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

S Krinsky,Z Huang

doi:10.1103/physrevstab.6.050702

Abstract

We present a statistical analysis of the temporal and spectral properties of self-amplified spontaneous emission from an energy-chirped electron beam passing through a long undulator. It is found that the coherence time is independent of the chirp, while the range of spectral coherence is linearly proportional to it. We consider the use of a monochromator to pick out a small temporal slice of the radiation output. For the filtered radiation pulse, we determine the pulse duration, the number of modes, and the energy fluctuation. We apply our analysis to schemes proposed to generate short x-ray pulses at the Linac Coherent Light Source.

Highlights

Single pass free-electron lasers (FELs) based on selfamplified spontaneous emission (SASE) are being developed as sources of high-brightness short-wavelength radiation
Since the radiated frequency is correlated with the temporal position along the pulse, a short segment of the original radiation is transmitted. This idea can be applied in two ways: (1) in the single-stage approach, the saturated chirped output from the full undulator is monochromated and the filtered radiation is transmitted to the experiment; (2) in the two-stage approach, the unsaturated chirped radiation from a first section of the undulator is extracted and used as a seed in the second section, where it is amplified to saturation by its interaction with the electron beam
The results presented in this paper will be important for frequency-chirped SASE FELs and for schemes using a monochromator to reduce the output pulse duration

Summary

INTRODUCTION

Single pass free-electron lasers (FELs) based on selfamplified spontaneous emission (SASE) are being developed as sources of high-brightness short-wavelength radiation. Since the radiated frequency is correlated with the temporal position along the pulse, a short segment of the original radiation is transmitted This idea can be applied in two ways: (1) in the single-stage approach, the saturated chirped output from the full undulator is monochromated and the filtered radiation is transmitted to the experiment; (2) in the two-stage approach, the unsaturated chirped radiation from a first section of the undulator is extracted and used as a seed, where it is amplified to saturation by its interaction with the electron beam. The results presented in this paper will be important for frequency-chirped SASE FELs and for schemes using a monochromator to reduce the output pulse duration

CHARACTERISTICS OF FREQUENCYCHIRPED SASE

PULSE SLICING USING A

SHORT X-RAY PULSES AT THE LCLS

SUMMARY AND DISCUSSION