The single spike operation regime has been analyzed in the case of the SPARC injector and freeelectron-laser. Four different beams at 50 pC are studied, with different production condition and performance.
The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive 500 nm FEL experiments in various configurations, a Thomson backscattering source and a plasma accelerator experiment (these last two ones jointly with the project PLASMONX). The SPARC photoinjector is also the test facility for the recently approved VUV FEL project named SPARX. As a first stage of the commissioning, a complete characterization of the photoinjector has been accomplished with a detailed study of the emittance compensation process downstream the gun-solenoid system: this lead to the first direct experimental demonstration of emittance oscillations in a drift. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the “invariant envelope” matching and the demonstration of the “velocity bunching” technique in the linac. SASE and SEEDING experiments are foreseen by the end of the current year. In this paper we report the experimental results obtained so far and the scientific program for the near future.
SPARC-X is a two branch project consisting in the SPARC test facility dedicated to the development and test of critical subsystems such as high brightness photoinjector and a modular expandable undulator for SASE-FEL experiments at 500 nm with seeding, and the SPARX facility aiming at generation of high brilliance coherent radiation in the 1.5-13 nm range, based on the achieved expertise. The projects are supported by MIUR (Research Department of Italian Government) and Regione Lazio. SPARC has completed the commissioning phase of the photoinjector in November 2006. The achieved experimental results are here summarized together with the status of the second phase commissioning plans. The SPARX project is based on the generation of ultra high peak brightness electron beams at the energy of 1 and 2 GeV generating radiation in the 1.5-13 nm range. The construction is at the moment planned in two steps starting with a 1 GeV Linac. The project layout including both RF-compression and magnetic chicane techniques has been studied.
The SPARC Project is starting the commissioning of its
photo-injector. RF gun, RF sources, RF network and
control, power supplies, emittance meter, beam
diagnostics and control to measure the RF gun beam have
been installed. The photocathode drive laser has been
characterized in terms of pulse shape and quality. We will
report also about first tests made on RF gun and on the
emittance meter device. Additional R&D on X-band and
S-band structures for velocity bunching are in progress, as
well as studies on new photocathode materials. We will
also discuss studies on solenoid field defects, beam based
alignments and exotic electron bunch production via
blow-out of short laser pulses.
The VISA II experiment entails the use of a chirped electron beam to drive a high gain SASE FEL. Sextupoles are implemented to correct the longitudinal aberrations affecting the high energy spread chirped beam during transport to the undulator. The output radiation is diagnosed with a modified frequency resolved optical gating (FROG) technique. The double differential energy spectrum is measured with a pair of slits and a set of gratings. In this paper, we report on start-to-end simulations, radiation diagnostics, as well as initial experimental results. Technical considerations for future experimental methods are also addressed.
The VISA II (Visible to Infrared SASE Amplifier) project, a consequent experiment to the succesful VISA enterprise, entails the use of a chirped electron beam to drive a high gain SASE FEL. The resulting ultra-short pulses will be characterized using an advanced FROG (Frequency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole corrections, the resulting high gain lasing, and computational analysis are briefly reported.
The VISA II (Visible to Infrared SASE Amplifier) project, a consequent experiment to the succesful VISA enterprise, entails the use of a chirped electron beam to drive a high gain SASE FEL. The resulting ultra-short pulses will be characterized using an advanced FROG (Frequency Resolved Optical Gating)technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole corrections, the resulting high gain lasing, and computational analysis are briefly reported.
We review the status of FEL source activity of the
ongoing SPARC FEL experiment, developed within the
framework of a collaboration among ENEA, CNR, INFN,
INFM, Sincrotrone Trieste and University of Rome Tor
Vergata. The project is aimed at realising a SASE-FEL
source, operating in the visible (around 500 nm), with an
extended range of tunability down to the VUV (100 nm)
by the use of the mechanism of non-linear harmonic
generation. The development of the relevant activities
foresees the realisation of an advanced 150 MeV photo-
injector source, aimed at producing a high brightness
electron beams, needed to drive a SASE-FEL experiment,
and a 14 m long undulator. We present the status of the
design and construction of SPARC FEL device. In
particular we discuss the choice of the project parameters,
their optimisation and the sensitivity of the SPARC
performance to any parameter variation. We will show,
using start-to-end simulations, what is the impact of the e-
beam and of the undulator parameters on the
characteristics of the output laser field and in particular on
the amount of the non-linearly generated power at higher
SPARX is an evolutionary project proposed by a
collaboration among ENEA-INFN-CNR-Universita` di
Roma Tor Vergata aiming at the construction of a FEL-
SASE X-ray source in the Tor Vergata Campus. The first
phase of the SPARX project, funded by Government
Agencies, will be focused on R&D activity on critical
components and techniques for future X-ray facilities as
described in this paper.
The Project SPARC (Sorgente Pulsata e Amplificata di Radiazione Coerente), proposed by a collaboration among ENEA-INFN-CNR-Universita' di Roma "Tor Vergata" -INFM-ST, was recently approved by the Italian Government and will be built at LNF of INFN. The aim of the project is to promote an R&D activity oriented to the development of a coherent ultra-brilliant X-ray source in Italy. This collaboration has identified a program founded on two main issues: the generation of ultra-high peak brightness electron beams and of resonant higher harmonics in the SASE-FEL process.
In this paper the classical theory of the transverse optical klystron is presented. The gain is obtained by solving analytically the Vlasov equation which governs the evolution of the electron beam along the undulator magnet. The initial energy distribution of the electron beam is assumed gaussian. Both the small signal and the saturation regime are investigated. (19 References).