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Fusion Science and Technology
Latest News
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
P. T. Bonoli, R. Parker, S. J. Wukitch, Y. Lin, M. Porkolab, J. C. Wright, E. Edlund, T. Graves, L. Lin, J. Liptac, A. Parisot, A. E. Schmidt, V. Tang, W. Beck, R. Childs, M. Grimes, D. Gwinn, D. Johnson, J. Irby, A. Kanojia, P. Koert, S. Marazita, E. Marmar, D. Terry, R. Vieira, G. Wallace, J. Zaks, S. Bernabei, C. Brunkhorse, R. Ellis, E. Fredd, N. Greenough, J. Hosea, C. C. Kung, G. D. Loesser, J. Rushinski, G. Schilling, C. K. Phillips, J. R. Wilson, R. W. Harvey, C. L. Fiore, R. Granetz, M. Greenwald, A. E. Hubbard, I. H. Hutchinson, B. LaBombard, B. Lipschultz, J. Rice, J. A. Snipes, J. Terry, S. M. Wolfe, Alcator C-Mod Team
Fusion Science and Technology | Volume 51 | Number 3 | April 2007 | Pages 401-436
Technical Paper | Alcator C-Mod Tokamak | doi.org/10.13182/FST07-A1430
Articles are hosted by Taylor and Francis Online.
This paper reviews the physics and technology of wave-particle-interaction experiments in the ion cyclotron range of frequencies (ICRF) and the lower hybrid (LH) range of frequencies (LHRF) on the Alcator C-Mod tokamak. Operation of fixed frequency (80 MHz) and tunable (40- to 80-MHz) ICRF transmitters and the associated transmission system is described. Key fabrication issues that were solved in order to operate a four-strap ICRF antenna in the compact environment of C-Mod are discussed in some detail. ICRF heating experiments utilizing the hydrogen (H) and helium-3 (3He) minority heating schemes are described, and data are presented demonstrating an overall heating efficiency of 70 to 90% for the (H) minority scheme and somewhat lower efficiency for (3He) minority heating. Mode conversion electron heating experiments in D(3He), D(H), and H(3He) discharges are also reported as well as simulations of these experiments using an advanced ICRF full-wave solver. Measurements of mode-converted ion cyclotron waves and ion Bernstein waves using a phase contrast imaging diagnostic are presented and compared with the predictions of a synthetic diagnostic code that utilizes wave electric fields from a full-wave solver. The physics basis of the LH current profile control program on Alcator C-Mod is also presented. Computer simulations using a two-dimensional (velocity space) Fokker Planck solver indicate that ~200 kA of LH current can be driven in low-density H-mode discharges on C-Mod with ~3 MW of LHRF power. It is shown that this off-axis LH current drive can be used to create discharges with nonmonotonic profiles of the current density and reversed shear. An advanced tokamak operating regime near the ideal no-wall limit is described for C-Mod, where ~70% of the current is driven through the bootstrap effect. The LH power is coupled to C-Mod through a waveguide launcher consisting of four rows (vertically) with 24 guides per row (toroidally). A detailed description of the LH launcher fabrication is given in this paper along with initial operation results.