Download or read book Studies of Beam Halo Formation in the 12GeV CEBAF Design written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam halo formation in the beam transport design for the Jefferson Lab 12GeV upgrade was investigated using 12GeV beam transport models as well as data from 6GeV CEBAF operations. Various halo sources were considered; these covered both nuclear interactions with beam gas as well as optics-related effects such as non linearities in the magnetic fields of the transport elements. Halo due to beam gas scattering was found to be less of a problem at 12GeV compared to the 6GeV machine. Halo due to non linear effects of magnetic elements was characterized as a function of beam orbit and functional forms of the distribution were derived. These functional forms were used as inputs in subsequent detector optimizations studies.

Download or read book Beam Physics for the 12 GeV CEBAF Upgrade Project written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam physics aspects of the 12 GeV Upgrade of CEBAF are presented. The CEBAF Upgrade to 12 GeV is achieved via 5.5 recirculations through the linacs, and the installation of 10 new high-gradient cryomodules. A new experimental hall, Hall D, is envisioned at the end of North Linac. Simulation results for straight-through and recirculated injectors are summarized and compared. Beam transport designs are discussed and evaluated with respect to matching and beam breakup (BBU) optimization. Effects of synchrotron radiation excitation on the beam properties are calculated. BBU simulations and derived specifications for the damping of higher order modes of the new 7-cell cavities are presented. The energies that provide longitudinal polarization in multiple experimental halls simultaneously are calculated. Finally, a detailed optics design for the Hall D transport line has been obtained.

Download or read book BEAM HALO FORMATION IN HIGH INTENSITY BEAMS written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

Download or read book Beam Dynamics and Instabilities in ELIC Design written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we report the first study of beam related instabilities in lepton ring of the proposed electron-ion collider beyond the 12 GeV upgrade of CEBAF at Jefferson lab. The design parameters are consistent with PEP-II. Present studies reveal that coupled bunch and two stream instabilities are important issues and we need feedback system. The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as future high energy particle accelerator beyond the 12 GeV upgrade of CEBAF. The MEIC will consist of the existing polarized electron source complex with 12 GeV upgrade and a new ion complex with polarized and unpolarized light to medium ions. The conceptual layout is shown in Fig. 1 and the basic parameters in comparison with the similar machines are discussed in Table 1. The maximum permissible collision frequency at 1.5 GHz is dictated by the existing electron machine, allowing the relatively small charge per bunch and large crossing angle resulting in the increased beam stability and high luminosity. In this paper, we present the preliminary study of collective effects for e-ring.

Download or read book Dynamics of Beam Halo in Mismatched Beams written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-power proton linacs for nuclear materials transmutation and production, and new accelerator-driven neutron spallation sources must be designed to control beam-halo formation, which leads to beam loss. The study of particle-core models is leading to a better understanding of the causes and characteristics of beam halo produced by space-charge forces in rms mismatched beams. Detailed studies of the models have resulted in predictions of the dependence of the maximum amplitude of halo particles on a mismatch parameter and on the space-charge tune-depression ratio. Scaling formulas have been derived which will provide guidance for choosing the aperture radius to contain the halo without loss.

Download or read book Beam Halo Formation and Loss Induced by Image charge Effects in a Small aperture Alternating gradient Focusing System written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of image charges on beam halo formation and beam loss in small-aperture alternating-gradient focusing systems are studied analytically, computationally, and experimentally. Nonlinear image-charge fields result in chaotic particle motion and the ejection of particles from the beam core into a halo. Detailed chaotic particle motion and structure of the particle phase space is studied, and the beam loss rate is computed for a long transport channel. Image-charge effects are also studied for a short transport channel, and compared with the Neutralized Transport Experiment (NTX) at LBNL.

Download or read book Mechanisms of Beam halo Formation in High intensity Linacs written by and published by . This book was released on 1994 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: An rms-mismatched beam with space-charge forces can evolve rapidly, and during the course of evolution its emittance grows and a diffuse halo forms. The halo is of particular concern for long-term operation of linacs such as those envisioned for accelerator transmutation of waste (ATW) because too much particle impingement on the accelerating structures would cause enough radioactivation to prohibit routine hands-on maintenance. Thus, halo suppression is a design consideration for these linacs. In this paper, the authors summarize both the physical processes associated with the rapid evolution of the rms-mismatched beam and a semianalytic formalism which was recently developed to account for them. They also provide representative results derived from the formalism.

Download or read book Electron Beam Halo Formation in High power Periodic Permanent Magnet Focusing Klystron Amplifiers written by Renato Pakter and published by . This book was released on 2000 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theory of High Brightness Beam Transport and Acceleration written by Yuri Batygin and published by World Scientific Publishing Company Incorporated. This book was released on 2002 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to the quickly developing area of high intensity particle beam physics. Beam emittance growth, halo formation and chaotic particle motion are the main areas of research in the new intense particle accelerators. Knowledge of those phenomena is crucial for the design of particle accelerators with space-charge dominated beams. This important book provides a new, self-consistent description of high brightness particle beams with essentially nonlinear space-charge forces. The emphasis is on the proper matching of the beam with focusing and accelerating structures to suppress beam emittance growth and halo formation.The book will be useful for researchers and engineers dealing with space-charge dominated beams and for graduate and undergraduate students who are starting to work in this field.

Download or read book Beam Halo Formation from Space charge Dominated Beams in Uniform Focusing Channels written by and published by . This book was released on 1993 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which results in a 2-component beam consisting of an inner core and an outer halo. The halo is very prominent in mismatched beams, and the potential for accelerator activation is of concern for a next generation of cw, high-power proton linacs that could be applied for intense neutron generators to process nuclear materials. We present new results about beam halo and the evolution of space-charge dominated beams from multiparticle simulation of initial laminar beams in a uniform linear focusing channel, and from a model consisting of single particle interactions with a uniform-density beam core. We study the energy gain from particle interactions with the space-charge field of the core, and we identify the resonant characteristic of this interaction as the basic cause of the separation of the beam into the two components. We identify three different particle-trajectory types, and we suggest that one of these types may lead to continuous halo growth, even after the halo is removed by collimators.

Download or read book New High Power Linacs and Beam Physics written by and published by . This book was released on 1997 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: New high-power proton linacs must be designed to control beam loss, which can lead to radioactivation of the accelerator. The threat of beam loss is increased significantly by the formation of beam halo. Numerical simulation studies have identified the space-charge interactions, especially those that occur in rms mismatched beams, as a major concern for halo growth. The maximum-amplitude predictions of the simulation codes must be subjected to independent tests to confirm the validity of the results. Consequently, the authors compare predictions from the particle-core halo models with computer simulations to test their understanding of the halo mechanisms that are incorporated in the computer codes. They present and discuss scaling laws that provide guidance for high-power linac design.

Download or read book Self consistent Beam Halo Studies Halo Diagnostic Development in a Continuous Linear Focusing Channel written by and published by . This book was released on 1994 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam halos are formed via self-consistent motion of the beam particles. Interactions of single particles with time-varying density distributions of other particles are a major source of halo. Aspects of these interactions are studied for an initially equilibrium distribution in a radial, linear, continuous focusing system. When there is a mismatch, it is shown that in the self-consistent system, there is a threshold in space-charge and mismatch, above which a halo is formed that extends to (approximately)1.5 times the initial maximum mismatch radius. Tools are sought for characterizing the halo dynamics. Testing the particles against the width of the mismatch driving resonance is useful for finding a conservative estimate of the threshold. The exit, entering and transition times, and the time evolution of the halo, are also explored using this technique. Extension to higher dimensions is briefly discussed.

Download or read book Mechanisms and Control of Beam Halo Formations in Intense Microwave Sources and Accelerators written by Chiping Chen and published by . This book was released on 2000 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Intrabeam Scattering and Halo Formation in Intense Ion Beams written by N. Uhlmann and published by . This book was released on 2002 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential problem for the operation of high current linacs is the control of beam losses due to halo formation. Here we concentrate on an interplay between intrabeam scattering (IBS) and the incidence of particles which are driven to high amplitudes by resonance with the nonlinear space charge fields of a mismatched beam. For these studies, we developed a particle core-molecular-dynamics (PCMD) method which suitably joins the time evolution in framework of the envelope equations and a calculation of IBS between pseudo-particles with a renormalized charge. With this technique we investigated continuous KV-beams in a FODO channel. Our first results strongly suggest, that IBS in fact supports the halo formation in a mismatched beam.

Download or read book Nonlinear resonance Analysis of Halo formation Excited by Beam core Oscillation written by Yoshito Shimosaki and published by . This book was released on 1999 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Halo Formation and Hollowing in Relativistic Electron Beams written by Richard F. Hubbard and published by . This book was released on 1988 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: A relativistic electron beam propagating through dense gas may evolve to a variety of current density profiles J sub b (r) depending on the beam temperature T and plasma current profile J sup P (r). Four broad classes of equilibria are identified in particle simulations: (1) Bennett-like or compact, (2) core and halo, (3) on-axis hollowed and (4) off-axis hollowed. The qualitative features of each class are reproduced in a simple analytical model which assumes an isothermal beam and a Bennett plasma current profile and iterates about an initial ansatz of a Bennett beam current profile. Bennett-like equilibria are produced when the return current fraction f is small or when T/T sub B = 1-f, where T sub B> 1-f and moderate or high f, the equilibrium consists of a compact core surrounded by a halo which may contain most of the beam current. In extreme cases (T/T sub B” 1-f and f close to unity), an off-axis density minimum occurs. (This is also referred to as off-axis hollowing.) For T/T sub B

Download or read book Multipass Beam Breakup Study at Jefferson Lab for the 12 GeV CEBAF Upgrade written by Ilkyoung Shin and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: