More than 15 Years of CW SRF Operation at ELBE

ELBE is a compact, accelerator-driven photon and particle source. Since 2001 it is operated as a user facility, providing more than 5500 hours of beam time each year. The electron accelerator is based on four superconducting 9-cell TESLA cavities that are driven in full CW operation to accelerate an average current of 1 mA up to beam energies of 40 MeV. The first part of the talk will summarize our experiences of operating TESLA cavities in CW. In detail, this includes their performance and attempts to improve it, as well as investigations on limitations. Additionally, we will discuss several issues that are related to the high average RF as well as beam power and we will present appropriate measures to protect the machine. In this regard, a resonant ring for RF component tests up to 100 kW was set up. The second part of the talk will focus on the development and operation of our SRF guns that are designed to produce short bunches with high charges and repetition rates of 1 MHz and beyond. Recently, SRF gun II was successfully transferred into routine user operation and delivers now more than 200 pC at 100 kHz to the experiment. First convincing results will be presented.