Author: Anisimov, P.M.
Paper Title Page
Automatic Tuning of the Electron Beam Parameters to Enhance LCLS FEL Performance Using ES  
  • P.M. Anisimov, A. Malyzhenkov, A. Scheinker
    LANL, Los Alamos, New Mexico, USA
  We report on the design of the new automatic fine tuning system for the electron beam parameters using extremum seeking (ES) to enhance LCLS FEL performance. ES is the fastest multidimensional optimization algorithm for finding extremum. First, we demonstrate ES capability to find optimum Twiss parameters of the electron beam and FODO lattice delivering maximum radiation power in Genesis simulations. Then, we use ES for taper optimization and compare the optimum performance with no taper configuration but optimum Twiss parameters. Moreover, we combine these two techniques together for fine tuning to enhance FEL performance even further. Finally, we propose applying ES for fine tuning at LCLS experimentally: Once FEL is tuned to operate at desirable user parameters, electron beam parameters are changed to maximize radiation power, while the last one remains above the lowest border specified by user during each step of the optimization.  
FRB04 Canonical Formulation of 1D FEL Theory Revisited, Quantized and Applied to Electron Evolution 1
  • P.M. Anisimov
    LANL, Los Alamos, New Mexico, USA
  An original FEL theory relied on quantum analysis of photon generation by relativistic electrons in alternating magnetic field.* In most cases, however, the system of pendulum equations for non-canonical variables and the theory of classical electromagnetism proved to be adequate. As XFELs advance to higher energy photons, quantum effects of electron recoil and shot noise has to be considered. This work presents quantization procedure based on the Hamiltonian formulation of an XFEL interaction in 1D case. The procedure relates the conventional variables to canonical coordinates and momenta and does not require the transformation to the Bambini-Renieri frame.** The relation of a field operator to a photon annihilation operator reveals the meaning of the quantum FEL parameter, introduced by Bonifacio, as a number of photons emitted by a single electron before the saturation takes place.*** The quantum description is then applied to study how quantum nature of electrons affects the startup of XFEL and how quantum electrons become indistinguishable from a classical ensemble of electrons due to their interaction with a ponderomotive potential of an XFEL.
* Madey JMJ 1971 J. Appl. Phys. 42 1906 13.
** Bambini A and Renieri A 1978 Lett. Nuovo Cimento 21 399-404.
*** Bonifacio R, Piovella N, Robb G R M and Schiavi A 2006 PRSTAB 9 090701.