Thermal design of GA ECH launcher mirror for long pulse operation

Each GA ECH launcher mirrors is used to transmit 800 kW of power to the plasma. Until 2000, the pulse length for use of these mirrors was limited to 2 s due to temperatures of the mirrors resulting from 1) a high ratcheted bulk temperature and 2) a large increase in temperature of the mirror during the pulse. A new design was proposed and implemented which has extended the capability of the mirror to 10 s with passive cooling. The important features of the new design are 1) increase in the passive heat transfer rate during cooling and 2) a modified shape of the mirror. The analysis shows that, the new mirrors can be used for 10 s pulses. The new mirrors have been installed in DIII-D, they have been used for up to 2 s pulses.