IFMIF-DONES RF System

Abstract The IFMIF-DONES accelerator cavities require around 5.7 MW of continuous RF power at 175 MHz to deliver a 125 mA and 40 MeV deuteron beam at the lithium target. The IFMIF-DONES RF System is composed of 56 RF Stations able to provide up to 200 kW RF power at 175 MHz in CW, delivering a grand total of 7.4 MW. Such a massive system requires an ambitious approach to be able to comply with the accelerator requirements with a high efficiency and a high availability. The newest advancements in the field of RF systems for accelerators, which are already implemented independently in some facilities, are integrated for the first time in a single system from the early design phases. The result of this approach is the RF Station, which is a totally independent and compact RF module containing all the components needed to feed, control, and protect the accelerator cavities. The amplification technology chosen is the Laterally-Diffused Metal-Oxide Semiconductor (LDMOS) transistor, providing a good efficiency and high robustness. The proposed RF power combination of up to 160 transistors is based on resonant cavity combiner, allowing a single-step combination that highly reduces the losses with respect to more traditional corporate combining schemes. In this proposal, the RF generation relies on a fully digital Low-Level RF (LLRF) providing accurate amplitude/phase control and high flexibility to implement all the required functions for a proper cavity operation. The RF Station has been designed maximizing the modularity and the reliability. In order to achieve the required modularity, the LDMOS transistors have been grouped in Amplifier Modules (AMDs) containing four of them but keeping independent outputs. Furthermore, the AC/DC power converters have also been grouped in modules feeding a common DC bus. The RF Station will have redundant modules to be able to operate properly in any condition, even with some of them failed. This innovative proposal for the IFMIF-DONES RF System design and detailed information on the RF Stations architecture are presented in this paper.