Performance and Perspective of Modern Synchrotron Light Sources

The first synchrotron radiation was used in a so called parasitic mode from high energy machines (1st generation). At the end of the 1970s and the beginning of 1980s accelerators dedicated to the production of synchrotron radiation were built (2nd generations). With the investigation and developments of insertion devices in the middle of 1980, the 3rd generation synchrotron radiation sources were built and emittances down to some nmrad could be reached. At present around 50 Synchrotron Radiation sources are existing around the world. All of these sources reached there the specification (energy, current, emittance, beam stability, etc.) very soon after the commissioning. With the 4th generation, emittances of down to around 100 pmrad should be reached. This is still a factor of 10 away from the requirement of a diffraction limited light source. According to the expertise in designing and operating of synchrotron radiation sources this should be reachable in the future, but only with circumferences of some kilometers like Petra III or PEP-X. Overall the performances and perspective of synchrotron light source are remarkable.