Progress on the upgrade of the TCV EC-system with two 1MW dual-frequency gyrotrons

The upgrade of the electron cyclotron (EC) system of the TCV tokamak has entered in its realization phase. The MW-class dual-frequency gyrotron design (84 or 126GHz/2s), based on the 140GHz W7-X gyrotron, is finalized and a contract for the manufacturing of two units has been placed with Thales Electron Devices (TED). For maintaining a high level of operational flexibility of the EC-system the integration of the dual-frequency gyrotrons adds a significant complexity in the evacuated HE₁₁ transmission line system connected to the various TCV low-field side and top launchers. Specific aspects of the gyrotrons design and their integration into the EC-system are described. The EC-system upgrade is an essential step of a larger extent upgrade of TCV.