Contribution to a conference proceedings

PUBDB-2026-03001

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png 25 years of FEL operation at FLASH (DESY)

Honkavaara, K. (Corresponding author)DESY*

2026
JACoW Publishing

This record in other databases:  

Please use a persistent id in citations: doi:10.18429/JACoW-LINAC2026-TH1A001

Abstract: First SASE lasing at the FLASH Free-electron laser (FEL) - at that time called as TTF FEL - was in February 2000. It was the first FEL worldwide producing SASE radiation at VUV wavelengths. Since then, over more than two decades, FLASH has provided high peak and average brilliance XUV and soft X-ray FEL radiation for user experiments. In order to keep FLASH as a state-of-the-art FEL, it has been continuously refurbished and upgraded. The most recent upgrade FLASH2020+ increased the energy of the superconducting linac to 1.35 GeV and reconstructed the FLASH1 undulator beamline. The new externally seeded FLASH1 will provide fully coherent radiation at up to MHz photon pulse repetition rate (in a burst). Moreover, thanks to the new APPLE-III undulators, a full polarization control is possible. As before, FLASH1 hosts also an electron beam driven THz source. FLASH2 continues in SASE operation. This paper provides an overview of FLASH’s evolution from a test facility for superconducting accelerator technology to a trailblazing and innovative FEL user facility.

---

Contributing Institute(s):

1. Beschleunigerphysik (MPY)
2. Maschinen Koordination FLASH (MFL)

Research Program(s):

1. 6G2 - FLASH (DESY) (POF4-6G2) (POF4-6G2)
2. 621 - Accelerator Research and Development (POF4-621) (POF4-621)

Experiment(s):

1. Facility (machine) FLASH

Appears in the scientific report 2026

---