Download or read book The Electron cloud Instability in the Arcs of the PEP II Positron Ring written by and published by . This book was released on 1998 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have applied our simulation code ''POSINST'' to evaluate, in linear approximation, the contribution to the growth rate of the electron-cloud instability (ECI) from the pumping sections and the dipole bending magnets in the arcs of the PEP-II positron ring. A key ingredient in our model is a detailed description of the secondary emission process off the TiN-coated chambers. Another important element is the analytic computation of the electric field produced by the beam, including the effects from surface charges. Space-charge forces of the electron cloud upon itself are also included, although these forces are negligible under nominal conditions. Bunch-length effects are optionally included by slicing the bunch into several kicks. We conclude that the growth rate is dominated by the pumping sections and scales linearly with the photoelectric yield Y'. For Y' = 1, our present estimate is in the range (almost equal to) 1000-1300 s−1, depending upon the value of the photon reflectivity R. This is in the range controllable by the transverse feedback system. The contributions to the growth rate from other magnets and from other sections of the ring remain to be evaluated.
Download or read book THE ELECTRON CLOUD INSTABILITY AT PEP II written by and published by . This book was released on 2002 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electron cloud instability (ECI) at PEP-II enlarges the positron beam size at high currents and reduces the luminosity. The electrons for this instability come from multipacting electrons in the straight section vacuum chambers and, perhaps, photo-emission and secondary emission of electrons from the vacuum ante-chambers in the arcs. Solenoid and transverse field magnets have been placed over the vacuum chambers with about a 30 gauss field to suppress ECI. These fields have been successful in reducing the positron beam size blow up. Only about half of the drift vacuum chambers in LER have been wound with solenoids. Earlier ECI measurements are described in reference [1].
Download or read book Physics of Intensity Dependent Beam Instabilities written by King-Yuen Ng and published by World Scientific. This book was released on 2006 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive treatment of intensity dependent particle beam instabilities in accelerating rings. Written for researchers, the material is also suitable for use as a textbook in an advanced graduate course for students studying accelerator physics.The presentation starts with a brief review of the basic concept of wake potentials and coupling impedances in the vacuum chamber followed by a discussion on static and dynamic solutions of their effects on the particle beams. Special emphasis is placed separately on proton and electron machines. Other special topics of interest covered include Landau damping, Balakin-Novokhatsky-Smirnov damping, Sacherer's integral equations, Landau cavity, saw-tooth instability, Robinson stability criteria, beam loading, transition crossing, two-stream instabilities, and collective instability issues of isochronous rings. After the formulation of an instability, readers are provided a thorough description of one or more experimental observations together with a discussion of the cures for the instability.Although the book is theory oriented, the use of mathematics has been minimized. The presentation is intended to be rigorous and self-contained with nearly all the formulas and equations derived.
Download or read book New Simulation Results for the Electron cloud Effect at the PEP II Positron Ring written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present simulation results for the emittance blowup due to the head-tail effect induced by the electron-cloud effect (ECE) in the low-energy ring (LER) at the PEP-II B factory at SLAC.
Download or read book The Electron cloud Instability in PEP II written by and published by . This book was released on 1997 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present an update on the estimate of the growth time of the multi-bunch transverse instability in the PEP-II collider arising from the interaction of the positron beam with the accumulated electron cloud. They estimate the contributions to the growth rate arising from the dipole magnets and from the pumping straight sections. They emphasize those quantities upon which the instability is most sensitive. The simulation includes measured data on the secondary emission yield for TiN-coated samples of the actual vacuum chamber. Although the analysis is still in progress, they conclude that the instability risetime is of order 1 ms, which is well within the range controllable by the feedback system.
Download or read book Glasfachschulen in der echoslovakischen Republik written by and published by . This book was released on 1927 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Particle Physics Reference Library written by Stephen Myers and published by Springer Nature. This book was released on 2020-01-01 with total page 867 pages. Available in PDF, EPUB and Kindle. Book excerpt: This third open access volume of the handbook series deals with accelerator physics, design, technology and operations, as well as with beam optics, dynamics and diagnostics. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A,B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access.
Download or read book Simulation of Head Tail Instability Caused by Electron Cloud in the Positron Ring at PEP II written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The head-tail instability caused by an electron cloud in positron storage rings is studied numerically using a simple model. In the model, the positron beam is longitudinally divided into many slices that have a fixed transverse size. The centroid of each slice evolves dynamically according to the interaction with a two-dimensional electron cloud at a given azimuthal location in the ring and a six-dimensional lattice map. A sudden and huge increase of the projected beam size and the mode coupling in the dipole spectrum are observed in the simulation at the threshold of the instability. Even below the threshold, the vertical beam size increases along a bunch train that has 8.5 ns bunch spacing. Above the threshold, a positive chromaticity can damp down the centroid motion but has very little effect on the blowup of the beam size. The results of the simulation are consistent with many observations at PEP-II.
Download or read book A New Chicane Experiment in PEP II to Test Mitigations of the Electron Cloud Effect for Linear Colliders written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.
Download or read book ECLOUD 02 written by Giovanni Rumolo and published by . This book was released on 2002 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Accelerator Physics 2003 written by M Berz and published by CRC Press. This book was released on 2005-02-01 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides an overview of the state of the art in computational accelerator physics, based on papers presented at the seventh international conference at Michigan State University in October 2002. The major topics covered in this volume include particle tracking and ray tracing, transfer map methods, field computation for time dependent Maxwell's equations and static magnetic problems, as well as space charge and beam-beam effects. The book also discusses modern computational environments, including parallel clusters, visualization, and new programming paradigms. It is ideal for scientists and engineers working in beam or accelerator physics and related areas of applied math and computer science.
Download or read book LHC Design Report written by and published by . This book was released on 2004 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The PEP Electron positron Ring written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The first stage of the positron-electron-proton (PEP) colliding-beam system which has been under joint study by a Lawrence Berkeley Laboratory-Stanford Linear Accelerator Center team for the past two years, will be the electron-positron storage ring. The physics justification for the ee− ring is summarized briefly and the proposed facility is described. The ring will have six arcs having gross radii of about 220 m and six interaction regions located at the centers of straight sections about 130 m long. The longitudinal distance left free for experimental apparatus at the intersection regions will be 20 m. The range of operating beam energies will be from 5 GeV to 15 GeV. The design luminosity at 15 GeV will be 1032cm/sup minus 2/s/sup minus 1/, and the luminosity will vary approximately as the square of the beam energy. Alternative methods under consideration for adjusting the beam cross-section are discussed. The designs of the storage ring subsystems and of the conventional facilities including the experimental halls at the interaction regions are described.
Download or read book TiN Coating of the PEP II Low energy Ring Aluminum Arc Vacuum Chambers written by and published by . This book was released on 1997 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The PEP-II Low-Energy Ring will operate at a nominal energy of 3.1 GeV with a positron beam current of 2.1 A. Design parameters for vacuum components are 3.5 GeV at 3 A. The arc vacuum system is based on an aluminum antechamber concept. It consists of 192 pairs of 2 m long magnet chambers and 5.5 m long pumping chambers. Titanium nitride coating of the entire positron duct is needed in order to suppress beam instabilities caused by multipactoring and the {open_quotes}electron-cloud{close_quotes} effect. An extensive R & D program has been conducted to develop coating parameters that give proper stoichiometry and a suitable thickness of TiN. The total secondary emission yield of TiN-coated aluminum coupons has been measured after the samples were exposed to air and again after electron-beam bombardment. A coating facility has been built to cope with the large quantity of production chambers and the very tight schedule requirements.
Download or read book Single Bunch Instability Driven by the Electron Cloud Effect in the Positron Damping Ring of the International Linear Collider written by A. Wolski and published by . This book was released on 2005 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book B Physics And Cp Violation Bcp4 Proceedings Of The International Workshop written by T Ohshima and published by World Scientific. This book was released on 2001-09-25 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers the first strong evidence of the existence of CP violation in neutral B decays extracted from sophisticated B factories in the US and Japan. It also holds out the expectation of rare B decays and D, K physics in the near future. In addition, new physics beyond the Standard Model is described. Both experimental and theoretical points of view are given.
Download or read book High Current Effects in The PEP II Storage Rings written by and published by . This book was released on 2009 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: High beam currents in PEP-II have been a challenge for vacuum system and ring components. For the (almost equal to) 1 cm long bunches peak currents exceed 100 A and modest impedance can give rise to voltage spikes and discharges. During the last two runs, difficulties arose from rf seals at the 'flex flanges' in the HER. High temperatures were seen and the seals turned out to be severely damaged by discharges. In the LER, the horizontal stripline kickers of the bunch-by-bunch feedback system experiences breakdown at high bunch current-Macor pins installed for mechanical stability turned out to be a weak spot causing discharges. Finally, in the HER an experiment to shorten the ion-clearing gap in the beam revealed signs of ion-induced instability indicating that the HER has been operating quite close to the stability limit. The effects shown here are relevant to future high-intensity electron and positron rings like SuperB and PEP-X.
