The upcoming High-Luminosity Large Hadron Collider (HL-LHC) program requires a beam performance in the CERN Proton Synchrotron (PS) that is at the limits of the current RF systems. Following the discontinuation of the RF tube production of the driver amplifiers a new solid-state design has been developed using radiation-hard amplifier technology. In view that the current system architecture has reached its maximum achievable gain, the goal was to reduce the cavity impedance encountered by high-intensity circulating beams. This reduction is achieved by increasing the fast feedback gain around the 10 MHz cavities. A 400W modular driver amplifier based on GaN technology and its control system have been prototyped and are currently in the testing phase. The FETs have been qualified for radiation in J-PARC and they will undergo additional irradiation time in the PS tunnel at CERN to additionally qualify the amplifier in its entirety. The paper outlines the modeling phase, the challenges encountered during prototyping, and the achieved results.

During the last long shutdown of the accelerators at CERN (LS2), the main radio frequency system of the Proton Synchrotron Booster (PSB) was upgraded. A wideband system with Finemet magnetic alloy cavities driven by solid-state amplifiers replaced several different ferrite-loaded cavities. In measurements post-LS2, the longitudinal beam stability did not match predictions, which triggered a survey of the PSB impedance model. This started with the Finemet RF system, which are expected to be the dominant impedance contribution. Single stretched wire measurements were carried out with a 6-cell Finemet test cavity with different amplifier configurations. Measurement results and electromagnetic simulations are presented in this paper and compared to the previous impedance model. The electromagnetic characterization presented in this contribution will complement the beam-based impedance and low-level RF measurements as an input for the simulations of beam stability.