Concept of Master Oscillator Upgrade for FLASH

FLASH, a soft X-ray free-electron laser facility, is currently subject to several ongoing and planned upgrade activities. The underlying control and synchronization systems also have to keep up with the changing requirements. Therefore, in order to provide improved performance and better maintenance experience, a new master oscillator system is proposed. Most significant improvement can be seen in the jitter performance, bringing sub-10 fs rms integrated jitter which is an order of magnitude better than the present system. The first parts of the system are expected to be operational in mid-2020, while the final system installation and commissioning are scheduled for the beginning of the year 2021.