Preparation for tests of a 110 GHz gyrotron with collector potential depression and status of the ECH system on the DIII-D Tokamak

A 110 GHz gyrotron designed for long pulse operation at P/sub rf/>1.0 MW is tested at the DIII-D facility. The unit is predicted to have efficiency >0.4 with collector potential depression. Some transmission line components require modification for operation at total rf energies >5 MJ per pulse. The ECH system is also being upgraded with the addition of three new gyrotrons.