Introduction & History

Elettra configuration before 2007

The electrons were generated in a LINAC and then injected in the ring. Electrons start off from a ceramic disc that is heated to very high temperature. An electric field of up to 100 kV draws out the electrons that are then accelerated through various radio-frequency structures that make up the LINAC. The LINAC was composed of the Gun (that houses the ceramic disc), a low energy bunching section and several high-energy sections. The overall length of the LINAC was 66 m and contained seven high-energy sections each 6m long. Between accelerating sections, quadrupole magnets keep the beam focused. The LINAC operated at 3 GHz and generated a pulse of electron bunches that are accelerated to a final energy which can be as high as 1.2 GeV. In order not to lose electrons as they are accelerated, the entire LINAC is under vacuum, as is the transfer line and storage ring. In this way collisions with gas molecules, that would otherwise cause the loss of electrons, are avoided.

 

 

 

The electrons are generated in a small linac. They start off from a ceramic disc that is heated to very high temperature. An electric field of up to 80 kV draws out the electrons that are then accelerated through two radio-frequency structures that make up the linac. The linac is composed of the Gun (that houses the ceramic disc), a low energy bunching section and two high-energy sections. The overall length of the linac is 12 m and contains two high-energy sections each 5m long. Between accelerating sections quadrupole magnets keep the beam focused. The linac operates at 3 GHz and generates a pulse of electron bunches that are accelerated to the final energy of 100 MeV. In order not to lose electrons as they are accelerated the entire linac is under vacuum, as is the transfer lines the booster and storage ring. In this way collisions with gas molecules, that would otherwise cause the loss of electrons, are avoided.









General layout of the accelerator complex showing the
position of the linac, transfer line and storage ring

The cathode (part of the gun)	The linac tunnel with the accelerating sections and magnets, in the front hanging from the ceiling the SLED cavities, nowadays used for the FERMI FEL

The electrons exiting the LINAC were then transported to the inner side of the storage ring by a transfer line (a series of deflection and focussing magnets). Both the LINAC and transfer line were below ground so as not to interfere with beamlines in the experimental hall. The storage ring was filled by a multi-turn injection process whereby pulses of electrons were gradually fed into the ring ten times a second until the desired current is achieved. Refilling the ring to high currents took 45 minutes.

The old transfer line	The old transfer line