[en] This paper presents the conceptual design of a high power radiation source with laser-like characteristics in the ultraviolet spectral range at the TESLA test facility (TTF). The concept is based on the generation of radiation in a regenerative FEL amplifier (RAFEL). The RAFEL described in this paper covers a wavelength range of 200-400 nm and provides a 9 MHz train of 200 fs pulses with 2 mJ of optical energy per pulse. The linac operates at 1% duty factor and the average output radiation power exceeds 100 W. The RAFEL will be driven by the spent electron beam leaving the soft X-ray FEL, thus providing minimal interference between these two devices. After leaving the soft X-ray FEL undulator the electron beam passes another undulator. In this conceptual design we assume to use a planar permanent magnet undulator with 85 periods and a period length of 7 cm. The maximum amplitude of the magnetic field is about 1.4 T. The proposed scheme possesses significant advantages. First, the RAFEL output radiation has the same time structure as the X-ray FEL. Second, the pulses from the RAFEL are naturally synchronized with the soft X-ray pulses from the TTF FEL. Therefore, it should be possible to achieve synchronization close to the duration of the radiation pulses (200 fs) for pump-probe techniques using either an UV pulse as a pump and soft X-ray pulse as a probe, or vice versa, allowing unprecedented insight into the dynamics of electronic excitations, chemical reactions and phase transitions of matter, from atoms, through organic and inorganic molecules and clusters, to surface, solids and plasmas. (orig.)