The UV European FEL at ELETTRA. Towards compatibility of storage ring operation for FEL and synchrotron radiation

The European Free Electron Laser (FEL) at ELETTRA has recently increased its maximum operating energy up to 1.5GeV, the highest electron-beam energy used so far for an FEL. This is an important improvement in the performance of the source, increasing the extracted power at wavelengths around 200nm and providing better beam stability and lifetime. Furthermore, this development represents a first step towards the solution of a crucial issue-the compatibility of FEL and normal synchrotron radiation operation at a user facility like ELETTRA. In this paper we discuss the most important aspects of this issue; in particular, we show that the properties of the electron beam in FEL mode can match the needs of normal synchrotron radiation experiments that require a few bunch filling of the storage ring.