHIC) using relativistic electron cooling of gold ion beams with energy of 100 GeV per nucleon. Furthermore, the ERL R&D program extends toward a possibility of using 10-20 GeV ERL for future electron-hadron/heavy ion collider, MeRHIC/eRHIC. These projects are the driving force behind the development of ampere-class ERL technology, which will find many applications including light sources and FELs. The intensive R&D program geared towards the construction of the prototype ERL is under way: from development of high efficiency photo-cathodes to the development of new merging system compatible with emittance compensation.

  9. Establishing an Initial Electron Beam Model with Monte Carlo Simulation for a Single 6 MV X-ray Medical Linac Based on Particle Dynamics Characteristics

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hong-bin; KONG Xiao-xiao; LI Quan-feng; LIN Xiao-qi; BAO Shang-lian

    2009-01-01

    Objective:In this study,we try to establish an initial electron beam model by combining Monte Carlo simulation method with particle dynamic calculation (TRSV) for the single 6 MV X-ray accelerating waveguide of BJ- 6 medical linac. Methods and Materials:1. We adapted the treatment head configuration of BJ- 6 medical linac made by Beijing Medical Equipment Institute (BMEI) as the radiation system for this study. 2. Use particle dynamics calculation code called TRSV to drive out the initial electron beam parameters of the energy spectrum, the spatial intensity distribution, and the beam incidence angle. 3. Analyze the 6 MV X-ray beam characteristics of PDDc, OARc in a water phantom by using Monte Carlo simulation (BEAMnrc,DOSXYZnrc) for a preset of the initial electron beam parameters which have been determined by TRSV, do the comparisons of the measured results of PDDm, OARm in a real water phantom, and then use the deviations of calculated and measured results to slightly modify the initial electron beam model back and forth until the deviations meet the error less than 2%. Results:The deviations between the Monte Carlo simulation results of percentage depth doses at PDDc and off-axis ratios OARc and the measured results of PDDm and OARm in a water phantom were within 2%. Conclusion:When doing the Monte Carlo simulation to determine the parameters of an initial electron beam for a particular medical linac like BJ- 6, modifying some parameters based on the particle dynamics calculation code would give some more reasonable and more acceptable results.

  10. Dynamics of Cavitation Clouds within a High-Intensity Focused Ultrasonic Beam

    Science.gov (United States)

    2012-03-01

    the cloud size. I. INTRODUCTION High-intensity focused ultrasound (HIFU), along with the associated cavitation , is used in a variety of fields. The...Article 3. DATES COVERED (From - To) March 2012- May 2012 4. TITLE AND SUBTITLE Dynamics of Cavitation Clouds within a High-Intensity Focused...in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line

  11. Non-equilibrium QCD Interplay of hard and soft dynamics in high-energy multi-gluon beams

    CERN Document Server

    Kinder-Geiger, Klaus

    1997-01-01

    A quantum-kinetic formulation of the dynamical evolution of a high-energy non-equilibrium gluon system at finite density is developed, to study the interplay between quantum fluctuations of high-momentum (hard) gluons and the low-momentum (soft) mean color-field that is induced by the collective motion of the hard particles. From the exact field-equations of motion of QCD, a self-consistent set of approximate quantum-kinetic equations are derived by separating hard and soft dynamics and choosing a convenient axial-type gauge. This set of master equations describes the momentum space evolution of the individual hard quanta, the space-time development of the ensemble of hard gluons, and the generation of the soft mean-field by the current of the hard particles. The quantum-kinetic equations are approximately solved to order g^2 (1+gA) for a specific example, namely the scenario of a high-energy gluon beam along the lightcone, demonstrating the practical applicability of the approach.

  12. Nonlinear dynamics of nanomechanical beam resonators: improving the performance of NEMS-based sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kacem, N; Hentz, S; Pinto, D; Reig, B; Nguyen, V [CEA/LETI-MINATEC, Grenoble (France)

    2009-07-08

    In order to compensate for the loss of performance when scaling resonant sensors down to NEMS, it proves extremely useful to study the behavior of resonators up to very high displacements and hence high nonlinearities. This work describes a comprehensive nonlinear multiphysics model based on the Euler-Bernoulli equation which includes both mechanical and electrostatic nonlinearities valid up to displacements comparable to the gap in the case of an electrostatically actuated doubly clamped beam. Moreover, the model takes into account the fringing field effects, significant for thin resonators. The model has been compared to both numerical integrations and electrical measurements of devices fabricated on 200 mm SOI wafers; it shows very good agreement with both. An important contribution of this work is the provision for closed-form expressions of the critical amplitude and the pull-in domain initiation amplitude including all nonlinearities. This model allows designers to cancel out nonlinearities by tuning some design parameters and thus gives the possibility to drive the resonator beyond its critical amplitude. Consequently, the sensor performance can be enhanced to the maximum below the pull-in instability, while keeping a linear behavior.

  13. Nonlinear dynamics of nanomechanical beam resonators: improving the performance of NEMS-based sensors.

    Science.gov (United States)

    Kacem, N; Hentz, S; Pinto, D; Reig, B; Nguyen, V

    2009-07-08

    In order to compensate for the loss of performance when scaling resonant sensors down to NEMS, it proves extremely useful to study the behavior of resonators up to very high displacements and hence high nonlinearities. This work describes a comprehensive nonlinear multiphysics model based on the Euler-Bernoulli equation which includes both mechanical and electrostatic nonlinearities valid up to displacements comparable to the gap in the case of an electrostatically actuated doubly clamped beam. Moreover, the model takes into account the fringing field effects, significant for thin resonators. The model has been compared to both numerical integrations and electrical measurements of devices fabricated on 200 mm SOI wafers; it shows very good agreement with both. An important contribution of this work is the provision for closed-form expressions of the critical amplitude and the pull-in domain initiation amplitude including all nonlinearities. This model allows designers to cancel out nonlinearities by tuning some design parameters and thus gives the possibility to drive the resonator beyond its critical amplitude. Consequently, the sensor performance can be enhanced to the maximum below the pull-in instability, while keeping a linear behavior.

  14. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Niu, B.

    1992-09-01

    High resolution He I[alpha] photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a soft'' mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  15. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Niu, B.

    1992-09-01

    High resolution He I{alpha} photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a ``soft`` mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  16. DYNAMIC STABILITY OF A BEAM-MODEL VISCOELASTIC PIPE FOR CONVEYING PULSATIVE FLUID

    Institute of Scientific and Technical Information of China (English)

    Xiaodong Yang; Tianzhi Yang; Jiduo Jin

    2007-01-01

    The dynamic stability in transverse vibration of a viscoelastic pipe for conveying pulsative fluid is investigated for the simply-supported case. The material property of the beammodel pipe is described by the Kelvin-type viscoelastic constitutive relation. The axial fluid speed is characterized as simple harmonic variation about a constant mean speed. The method of multiple scales is applied directly to the governing partial differential equation without discretization when the viscoelastic damping and the periodical excitation are considered small. The stability conditions are presented in the case of subharmonic and combination resonance. Numerical results show the effect of viscosity and mass ratio on instability regions.

  17. Molecular dynamics simulation of ion-beam-amorphization of Si, Ge and GaAs

    CERN Document Server

    Nord, J D; Keinonen, J

    2002-01-01

    We use molecular dynamics simulations to study ion-irradiation-induced amorphization in Si, Ge and GaAs using several different interatomic force models. We find that the coordination number is higher, and the average bond length longer, for the irradiated amorphous structures than for the molten ones in Si and Ge. For amorphous GaAs, we suggest that longer Ga-Ga bonds, also present in pure Ga, are produced during the irradiation. In Si the amorphization is found to proceed via growth of amorphous regions, and low energy recoils are found to induce athermal recrystallization during irradiation.

  18. A smart dynamic vibration absorber for suppressing the vibration of a string supported by flexible beams

    Science.gov (United States)

    Nambu, Yohsuke; Yamamoto, Shota; Chiba, Masakatsu

    2014-02-01

    This study aims to effectively and robustly suppress the vibration of tension-stabilized structures (TSSs) using a smart dynamic vibration absorber (DVA). In recent years, a strong need has emerged for high-precision and high-functionality space structural systems for realizing advanced space missions. TSSs have attracted attention in this regard as large yet lightweight structural systems with high storage efficiency. A fundamental issue in the application of TSSs is vibration control of strings, of which TSSs are predominantly composed. In particular, the suppression of microvibrations is difficult because the deformation is almost perpendicular to the direction of vibration. A DVA is an effective device for suppressing microvibrations. However, the damping performance is sensitive to changes in dynamic properties. Furthermore, aging degradation and temperature dependence negatively affect DVA performance. This study aimed to develop a smart, active DVA with self-sensing actuation to improve robustness. A small cantilever with a piezoelectric transducer was utilized as a smart DVA. Numerical simulations and experiments showed that a passive DVA and the smart DVA suppressed vibrations but that the smart DVA showed improved effectiveness and robustness.

  19. Pareto front analysis of 6 and 15 MV dynamic IMRT for lung cancer using pencil beam, AAA and Monte Carlo

    DEFF Research Database (Denmark)

    Ottosson, R O; Hauer, Anna Karlsson; Behrens, C.F.

    2010-01-01

    The pencil beam dose calculation method is frequently used in modern radiation therapy treatment planning regardless of the fact that it is documented inaccurately for cases involving large density variations. The inaccuracies are larger for higher beam energies. As a result, low energy beams are...

  20. Laser cooling of a stored ion beam: A first step towards crystalline beams

    Energy Technology Data Exchange (ETDEWEB)

    Hangst, J.S.

    1992-09-01

    This report discusses: a brief introduction to storage rings; crystalline beams; laser cooling of ion beams; description of astrid-the experimental setup; first experiments with lithium 7 ion beam; experiments with erbium 166 ion beams; further experiments with lithium 7 ion beams; beam dynamics, laser cooling,and crystalline beams in astrid; possibilities for further study in astrid.

  1. Effect of imperfections of the radial component of a magnetic field on beam dynamics in medical cyclotron C235-V3

    Science.gov (United States)

    Karamysheva, G. A.; Kostromin, S. A.; Morozov, N. A.; Samsonov, E. V.; Syresin, E. M.

    2014-11-01

    This paper presents numerical simulations and experimental results related to the effect of imperfections of the radial component of a magnetic field on the beam dynamics in the medical cyclotron C235-V3 of the Dimitrovgrad Proton Therapy Center. These imperfections in the region of the minimal axial betatron frequency lead to a transformation of coherent motion of the center of gravity of the beam to the incoherent motion of separate particles. The radial component increases the axial size of the beam by a factor of 2 at a radius of 20 cm, which produces additional losses of protons. To reduce undesirable actions of the radial component on the axial motion, the magnetic system in the central region has been optimized using two procedures: the positioning of shim correctors on sectors and selecting a special asymmetric arrangement of the upper and lower central plugs. This led to a twofold reduction in the axial size of the beam and a decrease in proton losses. Eventually, the beam transmission in C235-V3 has been increased to 72% without a limiting aperture diaphragm, which is commonly used in cyclotrons of this type. This makes it possible to reduce the irradiation dose of machine elements and increase the beam current at a deflector entrance of the cyclotron C235-V3 by a factor of 1.5 when compared to a serial C235 cyclotron.

  2. Historical Account And Branching To Rarefied Gas Dynamics Of Atomic and Molecular Beams : A Continuing And Fascinating Odyssey Commemorated By Nobel Prizes Awarded To 23 Laureates In Physics And Chemistry

    Science.gov (United States)

    Campargue, Roger

    2005-05-01

    This Historical Account derived in part from D. R. Herschbach was presented as an opening lecture of the Molecular Beam Session organized at the 24th International Symposium on Rarefied Gas Dynamics held in Bari, Italy, in July 2004. The emphasis is on the impressive results due to the molecular beam techniques in the last century. The first section summarizes the historical beam experiments performed by 14 Nobel Prize laureates having used the thermally effusive sources to establish the basic principles of Modern Physics. The second section is on the branching of Molecular Beams to Rarefied Gas Dynamics having permitted to investigate the physics of supersonic free jets and transform the molecular beam techniques. Finally, the last section relates the spectacular molecular beam experiments in helium free jet ultracooling, molecular spectroscopy, chemical reaction dynamics, clustering and modification of low density matter, and biomolecule mass spectrometry, rewarded by nine Nobel Prizes in Chemistry from 1986 to 2002.

  3. Simulation of Electron Beam Dynamics in the 22 MeV Accelerator for a Coherent Electron Cooling Proof of Principle Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Justin [Stony Brook Univ., NY (United States)

    2013-12-01

    Coherent electron cooling (CeC) offers a potential new method of cooling hadron beams in colliders such as the Relativistic Heavy Ion Collider (RHIC) or the future electron ion collider eRHIC. A 22 MeV linear accelerator is currently being built as part of a proof of principle experiment for CeC at Brookhaven National Laboratory (BNL). In this thesis we present a simulation of electron beam dynamics including space charge in the 22 MeV CeC proof of principle experiment using the program ASTRA (A Space charge TRacking Algorithm).

  4. Secure transmission of static and dynamic images via chaotic encryption in acousto-optic hybrid feedback with profiled light beams

    Science.gov (United States)

    Chatterjee, Monish R.; Almehmadi, Fares S.

    2015-01-01

    Secure information encryption via acousto-optic (AO) chaos with profiled optical beams indicates substantially better performance in terms of system robustness. This paper examines encryption of static and time-varying (video) images onto AO chaotic carriers using Gaussian-profile beams with diffracted data numerically generated using transfer functions. The use of profiled beams leads to considerable improvement in the encrypted signal. While static image encryption exhibits parameter tolerances within about +/-10% for uniform optical beams, profiled beams reduce the tolerance to less than 1%, thereby vastly improving both the overall security of the transmitted information as well as the quality of the image retrieval.

  5. Report of the group on beam-beam effects in circular colliders

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.A.

    1991-05-01

    We present a summary of the discussions and conclusions of the working group on beam-beam effects for circular colliders. This group was part of the larger beam-beam dynamics group at the 7th ICFA Workshop on Beam Dynamics, on the subject Beam-Beam and Beam-Radiation Interactions,'' held at UCLA, May 13--16, 1991. 15 refs.

  6. Photodissociation dynamics of the methyl perthiyl radical at 248 and 193 nm using fast-beam photofragment translational spectroscopy

    Science.gov (United States)

    Harrison, Aaron W.; Ryazanov, Mikhail; Sullivan, Erin N.; Neumark, Daniel M.

    2016-07-01

    The photodissociation dynamics of the methyl perthiyl radical (CH3SS) have been investigated using fast-beam coincidence translational spectroscopy. Methyl perthiyl radicals were produced by photodetachment of the CH3SS- anion followed by photodissociation at 248 nm (5.0 eV) and 193 nm (6.4 eV). Photofragment mass distributions and translational energy distributions were measured at each dissociation wavelength. Experimental results show S atom loss as the dominant (96%) dissociation channel at 248 nm with a near parallel, anisotropic angular distribution and translational energy peaking near the maximal energy available to ground state CH3S and S fragments, indicating that the dissociation occurs along a repulsive excited state. At 193 nm, S atom loss remains the major fragmentation channel, although S2 loss becomes more competitive and constitutes 32% of the fragmentation. The translational energy distributions for both channels are very broad at this wavelength, suggesting the formation of the S2 and S atom products in several excited electronic states.

  7. Ultrafast carrier dynamics and the role of grain boundaries in polycrystalline silicon thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Titova, Lyubov V.; Cocker, Tyler L.; Xu, Sijia; Baribeau, Jean-Marc; Wu, Xiaohua; Lockwood, David J.; Hegmann, Frank A.

    2016-10-01

    We have used time-resolved terahertz spectroscopy to study microscopic photoconductivity and ultrafast photoexcited carrier dynamics in thin, pure, non-hydrogenated silicon films grown by molecular beam epitaxy on quartz substrates at temperatures ranging from 335 °C to 572 °C. By controlling the growth temperature, thin silicon films ranging from completely amorphous to polycrystalline with minimal amorphous phase can be achieved. Film morphology, in turn, determines its photoconductive properties: in the amorphous phase, carriers are trapped in bandtail states on sub-picosecond time scales, while the carriers excited in crystalline grains remain free for tens of picoseconds. We also find that in polycrystalline silicon the photoexcited carrier mobility is carrier-density-dependent, with higher carrier densities mitigating the effects of grain boundaries on inter-grain transport. In a film grown at the highest temperature of 572 °C, the morphology changes along the growth direction from polycrystalline with needles of single crystals in the bulk of the film to small crystallites interspersed with amorphous silicon at the top of the film. Depth profiling using different excitation wavelengths shows corresponding differences in the photoconductivity: the photoexcited carrier lifetime and mobility are higher in the first 100-150 nm from the substrate, suggesting that thinner, low-temperature grown polycrystalline silicon films are preferable for photovoltaic applications.

  8. The Rapidity Density Distributions and Longitudinal Expansion Dynamics of Identified Pions from the STAR Beam Energy Scan

    Science.gov (United States)

    Flores, Christopher E.

    2016-12-01

    The Beam Energy Scan (BES) at the Relativistic Heavy-Ion Collider was proposed to characterize the properties of the medium produced in heavy-ion interactions over a broad range of baryon chemical potential. The aptitude of the STAR detector for mid-rapidity measurements has previously been leveraged to measure identified particle yields and spectra to extract bulk properties for the BES energies for | y | ≤ 0.1. However, to extract information on expansion dynamics and full phase space particle production, it is necessary to study identified particle rapidity density distributions. We present the first rapidity density distributions of identified pions from Au+Au collisions at √{sNN} = 7.7 , 11.5, and 19.6 GeV from the BES program as measured by the STAR detector. We use these distributions to obtain the full phase space yields of the pions to provide additional information of the system's chemistry. Further, we report the width of the rapidity density distributions compared to the width expected from Landau hydrodynamics. Finally, we interpret the results as a function of collision energy and discuss them in the context of previous energy scans done at the AGS and SPS.

  9. Self consistent thermal wave model description of the transverse dynamics for relativistic charged particle beams in magnetoactive plasmas

    CERN Document Server

    Fedele, Renato; De Nicola, Sergio; Shukla, P K; Jovanovic, Dusan

    2011-01-01

    Thermal Wave Model is used to study the strong self-consistent Plasma Wake Field interaction (transverse effects) between a strongly magnetized plasma and a relativistic electron/positron beam travelling along the external magnetic field, in the long beam limit, in terms of a nonlocal NLS equation and the virial equation. In the linear regime, vortices predicted in terms of Laguerre-Gauss beams characterized by non-zero orbital angular momentum (vortex charge). In the nonlinear regime, criteria for collapse and stable oscillations is established and the thin plasma lens mechanism is investigated, for beam size much greater than the plasma wavelength. The beam squeezing and the self-pinching equilibrium is predicted, for beam size much smaller than the plasma wavelength, taking the aberrationless solution of the nonlocal Nonlinear Schroeding equation.

  10. Dynamics of self-focusing and self-phase modulation of elliptic Gaussian laser beam in a Kerr-medium

    Indian Academy of Sciences (India)

    Tarsem Singh; Nareshpal Singh Saini; Shyam Sunder Kaul

    2000-09-01

    Using a direct variational technique involving elliptic Gaussian laser beam trial function, the combined effect of non-linearity and diffraction on wave propagation of optical beam in a homogeneous bulk Kerr-medium is presented. Particular emphasis is put on the variation of beam width and longitudinal phase delay with the distance of propagation. It is observed that no stationary self-trapping is possible. The regularized phase is also seen to be always negative.

  11. Free vibration analysis of straight-line beam regarded as distributed system by combining Wittrick-Williams algorithm and transfer dynamic stiffness coefficient method

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Myung Soo; Yang, Kyong Uk [Chonnam National University, Yeosu (Korea, Republic of); Kondou, Takahiro [Kyushu University, Fukuoka (Japan); Bonkobara, Yasuhiro [University of Miyazaki, Miyazaki (Japan)

    2016-03-15

    We developed a method for analyzing the free vibration of a structure regarded as a distributed system, by combining the Wittrick-Williams algorithm and the transfer dynamic stiffness coefficient method. A computational algorithm was formulated for analyzing the free vibration of a straight-line beam regarded as a distributed system, to explain the concept of the developed method. To verify the effectiveness of the developed method, the natural frequencies of straight-line beams were computed using the finite element method, transfer matrix method, transfer dynamic stiffness coefficient method, the exact solution, and the developed method. By comparing the computational results of the developed method with those of the other methods, we confirmed that the developed method exhibited superior performance over the other methods in terms of computational accuracy, cost and user convenience.

  12. Field calculations, single-particle tracking, and beam dynamics with space charge in the electron lens for the Fermilab Integrable Optics Test Accelerator

    CERN Document Server

    Noll, Daniel

    2015-01-01

    An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Single-particle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize the main findings and list directions for further work.

  13. Green's function and Bloch theory for the analysis of the dynamic response of a periodically supported beam to a moving load

    Science.gov (United States)

    Lassoued, R.; Lecheheb, M.; Bonnet, G.

    2012-08-01

    This paper describes an analytical method for the wave field induced by a moving load on a periodically supported beam. The Green's function for an Euler beam without support is evaluated by using the direct integration. Afterwards, it introduces the supports into the model established by using the superposition principle which states that the response from all the sleeper points and from the external point force add up linearly to give a total response. The periodicity of the supports is described by Bloch's theorem. The homogeneous system thus obtained represents a linear differential equation which governs rail response. It is initially solved in the homogeneous case, and it admits a no null solution if its determinant is null, this permits the establishment the dispersion equation to Bloch waves and wave bands. The Bloch waves and dispersion curves contain all the physics of the dynamic problem and the wave field induced by a dynamic load applied to the system is finally obtained by decomposition into Bloch waves, similarly to the usual decomposition into dynamic modes on a finite structure. The method is applied to obtain the field induced by a load moving at constant velocity on a thin beam supported by periodic elastic supports.

  14. Generation of multi-charged high current ion beams using the SMIS 37 gas-dynamic electron cyclotron resonance (ECR) ion source

    Energy Technology Data Exchange (ETDEWEB)

    Dorf, M.A., E-mail: dorf1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Zorin, V.G.; Sidorov, A.V.; Bokhanov, A.F.; Izotov, I.V.; Razin, S.V.; Skalyga, V.A. [Institute of Applied Physics RAS, 46 Ulyanov Street, 603950 Nizhny Novgorod (Russian Federation)

    2014-01-01

    A gas-dynamic ECR ion source (GaDIS) is distinguished by its ability to produce high current and high brightness beams of moderately charged ions. Contrary to a classical ECR ion source where the plasma confinement is determined by the slow electron scattering into an empty loss-cone, the higher density and lower electron temperature in a GaDIS plasma lead to an isotropic electron distribution with the confinement time determined by the prompt gas-dynamic flow losses. As a result, much higher ion fluxes are available; however a decrease in the confinement time of the GaDIS plasma lowers the ion charge state. The gas-dynamic ECR ion source concept has been successfully realized in the SMIS 37 experimental facility operated at the Institute of Applied Physics, Russia. The use of high-power (∼100 kW) microwave (37.5 GHz) radiation provides a dense plasma (∼10{sup 13} cm{sup −3}) with a relatively low electron temperature (∼50–100 eV) and allows for the generation of high current (∼1 A/cm{sup 2}) beams of multi-charged ions. In this work we report on the present status of the SMIS 37 ion source and discuss the advanced numerical modeling of ion beam extraction using the particle-in-cell code WARP.

  15. Improved crystallinity and dynamic mechanical properties of reclaimed waste tire rubber/EVA blends under the influence of electron beam irradiation

    Science.gov (United States)

    Ramarad, Suganti; Ratnam, Chantara T.; Khalid, Mohammad; Chuah, Abdullah Luqman; Hanson, Svenja

    2017-01-01

    Dependence on automobiles has led to a huge amount of waste tires produced annually around the globe. In this study, the feasibility of recycling these waste tires by blending reclaimed waste tire rubber (RTR) with poly(ethylene-co-vinyl acetate) (EVA) and electron beam irradiation was studied. The RTR/EVA blends containing 100-0 wt% of RTR were prepared in the internal mixer followed by electron beam (EB) irradiation with doses ranging from 50 to 200 kGy. The processing torques, calorimetric and dynamic mechanical properties of the blends were studied. Blends were found to have lower processing torque indicating easier processability of RTR/EVA blends compared to EVA. RTR domains were found to be dispersed in EVA matrix, whereas, irradiation improved the dispersion of RTR into smaller domains in EVA matrix. Results showed the addition of EVA improves the efficiency of irradiation induced crosslink formation and dynamic mechanical properties of the blends at the expense of the calorimetric properties. Storage and loss modulus of 50 wt% RTR blend was higher than RTR and EVA, suggesting partial miscibility of the blend. Whereas, electron beam irradiation improved the calorimetric properties and dynamic mechanical properties of the blends through redistribution of RTR in smaller domain sizes within EVA.

  16. Generation of multi-charged high current ion beams using the SMIS 37 gas-dynamic electron cyclotron resonance (ECR) ion source

    Energy Technology Data Exchange (ETDEWEB)

    Dorf, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zorin, V. G. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Sidorov, A. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Bokhanov, A. F. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Izotov, I. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Razin, S. V. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics; Skalyga, V. A. [Russian Academy of Sciences (RAS), Nizhny Novgorod (Russian Federation). Inst. of Applied Physics

    2013-06-02

    A gas-dynamic ECR ion source (GaDIS) is distinguished by its ability to produce high current and high brightness beams of moderately charged ions. Contrary to a classical ECR ion source where the plasma confinement is determined by the slow electron scattering into an empty loss-cone, the higher density and lower electron temperature in a GaDIS plasma lead to an isotropic electron distribution with the confinement time determined by the prompt gas-dynamic flow losses. As a result, much higher ion fluxes are available, however a decrease in the confinement time of the GaDIS plasma lowers the ion charge state. The gas-dynamic ECR ion source concept has been successfully realized in the SMIS 37 experimental facility operated at the Institute of Applied Physics, Russia. The use of high-power (~100 kW) microwave (37.5 GHz) radiation provides a dense plasma (~1013 cm-3) with a relatively low electron temperature (~50- 100 eV) and allows for the generation of high current (~1 A/cm2) beams of multi-charged ions. In this work we report on the present status of the SMIS 37 ion source and discuss the advanced numerical modeling of ion beam extraction using the particle-in-cell code WARP

  17. Dynamic imaging with a triggered and intensified CCD camera system in a high-intensity neutron beam

    Science.gov (United States)

    Vontobel, P.; Frei, G.; Brunner, J.; Gildemeister, A. E.; Engelhardt, M.

    2005-04-01

    When time-dependent processes within metallic structures should be inspected and visualized, neutrons are well suited due to their high penetration through Al, Ag, Ti or even steel. Then it becomes possible to inspect the propagation, distribution and evaporation of organic liquids as lubricants, fuel or water. The principle set-up of a suited real-time system was implemented and tested at the radiography facility NEUTRA of PSI. The highest beam intensity there is 2×107 cm s, which enables to observe sequences in a reasonable time and quality. The heart of the detection system is the MCP intensified CCD camera PI-Max with a Peltier cooled chip (1300×1340 pixels). The intensifier was used for both gating and image enhancement, where as the information was accumulated over many single frames on the chip before readout. Although, a 16-bit dynamic range is advertised by the camera manufacturers, it must be less due to the inherent noise level from the intensifier. The obtained result should be seen as the starting point to go ahead to fit the different requirements of car producers in respect to fuel injection, lubricant distribution, mechanical stability and operation control. Similar inspections will be possible for all devices with repetitive operation principle. Here, we report about two measurements dealing with the lubricant distribution in a running motorcycle motor turning at 1200 rpm. We were monitoring the periodic stationary movements of piston, valves and camshaft with a micro-channel plate intensified CCD camera system (PI-Max 1300RB, Princeton Instruments) triggered at exactly chosen time points.

  18. Effect of Self-Magnetic Fields on the Nonlinear Dynamics of Relativistic Electron Beam with Virtual Cathode

    CERN Document Server

    Hramov, A E; Koronovskii, A A; Filatova, A E; 10.1063/1.4765062

    2013-01-01

    The report is devoted to the results of the numerical study of the virtual cathode formation conditions in the relativistic electron beam under the influence of the self-magnetic and external axial magnetic fields. The azimuthal instability of the relativistic electron beam leading to the formation of the vortex electron structure in the system was found out. This instability is determined by the influence of the self-magnetic fields of the relativistic electron beam and it leads to the decrease of the critical value of the electron beam current (current when the non-stationary virtual cathode is formed in the drift space). The typical dependencies of the critical current on the external uniform magnetic field value were discovered. The effect of the beam thickness on the virtual cathode formation conditions was also analyzed.

  19. Studies on the beam dynamics at the harmonic double-side microtron of MAMI-C; Untersuchungen zur Strahldynamik am Harmonischen Doppelseitigen Mikrotron von MAMI-C

    Energy Technology Data Exchange (ETDEWEB)

    Dehn, Marco

    2013-10-28

    The Institut fuer Kernphysik at Mainz University operates a worldwide unique accelerator for experiments in nuclear and particle physics since 1990. The Mainzer Mikrotron (MAMI-B) uses three cascaded racetrack microtrons (RTM) with RF linacs operating at 2.45 GHz to accelerate a continuous electron beam of up to 100 μA to 855 MeV. In 1999 the realisation of the fourth stage - the Harmonic Double Sided Microtron (HDSM, MAMI-C) - reaching a maximum beam energy of 1.5 GeV was started. During the development some courageous decisions were necessary. For example the bending magnets with their field gradient and corresponding beam optical properties have large influence on the longitudinal beam dynamics. That in turn requires harmonic operation with two RF linacs operating at 4.9 GHz and 2.45 GHz. Many parameters of the machine settings (like RF voltage or phase) have great impact on the acceleration process but not always they are easily to quantify in physical units. Concerning the RTMs with their comparatively simple and well defined beam dynamics that is rather unproblematic. However, in the HDSM the larger number of parameters requires a more precise knowledge of these quantities. Therefore it is necessary to develop dedicated methods of beam diagnostics to check the important machine parameters against their design values. All these methods are not free of systematic errors or insufficiencies and thus fitting a model of the machine to measured data does not always yield unambiguous results. To overcome this problem a special kind of tomography is used to scan the longitudinal phase space resulting in acceptance measurements. The large amount of data with systematic variations now yields a better significance of the fitted parameters. The results of these investigations demonstrate that the accelerator as an entity acts as predicted and shows that many different configurations can be used to operate the HDSM. However, for most situations one single configuration is

  20. Dynamic Pull-In Investigation of a Clamped-Clamped Nanoelectromechanical Beam under Ramp-Input Voltage and the Casimir Force

    Directory of Open Access Journals (Sweden)

    Amir R. Askari

    2014-01-01

    Full Text Available The influence of the Casimir excitation on dynamic pull-in instability of a nanoelectromechanical beam under ramp-input voltage is studied. The ramp-input actuation has applications in frequency sweeping of RF-N/MEMS. The presented model is nonlinear due to the inherent nonlinearity of electrostatics and the Casimir excitations as well as the geometric nonlinearity of midplane stretching. A Galerkin based reduced order modeling is utilized. It is found that the calculated dynamic pull-in ramp input voltage leads to dynamic pull-in step input voltage by increasing the slope of voltage-time diagram. This fact is utilized to verify the results of present study.

  1. A method for the dynamic range extension of a pixelated Silicon detector beam profilometer based on the incomplete reset mechanism

    Science.gov (United States)

    Caccia, M.; Santoro, R.; Antonello, M.

    2017-03-01

    The SUCIMA collaboration, within a project supported by the European Commission in the Fifth Framework Program, developed a sensor for non-disruptive real-time beam profilometry for hadron therapy centres. The sensor, named MIMOTERA, has been used at different European facilities, imaging beams by direct impact on the sensor and by the detection of secondary electrons emitted by thin targets. In 2015, the detector has been thinned to 50 μm, integrated in a high vacuum and cryogenic temperature compliant assembly and successfully commissioned as antiproton beam monitor for the AEbar gIS experiment at CERN. The detector contributed to the optimisation of the experiment functionality providing the shape and position of the beam on a spill-by-spill basis. However, it failed in measuring the fluctuations of the beam intensity because the deposited energy exceeded the full well capacity and saturated the output signal. In order to recover this information, a method was developed based on the persistence of the signal in a series of frames that follows the one corresponding to the beam impact, due to the incomplete sensor reset. A laboratory test that makes use of a laser with tuneable intensity was designed and the method was qualified. This paper reports the description of the procedure and the main outcomes.

  2. Beam Dynamics Studies and the Design, Fabrication and Testing of Superconducting Radiofrequency Cavity for High Intensity Proton Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Saini, Arun [Univ. of Delhi, New Delhi (India)

    2012-03-01

    The application horizon of particle accelerators has been widening significantly in recent decades. Where large accelerators have traditionally been the tools of the trade for high-energy nuclear and particle physics, applications in the last decade have grown to include large-scale accelerators like synchrotron light sources and spallation neutron sources. Applications like generation of rare isotopes, transmutation of nuclear reactor waste, sub-critical nuclear power, generation of neutrino beams etc. are next area of investigation for accelerator scientific community all over the world. Such applications require high beam power in the range of few mega-watts (MW). One such high intensity proton beam facility is proposed at Fermilab, Batavia, US, named as Project-X. Project-X facility is based on H- linear accelerator (linac), which will operate in continuous wave (CW) mode and accelerate H- ion beam with average current of 1 mA from kinetic energy of 2.5 MeV to 3 GeV to deliver 3MW beam power. One of the most challenging tasks of the Project-X facility is to have a robust design of the CW linac which can provide high quality beam to several experiments simultaneously. Hence a careful design of linac is important to achieve this objective.

  3. An ASIC design for versatile receive front-end electronics of an ultrasonic medical imaging system--16 channel analog inputs and 4 dynamically focused beam outputs.

    Science.gov (United States)

    Park, Song B; Kwak, Jaeyoung; Lee, Kwyro

    2003-04-01

    An ultra large-scale ASIC is designed for the receive front-end electronics of an ultrasonic medical imaging system. The chip receives 16 channel analog rf signals and outputs 4 sets of sample-point-wise dynamically focused partial beam data. Four complete beam data sets are obtained in parallel by simply cascading as many chips as needed in an array system. High resolution of the focusing delay is obtained by nonuniformly selecting each channel data from a quadruply-interpolated rf data stream. The proposed ASIC can be applied to most practical array transducers in the frequency range of 2 to 10 MHz. The digital part of the designed ASIC can be implemented on a chip area of 17.9 microm2 with 0.18 mm CMOS technology, leaving sufficient room for 16 ADCs of 8 bits, 50 MHz on the 5.7 mm x 5.7 mm chip with a 208 pin package.

  4. Microwave measurements and beam dynamics simulations of the BNL/SLAC/UCLA emittance-compensated 1.6-cell photocathode rf gun

    Science.gov (United States)

    Palmer, Dennis T.; Miller, Roger H.; Winick, Herman; Wang, Xi J.; Batchelor, Kenneth; Woodle, Martin H.; Ben-Zvi, Ilan

    1995-09-01

    A dedicated low energy (2 to 10 MeV) experimental beam line is now under construction at Brookhaven National Laboratory/Accelerator Test Facility (BNL/ATF) for photocathode RF gun testing and photoemission experiments. Microwave measurements of the 1.6 cell photocathode RF gun have been conducted along with beam dynamics simulations of the emittance compensated low energy beam. These simulations indicate that the 1.6 cell photocathode RF gun in combination with solenoidal emittance compensation will be capable of producing a high brightness beam with a normalization rms emittance of (epsilon) n,rms approximately equals 1 (pi) mm mrad. The longitudinal accelerating field Ez has been measured as a function of azimuthal angle in the full cell of the cold test model for the 1.6 cell BNL/SLAC/UCLA #3 S-band RF Gun using a needle rotation/frequency perturbation technique. These measurements were conducted before and after symmetrizing the full cell with a vacuum pump out port and an adjustable short. Two different waveguide to full cell coupling schemes were studied. Experimental and theoretical studies of the field balance versus mode separation were conducted. The dipole mode of the full cell using the (theta) - coupling scheme is an order of magnitude less severe before symmetrization than the Z- coupling scheme. The multi-pole contribution to the longitudinal field asymmetry are calculated using standard Fourier series techniques for both coupling schemes. The Panofsky- Wenzel theorem is used in estimating the transverse emittance due to the multipole components of Ez. Detailed beam dynamics simulations were performed for the 1.6 cell photocathode RF gun injector using a solenoidal emittance compensation technique. The design of the experimental line along with a proposed experimental program using the 1.6 cell photocathode RF gun developed by the BNL/SLAC/UCLA RF gun collaboration is presented. This experimental program includes measurements of beam loading caused

  5. Development of a High Dynamic Range Beam Position Measurement system using Logarithmic Amplifiers for the SPS at CERN

    CERN Document Server

    Gonzalez, J L; Deplano, C; Savioz, J J

    2013-01-01

    A new Front-End electronics, based on Logarithmic Amplifiers, is currently being developed for the CERN SPS Multi Orbit POsition System (MOPOS). The aim is to resolve the multi-batch structure of the beams and cope with their large intensity range (> 70 dB). Position and intensity signals are digitized in the Front-End electronics installed in the tunnel. The data are then transmitted over a serial fibre-optic link to a VME Digital Acquisition board located in surface buildings. A first prototype, equipped with a calibration system, has been successfully tested on the SPS under different beam conditions, including single bunch, 25 ns and 50 ns bunch trains. The system architecture and the first beam measurements are reported in this paper

  6. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    CERN Document Server

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  7. Study of the transient effects of the space charge compensation on the dynamics of an intense beam; Etude des effets transitoires de la compensation de charge d'espace sur la dynamique d'un faisceau intense

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ismail, A

    2005-09-15

    A main interest in the design of ion accelerators is the control of the dynamics of intense beams at low energy. This dynamics is dominated by nonlinear effects of the Space Charge (SC) field. This SC field induces a halo formation which can induce losses along the transport. Once ionized by the beam, the residual gas, diffused by the source and produced by the desorption of the vacuum chamber of the accelerator, contributes to the production of electrons and ions. According to their sign of charge compared to the beam, these particles will be repelled or confined. The accumulation of particles in the beam contributes to the compensation of the SC field. However, this neutralization induces other non linearity which are dependent on time. This thesis presents an experimental and theoretical work of the SC compensation for ion beams (H{sup +} and H{sup -}). The dynamics of these beams is modelled by a new PIC code, CARTAGO, ensuring the coupling between the created plasma and the studied beams. A single-particle study introduces the dynamics of the plasma in presence of the SC field and of an external magnetic field. The modeling of the compensation with the 1D version of CARTAGO code gave the establishment times and the compensation degrees for several cases of beams and various gas pressures. The compensation of a protons beam was studied more particularly in the low-energy line of the Injector of Protons of High Intensity (IPHI) at Saclay. Simulations show an over-compensation of the space charge inside the focusing solenoid and outside the compensation is only partial. Experimental confrontations of the 2D(r,z) modeling results in a part of this line are also detailed. (author)

  8. Electron beam dynamics and self-cooling up to PeV level due to betatron radiation in plasma-based accelerators

    Science.gov (United States)

    Deng, Aihua; Nakajima, Kazuhisa; Liu, Jiansheng; Shen, Baifei; Zhang, Xiaomei; Yu, Yahong; Li, Wentao; Li, Ruxin; Xu, Zhizhan

    2012-08-01

    In plasma-based accelerators, electrons are accelerated by ultrahigh gradient of 1-100GV/m and undergo the focusing force with the same order as the accelerating force. Heated electrons are injected in a plasma wake and exhibit the betatron oscillation that generates synchrotron radiation. Intense betatron radiation from laser-plasma accelerators is attractive x-ray/gamma-ray sources, while it produces radiation loss and significant effects on energy spread and transverse emittance via the radiation reaction force. In this article, electron beam dynamics on transverse emittance and energy spread with considering radiation reaction effects are studied numerically. It is found that the emittance growth and the energy spread damping initially dominate and balance with radiative damping due to the betatron radiation. Afterward the emittance turns to decrease at a constant rate and leads to the equilibrium at a nanometer radian level with growth due to Coulomb scattering at PeV-level energies. A constant radiation loss rate RT=2/3 is found without regard to the electron beam and plasma conditions. Self-cooling of electron beams due to betatron radiation may guarantee TeV-range linear colliders and give hints on astrophysical ultrahigh-energy phenomena.

  9. A feasibility study of dynamic stress analysis inside a running internal combustion engine using synchrotron X-ray beams.

    Science.gov (United States)

    Baimpas, Nikolaos; Drakopoulos, Michael; Connolley, Thomas; Song, Xu; Pandazaras, Costas; Korsunsky, Alexander M

    2013-03-01

    The present investigation establishes the feasibility of using synchrotron-generated X-ray beams for time-resolved in situ imaging and diffraction of the interior components of an internal combustion engine during its operation. The demonstration experiment was carried out on beamline I12 (JEEP) at Diamond Light Source, UK. The external hutch of the JEEP instrument is a large-scale engineering test bed for complex in situ processing and simulation experiments. The hutch incorporates a large capacity translation and rotation table and a selection of detectors for monochromatic and white-beam diffraction and imaging. These capabilities were used to record X-ray movies of a motorcycle internal combustion engine running at 1850 r.p.m. and to measure strain inside the connecting rod via stroboscopic X-ray diffraction measurement. The high penetrating ability and high flux of the X-ray beam at JEEP allowed the observation of inlet and outlet valve motion, as well as that of the piston, connecting rod and the timing chain within the engine. Finally, the dynamic internal strain within the moving connecting rod was evaluated with an accuracy of ~50 × 10(-6).

  10. Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)

    DEFF Research Database (Denmark)

    Madsen, Peter Teglberg; Wisniewska, Danuta Maria; Beedholm, Kristian

    2010-01-01

    actuation of the left pair. It is demonstrated that porpoises, despite actuation of only one sound source, can change their output and sound beam probably through conformation changes in the sound-producing soft tissues and nasal sacs, and that the coupling of the phonic lips and the melon acts...

  11. Observed Orbit Effects during Long Range Beam-Beam Studies

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2012-01-01

    Possible limitations due to long range beam-beam effects at the LHC have been studied and are presented in this note. With a larger number of bunches and collisions in all interaction points, the crossing angles were reduced to enhance long range beam-beam effects. The analysis of the effects on the dynamic aperture and losses are documented in [1]. This note concentrates on the bunch-by-bunch orbit effects observed during the experiment.

  12. Pump-probe imaging of the fs-ps-ns dynamics during femtosecond laser Bessel beam drilling in PMMA.

    Science.gov (United States)

    Yu, Yanwu; Jiang, Lan; Cao, Qiang; Xia, Bo; Wang, Qingsong; Lu, Yongfeng

    2015-12-14

    A pump-probe shadowgraph imaging technique was used to reveal the femtosecond-picosecond-nanosecond multitimescale fundamentals of high-quality, high-aspect-ratio (up to 287:1) microhole drilling in poly-methyl-meth-acrylate (PMMA) by a single-shot femtosecond laser Bessel beam. The propagation of Bessel beam in PMMA (at 1.98 × 10⁸ m/s) and it induced cylindrical pressure wave expansion (at 3000-3950 m/s in radius) were observed during drilling processes. Also, it was unexpectedly found that the expansion of the cylindrical pressure wave in PMMA showed a linear relation with time and was insensitive to the laser energy fluctuation, quite different from the case in air. It was assumed that the energy insensitivity was due to the anisotropy of wave expansion in PMMA and the ambient air.

  13. Dynamic model of large amplitude vibration of a uniform cantilever beam carrying an intermediate lumped mass and rotary inertia

    OpenAIRE

    A. Nikkar; BAGHERI, S.; Saravi,M.

    2014-01-01

    In this paper, a mathematical model of large amplitude vibration of a uniform cantilever beam arising in the structural engineering is proposed. Two efficient and easy mathematical techniques called variational iteration method and He's variational approach are used to solve the governing differential equation of motion. To assess the accuracy of solutions, we compare the results with the Runge-Kutta 4th order. An excellent agreement of the approximate frequencies and periodic solutions with ...

  14. Fatigue Strength of Portal Frame Beam in High-grade Dynamic Consolidation Construction%高能级强夯施工时门架横梁的疲劳强度验算

    Institute of Scientific and Technical Information of China (English)

    王红霞

    2014-01-01

    为避免高能级强夯施工时横梁断裂的事故发生,在此根据试验数据对横梁疲劳强度进行分析研究,以供参考。%To avoid the beam fracture in high-grade dynamic compaction ,this paper analyzed the fatigue strength of cross beam of portal frame according to the test data ,to provide reference for practice .

  15. Spatial dynamics of laser-induced fluorescence in an intense laser beam: experiment and theory in alkali metal atoms

    CERN Document Server

    Auzinsh, Marcis; Ferber, Ruvin; Gahbauer, Florian; Kalnins, Uldis

    2015-01-01

    We have shown that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We developed a theoretical model that divided an intense laser beam into concentric regions, each with a Rabi frequency that corresponds to the intensity in that region, and solved a set of coupled optical Bloch equations for the density matrix in each region. Experimentally obtained magneto-optical resonance curves for the $F_g=2\\longrightarrow F_e=1$ transition of the $D_1$ line of $^{87}$Rb agreed very well with the theoretical model up to a laser intensity of around 200 mW/cm$^2$ for a transition whose saturation intensity is around 4.5 mW/cm$^2$. We have studied the spatial dependence of the fluorescence intensity in an intense laser beam experimentally and theoretically. An experiment was conducted whereby a broad, intense pump laser excited the $F_g=4\\longrightarrow F_e=3$ transition of the $D_2$ line of cesium while a weak, narrow probe ...

  16. Analysis of nonlinear dynamics of a cantilever beam-rigid-body MEMS gyroscope using a continuation method

    CERN Document Server

    Lajimi, Seyed Amir Mousavi

    2014-01-01

    The nonlinear dynamics of a microbeam-rigid body gyroscope are investigated by using a continuation method. To study the nonlinear dynamics of the system, the Lagrangian of the system is discretized and the reduced-order model is obtained. By using the continuation method, the frequency-response curves are computed and the stability of response is determined.

  17. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation%粘弹性地基上损伤粘弹性Timoshenko梁的非线性动力学行为

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  18. Beam Dynamics Studies of ECR Injections for the Coupled Cyclotron Facility at NSCL%NSCL从ECR离子源向CCF注入的离子束流动力学研究

    Institute of Scientific and Technical Information of China (English)

    X.Wu; Q.Zhao; D.Cole; M.Doleans; G.Machicoane; F.Marti; P.Miller; J.Stetson; M.Steiner; P.Zavodszky

    2007-01-01

    The Coupled Cyclotron Facility(CCF)has been operating at the NSCL since 2001,providing up to 160MeV/u heavy ion beams for nuclear physics experiments.Recent steps,particularly the improvement of the ECR-to-K500 injection line,were taken to improve the CCF performance.For that purpose an off-line ECR source.ARTEMIS-B,was built and used to investigate the impact on beam brightness under various source operating conditions,different initial focusing systems and current analysis dipole.Beam dynamics simulations including space-charge and 3D electrostatic field effects were performed and beam diagnostics including emittance scanner were used,leading to a better understanding of the CCF beam injection process New initial electrostatic focusing elements such as a large-bore quadrupole triplet and a quadrupole doubledoublet with compensating octupole were tested,and a new beam tuning procedure was established to improve the beam brightness for the CCF.Following these efforts,a significant increase of primary beam power out of the CCF has been achieved.

  19. Synthesis of dynamic phase profile by the correlation technique for spatial control of optical beams in multiplexing and switching

    Science.gov (United States)

    Bugaychuk, Svitlana A.; Gnatovskyy, Vladimir O.; Sidorenko, Andrey V.; Pryadko, Igor I.; Negriyko, Anatoliy M.

    2015-11-01

    New approach for the correlation technique, which is based on multiple periodic structures to create a controllable angular spectrum, is proposed and investigated both theoretically and experimentally. The transformation of an initial laser beam occurs due to the actions of consecutive phase periodic structures, which may differ by their parameters. Then, after the Fourier transformation of a complex diffraction field, the output diffraction orders will be changed both by their intensities and by their spatial position. The controllable change of output angular spectrum is carried out by a simple control of the parameters of the periodic structures. We investigate several simple examples of such management.

  20. Design and Experimental Implementation of a Beam-Type Twin Dynamic Vibration Absorber for a Cantilevered Flexible Structure Carrying an Unbalanced Rotor: Numerical and Experimental Observations

    Directory of Open Access Journals (Sweden)

    Abdullah Özer

    2015-01-01

    Full Text Available This paper presents experimental and numerical results about the effectiveness of a beam-type twin dynamic vibration absorber for a cantilevered flexible structure carrying an unbalanced rotor. An experimental laboratory prototype setup has been built and implemented in our laboratory and numerical investigations have been performed through finite element analysis. The proposed system design consists of a primary cantilevered flexible structure with an attached dual-mass cantilevered secondary dynamic vibration absorber arrangement. In addition, an unbalanced rotor system is attached to the tip of the flexible cantilevered structure to inspect the system response under harmonic excitations. Numerical findings and experimental observations have revealed that significant vibration reductions are possible with the proposed dual-mass, cantilevered dynamic vibration absorber on a flexible cantilevered platform carrying an unbalanced rotor system at its tip. The proposed system is efficient and it can be practically tuned for variety of design and operating conditions. The designed setup and the results in this paper can serve for practicing engineers, researchers and can be used for educational purposes.

  1. Linear array measurements of enhanced dynamic wedge and treatment planning system (TPS) calculation for 15 MV photon beam and comparison with electronic portal imaging device (EPID) measurements

    Science.gov (United States)

    Petrovic, Borislava; Grzadziel, Aleksandra; Rutonjski, Laza; Slosarek, Krzysztof

    2010-01-01

    Introduction. Enhanced dynamic wedges (EDW) are known to increase drastically the radiation therapy treatment efficiency. This paper has the aim to compare linear array measurements of EDW with the calculations of treatment planning system (TPS) and the electronic portal imaging device (EPID) for 15 MV photon energy. Materials and methods. The range of different field sizes and wedge angles (for 15 MV photon beam) were measured by the linear chamber array CA 24 in Blue water phantom. The measurement conditions were applied to the calculations of the commercial treatment planning system XIO CMS v.4.2.0 using convolution algorithm. EPID measurements were done on EPID-focus distance of 100 cm, and beam parameters being the same as for CA24 measurements. Results Both depth doses and profiles were measured. EDW linear array measurements of profiles to XIO CMS TPS calculation differ around 0.5%. Profiles in non-wedged direction and open field profiles practically do not differ. Percentage depth doses (PDDs) for all EDW measurements show the difference of not more than 0.2%, while the open field PDD is almost the same as EDW PDD. Wedge factors for 60 deg wedge angle were also examined, and the difference is up to 4%. EPID to linear array differs up to 5%. Conclusions The implementation of EDW in radiation therapy treatments provides clinicians with an effective tool for the conformal radiotherapy treatment planning. If modelling of EDW beam in TPS is done correctly, a very good agreement between measurements and calculation is obtained, but EPID cannot be used for reference measurements. PMID:22933916

  2. Flare plasma dynamics obseved with the YOHKOH Bragg crystal spectrometer. III. Spectral signatures of electron-beam-heated atmospheres.

    Science.gov (United States)

    Marriska, John. T.

    1995-05-01

    Using numerical simulations of an electon-beam-heated solar flare, we investigate the observational consequences of variations in the electron beam total energy flux and the low-energy cut off value for models with both low and high initial densities. To do this we use the evolution of the physical parameters of the simulated flares to synthesize the time evolution of the spectrum in the wavelength region surrounding tha Ca xix resonance line. These spectra are then summed over a 9 s time interval to simulate typical spectra from the Yohkoh Bragg crystal spectometer and the first three moments are computed for comparison with observational results. This comparison shows that no single low or high initial density model satisfies the observed average behavior of the Ca xix resonance line. Low initial density models produce too large a blue shift velocity, while high initial density model have lines that are too narrow. Comparison of these models with the Yohkok data suggests that the key problem for models of the impulsive phase ofa solar flare is producing significant amounts of stationary hot plasma early in the flare.

  3. Simulation of a Ball on a Beam Model Using a Fuzzy-dynamic and a Fuzzy-static Sliding-mode Controller

    Directory of Open Access Journals (Sweden)

    Muawia A. Magzoub

    2014-07-01

    Full Text Available This study presents the design of a Fuzzy Static (FS and a Fuzzy Dynamic (FD Sliding-Mode Controllers (SMC for both basic and complete ball on beam system. At first, the FSSMC was designed for the simplified and the complete models. Then, the FDSMC was designed on the simplified and the comprehensive models of the system in which the ball is placed on a beam as well. In addition, the lyapunov stability and linearization were used to check the stability of the system. There is an in-built issue of chattering with (FSSMC. However, (FDSMC counter it well. Also, FDSMC is effective with respect to matched disturbance rejection. It has been found out from this research study that the designs of the models which utilize a FDSMC with a comprehensive model of the system were more efficient than the designs that utilize the basic system’s prototype. Lastly, a comprehensive comparative analysis is provided and MATLAB/SIMULINK outcomes confirm the dominance of FDSMC.

  4. Dynamic Simulation of Torsion Beam Bracket%扭力梁安装支座动力学仿真分析

    Institute of Scientific and Technical Information of China (English)

    王亚南; 宋纪侠; 王彦

    2012-01-01

    In the paper,some torsion beam bracket is simulated with the help of dynamics software Adams/ride and Adams/car.According to contrast,we can conclude that the analysis result of torsion beam bracket in rear suspension assembly Adams/car is the same as that in whole vehicle Adams/ride.And then rear suspension assembly is simulated under different work conditions,and then the main cause of carling outrigger breakage is found out.%运用Adams/ride和Adams/car软件对某车型扭力梁安装支座进行动力学仿真分析。对比分析可知,运用Adams/car对后悬架系统进行扭力梁安装支座的受力分析基本能够模拟其在整车状态下Adams/ride的受力分析。进而对后悬架系统在不同工况下进行受力分析,找出纵梁舷外支架开裂的主要原因。

  5. Beam Loss and Beam Shape at the LHC Collimators

    CERN Document Server

    Burkart, Florian

    In this master thesis the beam loss and the beam shape at the LHC collimators was measured, analysed, presented and discussed. Beginning with a short introduction of the LHC, the experiments, the supercon- ducting magnet system, the basics on linear beam dynamics and a describtion of the LHC collimation system are given. This is followed by the presentation of the performance of the LHC collimation sys- tem during 2011. A method to convert the Beam Loss Monitor signal in Gy/s to a proton beam loss rate will be introduced. Also the beam lifetime during the proton physics runs in 2011 will be presented and discussed. Finally, the shape of the LHC beams is analysed by using data obtained by scraping the beam at the LHC primary collimators.

  6. About improving efficiency of the P3 M algorithms when computing the inter-particle forces in beam dynamics

    Science.gov (United States)

    Kozynchenko, Alexander I.; Kozynchenko, Sergey A.

    2017-03-01

    In the paper, a problem of improving efficiency of the particle-particle- particle-mesh (P3M) algorithm in computing the inter-particle electrostatic forces is considered. The particle-mesh (PM) part of the algorithm is modified in such a way that the space field equation is solved by the direct method of summation of potentials over the ensemble of particles lying not too close to a reference particle. For this purpose, a specific matrix ;pattern; is introduced to describe the spatial field distribution of a single point charge, so the ;pattern; contains pre-calculated potential values. This approach allows to reduce a set of arithmetic operations performed at the innermost of nested loops down to an addition and assignment operators and, therefore, to decrease the running time substantially. The simulation model developed in C++ substantiates this view, showing the descent accuracy acceptable in particle beam calculations together with the improved speed performance.

  7. Pareto front analysis of 6 and 15 MV dynamic IMRT for lung cancer using pencil beam, AAA and Monte Carlo

    DEFF Research Database (Denmark)

    Ottosson, R O; Hauer, Anna Karlsson; Behrens, C.F.

    2010-01-01

    of motion on the dose distribution was investigated. Four non-small cell lung cancer cases were selected for this study. Inverse planning was conducted using Varian Eclipse. A total number of 31 dynamic IMRT plans, distributed amongst the four cases, were created ranging from PTV conformity weighted...

  8. Static and dynamic analysis of Timoshenko beam model based on the finite volume method%Timoshenko梁静力学和动力学问题有限体积法求解

    Institute of Scientific and Technical Information of China (English)

    井丽龙; 张文平; 明平剑; 付丽荣; 刘晓刚

    2015-01-01

    为探究Timoshenko梁模型数值计算方法,开展了基于有限体积法的Timoshenko梁数值计算方法研究. 利用有限体积法对考虑剪切变形的梁进行了离散,并进行了静力学分析和动力学分析,通过几个经典算例将此方法所得到的数值解与解析解及有限元解进行了对比,结果证明,有限体积法有较高精度. 与此同时利用有限体积法离散Timoshenko梁时当梁为细长梁时不存在剪切自锁现象. 有限体积法可以应用于Timoshenko梁模型静力弯曲分析、固有特性和动力响应分析.%In order to explore a numerical simulation method based on the Timoshenko beam model, a study was done on beam numerical simulation using the Timoshenko beam model, based on the finite volume method ( FVM) . In order to examine the beam's shear deformation, the beam model was discretized by FVM, and static and dynamic analyses were conducted. After first calculating some typical examples, the derived numerical results and the analyt-ic solutions with FVM, a comparison was made with the solution by FVM. It is shown that FVM provides high preci-sion analysis, with no shear-locking phenomenon for thin and long beams when discretizing Timoshenko beam based on FVM. This validates FVM for analyzing Timoshenko beam static bending, inherent characteristics, and dynamic response problems.

  9. Tunable Beam Diffraction in Infiltrated Microstructured Fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.;

    We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites....

  10. Remarks on the derivation of the governing equations for the dynamics of a nonlinear beam to a non ideal shaft coupling

    Energy Technology Data Exchange (ETDEWEB)

    Fenili, André; Lopes Rebello da Fonseca Brasil, Reyolando Manoel [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo (Brazil); Balthazar, José M., E-mail: jmbaltha@gmail.com [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo, Brazil and Universidade Estadual Paulista, Faculdade de Engenharia Mec and #x00E (Brazil); Francisco, Cayo Prado Fernandes [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo, Brazil and Instituto de Aeronáutica e Espaço, Departamento de (Brazil)

    2014-12-10

    We derive nonlinear governing equations without assuming that the beam is inextensible. The derivation couples the equations that govern a weak electric motor, which is used to rotate the base of the beam, to those that govern the motion of the beam. The system is considered non-ideal in the sense that the response of the motor to an applied voltage and the motion of the beam must be obtained interactively. The moment that the motor exerts on the base of the beam cannot be determined without solving for the motion of the beam.

  11. Beam Dynamics Feasibility Study for an RFQ Sub-harmonic Pre-buncher at REX-ISOLDE

    CERN Document Server

    Magdau, I B

    2013-01-01

    The feasibility of using an external multi-harmonic buncher placed before the existing RFQ at REX-ISOLDE to increase the bunch spacing of post-accelerated beams at HIE-ISOLDE was confirmed. It was found that with a pre-buncher operating at a subharmonic frequency of 10.128 MHz (a factor 10 below the fundamental frequency of the RFQ) transmissions as high as 80% could be achieved in the main bunches separated by 98.7 ns. Such a time-structure will allow particle identification employing time-offlight techniques to be carried out by the users at HIE-ISOLDE. The optimal effective voltage for a drift length of 1.4 m between the pre-buncher and RFQ was found to be Veff = 0:8 kV, without any deterioration in the simulated nominal rms longitudinal emittance of rms = 0:28 ns keV/u. Significant reduction in the rms longitudinal emittance formed inside the RFQ was observed as the drift distance between the pre-buncher and RFQ was increased and the energy spread imparted by the pre-buncher decreased; within the physica...

  12. Plasma-beam traps and radiofrequency quadrupole beam coolers.

    Science.gov (United States)

    Maggiore, M; Cavenago, M; Comunian, M; Chirulotto, F; Galatà, A; De Lazzari, M; Porcellato, A M; Roncolato, C; Stark, S; Caruso, A; Longhitano, A; Cavaliere, F; Maero, G; Paroli, B; Pozzoli, R; Romé, M

    2014-02-01

    Two linear trap devices for particle beam manipulation (including emittance reduction, cooling, control of instabilities, dust dynamics, and non-neutral plasmas) are here presented, namely, a radiofrequency quadrupole (RFQ) beam cooler and a compact Penning trap with a dust injector. Both beam dynamics studies by means of dedicated codes including the interaction of the ions with a buffer gas (up to 3 Pa pressure), and the electromagnetic design of the RFQ beam cooler are reported. The compact multipurpose Penning trap is aimed to the study of multispecies charged particle samples, primarily electron beams interacting with a background gas and/or a micrometric dust contaminant. Using a 0.9 T solenoid and an electrode stack where both static and RF electric fields can be applied, both beam transport and confinement operations will be available. The design of the apparatus is presented.

  13. Simulation of bending stress variation in long buried thick-walled pipes under the earth’s movement using combined linear dynamics and beam theories

    Directory of Open Access Journals (Sweden)

    Salau Tajudeen A.O.

    2014-01-01

    Full Text Available This study reported a simulation approach to the understanding of the interactions between a buried pipe and the soil system by computing the bending stress variation of harmonically-excited buried pipes. The established principles of linear dynamics theory and simple beam theory were utilised in the analysis of the problem of buried pipe bending stress accumulation and its dynamics. With regards to the parameters that influence the bending stress variations, the most important are the isolation factor, uniform external load, and the corresponding limiting conditions. The simulated mathematical expressions, containing static and dynamic parameters of the buried pipe and earth, were coded in Fortran programming language and applied in the simulation experiment. The results obtained showed that harmonically-excited buried thick-walled pipe became stable and effective when the ratio of the natural frequency of vibration to the forced frequency is greater than 2.0, whenever the damped factor is used as the control parameter for the maximum bending stress. The mirror image of the stress variation produces variation in the location of the maximum bending stress in quantitative terms. The acceptable pipe materials for the simulated cases must have yield strength in bending greater than or equal to 13.95 MPa. The results obtained in this work fill a gap in the literature and will be useful to pipeline engineers and designers, as well as to environmental scientists in initialising and controlling environmental issues and policy formulation concerning the influence of buried pipe on the soil and water in the environment.

  14. Results of long range beam-beam studies and observations during operation in the LHC

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2011-01-01

    We studied possible limitations due to the long range beam-beam effects in the LHC. With a larger number of bunches and collisions in all interaction points, we have reduced the crossing angles to enhance long range beam-beam effects to evaluate their influence on dynamic aperture and losses. Experience from operation with reduced separation was analysed and provides additional evidence.

  15. Population dynamics ofPhilocheras trispinosus (Crangonidae) with abundance of other caridean shrimps (Crustacea:Decapoda) caught by beam trawl in the Southern Black Sea, Turkey

    Institute of Scientific and Technical Information of China (English)

    Sabri Bilgin; Necla Ylmaz

    2016-01-01

    Objective:To determine growth and reproduction biology ofPhilocheras trispinosus (P. trispinosus) with abundance of other caridean shrimps caught by beam trawl in the Southern Black Sea. Methods: Samplings were carried out monthly with a beam trawl of 2 m length and 15 mm cod-end mesh size between December 2012 and November 2013. All individuals were sampled between 1 and 40+ m water depth from 146 hauls. Results:A total of 550P. trispinosus, 618Palaemon adspersus, 12Palaemon serratus, 11Philocheras fasciatus and 10Crangon crangon were sampled during the study period. The crangonid shrimps started appearing during the winter and spring and the number of individuals increased to reach their highest value in mid-winter and mid-spring. The seasonal von Bertalanffy growth parameters forP. trispinosus were estimated asL∞ = 29.3 mm total length,K = 0.860/year,t0 = –0.900 year,C = 0.180, andts= 0.010. The start of the slow growth period was at the beginning of July (WP = 0.510). Ovigerous females appeared in the sampling area between January and April. Size at sexual maturity was estimated as 25.69 mm total length. Conclusions: The results supported the distribution and abundance of caridean shrimp species from the study area and the population dynamics of the most abundant shrimp species,P. trispinosus. The current study can be answered as baseline data prior to management strategies to ensure sustainable conservation of the shrimp species.

  16. ARTICLE Crossed Beams Study on the Dynamics of CI Atom Reaction with Silane%交叉分子束研究氯原子与硅烷的反应动力学

    Institute of Scientific and Technical Information of China (English)

    肖重发; 沈关林; 王秀岩; 杨学明

    2011-01-01

    The dynamics of the C1+SiH4 reaction has been studied using the universal crossed molecular beam method.Angular resolved time-of-flight spectra have been measured for the channel SiH3Cl+H.Product angular distributions as well as energy distributions in the center-of-mass frame were determined for the channel.Experimental results show that the SiH3Cl product is mainly backward scattered relative to the Cl atom beam direction, suggesting that the channel takes place via a typical SN2 type reaction mechanism.

  17. A combined molecular dynamics and kinetic Monte Carlo calculation to study sputter erosion and beam assisted deposition

    CERN Document Server

    Betz, G

    2002-01-01

    To extend the time scale in molecular dynamics (MD) calculations of sputtering and ion assisted deposition we have coupled our MD calculations to a kinetic Monte Carlo (KMC) calculation. In this way we have studied surface erosion of Cu(1 0 0) under 200-600 eV Cu ion bombardment and growth of Cu on Cu(1 0 0) for deposition at thermal energies up to energies of 100 eV per atom. Target temperatures were varied from 100 to 400 K. The coupling of the MD calculation to a KMC calculation allows us to extend our calculations from a few ps, a time scale typical for MD, to times of up to seconds until the next Cu particle will impinge/be deposited on the crystal surface of about 100 nm sup 2 in size. The latter value of 1 s is quite realistic for a typical experimental sputter erosion or deposition experiment. In such a calculation thermal diffusion processes at the surface and annealing of the surface after energetic ion bombardment can be taken into account. To achieve homo-epitaxial growth of a film the results cle...

  18. Exploring the dynamics of reaction N((2)D)+C2H4 with crossed molecular-beam experiments and quantum-chemical calculations.

    Science.gov (United States)

    Lee, Shih-Huang; Chin, Chih-Hao; Chen, Wei-Kan; Huang, Wen-Jian; Hsieh, Chu-Chun

    2011-05-14

    We conducted the title reaction using a crossed molecular-beam apparatus, quantum-chemical calculations, and RRKM calculations. Synchrotron radiation from an undulator served to ionize selectively reaction products by advantage of negligibly small dissociative ionization. We observed two products with gross formula C(2)H(3)N and C(2)H(2)N associated with loss of one and two hydrogen atoms, respectively. Measurements of kinetic-energy distributions, angular distributions, low-resolution photoionization spectra, and branching ratios of the two products were carried out. Furthermore, we evaluated total branching ratios of various exit channels using RRKM calculations based on the potential-energy surface of reaction N((2)D)+C(2)H(4) established with the method CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p)+ZPE[B3LYP/6-311G(d,p)]. The combination of experimental and computational results allows us to reveal the reaction dynamics. The N((2)D) atom adds to the C=C π-bond of ethene (C(2)H(4)) to form a cyclic complex c-CH(2)(N)CH(2) that directly ejects a hydrogen atom or rearranges to other intermediates followed by elimination of a hydrogen atom to produce C(2)H(3)N; c-CH(2)(N)CH+H is the dominant product channel. Subsequently, most C(2)H(3)N radicals, notably c-CH(2)(N)CH, further decompose to CH(2)CN+H. This work provides results and explanations different from the previous work of Balucani et al. [J. Phys. Chem. A, 2000, 104, 5655], indicating that selective photoionization with synchrotron radiation as an ionization source is a good choice in chemical dynamics research.

  19. Proton Beam Therapy Versus Conformal Photon Radiation Therapy for Childhood Craniopharyngioma: Multi-institutional Analysis of Outcomes, Cyst Dynamics, and Toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Andrew J. [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Greenfield, Brad [Department of Radiation Oncology, Baylor College of Medicine, Houston, Texas (United States); Mahajan, Anita [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Paulino, Arnold C. [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Department of Radiation Oncology, Baylor College of Medicine, Houston, Texas (United States); Okcu, M. Fatih [Department of Pediatrics, Texas Children' s Cancer and Hematology Center, Baylor College of Medicine, Houston, Texas (United States); Allen, Pamela K. [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Chintagumpala, Murali [Department of Pediatrics, Texas Children' s Cancer and Hematology Center, Baylor College of Medicine, Houston, Texas (United States); Kahalley, Lisa S. [Section of Psychology, Texas Children' s Cancer and Hematology Center, Baylor College of Medicine, Houston, Texas (United States); McAleer, Mary F.; McGovern, Susan L. [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Whitehead, William E. [Department of Neurosurgery, Texas Children' s Cancer and Hematology Center, Baylor College of Medicine, Houston, Texas (United States); Grosshans, David R., E-mail: dgrossha@mdanderson.org [Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States)

    2014-10-01

    Purpose: We compared proton beam therapy (PBT) with intensity modulated radiation therapy (IMRT) for pediatric craniopharyngioma in terms of disease control, cyst dynamics, and toxicity. Methods and Materials: We reviewed records from 52 children treated with PBT (n=21) or IMRT (n=31) at 2 institutions from 1996-2012. Endpoints were overall survival (OS), disease control, cyst dynamics, and toxicity. Results: At 59.6 months' median follow-up (PBT 33 mo vs IMRT 106 mo; P<.001), the 3-year outcomes were 96% for OS, 95% for nodular failure-free survival and 76% for cystic failure-free survival. Neither OS nor disease control differed between treatment groups (OS P=.742; nodular failure-free survival P=.546; cystic failure-free survival P=.994). During therapy, 40% of patients had cyst growth (20% requiring intervention); immediately after therapy, 17 patients (33%) had cyst growth (transient in 14), more commonly in the IMRT group (42% vs 19% PBT; P=.082); and 27% experienced late cyst growth (32% IMRT, 19% PBT; P=.353), with intervention required in 40%. Toxicity did not differ between groups. On multivariate analysis, cyst growth was related to visual and hypothalamic toxicity (P=.009 and .04, respectively). Patients given radiation as salvage therapy (for recurrence) rather than adjuvant therapy had higher rates of visual and endocrine (P=.017 and .024, respectively) dysfunction. Conclusions: Survival and disease-control outcomes were equivalent for PBT and IMRT. Cyst growth is common, unpredictable, and should be followed during and after therapy, because it contributes to late toxicity. Delaying radiation therapy until recurrence may result in worse visual and endocrine function.

  20. The stereo-dynamics of collisional autoionization of ammonia by helium and neon metastable excited atoms through molecular beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Falcinelli, Stefano, E-mail: stefano.falcinelli@unipg.it; Vecchiocattivi, Franco [Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia (Italy); Bartocci, Alessio; Cavalli, Simonetta; Pirani, Fernando [Department of Chemistry, Biology, and Biotechnology, University of Perugia, Via Elce di sotto 8, 06123 Perugia (Italy)

    2015-10-28

    A combined analysis of both new (energy spectra of emitted electrons) and previously published (ionization cross sections) experimental data, measured under the same conditions and concerning electronically excited lighter noble gas –NH{sub 3} collisional autoionization processes, is carried out. Such an analysis, performed by exploiting a formulation of the full potential energy surface both in the real and imaginary parts, provides direct information on energetics, structure, and lifetime of the intermediate collision complex over all the configuration space. The marked anisotropy in the attraction of the real part, driving the approach of reagents, and the selective role of the imaginary component, associated to the charge transfer coupling between entrance and exit channels, suggests that reactive events occur almost exclusively in the molecular hemisphere containing the nitrogen lone pair. Crucial details on the stereo-dynamics of elementary collisional autoionization processes are then obtained, in which the open shell nature of the disclosed ionic core of metastable atom plays a crucial role. The same analysis also suggests that the strength of the attraction and the anisotropy of the interaction increases regularly along the series Ne{sup *}({sup 3}P), He{sup *}({sup 3}S), He{sup *}({sup 1}S)–NH{sub 3}. These findings can be ascribed to the strong rise of the metastable atom electronic polarizability (deformability) along the series. The obtained results can stimulate state of the art ab initio calculations focused on specific features of the transition state (energetics, structure, lifetime, etc.) which can be crucial for a further improvement of the adopted treatment and to better understand the nature of the leading interaction components which are the same responsible for the formation of the intermolecular halogen and hydrogen bond.

  1. The stereo-dynamics of collisional autoionization of ammonia by helium and neon metastable excited atoms through molecular beam experiments.

    Science.gov (United States)

    Falcinelli, Stefano; Bartocci, Alessio; Cavalli, Simonetta; Pirani, Fernando; Vecchiocattivi, Franco

    2015-10-28

    A combined analysis of both new (energy spectra of emitted electrons) and previously published (ionization cross sections) experimental data, measured under the same conditions and concerning electronically excited lighter noble gas -NH3 collisional autoionization processes, is carried out. Such an analysis, performed by exploiting a formulation of the full potential energy surface both in the real and imaginary parts, provides direct information on energetics, structure, and lifetime of the intermediate collision complex over all the configuration space. The marked anisotropy in the attraction of the real part, driving the approach of reagents, and the selective role of the imaginary component, associated to the charge transfer coupling between entrance and exit channels, suggests that reactive events occur almost exclusively in the molecular hemisphere containing the nitrogen lone pair. Crucial details on the stereo-dynamics of elementary collisional autoionization processes are then obtained, in which the open shell nature of the disclosed ionic core of metastable atom plays a crucial role. The same analysis also suggests that the strength of the attraction and the anisotropy of the interaction increases regularly along the series Ne*((3)P), He*((3)S), He*((1)S)-NH3. These findings can be ascribed to the strong rise of the metastable atom electronic polarizability (deformability) along the series. The obtained results can stimulate state of the art ab initio calculations focused on specific features of the transition state (energetics, structure, lifetime, etc.) which can be crucial for a further improvement of the adopted treatment and to better understand the nature of the leading interaction components which are the same responsible for the formation of the intermolecular halogen and hydrogen bond.

  2. Beam loading

    CERN Document Server

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  3. 14th international symposium on molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation dynamics; and surfaces.

  4. 14th international symposium on molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    1992-09-01

    This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation & dynamics; and surfaces.

  5. Self accelerating electron Airy beams

    CERN Document Server

    Voloch-Bloch, Noa; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-01-01

    We report the first experimental generation and observation of Airy beams of free electrons. The electron Airy beams are generated by diffraction of electrons through a nanoscale hologram, that imprints a cubic phase modulation on the beams' transverse plane. We observed the spatial evolution dynamics of an arc-shaped, self accelerating and shape preserving electron Airy beams. We directly observed the ability of electrons to self-heal, restoring their original shape after passing an obstacle. This electromagnetic method opens up new avenues for steering electrons, like their photonic counterparts, since their wave packets can be imprinted with arbitrary shapes or trajectories. Furthermore, these beams can be easily manipulated using magnetic or electric potentials. It is also possible to efficiently self mix narrow beams having opposite signs of acceleration, hence obtaining a new type of electron interferometer.

  6. Electron beam induced and microemulsion templated synthesis of CdSe quantum dots: tunable broadband emission and charge carrier recombination dynamics

    Science.gov (United States)

    Guleria, Apurav; Singh, Ajay K.; Rath, Madhab C.; Adhikari, Soumyakanti

    2015-04-01

    CdSe quantum dots (QDs) were synthesized by a rapid and one step templated approach inside the water pool of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) based water-in-oil microemulsions (MEs) via electron beam (EB) irradiation technique with high dose rate, which favours high nucleation rate. The interplay of different experimental parameters such as precursor concentration, absorbed dose and {{W}0} values (aqueous phase to surfactant molar ratio) of MEs were found to have interesting consequences on the morphology, photoluminescence (PL), surface composition and carrier recombination dynamics of as-grown QDs. For instance, highly stable ultrasmall (∼1.7 nm) bluish-white light emitting QDs were obtained with quantum efficiency (η) of ∼9%. Furthermore, QDs were found to exhibit tunable broadband light emission extending from 450 to 750 nm (maximum FWHM ∼180 nm). This could be realized from the CIE (Commission Internationale d’Eclairage) chromaticity co-ordinates, which varied across the blue region to the orange region thereby, conferring their potential application in white light emitting diodes. Additionally, the average PL lifetime ≤ft( ≤ft \\right) values could be varied from 18 ns to as high as 74 ns, which reflect the role of surface states in terms of their density and distribution. Another interesting revelation was the self-assembling of the initially formed QDs into nanorods with high aspect ratios ranging from 7 to 20, in correspondence with the {{W}0} values. Besides, the fundamental roles of the chemical nature of water pool and the interfacial fluidity of AOT MEs in influencing the photophysical properties of QDs were investigated by carrying out a similar study in CTAB (cetyltrimethylammonium bromide; cationic surfactant) based MEs. Surprisingly, very profound and contrasting results were observed wherein ≤ft and η of the QDs in case of CTAB MEs were found to be at least three times lower as compared to that in AOT MEs.

  7. Controlling of Beam Halo-chaos by Adaptation Method

    Institute of Scientific and Technical Information of China (English)

    FANGJin-qing; GAOYuan; LUOXiao-shu

    2003-01-01

    In this paper, the parametric adaptation method for controlling the beam halo-chaos in the periodic focusing channels of high-current proton linacs is proposed. The study of proton beam halo-chaos based on controlled beam envelope equation and the Particles-in-Cell simulations for proton beam dynamics show that the proton beam chaotic envelope as well as the beam rsm radius can be controlled to the matched radius using this method.

  8. Parametric resonance in concrete beam-columns

    OpenAIRE

    Sharma,Mamta R.; Singh,Arbind K; Benipal,Gurmail S

    2014-01-01

    A dynamic instability, called parametric resonance, is exhibited by undampedelastic beam-columns when under the action of pulsating axial force. The scope of the existing theory of parametric resonance is restricted to physically linear beam-columns undergoing finite lateral displacements. In this Paper, the dynamic behaviour of physically nonlinear elastic cracked concrete beam-columns under pulsating axial force and constant lateral force is investigated. The constitutive equations derived ...

  9. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB.

    Science.gov (United States)

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  10. Beam collimator

    CERN Multimedia

    1977-01-01

    A four-block collimator installed on a control table for positioning the alignment reference marks. Designed for use with SPS secondary beams, the collimator operates under vacuum conditions. See Annual Report 1976 p. 121 and photo 7701014.

  11. 集中载荷作用下饱和多孔Timoshenko简支梁的动力响应%DYNAMICAL BEHAVIOR OF SIMPLY-SUPPORTED SATURATED POROELASTIC TIMOSHENKO BEAM UNDER A CONCENTRATED LOAD

    Institute of Scientific and Technical Information of China (English)

    欧阳煜; 张雅男

    2012-01-01

    Based on the mathematical model for dynamics of a saturated poroelastic Timoshenko beam, the dynamical behavior of a simply-supported saturated poroelastic Timoshenko beam, with two permeable ends and subjected to a sudden step load at its midpoint, is investigated. The analytical solution is obtained, and the variations of the dimensionless deflections, bending moments of the solid skeleton of the poroelastic beam, and equivalent couples of the pore fluid pressure against the dimensionless time are given. The effects of the shearing and rotation inertia of the cross section on the dynamical behavior are examined, and the dynamical behaviors of the saturated poroelastic Timoshenko, Shear, Rayleigh and Euler-Bernoulli beams are compared. It is shown that the shearifig effect increases the amplitudes and periods of the dynamical responses of the saturated poroelastic Timoshenko beam, while the rotation inertia effect of the cross section only increases the periods. The interaction between the solid skeleton and pore fluid plays a role as viscidity. With the interaction coefficient increasing, the deflections and bending moments of the saturated poroelastic beam decrease, and the amplitudes of the equivalent couple of the pore fluid pressure increase, furthermore, the attenuation of the vibration amplitudes is more rapidly with the increasing of the interaction coefficient. Meanwhile, with the slenderness ratio increasing, the amplitude and period of the saturated poroelastic Timoshenko beam decrease gradually, and they converge to those of the saturated poroelastic Euler-Bernoulli beam.%基于饱和多孔弹性Timoshenko梁的动力数学模型,研究了梁中点承受突加载荷作用两端可渗透饱和多孔弹性Timoshenko简支梁的动力响应,得到了问题的解析解,给出了梁中点无量纲挠度、固相骨架弯矩和孔隙流体压力等效力偶等随无量纲时间的响应。考察了剪切和横截面转动惯性效应等对动力响应

  12. Proceedings of the 1997 Particle Accelerator Conference Held in Vancouver, B.C., Canada on 12-16 May 1997. Volume 2: Beam Dynamics, Instrumentation and Controls.

    Science.gov (United States)

    2007-11-02

    Construction reports range from the CERN Large Hadron Collider and the Fermilab Main Injector and Recycler, to the BESSY-II light source and the TRIUMF-ISAC...include the initial operation of the SPring-8 light source, the PEP-II B-factory high-energy ring, the CERN LEP2 collider , and one sextant of RHIC...radioactive beam facility. Upcoming projects described include the US Spallation Neutron Source, the Japanese Hadron Facility and the RIKEN Beam

  13. Weak-strong Beam-beam Simulations for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Banfi, Danilo [Ecole Polytechnique, Lausanne; Barranco, Javier [Ecole Polytechnique, Lausanne; Pieloni, Tatiana [CERN; Valishev, Alexander [Fermilab

    2014-07-01

    In this paper we present dynamic aperture studies for possible High Luminosity LHC optics in the presence of beam-beam interactions, crab crossing schemes and magnets multipolar errors. Possible operational scenarios of luminosity leveling by transverse offset and betatron function are also studied and the impact on the beams stability is discussed.

  14. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  15. Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC Ⅱ. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.

  16. Cold and Slow Molecular Beam

    CERN Document Server

    Lu, Hsin-I; Wright, Matthew J; Patterson, Dave; Doyle, John M

    2011-01-01

    Employing a two-stage cryogenic buffer gas cell, we produce a cold, hydrodynamically extracted beam of calcium monohydride molecules with a near effusive velocity distribution. Beam dynamics, thermalization and slowing are studied using laser spectroscopy. The key to this hybrid, effusive-like beam source is a "slowing cell" placed immediately after a hydrodynamic, cryogenic source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH beams are created in two regimes. One modestly boosted beam has a forward velocity of vf = 65 m/s, a narrow velocity spread, and a flux of 10^9 molecules per pulse. The other has the slowest forward velocity of vf = 40 m/s, a longitudinal temperature of 3.6 K, and a flux of 5x10^8 molecules per pulse.

  17. Asymmetric acoustic transmission in graded beam

    Science.gov (United States)

    Jing, Li; Wu, Jiu Hui; Guan, Dong; Lu, Kuan; Gao, Nansha; Songhua, Cao

    2016-12-01

    We demonstrate the dynamic effective material parameters and vibration performance of a graded beam. The structure of the beam was composed of several unit cells with different fill factors. The dispersion relations and energy band structures of each unit cell were calculated using the finite element method (FEM). The dynamic effective material parameters in each unit cell of the graded beam were determined by the dispersion relations and energy band structures. Longitudinal wave propagation was investigated using a numerical method and FEM. The results show that the graded beam allows asymmetric acoustic transmission over a wide range of frequencies.

  18. Research into 2D Dynamics and Control of Small Oscillations of a Cross-Beam during Transportation by Two Overhead Cranes

    Directory of Open Access Journals (Sweden)

    Alexander V. Perig

    2017-01-01

    Full Text Available A new mathematical model of a 3DOF 2D mechanical system “transported cross-beam, two moving bridge cranes” has been proposed. Small system oscillations have been derived through the introduction of Lagrange equations. The numerical estimation of 3DOF system motion has been carried out with equation-based Modelica language. The present article uses the Lagrange method and numerical and optimization methods, realized with JModelica.org and Optimica freeware. The absolute swaying of the cross-beam with respect to the displacement of the two moving bridge cranes was estimated. The phase portraits of the 3DOF system for linear and angular coordinates were presented. An open loop optimal control problem was posed for the motion of the bridge cranes. A “bang-bang” control strategy was implemented for the derivation of an optimal control solution, which enables the travel of two bridge cranes at a prescribed distance for minimum time and minimum swaying of a heavy cross-beam. The derived results of the numerical simulation can be easily practically realized by crane operators with good agreement with simple engineering estimations. The proposed control strategy enables synchronous motion of two bridge cranes with a cross-beam that practically solves the posed problem of unwanted excessive oscillations of a heavy cross-beam during transportation.

  19. Sensitive beam current measurement for FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, Marcus; Kurian, Febin; Reeg, Hansjoerg [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Seidel, Paul; Neubert, Ralf [Friedrich-Schiller-Universitaet Jena (Germany); Geithner, Rene; Vodel, Wolfgang [Helmholtz-Institut Jena (Germany)

    2012-07-01

    Presently FAIR, the Facility for Antiproton and Ion Research, entered the final planning phase at GSI. The new accelerator facility requires precise devices for beam current measurements due to the large dynamics in beam intensities for the various synchrotrons, transport lines and storage rings. We report on the actual developments of beam diagnostic devices for the measurement of beam intensities ranging from 5 x 10{sup 11} uranium ions down to the detection of less than 10{sup 4} antiprotons. This contribution gives an overview of the planned instruments with a focus on non-intercepting beam current transformers, and summarizes the on-going development of a cryogenic current comparator.

  20. Laser wakefield acceleration of polarized electron beams

    Science.gov (United States)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  1. Dynamics

    CERN Document Server

    Goodman, Lawrence E

    2001-01-01

    Beginning text presents complete theoretical treatment of mechanical model systems and deals with technological applications. Topics include introduction to calculus of vectors, particle motion, dynamics of particle systems and plane rigid bodies, technical applications in plane motions, theory of mechanical vibrations, and more. Exercises and answers appear in each chapter.

  2. A Schrdinger formulation research for light beam propagation

    Institute of Scientific and Technical Information of China (English)

    刘承宜; 郭弘; 胡巍; 邓锡铭

    2000-01-01

    The wave equation of light beam propagation was written in the form of an axial-coordinate-dependent Schrodinger equation, and the expectation value of a dynamical variable, the trial function of variational approach and the ABCD law were discussed by use of quantum mechanics approach. In view of the evolution equations of expectation values of dynamical variables in the framework of quantum mechanics, the definition of a potential function representing the beam propagation stability and its universal formula with the quality factor, the universal formula of beam width and curvature radius for a paraxial beam and cylindrically symmetric non-paraxial beam, the general formula of second derivative of beam width with respect to the axial coordinate of beam for a paraxial beam, and the general criteria of the conservation of beam quality factor and the existence of a potential well of a potential function for a paraxial beam, were given or derived, respectively. Starting with the same trial function, the co

  3. INVESTIGATION OF DYNAMIC PARAMETRS OF SPLIT SKEWED BRIDGE SPANS IN CASE OF LOSS OF CONTACT BETWEEN END BEAM AND ITS SUPPORT

    Directory of Open Access Journals (Sweden)

    V.S.Safronov

    2015-02-01

    Full Text Available Statement of the problem. In order to get a valid estimate of risks of fracture during the mainten-ance of simply supported skew slab-and-girder reinforced concrete spans of highway bridges the influence of the supporting skew on the natural frequencies spectrum and the corresponding ei-genmodes in case of changing the design model due to loss of contact between beams and support.Results. Possible loss of contact between one of the marginal beams and its support near the sharp angle during the maintenance of transport facility depending on its type and geometrical parameters is substantiated. Modal and frequency spectrum analysis of spans in case of loss of contact between one of the marginal beams and its support is performed.Conclusions. The analysis revealed possible loss of contact between marginal beams and support, which increases as the skew angle grows and the width and length of the span reduce. A signifi-cant influence of support separation on eigenmodes and frequency spectrum of spans is revealed.

  4. Experimental observations and theoretical models for beam-beam phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Kheifets, S.

    1981-03-01

    The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10/sup 10/-10/sup 11/ and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented.

  5. Slow light beam splitter.

    Science.gov (United States)

    Xiao, Yanhong; Klein, Mason; Hohensee, Michael; Jiang, Liang; Phillips, David F; Lukin, Mikhail D; Walsworth, Ronald L

    2008-07-25

    We demonstrate a slow light beam splitter using rapid coherence transport in a wall-coated atomic vapor cell. We show that particles undergoing random and undirected classical motion can mediate coherent interactions between two or more optical modes. Coherence, written into atoms via electromagnetically induced transparency using an input optical signal at one transverse position, spreads out via ballistic atomic motion, is preserved by an antirelaxation wall coating, and is then retrieved in outgoing slow light signals in both the input channel and a spatially-separated second channel. The splitting ratio between the two output channels can be tuned by adjusting the laser power. The slow light beam splitter may improve quantum repeater performance and be useful as an all-optical dynamically reconfigurable router.

  6. Emittance Compensation in a Flat Beam RF Photoinjector

    Science.gov (United States)

    Rosenzweig, J. B.; Anderson, S.; Colby, E.; Serafini, L.

    1997-05-01

    The beam dynamics of a flat beam rf photoinjector, which is intended to produce asymmetric emittances for linear collider applications, are analyzed, by both analytical and computational methods. The analytical model is a generalization of the recently developed theory of emittance compensation in round beams(L.Serafini, and J.B. Rosenzweig, submitted to Physical Review E.), in which a new mode of laminar flow beam dynamics, the invariant envelope, is found to give the ideal conditions for emittance minimization. Three-dimensional rf and beam dynamics simulations are used to iluminate the analytical results. abstract.

  7. Fast method of the identification of dynamic load location on the beam%梁结构上动载荷位置识别的快速算法

    Institute of Scientific and Technical Information of China (English)

    张景; 张方; 姜金辉; 蒋祺

    2016-01-01

    This paper used a simply supported beam as a study objective ,and set up the finite element model of the beam by PATRAN to obtain the simulating displacement response of the beam .The code was written in MATLAB to identify the location of the dynamic load acting on the beam .This paper proposed a fast method based on the minimum discrimi‐nate coefficient method ,and it identified the the location of the dynamic load by the way of gradually approach .Com‐pared with the common method ,this method cut back the calculation process and time by reduce the division of the finite elements .Simulation showed that this fast method reduced the time of calculation with ensuring the accuracy and exact‐ness of the identification ,which brought convenience to the work of identifying dynamic loads .%将简支梁作为研究对象,通过PATRAN软件建立梁的有限元模型,仿真计算出梁的位移响应,再利用MATLAB编写算法,识别出作用在梁上的动载荷的位置。在最小判别系数法的基础上提出了一种快速算法,该算法通过逐步逼近的方式来识别动载荷的作用位置。与常规方法相比,该快速算法减少了有限单元的划分,所以有效地减少了计算过程并且缩短了计算时间。通过仿真计算,验证了这一快速算法在保证了识别精度和准确性的前提下,缩短了计算时间,为动载荷识别工作带来了便利。

  8. Evaluation of parotid function using dynamic parotid scintigraphy in nasopharyngeal carcinoma patients treated with external beam radiation therapy%腮腺动态显像评价鼻咽癌放疗对腮腺功能的影响

    Institute of Scientific and Technical Information of China (English)

    何小江; 黄劲雄; 俞浩; 吴华

    2008-01-01

    Objective To evaluation of the parotid function using dynamic parotid scintigraphy in nasopharyngeal carcinoma patients treated with external beam radiation therapy. Methods Twenty-one nasopharyngeal carcinoma patients were included into this study. Dynamic parotid scintigraphy was performed before and after external beam radiation therapy. Semi-qnantitative parameters of parotid (uptake index, excretion rate and excretion index) was used to evaluate the changes of parotid function. Results UI, ER and El of parotid were decreased markedly after external beam radiation therapy, t is 56.65, 41.34, 30.69 respectively, P<0.001. The uptake and excretion function of the parotid were all impaired, which correlated with the dry mouth symptom of the patients. Conclusion Dynamic parotid scintigraphy can play a key role in the evaluation of parotid function in nasopharyngeal carcinoma patients treated with external beam radiation therapy.%目的 探讨腮腺动态显像评价鼻咽癌放疗对腮腺功能影响的价值.方法 21例鼻咽癌患者分别于放疗前、后行放射性核素腮腺动态显像,计算腮腺摄取指数(UI)、酸刺激后的分泌率(ER)、分泌指数(EI)等半定量指标以评价放疗前后腮腺功能的变化.结果 放疗后与放疗前比较,所有患者UI、ER、EI均显著下降,t值分别为56.65、41.34、30.69, P<0.001,腮腺摄取与分泌功能均明显受损.与患者临床口干症状相符.结论 腮腺动态显像是一种评价鼻咽癌放疗对腮腺功能的影响的有用方法,具有临床应用价值.

  9. Simulating Transient Effects of Pulsed Beams on Beam Intercepting Devices

    CERN Document Server

    Richter, Herta; Noah Messomo, Etam

    2011-01-01

    The development in the physics community towards higher beam power through the possibilities of particle accelerators lead to challenges for the developers of elements which are exposed to effect of particle beams (beam intercepting devices = BIDs). For the design of BIDs, the increasing heat load onto these devices due to energetic and focused beams and - in most cases - their highly pulsed nature has to be taken into account. The physics requirements are sometimes opposed to the current state of the art. As one possibility of many in combining the different aspects for these ambitious demands, two highly developed computer programs, namely FLUKA and ANSYS AUTODYN, were joined for this dissertation. The former is a widely enhanced Monte-Carlo-code which specializes on the interaction of particles with static matter, while the latter is a versatile explicit code for the simulation of highly dynamic processes. Both computer programs were developed intensively over years and are still continuously enhanced in o...

  10. Transverse vibration of nematic elastomer Timoshenko beams

    Science.gov (United States)

    Zhao, Dong; Liu, Ying; Liu, Chuang

    2017-01-01

    Being a rubber-like liquid crystalline elastomer, a nematic elastomer (NE) is anisotropic viscoelastic, and displays dynamic soft elasticity. In this paper, the transverse vibration of a NE Timoshenko beam is studied based on the linear viscoelasticity theory of nematic elastomers. The governing equation of motion for the transverse vibration of a NE Timoshenko beam is derived. A complex modal analysis method is used to obtain the natural frequencies and decrement coefficients of NE beams. The influences of the nematic director rotation, the rubber relaxation time, and the director rotation time on the vibration characteristic of NE Timoshenko beams are discussed in detail. The sensitivity of the dynamic performance of NE beams to director initial angle and relaxation times provides a possibility of intelligent controlling of their dynamic performance.

  11. Beam instability Workshop - plenary sessions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions.

  12. A Real-Time FPGA based Algorithm for the combination of Beam Loss Acquisition Methods used for Measurement Dynamic Range expansion

    CERN Document Server

    Kwiatkowski, M; Alsdorf, M; Dehning, B; Vigano, W

    2012-01-01

    The aim of the Beam Loss Monitoring Dual Polarity (BLEDP) module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. The BLEDP module consists of eight analogue channels each with a fully differential integrator and an accompanying 16 bit ADC at the output of each analogue integrator. The on-board FPGA device controls the integral periods, instructs the ADC devices to perform measurements at the end of each period and collects the measurements. In the next stage it combines the number of charge and discharge cycles accounted in the last interval together with the cycle fractions observed using the ADC samples to produce a digitised high precision value of the charges collected. This paper describes briefly the principle of the fully differential integrator and focuses on the algorithm employed to process the digital data.

  13. Development of 2D particle-in-cell code to simulate high current, low energy beam in a beam transport system

    Indian Academy of Sciences (India)

    S C L Srivastava; S V L S Rao; P Singh

    2007-10-01

    A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of -uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.

  14. Operational Modal Analysis on laminated glass beams

    OpenAIRE

    López Aenlle, Manuel; Fernández, Pelayo; Villa García, Luis Manuel; Barredo Egusquiza, Josu; Hermanns, Lutz Karl Heinz; Fraile de Lerma, Alberto

    2011-01-01

    Laminated glass is a sandwich element consisting of two or more glass sheets, with one or more interlayers of polyvinyl butyral (PVB). The dynamic response of laminated glass beams and plates can be predicted using analytical or numerical models in which the glass and the PVB are usually modelled as linear-elastic and linear viscoelastic materials, respectively. In this work the dynamic behavior of laminated glass beams are predicted using a finite element model and the analytical model ...

  15. Beam screens for the LHC beam pipes

    CERN Multimedia

    Patrice Loïez

    1997-01-01

    Cross-section of LHC prototype beam pipes showing the beam screens. Slits in the screens allow residual gas molecules to be pumped out and become frozen to the walls of the ultra-cold beam pipe. Beam screens like these have been designed to line the beam pipes, absorbing radiation before it can hit the magnets and warm them up, an effect that would greatly reduce the magnetic field and cause serious damage.

  16. The dynamics of small-scale patchiness of plaice and sole as reflected in the catch rates of the Dutch beam trawl fleet and its implications for the fleet dynamics

    NARCIS (Netherlands)

    Poos, J.J.; Rijnsdorp, A.D.

    2007-01-01

    Catch rates of sole Solea solea and plaice Pleuronectes platessa in the Dutch beam trawl fleet operating in the North Sea show spatio-temporal variation. The variation in catch rates reflects differences in abundance of the species. Up to 45% of the variation in catch rates can be explained by the t

  17. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  18. Impurity Dynamics under Neutral Beam Injection at TJ-II (simulation); Dinamica de Impurezas durante la Inyeccion de Haces Neutros en el TJ-II (simulacion)

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.; Fuentes, C.; Liniers, M.

    2001-07-01

    In this study the simulations of plasma transport under NBI for TJ-II, previously performed, are extended. Since than a considerable number of important modifications have been introduced in the model: change of magnetic configuration, use of experimental initial profiles, expansion of the Data base from NBI calculations and, mainly, a detailed handling of impurities with inclusion of sputtering effects. Moreover there is now a particular emphasis on the analysis of the conditions for discharge collapse and on the possible effects of single beam injection. This analysis of impurity behaviour with sputtering shows that in the expected usual cases there is no radioactive collapse and that if the recycling coefficients remain lower the unity it is always possible to find a strategy for external gas puffing leading to a stationary state, with densities below the limit and efficient NBI absorption (>50%). The radioactive collapse can appear either at high densities (central value higher than 1.4x10''20 m''3), excessive influx of impurities (i. e. with sputtering rates higher than twice the expected values) o for insufficient injected beam power (less than 45 kW). The present study analyses only the 100{sub 4}4{sub 6}4 configuration of TJ-II, but future works will start a systematic scan of configuration using this same model. (Author) 12 Refs.

  19. 带动态边界的非均匀Timoshenko梁的反馈镇定%Feedback stabilization of nonuniform Timoshenko beam with dynamical boundary

    Institute of Scientific and Technical Information of China (English)

    阎庆旭; 冯德兴

    2003-01-01

    The boundary feedback consol problem for a nonuniform Timoshenko beam with a load at one end was stud-ied. First, a boundary feedback control scheme was proposed, and the well-posedness of the corresponding closed loop systemwas established. Then by using the multiplier method, it was proved that the closed loop system was exponentially stable if twoboundary feedback controls were applied simultaneously to the beam's tip where the load was carried.%对于一端具负载的非均质Timoshenko梁,研究了其边界反馈镇定问题.首先提出了一种边界反馈控制方案,建立了相应的闭环系统的适定性.然后利用乘子法证明了,当两个边界反馈控制同时作用于梁的负载端时,闭环系统是指数稳定的.

  20. Airy beam optical parametric oscillator.

    Science.gov (United States)

    Aadhi, A; Chaitanya, N Apurv; Jabir, M V; Vaity, Pravin; Singh, R P; Samanta, G K

    2016-05-04

    Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51-1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).

  1. The logarithmic beam position monitor

    Science.gov (United States)

    Medvedko, Evgeny A.; Smith, Stephen R.

    2000-11-01

    Modern logarithmic amplifiers offer wide dynamic range, high bandwidth, good logarithmic conformance, and low cost making them attractive for beam position measurements. A log-ratio beam position monitor has been designed and built at SLAC for use at the PEP-II B-Factory. An integrated circuit logarithmic amplifier from Analog Devices, the AD8307, recovers the envelope of the 476 MHz harmonic of the beam signal. A log BPM board with two logarithmic and one differential amplifier performs the basic function of forming an output voltage proportional to the difference of the logarithms of the signal amplitudes on opposite electrodes. This voltage is approximately linear with beam position. For this application, we have limited the video bandwidth of the log amps to 50 kHz in order to remove fill pattern dependence. The log BPM board has an interface for testing and simulating beam offsets. The log BPMs were developed for a PEP-II ring protection chassis. Here the log BPMs function to identify dangerous orbit excursions. These excursions are signaled to a system, which can dump the beam. Two such chassis serve to protect the PEP-II rings.

  2. Dynamic characteristic analysis of an open-loop system for an intelligent beam with interval parameters%区间参数智能梁结构开环系统动力特性分析

    Institute of Scientific and Technical Information of China (English)

    王敏娟; 陈建军; 魏永祥; 张超; 马洪波

    2012-01-01

    Structures with a piezoelectric intelligent beam were taken as study objects here. According to the method of interval analysis, the interval models of mass matrix and stiffness matrices with interval variables for structural physical parameters and geometric dimensions were built. From Rayleigh quotient for dynamic characteristic of structural vibration, and based on the interval algorithms, the computation expressions of natural frequencies of a structural open-loop system were deduced. Through an example, the effects of the uncertainty of the structural interval parameters on the structural natural frequency were inspected, and the model constructed and the method proposed here were verified. It was shown that the interval coefficient method is applicable in dealing with the dynamic characteristic of an open-loop system of an intelligent beam.%以区间参数压电智能梁结构为研究对象,在材料性能参数和几何尺寸为区间变量时采用区间分析法建立了结构质量矩阵和刚度矩阵的区间模型.从求解结构振动动态特性的Rayleigh商出发,利用区间变量运算法则推导出了结构开环系统固有频率的数字特征表达式.通过算例,考察了区间参数对结构固有频率特性的影响,验证了所建模型和方法的可行性与合理性.研究结果表明,文中利用区间系数分析法来研究压电智能梁结构开环系统的动力特性具有一定的工程应用价值.

  3. Optical Properties and Carrier Dynamics of GaAs/GaInAs Multiple-Quantum-Well Shell Grown on GaAs Nanowire by Molecular Beam Epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kwangwook; Ravindran, Sooraj; Ju, Gun Wu; Min, Jung-Wook; Kang, Seokjin; Myoung, NoSoung; Yim, Sang-Youp; Jo, Yong-Ryun; Kim, Bong-Joong; Lee, Yong Tak

    2016-12-01

    GaAs/GaInAs multiple-quantum-well (MQW) shells having different GaInAs shell width formed on the surface of self-catalyzed GaAs core nanowires (NWs) are grown on (100) Si substrate using molecular beam epitaxy. The photoluminescence emission from GaAs/GaInAs MQW shells and the carrier lifetime could be varied by changing the width of GaInAs shell. Time-resolved photoluminescence measurements showed that the carrier lifetime had a fast and slow decay owing to the mixing of wurtzite and zinc-blende structures of the NWs. Furthermore, strain relaxation caused the carrier lifetime to decrease beyond a certain thickness of GaInAs quantum well shells.

  4. Beam studies for the Proton Improvement Plan (PIP) -- reducing beam loss at the Fermilab Booster

    CERN Document Server

    Seiya, K; Johnson, D E; Kapin, V V; Pellico, W A; Tan, C Y; Tesarek, R J

    2015-01-01

    The Fermilab Booster is being upgraded under the Proton Improvement Plan (PIP) to be capable of providing a proton flux of $2.25^{17}$ protons per hour. The intensity per cycle will remain at the present operational $4.3^{12}$ protons per pulse, however the Booster beam cycle rate is going to be increased from 7.5 Hz to 15 Hz. One of the biggest challenges is to maintain the present beam loss power while the doubling the beam flux. Under PIP, there has been a large effort in beam studies and simulations to better understand the mechanisms of the beam loss. The goal is to reduce it by half by correcting and controlling the beam dynamics and by improving operational systems through hardware upgrades. This paper is going to present the recent beam study results and status of the Booster operations.

  5. Beam emittance reduction during operation of Indus-2

    Energy Technology Data Exchange (ETDEWEB)

    Fakhri, Ali Akbar, E-mail: fakhri@rrcat.gov.in; Kant, Pradeep; Ghodke, A. D.; Singh, Gurnam [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2015-11-15

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed.

  6. Periodic verification of beam with wedge dynamics through analysis of dynalog files; Verificacion periodica de hace con cuna dinamica mediante analisis de los archivos dynalog

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, C.; Perez-Alija, J.; Pedro, A.

    2013-07-01

    During the administration of the field such information is it sampled and collected in files called Dynalog. The objective of this work is the analysis of these files as a complement to regular quality control of the EDW technique, as well as the independent verification system of generation and control of dynamic wedge fields. (Author)

  7. The peculiarities of the dynamics of the relief induced by two-beam laser interference of silicon surface near the melting threshold

    Energy Technology Data Exchange (ETDEWEB)

    Libenson, M.N.; Makin, V.S.; Pestov, Yu.I.; Trubaev, V.V. [S.I. Vavilov State Optical Institute, Leningrad (Russian Federation)

    1996-12-31

    To study the material mechanisms of laser-induced silicon microrelief formation the periodic space-modulated heating up to melting point was used. On the basis of measurements of dynamics of surface thermal radiation and of the relief height the conclusion about material mechanisms of relief formation had been made.

  8. Analysis of transmission efficiency of SSRF electron beam transfer lines

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this article, the main factors which influence transmission efficiency of the SSRF electron beam transfer lines are described, including physical requirements for magnet system, vacuum system, beam diagnostic system,trajectory correction system, etc. The dynamic simulation calculation and transmission efficiency analysis of the SSRF electron beam transfer lines are presented, and the studies show that the design purpose of efficient beam transmission and injection will be achieved.

  9. A new method for beam stacking in storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2008-06-01

    Recently, I developed a new beam stacking scheme for synchrotron storage rings called 'longitudinal phase-space coating' (LPSC). This scheme has been convincingly validated by multi-particle beam dynamics simulations and has been demonstrated with beam experiments at the Fermilab Recycler. Here, I present the results from both simulations and experiments. The beam stacking scheme presented here is the first of its kind.

  10. Beam imaging sensor

    Energy Technology Data Exchange (ETDEWEB)

    McAninch, Michael D.; Root, Jeffrey J.

    2016-07-05

    The present invention relates generally to the field of sensors for beam imaging and, in particular, to a new and useful beam imaging sensor for use in determining, for example, the power density distribution of a beam including, but not limited to, an electron beam or an ion beam. In one embodiment, the beam imaging sensor of the present invention comprises, among other items, a circumferential slit that is either circular, elliptical or polygonal in nature.

  11. Ultracold ordered electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.

    1988-01-01

    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  12. Preservation of beam loss induced quenches, beam lifetime and beam loss measurements with the HERAp beam-loss-monitor system

    Science.gov (United States)

    Wittenburg, Kay

    1994-06-01

    The beam-loss-monitors (BLMs) in the HERA-proton-ring (HERAp) must fulfill the following requirements: They have to measure losses sensitive and fast enough to prevent the superconducting magnets from beam loss induced quenching; the dynamic range of the monitors must exceed several decades in order to measure losses during beam lifetimes of hundreds of hours as well as the much stronger losses that may quench superconducting magnets; they have to be insensitive to the synchrotron radiation of the adjacent electron-ring (HERAe); and their radiation hardness must allow a monitor-lifetime of a few years of HERA operation. These requirements are well satisfied by the HERAp-BLM-System.

  13. 23rd June 2010 - University of Bristol Head of the Aerospace Engineering Department and Professor of Aerospace Dynamics N. Lieven visiting CERN control centre with Beams Department Head P. Collier, visiting the LHC superconducting magnet test hall with R. Veness and CMS control centre with Collaboration Spokesperson G. Tonelli and CMS User J. Goldstein.

    CERN Multimedia

    Jean-Claude Gadmer

    2010-01-01

    23rd June 2010 - University of Bristol Head of the Aerospace Engineering Department and Professor of Aerospace Dynamics N. Lieven visiting CERN control centre with Beams Department Head P. Collier, visiting the LHC superconducting magnet test hall with R. Veness and CMS control centre with Collaboration Spokesperson G. Tonelli and CMS User J. Goldstein.

  14. A plasma wakefield acceleration experiment using CLARA beam

    CERN Document Server

    Xia, G; Clarke, J; Smith, J; Cormier-Michel, E; Jones, J; Williams, P H; Mckenzie, J W; Militsyn, B L; Hanahoe, K; Mete, O; Aimidula, A; Welsch, C P

    2014-01-01

    We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility CLARA (Compact Linear Accelerator for Research and Applications) at Daresbury Laboratory. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in electron beam driven plasma wakefield acceleration, e.g. high gradient plasma wakefield excitation driven by a relativistic electron bunch, two bunch experiment for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and some other advanced beam dynamics issues. This paper presents the feasibility studies of electron beam transport to meet the requirements for beam driven wakefield acceleration and presents the plasma wakefield simulation results based on CLARA beam parameters. Other possible experiments which can be conducted at the PARS beam line are also discussed.

  15. Chemical reaction dynamics of Rydberg atoms with neutral molecules: a comparison of molecular-beam and classical trajectory results for the H(n)+D2-->HD+D(n') reaction.

    Science.gov (United States)

    Song, Hui; Dai, Dongxu; Wu, Guorong; Wang, Chia Chen; Harich, Steven A; Hayes, Michael Y; Wang, Xiuyan; Gerlich, Dieter; Yang, Xueming; Skodje, Rex T

    2005-08-15

    Recent molecular-beam experiments have probed the dynamics of the Rydberg-atom reaction, H(n)+D2-->HD+D(n) at low collision energies. It was discovered that the rotationally resolved product distribution was remarkably similar to a much more limited data set obtained at a single scattering angle for the ion-molecule reaction H++D2-->D++HD. The equivalence of these two problems would be consistent with the Fermi-independent-collider model (electron acting as a spectator) and would provide an important new avenue for the study of ion-molecule reactions. In this work, we employ a classical trajectory calculation on the ion-molecule reaction to facilitate a more extensive comparison between the two systems. The trajectory simulations tend to confirm the equivalence of the ion+molecule dynamics to that for the Rydberg-atom+molecule system. The theory reproduces the close relationship of the two experimental observations made previously. However, some differences between the Rydberg-atom experiments and the trajectory simulations are seen when comparisons are made to a broader data set. In particular, the angular distribution of the differential cross section exhibits more asymmetry in the experiment than in the theory. The potential breakdown of the classical model is discussed. The role of the "spectator" Rydberg electron is addressed and several crucial issues for future theoretical work are brought out.

  16. 用于ABAQUS显式分析梁单元的混凝土单轴本构模型%Study on a Uniaxial Constitutive Model of Concrete for Explicit Dynamic Beam Elements of ABAQUS

    Institute of Scientific and Technical Information of China (English)

    王强; 潘天林; 刘明; 李哲

    2011-01-01

    目的 为实现采用梁单元进行钢筋混凝土杆系结构的弹塑性响应分析,对其混凝土本构关系进行二次开发,使ABAQUS软件提供的混凝土材料模型能用于三维梁单元.方法 利用ABAQUS用户自定义材料程序VUMAT接口,开发用于显式动力分析的梁单元混凝土单轴本构模型,并编制相应的计算程序,对低周往复加载下的钢筋混凝土柱进行数值模拟计算.结果 数值模拟结果能够较好地反映轴力对钢筋混凝土构件滞回性能的影响以及钢筋混凝土柱的双向弯曲耦合性能.结论 笔者所开发的混凝土本构模型能够用于多维受力状态下钢筋混凝土梁柱构件的受力行为分析,满足钢筋混凝土杆系结构动力弹塑性分析的需求.%In order to use the beam element of FEM software ABAQUS for analyzing the elastic-plastic dynamic response of RC truss structures, it is necessary to carry out a secondary development of the concrete constitutive for spatial beam element. In this paper,a uniaxial constitutive model of concrete is established. The material subroutine of this model is successfully developed and applied to explicit dynamic module of ABAQUS by means of user-defined subroutine interface VUMAT. Afterwards,the hysteretic performance of RC columns under cyclic loading is numerically simulated and compared with experiment results. The results show that the uniaxial constitutive model can rightly simulate the influence on the hysteretic performance of RC columns under varies axial load,as well as the bi-axes bending coupling performance. The established model can meet the demand of analyzing the elastic-plastic dynamic response of RC frame structures.

  17. Reflectance-anisotropy study of the dynamics of molecular beam epitaxy growth of GaAs and InGaAs on GaAs(001)

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Gallegos, J.; Lastras-Martinez, A.; Lastras-Martinez, L.F. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico); Balderas-Navarro, R.E. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico); Facultad de Ciencias, Universidad Autonoma de San Luis Potosi. Alvaro Obregon 64, San Luis Potosi (Mexico)

    2008-07-01

    Reflectance-Anisotropy (RA) observations during the Molecular Beam Epitaxy (MBE) growth of zincblende semiconductors films were carried out using the E{sub 1} optical transition as a probe. We follow the kinetics of the deposition of GaAs and In{sub 0.3}Ga{sub 0.7}As on GaAs(001) at growth rates of 0.2 and 0.25 ML/s, respectively. During growth we used a constant As{sub 4} or As{sub 2} flux pressure of 5 x 10{sup -6} Torr. Clear RA-oscillations were observed during growth with a period that nearly coincides with the growth period for a Ga-As bilayer. RHEED was used as an auxiliary technique in order to obtain a correlation between RHEED and RA oscillations. On the basis of our results, we argue that RAS oscillations are mainly associated to periodic changes in surface atomic structure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. INPHO project. Task 1: the setting of electron lines - beam dynamics; Projet INPHO. Tache 1: mise en place des lignes - faisceaulogie. Bilan de la phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Anselmetti, S.; Baze, J.M.; Brasseur, A.; Cazanou, M.; Cazaux, S.; Coadou, B.; Congretel, G.; Contrepois, P.; Curtoni, A.; Denis, J.F.; Desmons, M.; Dorlot, M.; Fontaine, M.; Jablonka, M.; Jannin, J.L.; Joly, J.M.; Launay, J.C.; Lotode, A.; Luong, M.; Mattei, P.; Nardin, P.; Perrin, J.L.; Saudemont, J.C.; Veyssiere, C. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, 91- Gif sur Yvette (France); Laine, F. [CEA Saclay, Dept. des Technologies du Capteur et du Signal (DRT/LIST/DETECS/SSTM/L2MA), 91 - Gif-sur-Yvette (France)

    2005-07-01

    The INPHO project aims at upgrading and optimizing the SAPHIR installation that is dedicated to the measurement (through the detection of photofission reactions) of radioactive wastes containing transuranium elements. Some modifications have been made during the phase I of the upgrading: -) the supply of power between the 2 parts of the accelerator has been modified. Now the setting of the beam energy does not imply to compensate for a phase shift; -) the vacuum level of the accelerator has been improved, it passed from 10{sup -6} torr to 7.10{sup -8} torr); and current measurers have been set on the electron line (there were no direct diagnostics previously). Other modifications are planned for the phase II of the upgrading. It concerns: -) the power supply of the electron gun; -) the control system; and the power supply of the klystron. In parallel with the phase II, feasibility studies have been led for the design of an electron line that will allow the electron-photon converter target to be as near as possible to the waste package to probe. (A.C.)

  19. Literature in Focus Beta Beams: Neutrino Beams

    CERN Multimedia

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  20. Studies of beam heating of proton beam profile monitor SEM's

    Energy Technology Data Exchange (ETDEWEB)

    Pavlovich, Zarko; Osiecki, Thomas H.; Kopp, Sacha E.; /Texas U.

    2005-05-01

    The authors present calculations of the expected temperature rise of proton beam profile monitors due to beam heating. The profile monitors are secondary emission monitors (SEM's) to be made of Titanium foils. The heating is studied to understand whether there is any loss of tension or alignment of such devices. Additionally, calculations of thermally-induced dynamic stress are presented. Ti foil is compared to other materials and also to wire SEM's. The calculations were initially performed for the NuMI beam, where the per-pulse intensity is quite high; for completeness the calculations are also performed for other beam energies and intensities.