The
overall SPARC (Sorgente Pulsata
Auto-amplificata di Radiazione
Coerente) project consists of 4 main lines of
activity aiming at several goals: their common denominator
is to explore the scientific and technological issues that
set up the most crucial challenges on the way to the
realization of a SASE-FEL based X-ray source, the SPARX
proposal. These are:
1)
150 MeV Advanced Photo-Injector
Since
the performances of X-ray SASE-FEL's are critically
dependent on the peak brightness of the electron beam
delivered at the undulator entrance, we want to investigate
two main issues - generation of the electron beam and bunch
compression via magnetic and/or RF velocity bunching - by
means of an advanced system delivering 150 MeV electrons,
the minimum energy to avoid further emittance dilutions due
to time-dependent space charge effects.
2)
SASE-FEL Visible-VUV Experiment
In
order to investigate the problems related to matching the
beam into an undulator and keeping it well aligned to the
radiation beam, as well as the generation of non-linear
coherent higher harmonics, we want to perform a SASE FEL
experiment with the 150 MeV beam, using a segmented
undulator with additional strong focusing, to observe FEL
radiation at 530 nm and below.
3)
X-ray Optics/Monochromators
The
X-ray FEL radiation will provide unique radiation beams to
users in terms of peak brightness and pulse time duration
(100 fs), posing at the same time severe challenges to the
optics necessary to guide and handle such radiation. This
project will pursue also a vigorous R&D activity on the
analysis of radiation-matter interactions in the spectral
range typical of SASE X-ray FEL's (from 0.1 to 10 nm), as
well as the design of new optics and monochromators
compatible with these beams.
4)
Soft X-ray table-top Source
In
order to test these optics and to start the R&D on
applications, the project will undertake an upgrade of the
presently operated table-top source of X-rays at
INFM-Politecnico Milano, delivering 107 soft
X-ray photons in 10-20 fs pulses by means of high harmonic
generation in a gas.