Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

Abstract

High power attosecond (as) X-ray pulses are in great demand for ultrafast dynamics and high resolution microscopy. We numerically demonstrate the generation of a~230 attosecond, 1.5 terawatt (TW) pulse at a photon energy of 1 keV, and a 115 attosecond, 1.2 TW pulse at a photon energy of 12.4 keV, using the realistic electron beam parameters such as those of Korean X-ray free electron laser (XFEL) in a tapered undulator configuration. To compensate the energy loss of the electron beam and maximize its radiation power, a tapering is introduced in the downstream section of the undulator. It is found that the tapering helps in not only amplifying a target radiation pulse but also suppressing the growth of satellite radiation pulses. Tapering allows one to achieve a terawatt-attosecond pulse only with a 60 m long undulator. Such an attosecond X-ray pulse is inherently synchronized to a driving optical laser pulse; hence, it is well suited for the pump-probe experiments for studying the electron dynamics in atoms, molecules, and solids on the attosecond time-scale. For the realization of these experiments, a high level of synchronization up to attosecond precision between optical laser and X-ray pulse is demanded, which can be possible by using an interferometric feedback loop.

Toward the Generation of an Isolated TW-Attosecond X-ray Pulse in XFEL

“…This article reviews several schemes among the previously published studies [37][38][39][40][41][42][43][44], assessing the feasibility of each scheme for the realization of the TW-as XFEL. The methods involved in beam emittance modulation or beam tilting are reviewed in Section 2.…”

X-ray Free-Electron Laser

“…Szlchetko et al describe a dispersive inelastic X-ray scattering spectrometer for XFELs [11], while Usenko et al describe a split-and-delay unit for FEL interferometry in the XUV spectral range [12]. Kumar et al discuss a plan for terawatt-isolated attosecond X-ray pulse generation using a tapered XFEL (PAL-XFEL) [13].…”