Physical Review Special Topics-accelerators and Beams最新文献_第9页

Beam-based model of broad-band impedance of the Diamond Light Source 基于光束的金刚石光源宽带阻抗模型

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-23 DOI: 10.1103/PHYSREVSTAB.18.064401

V. Smaluk, I. Martin, R. Fielder, R. Bartolini

引用次数: 9

Girder deformation related phase errors on the undulators for the European X-Ray Free Electron Laser 欧洲x射线自由电子激光器波动器上与梁变形相关的相位误差

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-22 DOI: 10.1103/PHYSREVSTAB.18.060704

Yuhui Li, B. Ketenoglu, J. Pflueger

引用次数: 7

Measurements of intrinsic emittance dependence on rf field for copper photocathodes 铜光电阴极本征发射度随射频场的测量

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-22 DOI: 10.1103/PHYSREVSTAB.18.063401

E. Prat, S. Bettoni, H. Braun, M. Divall, T. Schietinger

引用次数: 7

Calculations of safe collimator settings and β * at the CERN Large Hadron Collider 欧洲核子研究中心大型强子对撞机安全准直器设置和β *的计算

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-22 DOI: 10.1103/PHYSREVSTAB.18.061001

R. Bruce, R. Assmann, S. Redaelli

{"title":"Calculations of safe collimator settings and β * at the CERN Large Hadron Collider","authors":"R. Bruce, R. Assmann, S. Redaelli","doi":"10.1103/PHYSREVSTAB.18.061001","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.061001","url":null,"abstract":"The first run of the Large Hadron Collider (LHC) at CERN was very successful and resulted in important physics discoveries. One way of increasing the luminosity in a collider, which gave a very significant contribution to the LHC performance in the first run and can be used even if the beam intensity cannot be increased, is to decrease the transverse beam size at the interaction points by reducing the optical function β . However, when doing so, the beam becomes larger in the final focusing system, which could expose its aperture to beam losses. For the LHC, which is designed to store beams with a total energy of 362 MJ, this is critical, since the loss of even a small fraction of the beam could cause a magnet quench or even damage. Therefore, the machine aperture has to be protected by the collimation system. The settings of the collimators constrain the maximum beam size that can be tolerated and therefore impose a lower limit on β . In this paper, we present calculations to determine safe collimator settings and the resulting limit on β , based on available aperture and operational stability of the machine. Our model was used to determine the LHC configurations in 2011 and 2012 and it was found that β could be decreased significantly compared to the conservative model used in 2010. The gain in luminosity resulting from the decreased margins between collimators was more than a factor 2, and a further contribution from the use of realistic aperture estimates based on measurements was almost as large. This has played an essential role in the rapid and successful accumulation of experimental data in the LHC.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73573800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 44

rf-induced beam dynamics in rf guns and accelerating cavities 射频枪和加速腔中射频诱导束流动力学

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-18 DOI: 10.1103/PHYSREVSTAB.18.064801

K. Floettmann

引用次数: 24

Simple method to suppress the fundamental in a harmonic free electron laser 一种抑制谐波自由电子激光器基波的简单方法

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-18 DOI: 10.1103/PHYSREVSTAB.18.060703

G. Penn

{"title":"Simple method to suppress the fundamental in a harmonic free electron laser","authors":"G. Penn","doi":"10.1103/PHYSREVSTAB.18.060703","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.060703","url":null,"abstract":"Preliminary studies of harmonic lasing have shown significant promise as a method to produce radiation at higher photon energies for a given electron energy and for a given undulator. The basic idea is to suppress radiation at the fundamental resonant wavelength, and allow radiation at a specific harmonic to grow exponentially without being driven by nonlinear processes at the fundamental. This has several potential benefits: higher photon energies for the same undulator field, plus significantly more power and smaller bandwidth compared to extracting nonlinear radiation at the harmonic after the fundamental has reached saturation. In this paper, we use beam parameters from the current design of LCLS-II to take a critical look at the challenge of suppressing radiation at the fundamental wavelength and to evaluate how much of an improvement in terms of photon energy reach and brightness can be achieved through harmonic lasing. For undulators with adjustable magnetic fields, a scheme is presented which can delay the onset of saturation at the fundamental wavelength by a factor of 2. Performance characteristics and especially spectral brightness are compared to self-seeded beam lines as an alternative method to reduce bandwidth, as well as with more conventional SASE beam lines.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83167698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Physics of fully-loaded laser-plasma accelerators 满载激光等离子体加速器物理学

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-17 DOI: 10.1103/PHYSREVSTAB.18.061301

E. Guillaume, A. Döpp, C. Thaury, A. Lifschitz, J. Goddet, A. Tafzi, F. Sylla, G. Iaquanello, T. Lefrou, P. Rousseau, K. T. Phuoc, V. Malka

引用次数: 27

Observation of redshifting and harmonic radiation in inverse Compton scattering 逆康普顿散射中红移和谐波辐射的观测

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-17 DOI: 10.1103/PHYSREVSTAB.18.060702

Y. Sakai, I. Pogorelsky, O. Williams, F. O’Shea, S. Barber, I. Gadjev, J. Duris, P. Musumeci, M. Fedurin, A. Korostyshevsky, B. Malone, C. Swinson, G. Stenby, K. Kusche, M. Babzien, M. Montemagno, P. Jacob, Z. Zhong, M. Polyanskiy, V. Yakimenko, J. Rosenzweig

{"title":"Observation of redshifting and harmonic radiation in inverse Compton scattering","authors":"Y. Sakai, I. Pogorelsky, O. Williams, F. O’Shea, S. Barber, I. Gadjev, J. Duris, P. Musumeci, M. Fedurin, A. Korostyshevsky, B. Malone, C. Swinson, G. Stenby, K. Kusche, M. Babzien, M. Montemagno, P. Jacob, Z. Zhong, M. Polyanskiy, V. Yakimenko, J. Rosenzweig","doi":"10.1103/PHYSREVSTAB.18.060702","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.060702","url":null,"abstract":"Inverse Compton scattering of laser photons by ultrarelativistic electron beam provides polarized x- to $ensuremath{gamma}$-ray pulses due to the Doppler blueshifting. Nonlinear electrodynamics in the relativistically intense linearly polarized laser field changes the radiation kinetics established during the Compton interaction. These are due to the induced figure-8 motion, which introduces an overall redshift in the radiation spectrum, with the concomitant emission of higher order harmonics. To experimentally analyze the strong field physics associated with the nonlinear electron-laser interaction, clear modifications to the angular and wavelength distributions of x rays are observed. The relativistic photon wave field is provided by the ps ${mathrm{CO}}_{2}$ laser of peak normalized vector potential of $0.5l{a}_{L}l0.7$, which due to the quadratic dependence of the strength of nonlinear phenomena on ${a}_{L}$ permits sufficient effects not observed in past 2nd harmonic study with ${a}_{L}ensuremath{approx}0.3$ laser [, Phys. Rev. Lett. 96, 054802 (2006)]. The angular spectral characteristics are revealed using $K$-, $L$-edge, and high energy attenuation filters. The observation indicates existence of the electrons' longitudinal motion through frequency redshifting understood as the mass shift effect. Thus, the 3rd harmonic radiation has been observed containing on-axis x-ray component that is directly associated with the induced figure-8 motion. These are further supported by an initial evidence of off-axis 2nd harmonic radiation produced in a circularly polarized laser wave field. Total x-ray photon number per pulse, scattered by 65 MeV electron beam of 0.3 nC, at the interaction point is measured to be approximately ${10}^{9}$.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83222365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Novel technique for injecting and extracting beams in a circular hadron accelerator without using septum magnets 在环形强子加速器中不使用隔磁体注入和提取光束的新技术

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-06-16 DOI: 10.1103/PHYSREVSTAB.18.074001

A. Franchi, M. Giovannozzi

引用次数: 3

Analytical study on emittance growth caused by roughness of a metallic photocathode 金属光电阴极粗糙度引起发射率增长的分析研究

Physical Review Special Topics-accelerators and Beams Pub Date : 2015-05-29 DOI: 10.1103/PHYSREVSTAB.18.053401

Zhe Zhang, Chuanxiang Tang

引用次数: 16