New Control Structure of the 200 MHz RF System in the CERN PS

The 200 MHz RF system is an essential tool for the preparation of high-intensity beams in the CERN PS. Presently, six RF cavities are operated to control the longitudinal bunch emittance and rebunching of the beam before the transfer to the SPS. Cavities are selected for the various processes with a dedicated hardware matrix, switching the individual timing pulses and voltage programs per cavity. However, the electronics used for the matrix hardware is obsolete and its reliability cannot be guaranteed due to a lack of spare modules and components. Instead of replacing the old hardware matrix by modern hardware, this note describes a new control structure for the 200MHz RF system so that no dedicated hardware will be required anymore. The implementation of the new control structure is based on two main concepts. Firstly, linked timing trees per blow-up or rebunching are used to handle all related timing and to store one row of the matrix. Secondly, as a reflection of the RF signal generation for the 200 MHz system, where all units always receive the same RF signal, the new implementation features a single global voltage program function. Internal stops in the voltage program function are restarted by timings in the linked trees and assure inherent coherence between timings and voltage programs for the cavities. After a description of the requirements of the present hardware in terms of timing signals and functions, functional s pecification of the new application program is given.