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We demonstrate the generation of coherent soft x-ray free-electron laser (FEL) pulses with a duration below 1 fs using nonlinear compression with a low-charge electron beam (10 pC). The approach is simple, and it does not require any special hardware, so it can be readily implemented at any x-ray FEL facility. We present temporal and spectral diagnostics confirming the production of single-spike sub-femtosecond pulses for photon energies of 642 and 1111 eV. Our work will be important for ultrafast FEL applications requiring soft x-rays. [ABSTRACT FROM AUTHOR]

The Paul Scherrer Institute is implementing laser-based seeding in the soft X-ray beamline (Athos) of its free-electron laser, SwissFEL, to enhance the temporal and spectral properties of the delivered photon pulses. This technique requires, among other components, two identical modulators for coupling the electron beam with an external laser with a wavelength range between 260 and 1600 nm. The design, magnetic measurements results, alignment, operation and also details of the novel and exotic magnetic configuration of the prototype are described. [ABSTRACT FROM AUTHOR]

A transverse tilt of the electron beam is normally not wanted in X-ray free-electron-laser (XFEL) facilities, since in a typical undulator beamline with quadrupole magnets only the central part of the beam with negligibly small betatron oscillations will produce significant XFEL radiation. In this work we present special configurations for which a transverse tilt can actually be used to improve the XFEL performance. In particular, we show with numerical simulations how tilted electron beams can be employed to generate two-color XFEL pulses, ultra-large-bandwidth XFEL radiation, and high-power and short duration XFEL radiation. We present and assess different mechanisms to generate the transverse tilt, namely a transverse deflecting structure, transverse wakefields, and introducing dispersion to an energy-chirped beam. [ABSTRACT FROM AUTHOR]

Abstract The Accelerator on a Chip International Program (ACHIP) is an international collaboration, funded by the Gordon and Betty Moore Foundation, with the goal of demonstrating that laser-driven accelerator can be integrated on a chip to fully build an accelerator based on dielectric structures. PSI will provide access to the high brightness electron beam of SwissFEL to test structures, approaches and methods towards achieving the final goal of the project. In this contribution, we will describe the two interaction chambers installed on SwissFEL to perform the proof-of-principle experiments. In particular, we will present the positioning system for the samples, the magnets needed to focus the beam to sub-micrometer dimensions and the diagnostics to measure beam properties at the interaction point. [ABSTRACT FROM AUTHOR]