THOBNO —  Short Wavelength   (29-Aug-13   12:00—12:30)
Chair: H.-H. Braun, CERN, Geneva, Switzerland
Paper Title Page
THOBNO01 Three Unique FEL Designs for the Next Generation Light Source 734
 
  • G. Penn, D. Arbelaez, J.N. Corlett, P. Emma, G. Marcus, S. Prestemon, M.W. Reinsch, R.B. Wilcox
    LBNL, Berkeley, California, USA
  • A. Zholents
    ANL, Argonne, USA
 
  The NGLS is a next generation light source initiative spearheaded by the Lawrence Berkeley National Laboratory and based on an array of free-electron lasers (FEL) driven by a CW, 1-MHz bunch rate, superconducting linear accelerator. The facility is being designed to produce high peak and high average brightness coherent soft x-rays in the wavelength range of 1-12 nm, with shorter wavelengths accessible in harmonics or in expansion FELs. The facility performance requirements are based on a wide spectrum of scientific research objectives, requiring high flux, narrow-to-wide bandwidth, broad wavelength tunability, femtosecond pulse durations, and two-color pulses with variable relative timing and polarization, all of which cannot be encompassed in one FEL design. In addition, the cost of the facility requires building in a phased approach with perhaps three initial FELs and up to 9-10 FELs in the long term. We describe three very unique and complimentary FEL designs here as candidates for the first NGLS configuration.  
slides icon Slides THOBNO01 [1.331 MB]  
 
THOBNO02 Transverse Gradient Undulators for a Storage Ring X-ray FEL Oscillator 740
 
  • R.R. Lindberg, K.-J. Kim
    ANL, Argonne, USA
  • Y. Cai, Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by U.S. Dept.~of Energy, Office of Basic Energy Sciences, Contract No.~DE-AC02-06CH11357.
An x-ray FEL oscillator (XFELO) is a fully coherent 4th generation source with complementary scientific applications to those based on self-amplified spontaneous emission*. While the naturally high repetition rate, intrinsic stability, and very small emittance produced by an ultimate storage ring (USR) makes it a potential candidate to drive an XFELO, the energy spread is typically an order of magnitude too large for sufficient gain. On the other hand, Smith and coworkers** showed how the energy spread requirement can be effectively mitigated with a transverse gradient undulator (TGU): since the TGU has a field strength that varies with transverse position, by properly correlating the electron energy with transverse position one can approximately satisfy the FEL resonance condition for all electrons. Motivated by recent work in the high-gain regime***, we investigate the utility of a TGU for low gain FELs at x-ray wavelengths. We find that a TGU may make an XFELO realizable in the largest ultimate storage rings now under consideration (e.g., in either the old Tevatron or PEP-II tunnel).
* K.-J. Kim, Y. Shvyd'ko and S. Reiche, PRL 100 244802 (2008).
** T. Smith, et al., J. Appl. Phys. 50, 4580 (1979).
*** Z. Huang, Y. Ding, and C.B. Schroeder, PRL 109, 204801 (2012).
 
slides icon Slides THOBNO02 [1.208 MB]