Radio Frequency System

The storage ring RF systems shall replace the energy lost by the electron beam turn by turn. Because of the full energy injection and the top up operation, the energy delivered by the RF systems is almost constant.

  2 GeV
310 mA
2.4 GeV
140 mAv
Harmonic number 432    432  
Revolution frequency 1,16 1,16 MHz
Available RF power 315  315  kW
Accelerating Voltage 1680   1680   kV
Synchrotron frequency 11  11  kHz
Total Losses 112 112 kW
Power to the beam 72 62 kW

Four ELETTRA type cavities are installed in the short straight section of the storage ring. The ELETTRA type cavity is a single cell, made of oxygen free high conductivity (OFHC) copper.

Elettra Cavity
Resonant frequency 499,654 MHz
Unloaded Q    40000    
Shunt impedance (transit time included)        > 3.2 MW
Wall losses     65 kW
Accelerating voltage     650 kV
Tuning range        ± 200 kHz
Frequency set      ±1 MHz

Each cavity is powered by one RF source plant. Three RF power source are the 60 kW klystron transmitters and the RF power line is a coaxial one.
Last transmitter is a 150 kW Inductive Output Tube one: waveguide WR1800 run is then used to deal with such power level.
All the plants have high power circulator to decouple the transmitter from the load.
Frequency, amplitude and phase feedback loops on the RF chain keeps the proper accelerating voltage along each cavity, according to the stored electron beam need.
The RF phase shift among the RF plants can be precisely arranged.
The longitudinal High Order Modes (HOM) of the cavity are not damped. Their high quality factors allow to tune them far away from the beam resonances by mean of the accurate cavity cooling temperature set  (temperature accuracy = 0.1° C) in order to avoid any dangerous beam-HOM interactions. 

Last Updated on Friday, 13 January 2012 14:06