RF Group

Responsible for the RF Acceleration and Transverse Damping Systems for CERN accelerators. Our team operates the RF systems of existing accelerators and participates to the design of future accelerators and upgrades to existing machines.

Why Radio Frequency?

Charged particles are accelerated by electric fields – the energy they can gain in the process is given by the product voltage times charge. To reach energies above some MeV, one needs fields varying in time at a high (radio) frequency and the particle beam in bunches rather than continuous. This is why Radio Frequency is the technique of choice for particle accelerators.

How does RF interact with the beam

The keyword here is “cavity”: a cavity (an evacuated metallic hollow) can support an electromagnetic field at a given (radio) frequency. An accelerating cavity is constructed such that beam can pass through it (beam pipes upstream and downstream) and that the electric field points in the direction of particle motion (beam axis). In this way, a passing particle beam bunch is accelerated and gains energy. This energy has to be resupplied to the cavity from a powerful RF amplifier via a power coupler. The phase of the cavity field has to be precisely controlled such that the accelerating voltage has the right direction when the bunch passes.