The European XFEL and FLASH
The DESY facility FLASH is a smaller version of the future European XFEL. Both light sources generate X-ray radiation, which differs essentially in its wavelength.
FLASH and the European XFEL rely on the same operating principle: Electrons are first brought to high energies in an accelerator and then made to radiate high-intensity X-ray flashes.
The light from the two facilities differs mainly in its wavelength (colour). Whereas around four nanometers (four billionths of a metre) are reached at FLASH, the European XFEL will generate laser light with more than 80 times shorter wavelengths. Using the light from FLASH, scientists can already make out single molecules; at the European XFEL, they will be even able to observe their atomic structure.
FLASH has been in operation for experiments since 2005 and is being developed even further. Today already, new experimental methods enabling completely novel experiments are being devised and exploited at FLASH. These methods will be refined in the coming years and will then also be available for research at the European XFEL.
FLASH is a facility of the Helmholtz research centre DESY. It is located on the DESY site in Hamburg. The European XFEL will be around 10 times larger than FLASH. The facility is under construction between the DESY site and the town of Schenefeld and will operated by an independent research organization, the European XFEL GmbH.
More about FLASH
| European XFEL | FLASH | ||
|---|---|---|---|
| Abbreviation for | European X-ray Free-Electron Laser | Free-Electron Laser in Hamburg | |
| Start of commissioning | 2016 | 2004 | |
| Length of the accelerator | 1.7 kilometres | 0.15 kilometres | × 11 |
| Length of the facility | 3.4 kilometres | 0.3 kilometres | × 11 |
| Number of accelerator modules | 100 | 7 | × 14 |
| Maximum electron energy | 17.5 billion electron volts (17.5 GeV) | 1 billion electron volts (1 GeV) | 17.5 |
| Minimum wavelength of the laser light | 0.05 nanometre (of the order of an atom) |
4.1 nanometres (of the order of a molecule) |
× 1/82 |
| Number of undulators (magnet structures for light generation) | 3, upgradeable to 5 | 1 | |
| Number of experiment stations | 6, upgradeable to 10 | 5 | × 2 |
| Location | Hamburg and Schenefeld | Hamburg | |
| Operator | European XFEL GmbH | DESY |
The European XFEL in international comparison
Besides the European XFEL in Germany, next-generation light sources also exist in Japan and in the USA. The European XFEL will be the last of the three facilities to take up research operation; its performance, however, will make it outstanding.
X-ray laser facilities are being constructed all over the world: LCLS in California, SACLA in Japan, and the European XFEL in Germany. The operating principles of these facilities are very similar. Electrons are first accelerated to high energies and then made to generate high-intensity X-ray laser light. Whereas LCLS and SACLA rely on conventional accelerator technologies, however, the European XFEL will operate at minus 271 degrees Celsius using superconducting technology.
Superconduction allows the creation of an electron beam of especially high quality composed of many electron bunches aligned one behind the other. This enables the European XFEL to generate many more light flashes per second than the other two facilities. The number of usable light flashes is increased as well. Certain experiments will thus only be possible at the European XFEL, and others can be carried out much faster. The higher number of electron bunches also allows more experiment stations to be operated simultaneously.
| LCLS | SACLA | European XFEL | |
|---|---|---|---|
| Abbreviation for | Linac Coherent Light Source | SPring-8 Angstrom Compact Free Electron Laser | European X-Ray Free-Electron Laser |
| Location | California, USA | Japan | Germany |
| Start of commissioning | 2009 | 2011 | 2016 |
| Accelerator technology | normal conducting | normal conducting | superconducting |
| Number of light flashes per second | 120 | 60 | 27 000 |
| Minimum wavelength of the laser light | 0.15 nanometres | 0.08 nanometres | 0.05 nanometres |
| Maximum electron energy | 14.3 billion electron volts (14.3 GeV) | 6-8 billion electron volts (6-8 GeV) | 17.5 billion electron volts (17.5 GeV) |
| Length of the facility | 3 Kilometer | 750 Meter | 3.4 Kilometer |
| Number of undulators (magnet structures for light generation) | 1 | 3 | 3, upgradeable to 5 |
| Number of experiment stations | 3-5 | 4 | 6, upgradeable to 10 |
| Peak brilliance [photons / s / mm2 / mrad2/ 0.1% bandwidth] |
2·1033 | 1·1033 | 5·1033 |
| Average brilliance [photons / s / mm2 / mrad2/ 0.1% bandwidth] |
2.4·1022 | 1.5·1023 | 1.6·1025 |
