Fifty years of progress in ICRF, from first experiments on the Model C Stellarator to the design of an ICRF system for DEMO

The first significant use of ICRF occurred in the Model C stellarator in 1969, now 50 years ago. In the 70s, the emphasis was on understanding and optimizing the heating method, while in the 80s, power in the MW range became available on PLT, ASDEX, JET and TFTR. The 90s saw the start of ICRF on larger machines such as JT60, Tore Supra, Alcator C-mod and ASDEX Upgrade as well as the first applications of ICRF on D-T plasmas in JET and TFTR. ICRF capabilities beyond heating were experimentally investigated on JET in the early 2000s. From 2010, with machines such as ASDEX Upgrade and JET transiting to full-metal first walls, the interaction of the ICRF with the plasma edge became again a pressing issue. The talk aims at providing an overview of 50 years of ICRF research, thereby putting the progress of the ICRF scheme in an historical perspective. It shows what has been accomplished, how problems that surfaced have been overcome and develops a view for the future.