Effect of the parametric beam instability (PBI) of the relativistic electron beam in a crystal was analyzed theoretically in1 (see also2). This effect is analogous to self-amplification of spontaneous emission (SASE) mechanism for X-ray Free Electron Laser (XFEL) with an undulator. However, in the case of PBI the transversal modulation of the beam is defined by channeling of the electron in a crystal and the longitudinal modulation arises because of the parametric X-ray radiation mechanism. It is shown in the present paper that the current density J in the electron bunch typical for FEL facility is enough for the beam self-modulation within the X-ray range if the crystal thickness is larger than the crystal absorption length L ≥ Labs. This process could be used for generation of the coherent X-ray pulses if the time τd of the crystal destruction affected by the electron bunch is less than its passing time τd< L=c. The value τd(J) is estimated for the case of the FLASH electron bunch propagating through a Si crystal.
Interaction of the X-ray Free Electron Laser (XFEL) femtosecond pulses with a crystal is investigated beyond the means of the conventional linear response theory. In order to analyze the time dependence of the X-ray scattering properties of a crystal we analyze the electron density evolution on the basis of rate equations.1 In order to take into account the influence of the electron plasma that appears due to the ionization of the atoms of a crystal we couple the system of rate equations to the Boltzmann kinetic equation. As a result, the system of master equations involves such evolution channels as: photoionization, Auger recombination, electron impact ionization, electron-electron scattering and three body recombination. In order to consider these channels effectively expressions for the cross sections of these processes are calculated within the framework of the effective charge approximation.2 The numerical algorithm and software are developed for calculation of the intensity of the diffraction reflection of the XFEL pulse taking into account the specific characteristics of the kinetic processes in a crystal. Numerical results are analyzed on the example of the Si crystal in the wide range of the pulse parameters variation.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.