Fast‐Wave ICRF Minority‐Regime Heating Experiments on the Tore Supra Tokamak

Up to 4 MW of rf power at 57 MHz has been coupled to Ohmic target plasmas during the first ICRF heating experiments on Tore Supra. A total of 12 MW of rf power will ultimately be available from six tetrode amplifiers and will be coupled to the plasmas using three ORNL/CEA‐designed resonant double‐loop antennas. During these first experiments, two antennas were used, with one or two energized at a time. The antenna loading with plasma was observed to be well over an order of magnitude greater than that without plasma. In addition, one kilo‐electron‐volt of electron heating, significant minority nonthermal ions, and significant increases in diamagnetic stored energy were observed. A comparison of in‐phase and out‐of‐phase antenna operation showed the same increase in stored energy, less radiated power, and a larger drop in loop voltage for out‐of‐phase operation. Confinement scaling agrees with the ITER scaling law.