The MAX IX Laboratory in Lund, Sweden, is currently operating three storage rings for synchrotron radiation. An upgrade of of the laboratory is currently being built containing two low emittance storage rings at 1.5 and 3 GeV and a 3 GeV linear accelerator. The new MAX IV will go into operation in 2016. A free electron laser is planned to become a part of the MAX IV facility and is created in two phases.

In the first phase a Short Pulse Facility (SPF) driven by the 3 GeV linac system is built. Here, short and highly brilliant X-ray pulses will be produced by spontaneous radiation in undulators and fed to the FemtoMAX beamline. The MAX IV FEL is planned as a second phase, but has not been funded to date. An extension of the linac up to 5-6 GeV is foreseen as driver of the X-ray FEL. The MAX IV linac system was installed in 2013 and is to a large extent already adapted to be expanded into a driver of an FEL.

A low emittance photo cathode gun is used as injector and two bunch compressors reduce the bunch length below 100 fs. Preliminary design of an FEL system targets wavelengths in the Ångström region, pulses shorter than 100 fs, seeding and multi GW peak power. Branch lines will be able to produce soft X-rays in the nanometer range. The envisaged FEL system will be utilizing the main components of electron gun, gun lasers, linac system, bunch compressors already installed in the 300 m MAX IV tunnel. The additional investments should thus be relatively moderate to achieve a full FEL.

For more than 20 years, development of FEL techniques has been performed at MAX-lab (now the MAX IV Laboratory). From coherent harmonic generation at the MAX I storage ring via harmonic generation and seeding at the FEL test facility on a 400 MeV linac system and now the commissioning of the SPF and highly compressed low emittance electron pulses at 3 GeV.

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