The 120 kW solid state amplifier system for the FRIB RFQ

The Facility for Rare Isotope Beams (FRIB) radio frequency quadrupole (RFQ) runs in continuous wave mode at 80.5 MHz with an input power up to 120 kW. The current tetrode amplifier had some failures and was greatly improved during commissioning and early operations. However, some potential failures may cause long repair time and compromise overall system availability. In comparison, the solid state amplifiers have shorter repair time due to the modular design and absence of high voltage. Currently FRIB is commissioning the 120 kW solid state amplifier system. It uses the same 2 kW 80.5 MHz modules as those used in FRIB linear segment 1. This allows the sharing of spares as well as reducing the effort for developing new controls and maintenance procedures. Each of the eight racks includes six amplifier modules and can output 15 kW power into a matched load. The system uses 3 dB quadrature hybrid couplers in a 3-stage corporate power combining scheme to achieve 120 kW. The paper will detail the design and commissioning of this system.