Design of a high power ICRF transmission system for D-III D

The 20 MW D-III D (Doublet III reconfigured with a large dee-shaped vacuum vessel) ICRF transmission system is required to deliver 5 MW to each of four launchers for 10 seconds using as basic inputs the 16 1.25 MW power modules. The design presented satisfies this requirement by four sets of power combiners each of which merges the outputs of four 1.25 MW power modules into a single 9 3/16'' coaxial line that extends to the torus. The details of how the power is combined, coaxial line size selection, associated instrumentation, feedback control of the phasing, line matching to load and other design features will be presented. A disadvantage of such a system architecture is the severe penalty in both overall system power and spectral content of the launcher array associated with loss of a single power module. A novel switching arrangement will be discussed which shows how a single spare power module can be switched into the circuit to facilitate the servicing of any non-functioning module without significant loss of experimental time