Moving towards beam energies around 2-6 MeV in ultrafast electron diffraction (UED) experiments allows achievement of larger coherence length for better *k*-space resolution, while the temporal resolution is improved when shorter electron bunches are generated and the velocity mismatch between the optical pump and UED probe is reduced. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a series of superconducting cw RF (SRF) guns has been designed, build, and tested, with the latest version currently in routine operation as one of the electron sources for the ELBE Center for High Power Radiation. This SRF photoinjector produces bunches with a few-MeV energies at up to MHz repetition rates, making it a suitable electron source also for MeV-UED experiments. The high repetition rate provides a significant advantage for the characterization of samples with low scattering cross-sections such as liquids and gases. In this paper, we outline the conceptual MeV-UED instrument program under development at HZDR. We also showcase the beam quality achieved in first simulations of the ELBE SRF gun operating at low bunch charge as an electron source for diffraction experiments.

The ELBE radiation source at HZDR has a long success story of delivering bright and powerful infrared and THz beams to a broad user community. Following the science driven user requests we have written a conceptual design report for the Dresden Advanced Light Infrastructure (DALI) as a successor to ELBE. The proposed DALI facility aims to increase the spectral brightness and pulse energy by orders of magnitude while providing two decades of tunability over the whole THz spectrum. It utilizes different radiation production schemes adapted to the wavelength range - super-radiant undulator sources for the long-wavelength THz range and an optical klystron driven by an oscillator FEL for the far-IR range. All sources are driven by superconducting linear accelerators allowing CW operation. The facility layout is chosen such that parallel operation of all sources is possible and great versatility is available to provide users with pulse repetition rates from single-shot to 1 MHz with flexible timing and the ability to combine sources. A positron source and a UED setup are planned to complete the facility.

Moving towards beam energies around 2-6 MeV in ultrafast electron diffraction (UED) experiments allows achievement of larger coherence length for better *k*-space resolution, while the temporal resolution is improved when shorter electron bunches are generated and the velocity mismatch between the optical pump and UED probe is reduced. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a series of superconducting cw RF (SRF) guns has been designed, build, and tested, with the latest version currently in routine operation as one of the electron sources for the ELBE Center for High Power Radiation. This SRF photoinjector produces bunches with a few-MeV energies at up to MHz repetition rates, making it a suitable electron source also for MeV-UED experiments. The high repetition rate provides a significant advantage for the characterization of samples with low scattering cross-sections such as liquids and gases. In this paper, we outline the conceptual MeV-UED instrument program under development at HZDR. We also showcase the beam quality achieved in first simulations of the ELBE SRF gun operating at low bunch charge as an electron source for diffraction experiments.