Method of Linear Invariants for description of beam dynamics of FEL undulator

An exact solution to the quartic equation in the wiggler frequency ωw , which represents the dispersion relation for this system, is obtained. The effects of the frequency of the wiggler ωw on the electron's velocities (v || and vw) are investigated. The regions of interest for the allowed wiggler frequency ωw for both group I and group II electron trajectories are discussed.

In the quest for ultra-compact sources, a test experiment is under preparation, to couple an electron beam from a laser driven plasma accelerator, stable and tunable in energy, to an undulator. The electron beam is generated in the colliding laser pulses scheme, by focusing two short and intense laser pulses in an underdense plasma plume. The electron bunch has an energy tunable in the range 100 − 300M eV with 1% energy spread, a length 10f s, a charge in the 10pC range, while its radius and divergence are respectively 1μm and 3mrad. As a first step toward a FEL experiment, the transport and radiation through an undulator of this short and compact electron beam is studied. Numerical predictions for the spontaneous emission through an undulator in the 40−120nm range is presented.

Physics of Plasmas, 2010

Chaotic behavior of an electron motion in combined backward propagating electromagnetic wiggler and ion-channel electrostatic fields is studied. The Poincaré surface-of-sections are employed to investigate chaotic behavior of electron motion. It is shown that the electron motion can exhibit chaotic behavior when the ion-channel density is low or medium, while for sufficiently high ion-channel density, the electron motion becomes regular (nonchaotic). Also, the chaotic trajectories decrease when the effects of self-fields of electron beam are taken into account and under Budker condition all trajectories become regular. The above result is in contrast with magnetostatic helical wiggler with axial magnetic field in which chaotic motion is produced by self-fields of electron beam. The chaotic and nonchaotic electron trajectories are confirmed by calculating Liapunov exponents.

Journal of Applied Physics, 1981

1981

Free electron lasers Sideband instabilities Microwave generation ..,.. .id. iln.c.itr-"< id.niilr by Mo«* numb.o 20.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2008

An ultracompact brilliant coherent x-ray source, where both the accelerator and the wiggler are provided by intense laser pulses, promises unsurpassed spectral and temporal qualities.

A Hamiltonian theory, in which electromagnetic space waves and longitudinal electric fields are incorporated by means of their vector potentials, is used to calculate particle motion in linear electron accelerators. In particular these calculations have been applied to the Eindhoven 10 MeV travelling-wave linac as well as to the Eindhoven racetrack microtron accelerating cavity. The calculations are in good agreement with simulations performed by particle-tracking codes.

IEEE Journal of Quantum Electronics, 2000

We present theoretical studies of the possibility of a freeelectron laser in the XUV and soft X-ray region of the spectrum, using a counterpropagating CO2 laser beam as an undulator. A one-dimensional model is used to evaluate the single-pass power gain of such a device. The detrimental effects due to the energy spread, emittance of the electron beam, and the diffraction of the electromagnetic undulator are explicitly incorporated in the formalism. An oscillator experiment has also been considered. We derive the solutions of the optical pulse evolution equation in the weak field, low gain, and long electron pulse regime.

The European Physical Journal B, 2006

A reduced Hamiltonian formulation to reproduce the saturated regime of a Single Pass Free Electron Laser, around perfect tuning, is here discussed. Asymptotically, Nm particles are found to organize in a dense cluster, that evolves as an individual massive unit. The remaining particles fill the surrounding uniform sea, spanning a finite portion of phase space, approximately delimited by the average momenta ω+ and ω−. These quantities enter the model as external parameters, which can be self-consistently determined within the proposed theoretical framework. To this aim, we make use of a statistical mechanics treatment of the Vlasov equation, that governs the initial amplification process. Simulations of the reduced dynamics are shown to successfully capture the oscillating regime observed within the original N -body picture.

European Physical Journal D, 2010

An analytic linear theory of the electron dynamics in a three-dimensional helical wiggler free electron laser (FEL) with axial magnetic field is presented. Orbits are obtained by perturbing the steady state-trajectories in order to determine the characteristic frequencies Ω± of the FEL. The effect of the self-fields on electron dynamics is studied and modified steady-state orbits and their stabilities have

Plasma Physics and Controlled Fusion, 2019

By deriving the 3/2 dimensional Hamiltonian equations for electrons in the intense laser radiation and quasi-static transverse electric and longitudinal magnetic fields, the electron heating mechanisms are examined both for low harmonic resonance of electron frequency in the static fields with the laser frequency and for high harmonic resonances where the overlapping of broadened resonances causes the stochastic heating. For both cases, the maximum electron kinetic energies, well beyond the ponderomotive scaling, depend only on a small parameter combining the laser amplitude, electrostatic field strength and the conserved dephasing rate.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1985

This work was supported by DARPA under contract No. 3817. 19. KEY WORDS (Continue on~n.. Ode.i InoCf.8.n..vd Idenify by block n..anbet) Free electron laser Incoherent radiation Spontaneous radiation Oscillator start-up 20. ABSTRACT (Continuo on reverse side if necosmory .,d Idenify by block-or) An analysis of the free electron laser (FEL) oscillator start-up problem in the linear regime is presented. The model is spatially one dimensional, though many important three dimensional effects are included heuristically. The electron beam consists of pulses of arbitrary shape separated by approximately twice the radiation transit time. The small gain/pass approximation is employed in deriving an energy. (Continues) DD ,'N, 1473 EDITION OF 1 NO11V IS OSSOLETK S/N 0102-014-6601 SECURITY CLASSIFICATION OF TIS PAGE (fton Dot* Eniorod) SECuRiTY CL ASSI,CATION OF T.IS PAGE (hn Data En-r .d) 20 ABSTRACT (Contine.d) rate equation, which described the evolution of the radiation pulses within the resonator. The wiggler field is assumed to occupy a portion of the finite Q resonator. In the energy rate equation, the spontaneous (incoherent) radiation term is represented by a source matrix, while the stimulated (coherent) radiation term is represented by a gain matrix. The effect of small variations in the mirror separation are investigated in the context of laser lethargy. Our analysis suggests possible methods which could substantially shorten the start-up times in FEL oscillators. Finally, our results are compared with the FEL oscillator experiments performed at Stanford University. SE1URITY CLASSIFICATION OF THIS PAGEIf'Wt.n Dt Enre,.d) 7 Ji I THE EVOLUTION OF SPONTANEOUS AN) COHERENT RADIATION IN THE FREE ELECTRON LASER OSCILLATOR 1.

Physics of Plasmas, 2010

The system of the nonlinear nonstationary equations describing spatial-temporal dynamics of the amplitudes of an undulator radiation and a space charge wave of a relativistic electron beam in the resonator is obtained. The electrostatic longitudinal wiggler is considered. A bunch of the electron beam injects to the resonator, at the ends of which two mirrors are placed. After the interaction of electrons of bunch with radiation in the presence of wiggler and after amplifying electromagnetic pulse, a part of radiation is reflected back by semitransparent mirror. Then, it reaches to the initial of the system where the other mirror is placed. Synchronously, when the pulse is reflecting, the other electron bunch enters to the resonator and interacts with the pulse. This operation has simulated until saturation of growth of the electromagnetic pulse. The dynamics of the problem is simulated by the method of macro particles. The dynamics of pulse amplification, motion of the electrons, an...

Physics of Plasmas, 2011

13th Fluid and PlasmaDynamics Conference, 1980

This paper presents a self-consistent non-linear treatment of the finite transverse dimensional effects associated with (i) the wiggler field, (ii) the electron beam and (iii) the radiation beam of the free electron laser (FEL) in a steady state amplifying configuration. Our formulation incorporates various efficiency enhancement schemes. A linearly polarized magnetic wiggler is used for our formulation. The inherent gradient of the magnetic wigglers in the transverse direction introduces betatron oscillations, which cause an increase in the effective axial beam temperature.