Design description and thermo-hydraulic assessment of the steering mirror for the EU DEMO Electron Cyclotron system

Six Electron Cyclotron (EC) launchers are currently envisaged to be installed at the Equatorial Ports (EP) of the EU DEMO Tokamak with the purpose of delivering up to 130 MW for plasma bulk heating (BH), thermal instability (TI) control and magnetohydrodynamic (MHD) mode suppression. The MHD stabilization will be performed by two mid steering antennas (MSA) with a fixed mirror and a steerable mirror, each reflecting three mm-wave beams with a nominal power of 2 MW. A new proposal for the steering mechanism, which completely avoids the use of flexible cooling pipes, is described and analysed in this paper. In this new concept, the flexure pivot blades feature inner channels that enable cooling water to flow through them and remove the deposited heat efficiently. The thermo-hydraulic analysis shows that the flexure pivots experience moderately low temperature values, particularly when compared with previous uncooled designs. However, the flow velocities along the channels are relatively high, which is translated in a remarkable overall pressure drop in the system.