The RF system for any particle accelerator has to provide the accelerating voltage and make up for any power losses. Power is lost through synchrotron light emitted at the bending magnets or insertion devices, or through parasitic losses because of the vacuum chamber impedances. The quantum lifetime is directly dependent on the RF overvoltage, as is the Touschek lifetime via the energy acceptance.

In calculating the RF power requirements, an estimate is made of the maximum energy lost when all the IDs are installed. The RF System for the Diamond needs to provide an accelerating voltage of 5.1 MV and sufficient RF power to make up synchrotron radiation losses of around 1.785 MeV per turn for a beam current of 300 mA.

Injection into the storage ring is eased and optimised if the storage ring frequency is a sub harmonic of the linac frequency, so RF frequency has been chosen as 499.654 MHz, i.e. one sixth the frequency of the linac. On day one of operations, two superconducting RF cavities were in place, with a third being designed in. Each RF cavity is fed from its own RF amplifier system, either superpower klystrons or inductive output tubes (IOTs). A single cryogenic system supplies the liquid helium to cool and maintain the cavities at the operating temperature of 4.3 K.

Basic RF Parameters