Author: Bane, K.L.F.
Paper Title Page
MOPS085 Wakefield Calculations for the LCLS in Multibunch Operation* 802
 
  • K.L.F. Bane
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
Normally the Linac Coherent Light Source (LCLS) operates in single-bunch mode, sending a bunch of up to 250 pC charge at 120 Hz through the linac and the undulator, and the resulting FEL radiation into one of the experimental hutches. With two bunches per rf pulse, each pulse could feed either two experiments or one experiment in a pump-probe type configuration. Two-bunch FEL operation has already been briefly tested at the LCLS, and works reasonably well*, although not yet routinely. In this report we study the longitudinal and transverse long-range (bunch-to-bunch) wakefields of the linacs and their effects on LCLS performance in two-bunch mode. The longitudinal wake changes the average energy and chirp at the second bunch, and the transverse wake misaligns the second bunch (in transverse phase space) in the presence of e.g. transverse injection jitter or quad misalignments. Finally, we extend the study to consider the LCLS with trains of up to 20 bunches per rf pulse.
* F.-J. Decker et al, "A demonstration of multi-bunch operation in the LCLS," Proceedings of FEL2010, Malmoe, Sweden, p. 467.
 
 
WEPC105 Multiparticle Simulation of Intrabeam Scattering for SuperB 2259
 
  • T. Demma, M.E. Biagini, M. Boscolo
    INFN/LNF, Frascati (Roma), Italy
  • K.L.F. Bane, A. Chao, M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  Intrabeam scattering (IBS) is associated with multiple small angle scattering events leading to emittance growth. In most electron storage rings, the growth rates arising from IBS are much longer than damping times due to synchrotron radiation, and the effect on emittance growth is negligible. However, IBS growth rates increase with increasing bunch charge density, and for storage rings such as SuperB, that operate with high bunch charges and very low vertical emittance, the IBS growth rates can be large enough to produce significant emittance increase. Several formalisms have been developed for calculating IBS growth rates in storage rings*. However these models, based on Gaussian bunch distributions, cannot investigate some interesting aspects of IBS such as its evolution during the damping process and its effect on the beam distribution. We developed a multiparticle tracking code, based on the Binary Collision Model**, to investigate these effects. In this communication we present the structure of the code and simulation results obtained with particular reference to the SuperB parameters. Simulation results are compared with those of conventional IBS theories.
* A. Piwinski, Lect. Notes Phys. 296 (1988); J.D. Bjorken and S.K. Mtingwa, Part. Accel. 13 (1983); K. Kubo et al., Phys. Rev. ST-AB 8 (2005).
** Peicheng Yu et al., Phys. Rev. ST–AB 12 (2009).
 
 
THPC075 Lattice Design for PEP-X Ultimate Storage Ring Light Source 3068
 
  • Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.