Author :
Wukitch, S.J. ; Beck, W. ; Fitzgerald, E. ; Granetz, R. ; Gwinn, D. ; Grimes, M. ; Irby, I. ; Marmar, E. ; Terry, D. ; Titus, P. ; Vieira, R. ; Wolfe, S. ; Zaks, J. ; Bernabei, S. ; Ellis, R. ; Gereg, L. ; Hosea, J. ; Loesser, D. ; Schilling, G. ; Wilson,
Abstract :
Recent Alcator C-Mod experimental campaigns have focused upon the study of the Advanced Tokamak regimes, which includes characterization of the RF heating, the formation and dynamics of internal barriers, H-mode edge pedestal, and divertor and scrape-off physics. The ICRF system has been recently upgraded with the improved performance of the 4-strap antenna. Total ICRF power in excess of 5 MW has been launched successfully into the plasma during this campaign. Due to the compact nature of C-Mod, the power feeds for the antenna are vacuum strip lines. Their orientation, to the tokamak B-field, is governed by maintaining E<15 kV/cm in locations where the RF E-field is parallel to tokamak B-field. Other modifications included improved protection tile grounding and installation of protective shields for Faraday screen ceramic isolators. The antennas also make use of BN protection tiles to eliminate high Z impurities from the antennas. The present empirical power limit results from arcing in a region of the antenna strap where E∼15 kV/cm and parallel to B and injections from the metallic fasteners used to attach the BN tiles to the antenna.
Keywords :
antennas in plasma; fusion reactor design; fusion reactor divertors; fusion reactor ignition; plasma boundary layers; plasma impurities; plasma instability; plasma radiofrequency heating; plasma toroidal confinement; 4-strap antenna; 5 MW; Advanced Tokamak regimes; Alcator C-Mod tokamak status; BN; Faraday screen ceramic isolators; H-mode edge pedestal; ICRF system; RF heating; divertor; empirical power limit; fusion reactors; high Z impurities; internal barriers; protection tile grounding; protective shields; scrape-off physics; vacuum strip lines; Antenna feeds; Ceramics; Grounding; Heating; Physics; Plasmas; Protection; Radio frequency; Tiles; Tokamaks;
