ENEA C.R. Frascati, Frascati (Roma)
SPARC is a single pass free electron laser test facility realized in collaboration between the main Italian research institutions and devoted to experiments of light amplification in different beam conditions. We have reached full saturation at 540nm by operating the FEL with a compressed beam obtained with "velocity bunching". The strongly chirped longitudinal phase space resulting from the compression process has been compensated by accordingly tapering the undulator gaps. Spectra with and without taper have been collected and an increase of about a factor 5 of the pulse energy in combination with spectra with a single coherence region have been detected in presence of the taper. The FEL has been operated as an amplifier and as a two stages cascade seeded with the second harmonic of the Ti:Sa driver laser generated in a crystal and with higher order harmonics generated in a gas cell. In seeded mode the cascade has been operated in saturated conditions with the observation of the third harmonic in the radiator at 67nm. High order harmonics up to th 11th at 37 nm have been observed from the seeded amplifier in deeply saturated conditions.
ELETTRA, Basovizza
Diamond, Oxfordshire
University of Nova Gorica, Nova Gorica
JLAB, Newport News, Virginia
LBNL, Berkeley, California
ENEA C.R. Frascati, Frascati (Roma)
DEEI, Trieste
MAX-lab, Lund
Some experiences have recently been collected from the FERMI@elettra Free Electron Laser first bunch compressor area. This includes a magnetic compressor, diagnostics for the characterization of the longitudinal and transverse phase space and suitable optics for matching to the downstream part of the linac. We report on the beam dynamics investigations in comparison with the modeling as well as the high level software control that has allowed this experience.
Universita' degli Studi di Milano, Milano
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
We have written and numerically solved a set of 1-d FEL equations for electrons and radiation without the need of the slowly varying envelope approximation (SVEA). The equations, which take into account both forward and backward waves, have been applied to the case of a very short beam, as long as few wavelenghts, and to the case of long beams with short density modulations.
ENEA C.R. Frascati, Frascati (Roma)
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
CEA, Gif-sur-Yvette
SOLEIL, Gif-sur-Yvette
Università di Roma II Tor Vergata, Roma
LUXOR, Padova
LOA, Palaiseau
UCLA, Los Angeles, California
INFN-Roma, Roma
Rome University La Sapienza, Roma
ISM-CNR, Rome
SPARC is a single pass free electron laser test facility realized in collaboration between the main Italian research institutions and devoted to experiments of light amplification in different beam conditions. While the laser was commissioned in self amplified spontaneous emission (SASE) mode during the last year, the operation in seeded mode has been recently demonstrated. The amplifier has been seeded with the second harmonic of the Ti:Sa driver laser generated in a crystal and with higher order VUV harmonics generated in a gas cell. The comparison between seeded and unseeded FEL emission will be discussed. The laser has been also operated in a new SASE configuration with a strongly chirped longitudinal e-beam phase space resulting from the RF compression. The chirp has been compensated by accordingly tapering the undulator gaps. Spectra with and without taper have been collected. An increase of about a factor 5 of the pulse energy in combination with spectra with a single longitudinal coherence region have been detected in presence of the taper. The combination of the chirp with the input seed is under study.
ENEA C.R. Frascati, Frascati (Roma)
In this contribution we combine concepts from different fields to show that the stimulated annihilation of positronium could be technologically achievable in the next future, providing a source of gamma rays to to be exploited for a wealth of applications. We analyze the feasibility of such a device by developing a preliminary design of an electron-positron recombination device for the generation of a “gamma ray laser”.