Author: Russell, S.J.
Paper Title Page
TUOCN3 Application of the Eigen-Emittance Concept to Design Ultra-Bright Electron Beams 752
 
  • L.D. Duffy, K. Bishofberger, B.E. Carlsten, S.J. Russell, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  • A. Dragt
    UMD, College Park, Maryland, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.
Using correlations at the cathode to tailor the beam’s eigen-emittances is a recent concept made useful by the symplectic nature of Hamiltonian systems. While introducing correlations does not change the overall 6-dimensional phase space volume, it can change the partitioning of this volume into the longitudinal and two transverse emittances, which become the eigen-emittances if the initial correlations are removed. In principle, this technique can be used to generate beams with highly asymmetric emittances, such as those needed for the next generation of very hard X-ray free-electron lasers. Based on linear correlations, the applicability of this approach is limited by the magnitude of nonlinear effects in photoinjectors. We review the eigen-emittance concept and present a linear eigen-emittance design leading to a highly partitioned, and transversely ultra-bright, electron beam. We also present numerical tools to examine the evolution of the eigen-emittances in realistic accelerator structures and results indicating how much partitioning is practical.
 
slides icon Slides TUOCN3 [0.530 MB]  
 
TUODS1 MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design 799
 
  • B.E. Carlsten, C.W. Barnes, K. Bishofberger, L.D. Duffy, C.E. Heath, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, E.I. Simakov, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work is supported by the U.S. Department of Energy through the LANL/LDRD and MaRIE programs.
The proposed Matter-Radiation Interactions in Extremes (MaRIE) facility at the Los Alamos National Laboratory will include a 50-keV X-Ray Free-Electron Laser (XFEL), a significant extension from planned and existing XFEL facilities. To prevent an unacceptably large energy spread arising from energy diffusion, the electron beam energy should not exceed 20 GeV, which puts a significant constraint on the beam emittance. To achieve a sufficiently high gradient of 50 MV/m, an rf frequency of 11.424 GHz is considered. A 100-pC baseline design is presented along with advanced technology options to increase the photon flux and to generate longitudinal coherency through single-bunch optical seeding, pre-bunching the electron beam, and combinations of these techniques.
 
slides icon Slides TUODS1 [0.751 MB]  
 
WEP033 Using an Emittance Exchanger as a Bunch Compressor 1555
 
  • B.E. Carlsten, K. Bishofberger, L.D. Duffy, Q.R. Marksteiner, S.J. Russell, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
 
  Funding: This work is supported by the U.S. Department of Energy through the LANL/LDRD program.
An Emittance EXchanger (EEX), like a chicane, can be used for bunch compression. However, it offers a unique characteristic: the R56 term in an EEX vanishes, which decouples the final longitudinal position from the particles’ energies, thereby suppressing the microbunch instability. Also, it can provide simultaneous compression in both the longitudinal and one transverse dimensions, where, for example, the final longitudinal size is smaller than the initial horizontal size and the final horizontal size is smaller than the initial longitudinal size. In this scheme, there is no dependence on an energy slew needed for compressing the beam, simplifying the rf requirements. A bunch-compression scheme using two EEXs is presented, including CSR calculations.