Novel Sources for Synchrotron Light

E. Weckert HASYLAB at DESY, Notkestrasse 85, 22603 Hamburg, Germany

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During the past decades synchrotron radiation has become an amazingly versatile tool for a very large range of applications ranging from basic physics, materials science, condensed matter physics, chemistry to life sciences, just to mention a few. The properties most widely exploited are high brilliance or flux, tunability, polarisation, and temporal resolution. More recently with the advent of third generation synchrotron sources providing very small source sizes partially coherent radiation even in the X-ray regime is available which enables a large number of new experiments. However, as far as it concerns pulse length and coherence traditional storage ring based sources encounter limits that cannot easily be surpassed. Having also these applications in mind new concepts have been developed. Mainly in the US plans are worked out for linac driven storage rings. In these devices electrons circulate only once in a storage ring after they have been accelerated by a high current/power linac. The emittance of such a source would be considerably smaller than that of a normal storage ring of the same size. A totally coherent beam down in wavelengths to the A-regime will be delivered by so-called X-ray free electron lasers proposed in the US (Stanford), in Germany (DESY, Hamburg), and in Japan (Spring8/KEK). In these systems the beam of a linac is directly fed through very long undulators where X-rays are generated according to the so-called self-amplified spontaneous emission process. The radiation after such a device will be fully coherent in the transverse direction and the pulse length will be in the 0.1 ps regime. These are properties unseen so far. The peak (average) brilliance of such an X-ray free electron laser will be about ten (five) orders of magnitude higher compared to the most advanced present day synchrotron radiation sources.

DOI: 10.12693/APhysPolA.101.565 PACS numbers: 52.59.-f