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Parameters of the RF system

Vital part of the storage ring, the RF system provides the accelerating field for the electron beam. 

The electromagnetic energy, generated by the RF power amplifiers, is transferred to the electron bunches each time they pass through the accelerating cavities. The brightness of the beam can be limited by oscillations of the electron bunches, excited by the high order modes (HOM) of the cavities. The use of superconducting cavities makes the damping of these parasitic modes easier, and therefore helps improving the beam stability. The SOLEIL cryomodule relies on a "home made" design, based on a pair of cavities inside a single cryomodule. Four HOM couplers located on their connection tube provide a strong attenuation of the HOM impedances and couple out the induced HOM power without disturbing the accelerating mode.

Each of the four cavities is powered by one 190 kW solid state amplifier - also developed at SOLEIL

RF system parameters

Cryomodule with 2 superconducting cavities

Number of cryomodules / cavities 2 / 4
Harmonic number h 416
RF Frequency [MHz] f0 352.202
Energy loss per turn [keV] U 944 + 184 (ID) + 22 (parasitic modes)
RF power [kW]    575 @ 500 mA
Nom./Max. RF voltage peak value Vmax 3.0 / 4.5
RF Energy acceptance [%] σE/E 6.21
Geometrical impedance per cavity cell [Ω] R/Q 45
Quality factor  Q0/Qex 2  109 / 1  105
Number of 180 kW solid state amplifiers Total of 4 (1 per cavity)

Cryogenic system 
Helium power refrigeration at 4.5 K [W] 
Liquefaction rate, simultaneously [l/h]

1 refrigerator/liquefier for the 2 cryomodules