HIGH-POWER (3-MW) LONG-PULSE (3-s) RADIO-FREQUENCY SYSTEM FOR ION CYCLOTRON RESONANCE HEATING EXPERIMENTS ON TEXTOR.

A multimegajoule ion cyclotron resonance heating (ICRH) experiment was installed on the Torus Experiment for Technology-Oriented Research (TEXTOR) tokamak. The system consists of two independent power lines each designed to generate and launch 1. 5 Mw of radio-frequency (rf) power into the machine during a 3-s period in the 25- to 29-MHz frequency range. Each power line consists of the following items: (a) a 1. 5-Mw transmitter, (b) a transmission line system, including a two-stub tuner, made of pressurized 155. 6-mm (6. 125-in. ) and 228. 6-mm (9-in. ) rigid coaxial line components, and (c) an interface linking the transmission line to the antenna of the shielded stripline type placed along the tokamak's hot liner. Details of the line and antenna diagnostics and data acquisition system together with the subsequent impedance characteristic calculations are given. The rf radiation shielding for the ICRH experiment is explained. The control of the rf setup as a TEXTOR subsystem and the generator pulse control and operation modes are outlined. The antenna loading and power limitation in the presence of plasma and the conditioning procedure are discussed. Finally, the new rf system compatible with the toroidal pump limiter Advanced Limiter Test-II is presented.