European Facilities

FELs that are part of LEAPS

European XFEL

The European XFEL is a 3.4 km long X-ray free-electron laser facility that is currently (2017) entering its operation phase, extending from the German city of Hamburg to the neighbouring town of Schenefeld in the federal state of Schleswig-Holstein. It will generate the world's brightest ultrashort X-ray pulses that will enable scientists to map the atomic details of viruses, decipher the molecular composition of cells, take three-dimensional images of the nanoworld, film chemical reactions, and study processes such as those occurring deep inside planets. With its repetition rate of 27 000 pulses per second and a peak brilliance a billion times higher than that of the best synchrotron X-ray radiation sources, the European XFEL will open up new research opportunities for scientists and industrial users.

The facility is being realized as a joint effort of many partners. To this end, the European X-Ray Free-Electron Laser Facility GmbH, a limited liability company under German law that was officially founded in Hamburg on 28 September 2009, cooperates closely with the research centre DESY and other organizations worldwide. Civil construction started in early 2009 and user operation is planned to start in 2017. Presently, 11 countries are participating in the European XFEL project: Denmark, France, Germany, Hungary, Italy, Poland, Russia, Slovakia, Spain, Sweden, Switzerland, and the United Kingdom.

Beamlines: 3, upgradeable to 5

Scientific instruments: 6, upgradeable to 10


Operated by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the free-electron-laser facility FELBE provides picosecond infrared pulses. Two free-electron lasers cover the mid- and far-infrared spectral range from 4 - 250 µm. Pulse duration and pulse energy vary with wavelength and lie in the range from 1 - 25 ps and 100 nJ - few µJ, respectively. FELBE can operate in three different modes:

-       continuous pulsing with a repetition rate of 13 MHz
-       pulsing with 1 kHz by applying a pulse picker
-       macro-bunch operation with bunch length > 100 µs and macro-bunch repetition rates ≤ 25 Hz.

The user labs at FELBE are equipped mainly for time-resolved spectroscopy. Various tabletop near-infrared and THz sources can be synchronized to FELBE and setups exist for single-colour and two-colour pump-probe experiments, time-resolved photoluminescence measurements, near-field spectroscopy and Fourier-transform infrared spectroscopy. Samples can be studied in an 8 T split-coil magnet with optical access. Furthermore FELBE is linked to the Dresden High Magnetic Field Laboratory, which enables infrared spectroscopy in pulsed magnetic fields.


The FELIX (Free Electron Lasers for Infrared eXperiments) Laboratory at the Radboud University in Nijmegen is an international user facility providing the scientific community with tunable radiation of high brightness in the mid- and far-infrared as well as the THz regime. The laboratory exploits a suite of free electron lasers (FELs); two independent accelerators drive together four FELs: FEL-1, FEL-2, FELICE and FLARE. In total they cover a spectral range that extends from 3 to 1500 µm. Pulse duration and pulse energy vary with wavelength but range in general between 1 - 50 ps and 5 -50 µJ. The temporal and transverse beam profiles are close to transform, respectively diffraction limited.

The infrared and THz radiation of the FELIX lasers interacts with molecules and materials. This can reveal detailed information about 3D structure, functional properties and electronic properties. Primary applications of the FELIX lasers are found in areas benefitting either from the high brightness or the high fluence of the light sources. In 15 dedicated experimental stations, advanced equipment such as FTICR mass spectrometers, (cold) ion traps, molecular beam/cluster machines and four-wave-mixing setups are available to the users. Auxiliary equipment such as fs laser, ns laser in the IR/VIS/UV range, FTIR and TDS spectrometers, cryostats, magnets etc. are accessible for experimental campaigns or characterisation. Unique stations are those connected to FELICE for intra-cavity experiments where the intensity at the point of the experiment is 50 to 100 times higher compared to the conventional user station. The FELIX lasers also connect to the magnets of the high field magnet laboratory (HFML); the combination enables simultaneous studies in high magnetic fields up to 33 Tesla (45 T in 2018) and under intense infrared and THz radiation.


FERMI is a state of the art Free Electron Laser (FEL) source, based on a high gain harmonic generation free electron laser. The FEL is seeded in the UV by a tunable solid state laser system. The seed is multiplied in frequency in the FEL cascade extending the operation in the VUV soft X-ray range of the spectrum. Two FEL undulator lines, FERMI FEL-1 and FEL-2, are optimized to deliver radiation in the ranges 100-20 nm and 20-4 nm respectively.

Seeded operation ensures control of the FEL spectrum, pulse duration and synchronization with conventional laser sources for pump and probe applications. Synchronized radiation pulses of duration less than 100 fs, characterized by unprecedented spectral purity and stability for this class of lasers are available.

Both FEL-1 and FEL-2 lines have reached the expected performance and are open to external users.. Activities with users are characterized by a high degree of interaction and collaboration, which has stimulated the development of several new operational schemes, for example two color experiments based on FEL pump and FEL probe pulses. A portion of the seed laser is transported to the experimental station as a user laser in the IR or UV, with unprecedented time jitter values between the user laser and the FEL, namely less than 6 fs.


FLASH (Free Electron Laser in Hamburg), is the world’s first FEL designed and constructed for the extended ultraviolet and soft X-ray spectral range (XUV) by the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany. This facility has provided extremely bright, coherent and ultra short XUV pulses for a broad science programme conducted by scientists from all over the world since 2005. FLASH has also served as a pilot facility for the European XFEL which has been under construction in Hamburg since 2009 and is based on the same accelerator technology.
More information on the FLASH machine and the FLASH photon beamlines and user operation can be found on our websites.

FLASH is a high-gain FEL which achieves laser amplification and saturation in a single pass of a relativistic electron packet through a magnetic structure called undulator. The electron bunches are produced in a short-pulse laser-driven photo injector and accelerated by a superconducting linear accelerator. The superconducting technique allows to accelerate thousands of bunches per second which is not possible with other technologies. The lasing process is initiated by spontaneous radiation in the undulator, and brought to saturation by the self-amplified spontaneous emission (SASE) process. Femtosecond coherent light pulses emerge from the 30 m long undulator in the accelerator tunnel and can be delivered alternatively to five experimental stations in the FLASH experimental hall by a photon beam transport system operating under ultra-high vacuum conditions.

FLASH covers a wavelength range of approximately 4 - 45 nm with pulse energies up to ~500 µJ and pulse durations between <50 fs and 200 fs. In addition, a planar electromagnetic undulator with ten periods just behind the SASE undulator can be used to create strong, coherent THz radiation pulses with pulse energies of ~100 μJ which are strictly synchronous with the FEL pulses and can be combined with them on a sample with variable time delay. Ultrafast optical laser systems synchronised with the FEL are also available for the experiments.

Since 2012, a major upgrade is being undertaken at FLASH, with the construction of a second undulator tunnel and a new experimental hall with the aim of doubling the throughput of experiments. A fast electron beam switch is installed immediately behind the last superconducting accelerator module, enabling distribution of the accelerated and compressed electron beam to both FEL undulator lines, i.e. FLASH1 (first beamline) and FLASH2 (new). FLASH2 covers essentially the same spectral range as FLASH1, however, its variable-gap undulator enables two experiments taking data at two distinct wavelengths quasi- simultaneously. In addition to the SASE mode used in FLASH1, seeding options are considered for the extension to improve beam quality. It is planned to start user experiments on FLASH2 in 2016, with initially two beamlines.


The new X-ray laser project known as SwissFEL, will extend PSI’s unique platform of large interdisciplinary research facilities to serve international research teams from universities and industry. SwissFEL is an essential part of PSI’s strategic focus and will establish Switzerland’s leading position in scientific research for years to come. It will attract top scientists from all over the world and enhance PSI’s acknowledged position as a world-class research institute. Furthermore, the new high-tech facility will provide an incentive for Swiss industry through which existing highly-qualified jobs can be maintained and new ones created.

On December 5th 2016 PSI has inaugurated in the presence of the President of Switzerland Johann Schneider-Ammann the X-ray FEL facility SwissFEL, after 4 years of construction. The facility consists of a low emittance injector, a 6 GeV linear electron accelerator, a string of 12 undulator magnets designed for FEL lasing at photon energies of up to 12.8 keV and the photon beamlines and end-stations. The SwissFEL building is located in a forest site nearby PSI. It’s total building length is 740m. In the initial configuration SwissFEL’s hard X-ray beamline “ARAMIS” is equipped with two end stations for user experiments dedicated for studies in photochemistry/photobiology, structural biology and condensed matter physics.

First electrons where transported to the main electron beam dump on November 11th 2016 and very first lasing at a moderate wavelength of 24 nm was achieved on December 2nd 2016.

During 2017 the facility will be commissioned to nominal performance with first pilot experiments scheduled for autumn 2017. Regular user operation will start in 2018. In parallel the construction of a second FEL line “ATHOS” dedicated for soft X-rays has been launched, which will be completed in 2020.

The technical design of SwissFEL has to keep a delicate balance between the demand from experimentalists for breathtaking performance in terms of photon beam properties, on the one hand, and essential requirements for a user facility, such as confidence in technical ability, reliable and stable functioning, and economy of installation and operation, on the other hand. The baseline design aims to produce FEL pulses covering the wavelength 1 Å - 70 Å, with a compact and economic design which is affordable on the scale of a national laboratory.