Integrating a distributed antenna in DEMO: Requirements and challenges

The use of efficient heating and current drive systems is an important research priority for DEMO. The ion cyclotron range of frequency (ICRF) system is a promising candidate given decades of proven operational experience and low price equipment up to the MW level. ICRF antenna is presently situated in a port of limited size in the vacuum vessel (VV), which may be accompanied with operational limitations in DEMO, primarily because such configurations present high power density structures that can undergo malfunctions for the power levels anticipated for DEMO, because of voltage stand-off limitations. To mitigate this, a novel ICRF antenna is under development and consists of toroidally distributed identical radiating straps integrated inside the blanket First Wall. Given the antenna concept novelty and the strict requirements on the performance of DEMO, substantial design and integration efforts are needed. This paper highlights the requirements on the ICRF antenna and the challenges facing its integration in DEMO.