Statistical correlations and intensity spiking in the SASE FEL

Abstract

In the linear regime before saturation, we describe the statistical correlations in the narrow band chaotic output of the SASE FEL. At a fixed position along the undulator axis, we derive joint probability distributions for the intensity in the output pulse to have values 1 I and 2 I at times 1 t and 2 t , and for the spectral intensity to have values ~1I and ~2I at frequencies 1 ω and 2 ω . Probability distributions for the peak values of intensity in the time and frequency domains are also determined.

Frequency chirped self-amplified spontaneous-emission free-electron lasers

“…In Ref. [12], it was shown that for unchirped SASE the number of temporal spikes is N S 0:711M, where following Rice [14], the temporal spikes were characterized by the existence of local maxima of the intensity. If we define the full spectral width to be !…”

Analysis of statistical correlations and intensity spiking in the self-amplified spontaneous-emission free-electron laser

“…Because SASE starts from the shot noise, a proper theory requires a statistical treatment of the output radiation [6 -17]. Average properties of the output were studied in [6 -12] and fluctuations were considered in [13][14][15][16][17]. To describe the shot noise, one considers the arrival time of the individual electrons at the undulator entrance to be independent random variables, and one determines the statistical properties of the output radiation by averaging over the stochastic ensemble of arrival times.…”

“…Some of the results of our analysis were presented in Ref. [17]. In the earlier work [14] reviewed above, two important distributions of a ''global'' nature were derived: the exponential distribution [Eq.…”

Experimental study of a high-gain harmonic-generation free-electron laser in the ultraviolet

“…The average spacing between the spikes in the SASE spectrum gives an estimate of the radiation pulse length according to [23] T b 2 0:64c 1 ps:…”