Free-electron lasers (FELs) are promising devices for generating light with laser-like properties in the extreme ultraviolet and X-ray spectral regions. Recently, FELs based on the self-amplified spontaneous emission (SASE) mechanism have allowed major breakthroughs in diffraction and spectroscopy applications, despite the relatively large shot-to-shot intensity and photon-energy fluctuations and the limited longitudinal coherence inherent in the SASE mechanism. Here, we report results on the initial performance of the FERMI seeded FEL, based on the high-gain harmonic generation configuration, in which an external laser is used to initiate the emission process. Emission from the FERMI FEL-1 source occurs in the form of pulses carrying energy of several tens of microjoules per pulse and tunable throughout the 65 to 20 nm wavelength range, with unprecedented shot-to-shot wavelength stability, low-intensity fluctuations, close to transform-limited bandwidth, transverse and longitudinal coherence and full control of polarization

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Few of the TTF cryomodules have been equipped with Wire Position Monitors (WPM) for the on line monitoring of cold mass movements during cool-down, warm-up and operation. Each sensor can be used as a detector for mechanical vibrations of the cryostat. A Digital Receiver board is used to sample and analyze with high frequency resolution, the WPM picked up signals, looking to its amplitude modulation in the microphonic frequency range. Here we describe the new acquisition system and show the first vibration spectra detected during normal operation of the TTF cryomodules # 4 and #5.

FERMI@Elettra is the first seeded VUV/soft X-ray FEL source. It is composed of two undulatory chains: the low energy branch (FEL1) covering the wavelength range from 20 nm up to 100 nm, and the high energy branch (FEL2, employing a double stage cascade), covering the wavelength range from 4 nm up to 20 nm. At the end of 2012 FEL1 has been opened to external users while FEL2 has been turned on for the first time having demonstrated that a double cascade scheme is suitable for generating high intensity coherent FEL radiation. In this paper we will share our experience and will show our most recent results for both FERMI FEL1 and FEL2 sources. We will also present a brand new machine scheme that allows to perform two-colour pump and probe experiments as well as the first experimental results.

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