Introduction & History

Elettra is the third generation storage ring (2 and 2.4 GeV ) that has been in operation since October 1993. It has been optimised to provide the scientific community with photons in the energy range from a few to several tens of KeV with spectral brightness of up to 1019 photons/s/mm2/mrad2/0.1%bw and is continuously upgraded in order to be competitive with the most recent sources.

There were three phases and two main upgrades in the operations of Elettra. In the first phase from 1993 to 2007 Elettra operated in the ramping mode. The injector was providing 1 GeV electrons to the storage ring that were further accelerated by ramping the storage ring to the final operational energy 2 or 2.4 GeV for users. Refill occurred once per day.

Ramping operations, intensity in mA ( y-axis) 

Since 2007 Elettra constructed a full energy injector consisting of a small LINAC (LINear ACcelerator) and a full energy booster that accelerates and injects electrons at the final energy of 2 and 2.4 GeV (the 1 GeV old injector has been partially refurbished and used in the new FERMI@Elettra FEL facility, the new 1.2 – 1.8 GeV  Free Electron Laser in construction here).

  Full energy injection operations, intensity in mA (y-axis ) 



Finally since 2010 Elettra operates in the top up mode for both 2 and 2.4 GeV operational energy.

Top up operations, intensity in mA (y-axis) 


 Additionally to Elettra, a storage ring Free Electron Laser(SR-FEL) is operating keeping Elettra at the forefront of fourth generation photon sources. The SR-FEL using SRHG method operates at 2 GeV, producing coherent fs-light pulses with variable polarization in the vacuum ultraviolet since some years. Already this beamline is used for experiments.

Brightness of the synchrotron radiation for various ID's and bending magnets as a function of photon energy

Synchrotron radiation is produced when electrons travelling at relativistic speeds are deflected in magnetic fields. The storage ring is made up of four types of magnets: bending magnets that deflect the circulating electron beam into a closed circular path, quadrupoles that focus the beam, sextupoles that compensate chromatic and non-linear effects and steerer magnets that perform small adjustments to the circular trajectory. The arrangement of magnets forms a lattice of magnetic confinement elements. The lattice used for ELETTRA is an expanded Chaseman Green type also known as a double bend achromat. The ring is made up of twelve identical groups of magnets forming a ring roughly 260 m in circumference. A characteristic of third generation synchrotrons is the space that is made available in the lattice, the so called long straight sections, to install insertion devices of lengths up to 4.5 m. These are the principal sources of high brightness photons and are composed of arrays of magnetic poles that force the circulating electrons along serpentine trajectories. Insertion devices are of many types (electromagnets or permanent magnets) and depending on the magnetic configuration can be made to produce linear to circular polarised light. The wavelength of the light is tuneable by changing the magnetic field acting on the electron beam. For the electromagnets this is performed by changing the current flowing in the coils, whilst for the permanent magnets the field is changed by varying the distance between the top and bottom magnet arrays. One of these sections is used for injecting electrons into the storage ring.

Last Updated on Thursday, 01 December 2011 16:32