accelerator is an Energy Recovery Linac (ERL) that incorporates all the
features of the 4th generation light source albeit at smaller scale. An
ERL is not restricted by the dynamic properties of storage rings and,
therefore, can attain an unprecedented electron beam brightness limited
only by the electron gun. Energy recovery allows also a significant
increase in an average power of the light sources (without building a
dedicated power station nearby!).
The ability to produce
ultra-short electron bunches well below 1ps and an availability of
several light sources including an infra-red free electron laser,
coherent THz radiation, a powerful TW laser, enables many different
areas of science to be pursued. You can read more about this in the ALICE projects section.
DC photoelectron gun generates short low emittance electron bunches
with the length of several ps and accelerates them to a modest 350keV.
The nominal bunch charge on ALICE is 80pC. The bunches are produced in
trains lasting from ~10ns to 100ms and the train repetition frequency
can vary from 1 to 20Hz. Within the train, the bunches are separated by
12.3ns that corresponds to the laser pulse repetition frequency of
The electron beam is then injected into the
superconductive linac (booster), accelerated to the energy of 8.35MeV
and transported to the main linac that increases the beam energy to
35MeV. Both superconductive linacs are cooled down to approximately 2o K
with liquid helium. The accelerating phase of the main linac is chosen
such that a specific energy chirp is introduced along the bunch so that
it can be later compressed longitudinally in a magnetic chicane (bunch
compressor). The beam reaches the chicane after being turned by 180o in
the first triple bend achromat ARC1.
After compression, the
beam, consisting now of sub-picosecond bunches, enters the magnetic
undulator that constitutes a major part of the mid-IR Free Electron
Laser (FEL). This laser generates IR light with the wavelength of ~5μm.
spent electron beam is returned back to the entrance of the main linac
via the second ARC2 at a precise time when the RF phase is exactly
opposite to the initial accelerating phase. This condition requires an
accurate adjustment of the electron beam path length that is
accomplished by moving the ARC1 as a whole. The beam is now decelerated
thus giving its energy back to the electromagnetic field inside the
linac RF cavities (energy recovery) and emerges from the linac having
the original energy of 8.35MeV. This energy recovered beam is diverted
to the beam dump ending its short but useful life.
detailed information on ALICE components, systems and their operation
please follow the links in the menu on the left hand side of this page.