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Venturini, M.

Paper Title Page
MOPCH047 Study of the Electron Beam Dynamics in the FERMI @ ELETTRA Linac 145
 
  • M. Cornacchia, P. Craievich, S. Di Mitri
    ELETTRA, Basovizza, Trieste
  • I.V. Pogorelov, J. Qiang, M. Venturini, A. Zholents
    LBNL, Berkeley, California
  • D. Wang
    MIT, Middleton, Massachusetts
  • R.L. Warnock
    SLAC, Menlo Park, California
  
  A study of the electron beam dynamics in the linac is made within the framework of the design of a free electron laser (FEL) at the Syncrotrone Trieste*. A scope of the work includes analysis of two operational scenarios, one with relatively long electron bunches of the order of 1.5 ps and a moderate peak current of 500 A and one with shorter bunches of the order of 0.7 ps and higher peak current of the order of 800 A. In both cases, care has been taken to preserve the slice and projected emittances formed in the photocathode gun injector and to minimize the slice energy spread. The latter goal is accomplished by balancing the onset of the microbunching instability driven by the longitudinal space charge forces and the emission of coherent synchrotron radiation using Landau damping produced by a so-called laser heater. Various analytical techniques and tracking codes have been employed to obtain the reported results.

*C. Bocchetta, et al., this conference.

 
MOPLS138 Space Charge and Equilibrium Emittances in Damping Rings 882
 
  • M. Venturini
    LBNL, Berkeley, California
  • K. Oide
    KEK, Ibaraki
  • A. Wolski
    Liverpool University, Science Faculty, Liverpool
  
  The unusual combination of small beam size and long ring circumference may cause space charge to have noticeable effects on the beam dynamics of the ILC (International Linear Collider) damping rings. One possible consequence is a modification of the vertical equilibrium emittance resulting from a non-ideal lattice. One simple way to account for this effect is to model space charge in the linear approximation within the framework of Oide's envelope (or Chao's matrix) formalism, whis is commonly used to calculate equilibrium emittances in lepton storage rings. However, this model would likely overestimate the effect as a linear approximation for space charge is accurate only in a small neighborhood of a bunch center. For a more accurate modelling, we propose to make use of Sacherer's envelope equations consisting of a closed set of equations for the second moments of a beam distribution that account for the nonlinear dependence of the space-charge force. Here we will illustrate how Sacherer's equations can be combined with Oide's formalism and apply the result to the ILC damping rings.