TY - CPAPER
AU - Nguyen, D.C.
AU - Anisimov, P.M.
AU - Buechler, C.E.
AU - Marksteiner, Q.R.
TI - Distributed Seeding for Narrow-band X-ray Free-Electron Lasers
J2 - Proc. of FEL2015
AB - The MaRIE XFEL is the proposed XFEL driven by a 12-GeV electron beam to generate coherent 42-keV photons based on a new seeding technique called distributed seeding (DS). This paper presents details of the distributed seeding technique using Si(111) Bragg crystals as the spectral filters. DS differs from self-seeding in three important aspects. First, DS relies on spectral filtering of the undulator radiation at more than one location early in the exponential gain curve. This leads to an FEL output that is dominated by the coherent seed signal, not SASE noise. Secondly, DS affords the ability to select a wavelength longer than the peak of the SASE gain curve, which leads to improved spectral contrast of the seeded FEL over the SASE background. Lastly, the power growth curves in successive DS stages exhibit the behavior of an FEL amplifier, i.e. a lethargy region followed by the exponential growth region. This behavior results in FEL output pulses that are less spiky than the SASE pulses. Using 3D Genesis simulations, we show that DS with two filters provides a 12X enhancement in spectral brightness relative to SASE and that DS with three filters produces negligible SASE background. The DS FEL spectrum has a relative spectral bandwidth (FWHM) of 8 X 10⁻⁵ with about 9 spectral modes.
PB - JACoW
CY - Geneva, Switzerland
SP - 301
EP - 304
KW - undulator
KW - radiation
KW - electron
KW - FEL
KW - simulation
DA - 2015/12
PY - 2015
SN - 978-3-95450-134-2
DO - 10.18429/JACoW-FEL2015-TUB02
UR - http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tub02.pdf
ER -