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SPARC and SPARX are two different initiatives toward an Italian Free Electron Laser (FEL) source operating in the Self Amplified Spontaneous Emission (SASE) mode, in which several national research institutions are involved. SPARC is a high gain FEL project devoted to provide a source of visible and VUV radiation while exploiting the SASE mechanism. An advanced Photo-Injector system, emittance compensating RF-gun plus a 150 MeV Linac, will inject a high quality e-beam into the undulator to generate high brilliance FEL radiation in the visible region at the fundamental wavelength, (∼500 nm). The production of flat top drive laser beams, high peak current bunches, and emittance compensation scheme will be investigated together with the generation of higher harmonic radiation in the VUV region. SPARX is the direct evolution of such a high gain SASE FEL toward the 13.5 and 1.5 nm operating wavelengths, at 2.5 GeV. To get the required value for the bunch peak current, Ipeak ≈ 2.5 kA, the “hybrid” scheme, RF-compression stage plus magnetic chicane, is analyzed and compared with the more standard double stage of magnetic compression. The two options are reviewed considering the tolerance to the drive laser pulse phase jitter.

The choice of a suitable geometry in designing a radio-frequency cavity for e+ e- storage ring allows the reduction of multipacting (MP) discharges. We have studied the behaviour of resonant electron discharges in the RF cavity of the Adone storage ring in Frascati, that shows a broad MP barrier in the 35 to 70 kV range of the accelerating voltage. It can be explained by one point MP on the end-plates of the resonator. Our computer simulations of the trajectories of electrons in the RF fields of the cavity clearly show multipacting trajectories in that region of the cavity at about that field level. On the base of our experimental measurements and simulations, the design of a new RF cavity, multipactor free in the end-plates region, is presented.

A 1.9 Tesla, 6 full poles wiggler magnet, decreasing the critical wavelength of synchrotron radiation in Adone from 8.3 Å to 4.4 Å has been built in the Frascati National Laboratories. The results of the first measurements are presented.