PLANNING, CONSTRUCTION AND OPERATION EXPERIENCE OF THE ASDEX UPGRADE ECRH SYSTEM

In 1989 it was decided that ASDEX Upgrade should have an ECRH system. The plans for a 140 GHz/2 MW/2 s system were finally approved in 1993. The system comprises 4 gyrotrons with 4 separate transmission lines and launchers. Although a 0.5 s test gyrotron was already installed in autumn 1994, it was only in summer 1997 that the first gyrotron of the final system was ready for use in the experimants, and in spring 2000 the system was completed with all 4 gyrotrons, Since then failure of gyrotrons and a long time needed for their replacement reduced temporarily the available power. This paper reviews the planning, construction and operation of this system, and some unforseen problems encountered.