STATISTICAL PROPERTIES OF RADIATION FROM VUV AND X-RAY FREE-ELECTRON LASER

The paper presents a comprehensive analysis of the statistical propert ies of the radiation from a self-amplified spontaneous emission (SASE) free electron laser operating in linear and nonlinear mode. The inves tigation has been performed in a one-dimensional approximation assumin g the electron pulse length to be much larger than a coherence length of the radiation, The following statistical properties of the SASE FEL radiation have been studied in detail: time and spectral field correl ations, distribution of the fluctuations of the instantaneous radiatio n power, distribution of the energy in the electron bunch, distributio n of the radiation energy after the monochromator installed at the FEL amplifier exit and radiation spectrum. The linear high gain limit is studied analytically. it is shown that the radiation from a SASE FEL o perating in the linear regime possesses all the features corresponding to completely chaotic polarized radiation. A detailed study of statis tical properties of the radiation from a SASE FEL operating in linear and nonlinear regime has been performed by means of time-dependent sim ulation codes. All numerical results presented in the paper have been calculated for the 70 nm SASE FEL at the TESLA Test Facility being und er construction at DESY. (C) 1998 Elsevier Science B.V.