FEL2015 - List of Authors (Anisimov, P.M.)

Paper	Title	Page
TUB02	Distributed Seeding for Narrow-band X-ray Free-Electron Lasers	301
	D.C. Nguyen, P.M. Anisimov, C.E. Buechler, Q.R. Marksteiner LANL, Los Alamos, New Mexico, USA
	Funding: We thank Bruce Carlsten, John Lewellen, Steve Russell, and Rich Sheffield (LANL), Craig Ogata and Yuri Shvyd'ko (ANL) for helpful discussion, and the MaRIE project for financial support. 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.
	Slides TUB02 [1.241 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUP006	Quantum Nature of Electrons in Classical X-ray FELs	338
	P.M. Anisimov LANL, Los Alamos, New Mexico, USA
	X-ray FELs built to date are well described by the classical theory. This theory in its simplest form is expressed as a system of pendulum equations for electrons coupled to the electromagnetic field. The FEL interaction requires bunching of the electrons on a scale less than radiation wavelength. The progress in the development of FELs and the need to reach even shorter laser radiation wavelength with low energy electrons require that the quantum characteristic of the FEL interaction to be properly considered. Quantum theories have been already proposed by a number of authors. These theories, however, have been developed for regimes that are not relevant for modern/planned X-ray FELs. Here, we focus on quantum effects in modern/future X-ray FELs and stop treating an electron as a point-particle. This results in quantum reduction of the bunching! Starting with the analysis of the free space dispersion for the electron wave packet, we will present a modified 1D FEL theory that takes into account the quantum uncertainty of the electron position in X-ray FELs. This theory allows for a unified classification of FELs with respect to the wave nature of an electron that shows a planned FEL at Los Alamos National Lab to be most affected. The Genesis simulation code has been modified in order to include quantum reduction of the bunching that lead to interesting results. LA-UR-15-26276
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

Paper

Title

Page

Distributed Seeding for Narrow-band X-ray Free-Electron Lasers

301

D.C. Nguyen, P.M. Anisimov, C.E. Buechler, Q.R. Marksteiner
LANL, Los Alamos, New Mexico, USA

Funding: We thank Bruce Carlsten, John Lewellen, Steve Russell, and Rich Sheffield (LANL), Craig Ogata and Yuri Shvyd'ko (ANL) for helpful discussion, and the MaRIE project for financial support.
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.

Slides TUB02 [1.241 MB]

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUP006

Quantum Nature of Electrons in Classical X-ray FELs

338

P.M. Anisimov
LANL, Los Alamos, New Mexico, USA

X-ray FELs built to date are well described by the classical theory. This theory in its simplest form is expressed as a system of pendulum equations for electrons coupled to the electromagnetic field. The FEL interaction requires bunching of the electrons on a scale less than radiation wavelength. The progress in the development of FELs and the need to reach even shorter laser radiation wavelength with low energy electrons require that the quantum characteristic of the FEL interaction to be properly considered. Quantum theories have been already proposed by a number of authors. These theories, however, have been developed for regimes that are not relevant for modern/planned X-ray FELs. Here, we focus on quantum effects in modern/future X-ray FELs and stop treating an electron as a point-particle. This results in quantum reduction of the bunching! Starting with the analysis of the free space dispersion for the electron wave packet, we will present a modified 1D FEL theory that takes into account the quantum uncertainty of the electron position in X-ray FELs. This theory allows for a unified classification of FELs with respect to the wave nature of an electron that shows a planned FEL at Los Alamos National Lab to be most affected. The Genesis simulation code has been modified in order to include quantum reduction of the bunching that lead to interesting results. LA-UR-15-26276

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)