Vélez, A.V. Glock, H.-W. Glöckner, F. Hall, B.D.S. Knobloch, J. Neumann, A. Schnizer, P. Sharples, E. Tsakanian, A.V. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-MOYA02 English 29-35 MOYA02 ion cavity HOM SRF synchrotron Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-MOYA02 http://jacow.org/srf2017/papers/moya02.pdf The BESSY VSR project represents an exciting alternative to diffraction limited storage rings in the development of a next generation light source. Such a system should be capable to store "standard" (some 10 ps long) and "short" (ps and sub-ps long) pulses simultaneously in the storage ring opening the door to picosecond dynamic and high-resolution experiments at the same facility. This unique feature can be created by the introduction of the beating effects produced by higher harmonic SRF cavity systems (1.5 GHz & 1.75 GHz). The challenging design specifications as well as the technological demands on the SRF system make BESSY VSR a defiant project where non-standard techniques such as waveguide-damped cavities have been further developed. This talk focuses on the new SRF developments that includes wveguide-damped cavities, high-power couplers and higher-order mode absorbers that must handle nearly 2 kW of HOM power. The cryomodule design and its interaction with the beam will also be discussed.