Storage Ring

The beam is guided onto the pseudo-circular orbit by 64 bending magnets and is focused by 320 quadrupoles. The effect linked to the energy dispersion of the electrons (chromatic aberration) is done by 224 sextupoles.

The storage ring components are arranged in 16 superperiod cells with the same magnet distribution (Chasmann-Green structure).
Each cell has one straight section of 6 meters long where insertion device sources (IDs) of up to 5 m long can be installed.

In order to serve all types of experiments, two classes of Ids are used : undulators and wigglers. Both are made of permanent blocks which force the electron beam onto a sinusoidal trajectory and therefore stimulate radiation.

Since the electrons radiate photons as they passes through the bending magnets and the IDs, Radio-Frequency cavities are needed to restore any loss and maintain the energy close to the nominal 6 GeV.

The photon beam is extracted tangentially to the source and send on the studied sample through the beam lines.

The essential target specification is expressed in terms of brilliance of undulator beams in the fundamental of the photon energy spectrum. To maximise this figure, one has to combine in an optimal way :

• the beam energy (6 GeV)
• the beam intensity (200 mA)
• the smallest achievable emittance (now x = 4 10^-9 mrad with 1% coupling)
• the gap, the field and the period of the insertion devices.