Author: Marksteiner, Q.R.
Paper Title Page
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.
 
 
THP162 Design Studies of Coherent Prebunching and Emittance Reduction for the MaRIE XFEL 2414
 
  • Q.R. Marksteiner, K. Bishofberger, B.E. Carlsten, L.D. Duffy, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Supported by US Department of Energy Grant LDRD 20110067DR.
There are several schemes currently being investigated which use modulator and dispersive sections to step the coherent bunching of the electron beam up to higher harmonics. X-ray FELs generally operate in a regime where the FEL parameter ρ is equal to or less than the effective energy spread introduced from the emittance in the electron beam. Because of this large effective energy spread, the energy modulation introduced from harmonic generation schemes would seriously degrade FEL performance. This problem can be mitigated by incorporating the harmonic generation scheme at an electron kinetic energy lower than the energy at the final undulator. This will help because the effective energy spread from emittance is reduced at lower energies, and can be further reduced by making the beam transversely large. Then the beam can be squeezed down slowly enough in the subsequent accelerator sections so that geometric debunching is avoided. Here we show analytical results that demonstrate the feasibility of this harmonic pre-bunching scheme.