Electromagnetic Design of an 80.5 MHz RFQ for the RIA Driver Linac

The Rare Isotope Accelerator (RIA) (1) requires a high power linac capable of accelerating all ions through ura- nium to energies 400 MeV/u with a beam power of 100 to 400 kW. The first accelerating structure would be an RFQ. Elecrodynamic simulations using the MAFIA code (2) have been performed to optimize the RFQ resonator. We present the design of an IH-RFQ (Interdigital H-Type) and of a 4-Rod RFQ. The operation frequency is 80.5 MHz and the resonator has a length of 493 cm. Because of the specified cw operation, optimization of the shunt im- pdance and the cooling requirements are major issues. It was determined that an RF power of 20 kW/m (IH RFQ) and 26 kW/m (4-Rod RFQ) would be required to reach the design voltage of 60 kV.