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Author : T. Higo
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (247 download)
Download or read book Detuned Accelerating Structure for Linear Collider written by T. Higo and published by . This book was released on 1998 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : T. Higo
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (258 download)
Download or read book Precise Fabrication of X-band Detuned Accelerating Structure for Linear Collider written by T. Higo and published by . This book was released on 1995 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Vasim Firoj Khan
Publisher :
ISBN 13 :
Total Pages : 230 pages
Book Rating : 4.:/5 (768 download)
Download or read book A Damped and Detuned Accelerating Structure for the Main Linacs of the Compact Linear Collider written by Vasim Firoj Khan and published by . This book was released on 2011 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Linear colliders are an option for lepton collision at several TeV. The Compact Linear Collider (CLIC) aims at electron and positron collisions at a centre of mass energy of 3 TeV. In CLIC, the main accelerating structures are designed to operate at an X-band frequency of 12 GHz with an accelerating gradient of 100 MV/m. Two significant issues in linear accelerators that can prevent high gradient being achieved are electrical breakdown and wakefields. The baseline design for the CLIC main linacs relies on a small aperture size to reduce the breakdown probability and a strong damping scheme to suppress the wakefields. The strong damping scheme may have a higher possibility of electrical breakdown. In this thesis an alternative design for the main accelerating structures of CLIC is studied and various aspects of this design are discussed. This design is known as a Damped and Detuned Structure (DDS) which relies on moderate damping and strong detuning of the higher order modes (HOMs). The broad idea of DDS is based upon the Next Linear Collider (NLC) design. The advantages of this design are: well damped wakefields, minimised rf breakdown probability and reduced size of the structure compared to the strong damping design. Procedures necessary to minimise the rf monopole fields and enhance the wakefield suppression are discussed. The rf as well as mechanical designs of a test structure are presented. This unique design forms the basis of this research and allows both the electrical breakdown and beam dynamics constraints to be simultaneously satisfied.
Author : Wei Gai
Publisher : World Scientific
ISBN 13 : 9814602116
Total Pages : 176 pages
Book Rating : 4.8/5 (146 download)
Download or read book High Gradient Accelerating Structure - Proceedings Of The Symposium On The Occasion Of 70th Birthday Of Junwen Wang written by Wei Gai and published by World Scientific. This book was released on 2014-10-24 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume, for the symposium in honor of Junwen Wang's 70th anniversary, is dedicated to his many important achievements in the field of accelerator physics.It includes the discussions of recent advances and challenging problems in the field of high gradient accelerating structure development.
Author :
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (727 download)
Download or read book Design of the Detuned Accelerator Structure written by and published by . This book was released on 1993 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a summary of the design procedure for the detuned accelerator structure for SLAC's Next Linear Collider (NLC) program. The 11.424 GHz accelerating mode of each cavity must be synchronous with the beam. The distribution of the disk thicknesses and lowest synchronous dipole mode frequencies of the cavities in the structure is Gaussian in order to reduce the effect of wake fields. The finite element field solver YAP calculated the accelerating mode frequency and the lowest synchronous dipole mode frequency for various cavity diameters, aperture diameters and disk thicknesses. Polynomial 3-parameter fits are used to calculate the dimensions for a 1.8 m detuned structure. The program SUPERFISH was used to calculate the shunt impedances, quality factors and group velocities. The RF parameters of the section like filling time, attenuation factor, accelerating gradient and maximum surface field along the section are evaluated. Error estimates will be discussed and comparisons with conventional constant gradient and constant impedance structures will be presented.
Download or read book Comparative Study of Medium Damped and Detuned Linear Accelerator Structures written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Long range wakefields are a serious concern for a future linear collider based on room temperature accelerating structures. They can be suppressed either by detuning and or local damping or with some combination of both strategies. Detuning relies on precisely phasing the contributions of the dipole modes excited by the passage of a single bunch. This is accomplished by controlling individual mode frequencies, a process which dictates individual cell dimensional tolerances. Each mode must be excited with the correct strength; this in turn, determines cell-to-cell alignment tolerances. In contrast, in a locally damped structure, the modes are attenuated at the cell level. Clearly, mode frequencies and relative excitation become less critical in that context; mechanical fabrication tolerances can be relaxed. While local damping is ideal from the stand-point of long range wakefield suppression, this comes at the cost of reducing the shunt impedance and possibly unacceptable localized heating. Recently, the Medium Damped Structure (MDS), a compromise between detuning and local damping, has generated some interest. In this paper, we compare a hypothetical MDS to the NLC Rounded Damped Detuned Structure (RDDS) and investigate possible advantages from the standpoint fabrication tolerances and their relation to beam stability and emittance preservation.
Download or read book High Frequency Planar Accelerating Structures for Future Linear Colliders written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern microfabrication techniques based on deep etch x-ray lithography (LIGA) can be used to produce large-aspect-ratio, metallic or dielectric, planar structures suitable for high-frequency RF acceleration of charged particle beams. Specifically, these techniques offer significant advantages over conventional manufacturing methods for future linear colliders (beyond NLC, the Next Linear Collider) because of several unique systems requirements. First, to have the required ac ''wall plug'' power within reasonable limits, such future linear colliders (≥ 5TeV) must operate at high frequency (≥ 30GHz). This implies the need of a large number of intricate accelerating structures with ever smaller dimensions and extremely tight manufacturing tolerances, imposing new challenges in mass-production, precision fabrication techniques. Microfabrication is particularly suitable for meeting this need. Secondly, luminosity requirements suggest the use of multi-bunch acceleration of electrons and positrons in the linear collider. In order for these schemes to accelerate low-emittance beams over a long distance, it is important that the wakefield effects be reduced to a minimum in the accelerating structure. Asymmetric planar structures have more geometric degrees of freedom than cylindrically symmetric structures. In addition to detuning, these can be utilized to further reduce the wakefields. Thirdly, in order to clearly discriminate physics events in the final interaction point at which electrons and positrons collide, it is required that secondary particle production from beamstrahlung be minimized. Flat electron and positron beams with a large aspect ratio will be beneficial in reducing beamstrahlung in the final focus region, but cause the beam to be more sensitive to wakefields in the vertical dimension. In principle, a flat beam can be accelerated in a planar structure with reduced wakefield in the vertical direction for the entire length of the accelerator.
Author :
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (684 download)
Download or read book Design of a 30 GHz Damped Detuned Accelerating Structure written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the framework of the SLAC/CERN studies of 30 GHz linear colliders, an attempt has been made to scale as closely as possible the existing X-band NLC damped detuned accelerating structure to 30 GHz. A simple scaling was not possible because of mechanical and RF constraints. The 30 GHz design has 101 cells and a minimum aperture of 3.4 mm. In order to obtain acceptably small values for both the single-bunch transverse wakefield and the long-range multibunch wakefield a relatively large non-linear variation of the iris thickness was introduced in addition to the iris diameter variation. The resulting wakefield has a short-range value of 1290 V/pC/mm/m and a long range value below 10 V/pC/mm/m.
Author :
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (684 download)
Download or read book Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following successful design and fabrication of damped detuned structures, the R and D for the accelerating structures of the NLC/JLC linear collider project proceeded to studies of Rounded Damped Detuned Structure with curved cross section of the cavity shape for increased shunt impedance. The important features of the structure are the accurately tuned accelerating mode frequency and the distribution of the first dipole modes smooth and close to the design distribution. These requirements were met based on the high-accuracy diamond turning with its capability to realize the periphery tolerance of two microns. The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the accelerating mode frequency averaged over a structure was 0.1 MHz by applying a feed-forward method.
Author : T. Shintake
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (258 download)
Download or read book HOM-free Linear Accelerating Structure for E+e- Linear Collider at C-band written by T. Shintake and published by . This book was released on 1995 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : T. Higo
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (255 download)
Download or read book X-band Accelerating Structure for Japan Linear Collider written by T. Higo and published by . This book was released on 1991 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (727 download)
Download or read book The Next Linear Collider Test Accelerator written by and published by . This book was released on 1993 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past several years, there has been tremendous progress the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse compression systems and damped/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams necessary for an NLC, we are building an NLC Test Accelerator (NLCTA). The goal of the NLCTA is to bring together all elements of the entire accelerating system by constructing and reliably operating an engineered model of a high-gradient linac suitable for the NLC. The NLCTA will serve as a testbed as the design of the NLC evolves. In addition to testing the RF acceleration system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration. In this paper, we will report oil the status of the design, component development, and construction of the NLC Test Accelerator.
Author :
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (684 download)
Download or read book A Damped Detuned Structure for the Next Linear Collider written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: An X-band Damped Detuned Structure (DDS) for NLC has been fabricated as part of a collaboration between KEK and SLAC. The individual cells were diamond point machined and microwave tested at KEK. The cells were diffusion bonded at SLAC. The structure has been cold tested. The time dependence of the beam induced dipole wakefields have been measured with the SLC beam in the test station ASSET. The structure is designed so that the dipole modes have an approximately gaussian density distribution in the frequency domain. This gives an approximately gaussian decrease of the wakefields for short times (about 10 ns), which is produced by the interference among the 206 modes in the lowest dipole mode band of the 206 cell structure. Without damping, however, the wakefields then rise back to a level which is approximately equal to the expected incoherent level from the 206 modes. The damping is accomplished by means of 4 rectangular slots or manifolds (approximately 5 mm by 10 mm) equally spaced in azimuth around the structure and running the full length of the structure. These manifolds act as single mode rectangular waveguides for the lowest band dipole modes, but are cut off for the accelerating mode. The manifolds are coupled to every cell in the structure, except for 3 at each end, by means of radial slots. Each of the four manifolds will have the dipole mode frequencies traveling in both directions and so are terminated on both ends. The structure will be installed in the NLC Test Accelerator this fall.
Author :
Publisher :
ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (683 download)
Download or read book SCATTERING MATRIX ANALYSIS OF THE NLC ACCELERATING STRUCTURE. written by and published by . This book was released on 1999 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Next Linear Collider (NLC)[1], long trains of short, intense bunches are accelerated through the linac on their way to the collision point. One serious problem that needs to be addressed is the multi-bunch, beam break-up instability in the linac. To counteract this instability the accelerating structures are designed so that the dipole mode wakefields are detuned and weakly damped. Detuning is accomplished by gradually varying the dimensions of the 206 cavity cells in each structure, and weak damping by surrounding the structure with four manifolds, which allow the dipole modes to weakly couple out of the cells. In order to design and predict the performance of such a structure in the NLC, it is necessary to be able to calculate accurately the strength of its long-range wakefields. NLC detuned structures were designed first using an equivalent circuit approach, for example, the double band model of Ref. [2]. With the introduction of weak damping, a more elaborate equivalent circuit approach was required[3]. Other methods that have been used for detuned structures are the open-mode, field expansion method[4], and a finite element calculation employing 206 parallel processors[5]. A scattering matrix method can also be applied to cavities that consist of a series of waveguide sections[6], such as the NLC structure, and such a method has also been applied to the problem of detuned accelerating [7], [8]. Among its natural strengths when applied to structure problems are the ability to model the effects of complicated 3 dimensional couplers and to investigate the behavior of higher passband modes. In this report we will employ a computer program that uses such an approach [9], to demonstrate that the scattering matrix method can yield accurate results concerning the wakefields of damped, detuned accelerating structures. We begin by calculating the dipole mode impedance and of a slightly simplified version of a detuned (DT) structure, results which we compare with those of the double circuit model. An important related problem is wakefield effect caused by internal structure misalignments, a problem which has the special difficulty of no longer being cylindrically symmetric; and we next study the transverse kicks to the beam caused by misaligning just one cell in a DT structure, and compare results with those of a perturbation calculation based on the circuit model. Finally, a future goal is to be able to use the scattering matrix formalism to model the more complicated NLC damped, detuned structure (DDS), and we present some preliminary results toward this goal.
Download or read book Accelerator Structures for Linear Colliders written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Linear Colliders require high gradient (to reduce length dependent costs), high shunt impedance (to reduce power dependent costs) accelerator structures in which the long range dipole wakefields have been reduced by 2 to 3 orders of magnitude. The precise dipole wake reduction factor required depends on many factors. These include the beam intensity and time structure, the accelerator aperture and accelerating gradient, the strength of the focusing, the alignment precision and position stability of accelerator structures and the focusing elements, the effectiveness of the tuning procedure and feedback system, the pulse to pulse stability of the injected beam, and the required emittance at the final focus. For the purposes of this paper the authors accept that large reduction factors are required and discuss various approaches to achieving them. There are basically two approaches: detuning and damping, which are often used in combination. Damping can be accomplished either by introducing loss selectively into the accelerating structure cells, or by coupling the dipole modes out of the accelerating region and absorbing them in external loads or lossy materials. Detuning can greatly reduce the amount of damping required by causing the dipole modes to decohere, and it is possible to achieve destructive interference so that the wakefields from different cells in the accelerator cancel each other as seen by the bunches of electrons travelling through the linac. Several different approaches have achieved large reduction in the long-range dipole wakefields so that they pose no restriction on the length of the bunch trains which can be used for linear colliders.
Author :
Publisher :
ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (685 download)
Download or read book High Gradient Tests of SLAC Linear Collider Accelerator Structures written by and published by . This book was released on 1994 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the current SLAC R & D program to develop room temperature accelerator structures for the Next Linear Collider (NLC). The structures are designed to operate at 11.4 GHz at an accelerating gradient in the range of 50 to 100 MV/m. In the past year a 26 cm constant-impedance traveling-wave section, a 75 cm constant-impedance traveling-wave section, and a 1.8 m traveling-wave section with detuned deflecting modes have been high-power tested. The paper presents a brief description of the RF test setup, the design and manufacturing details of the structures, and a discussion of test results including field emission, RF processing, dark current spectrum and RF breakdown.
Author : R. W. Assmann
Publisher :
ISBN 13 :
Total Pages : 86 pages
Book Rating : 4.X/5 (4 download)
Download or read book A 3 TeV E+ E- Linear Collider Based on CLIC Technology written by R. W. Assmann and published by . This book was released on 2000 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
