Developing the next LHCD source for Tore Supra

Abstract One of the main Tore Supra objectives is to produce long and high performance discharges, studies which are crucial for the next step. In the frame of the CIMES project, associated with the manufacture of an ITER relevant PAM launcher, a new klystron is under development at Thales Electron Devices. The upgrade will lead to an installed power of 12 MW in the lower hybrid transmitter. Each of the 16 tubes will work at 3.7 GHz, 76 kV, 22 A with an efficiency up to 45%, providing 700 kW on a VSWR up to 1.4, during 1000 s. Two factory prototypes have been manufactured and tested on the Thales test bed. The first one is installed on Tore Supra Lower Hybrid test bed. Up to now, 770 kW at 75 kW, 22 A (50% duty cycle) have been achieved on matched load. A prototype, derived from these two factory prototypes, will reach full performance in few months. The tube's parameters are described in this paper. They are compared to those of the TH2103 presently used in the transmitter and their choices are detailed and explained. The results obtained with prototypes as well as the technological difficulties are presented and analysed.