Author: Faatz, B.
Paper Title Page
Study of the Next Major Flash Upgrade: FLASH2020  
  • B. Faatz
    DESY, Hamburg, Germany
  The FLASH facility has delivered beam to two experiments simultaneously since Spring 2016. Both users can request a large variety of parameters independently, without interfering with the other experiment and the setup for both users can take place in parallel. For several years, a study has started to plan for the next major upgrade, referred to as FLASH2020. The ultimate goal is a CW version of FLASH with up to 1 million bunches per second which should be able to go down in wavelength to cover the complete water window. In this presentation we will present the different upgrade scenarios that are under discussion. Also we present tests already performed and planned for the near future to optimize the design and maximize the flexibility of the new facility.  
MOP031 First Operation of a Harmonic Lasing Self-Seeded FEL 1
  • E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov
    DESY, Hamburg, Germany
  Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows it to provide brilliant beams of higher-energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL), that allows it to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper, we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.