Concept of an Infrared FEL for the Chemical Dynamics Research Laboratory at PETRA IV

We describe an infrared free electron laser (FEL), proposed as a part of a user facility that also incorporates synchrotron-radiation beamlines for the PETRA IV. The FEL itself addresses the needs of the chemical sciences community for a high-brightness, tunable source covering a broad region of the infrared spectrum - from 5 to 100 mkm. The user facility will allow, for the first time, the integrated and simultaneous use of dedicated infrared FEL and synchrotron-radiation beamlines for pump-probe experiments that will focus on gaining a rigorous molecular-level understanding of combustion and other energetic molecular processes. These (pump-probe) requirements dictate the use of storage ring RF structures and cw operation. The technical approach adopted in FEL design uses an old PETRA III RF system and accelerating cavities. The primary motivation for adopting this approach was to minimize facility costs.