Heading From W7-X Gyrotrons Towards Gyrotrons for Demo: Research Strategy and Recent Developments at Kit

ECH&CD in future fusion reactors such as the European DEMOnstration power plant may require the availability of gyrotrons with operating frequency significantly above 200 GHz, RF output power of 2 MW, and total efficiency above 60 %. Depending on the technology for RF beam steering into the plasma, fast frequency tuning in steps of around 2 – 3 GHz might be required for plasma stability control. “Multi-purpose” operation at multiples of the λ/2-resonance frequency of the synthetic diamond gyrotron RF output window, hence in leaps of about 30 – 40 GHz might be considered for plasma start-up, heating and current drive. The combination of all those requirements challenges present-day technological limits for gyrotrons.