Since 2003, PSI has been investigating an advanced Low Emittance Gun (LEG) based XFEL facility to supply coherent, ultra-bright, and ultra-short photon beams covering the wavelengths from 0.1 nm to 10 nm. To build the facility within a length of 800 m, challenging beam parameters are required at the entrance of the undulators. For the first two FEL beamlines (FEL1 and FEL2), the required normalized slice emittance, slice energy spread, and peak current are about 0.2 μm, 0.6 MeV, and 1.5 kA respectively. However, the required beam parameters for the third FEL beamline (FEL3), covering 1 nm to 10 nm, are somewhat flexible. Therefore we are developing two different gun technologies. The 1 MV high gradient pulsed diode and field emission based advanced LEG will be used for the first two FEL beamlines, while a CTF3 gun based RF photoinjector will be used for the third FEL beamline. To test these two injector technologies, a 250 MeV injector test facility will be constructed at PSI from 2008. In this paper, we describe beam dynamics for two different injector optimizations of the CTF3 RF gun based injector test facility.

Illumination of a ZrC needle with short laser pulses (16 ps, 266 nm) while high voltage pulses (-60 kV, 2 ns, 30 Hz) are applied, produces photo-field emitted electron bunches. The electric field is high and varies rapidly over the needle surface so that quantum efficiency (QE) near the apex can be much higher than for a flat photocathode due to the Schottky effect. Up to 150 pC (2.9 A peak current) have been extracted by photo-field emission from a ZrC needle. The effective emitting area has an estimated radius below 50 microm leading to a theoretical intrinsic emittance below 0.05 mm mrad.

Today most of the X-rays Free-Electron Laser projects are based on state of the art RF guns, which aim at a nor- malized electron beam emittance close to 1 mm·mrad. In this paper we report on the progress made at PSI towards a hybrid DC + RF Low Emittance Gun (LEG) capable of producing a beam with an emittance below 0.1 mm·mrad. To reduce the intrinsic thermal emittance at the LEG cath- ode the electrons are extracted from nano-structured field- emitters. A gun test facility is under construction wherein after emission the beam is accelerated up to 500 keV in a diode before being injected and accelerated in a two- frequency 1.5-cell RF cavity. The fast acceleration in the diode configuration allows to minimize the emittance di- lution due to the strong space charge forces. The two- frequency RF structure is optimized to limit the emittance blow-up due to the non-linearity of the RF field.

The FERMI @ ELETTRA project is aiming, in a first stage, for the construction of a single-pass FEL in the wavelength range from 100 nm to 40 nm. As a next step, the energy range of the existing accelerator system will be increased to reach the final wavelength target of 1.2 nm. Theoretical studies have been carried out in order to support the initial phase of the project. In particular, we report here on first integrated tracking simulation from the cathode through the undulators performed using different numerical codes. PACS codes: 41.60Ap, 41.60.Cr 41.85Ja, 52.59.Rz

Together with the INFM and other Italian institutes, Sincrotrone Trieste has proposed and developed FERMI@ELETTRA in response to the Italian government's call for proposals from national institutes for a multipurpose pulsed laser X-ray source. The proposed FEL source will be located at the third-generation synchrotron radiation facility ELETTRA and will utilize the fully available 1.0-GeV normal conducting linac. The project is organized along three stages of development, allowing gradual improvements for the production of 40-, 10-, and 1.2-nm radiation. The first two phases involve upgrading the linac with a high-brightness photo-injector and bunch compressor for the generation of increasingly higher quality electron beams. The third phase requires both an increase in peak current and beam energy to 3.0GeV. The requirements of the user-community necessitate reproducible radiation sources with controllable polarization and wavelength. For this APPLE-type undulators will be implemented and seeding schemes will be used where possible. An overview of the proposal is presented elucidating linac upgrades and overall layout, electron beam simulations, and laser seed schemes.