Amanda Hubbard

Learn More
High resolution measurements on the Alcator C-Mod tokamak [I.H. Hutchinson et al, Phys. Plasmas 1, 1551 (1994)] of the transport barrier in the “Enhanced Dα” (EDA) regime, which has increased particle transport without large edge localized modes, show steep density and temperature gradients over a region of 2-5 mm, with peak pressure gradients up to 12(More)
The Thomson scattering (TS) diagnostics set [Rev. Sci. Instrum. 70, 759 (1999); Rev. Sci. Instrum. 72, 1107 (2001)] on the Alcator C-Mod tokamak [Phys. Plasmas 1, 1511 (1994)] has been upgraded to deliver measurements of electron temperature (Te) and density (ne) with improved temporal and spatial resolution. Two 30 Hz, 1.3 J Nd-doped yttrium aluminum(More)
An improved energy confinement regime, I-mode is studied in Alcator C-Mod, a compact high-field divertor tokamak using Ion Cyclotron Range of Frequencies (ICRF) auxiliary heating. I-mode features an edge energy transport barrier without an accompanying particle barrier, leading to several performance benefits. H-mode energy confinement is obtained without(More)
61 0164-0313/02/0600–0061/0 © 2003 Plenum Publishing Corporation 1 (Chair), Princeton Plasma Physics Laboratory. 2 University of California, Los Angeles. 3 University of California, San Diego. 4 General Atomics. 5 Fusion Power Associates. 6 MIT Plasma Science and Fusion Center. 7 CH2M Hill. 8 University of Washington. 9 Lawrence Livermore National(More)
Global and local transport experiments in Ohmic, L-mode and H-mode regimes on the Alcator CMod tokamak are summarized. For Ohmic plasmas, earlier results derived for energy confinement scaling in the Alcator (linear) regime have been confirmed and the saturated confinement regime has been shown to be equivalent to L-mode. For auxiliary heated regimes, C-Mod(More)
J.A. Goetz, B. LaBombard, B. Lipschultz, C.S. Pitcher, J.L. Terry, C. Boswell, S. Gangadhara, D. Pappas, J. Weaver,a) B. Welch,a),b) R.L. Boivin, P. Bonoli, C. Fiore, R. Granetz, M. Greenwald, A. Hubbard, I. Hutchinson, J. Irby, E. Marmar, D. Mossessian, M. Porkolab, J. Rice, W.L. Rowan,c) G. Schilling,d) J. Snipes, Y. Takase,e) S. Wolfe, and S. Wukitch(More)
In Alcator C-Mod discharges lower hybrid waves have been shown to induce a countercurrent change in toroidal rotation of up to 60 km/s in the central region of the plasma (r/a approximately <0.4). This modification of the toroidal rotation profile develops on a time scale comparable to the current redistribution time (approximately 100 ms) but longer than(More)
Studies of potential Plasma Facing Component (PFC) materials for a magnetic fusion reactor generally conclude that tungsten is the best choice due to its low tritium (T) retention, capability to handle high heat fluxes with low erosion, and robustness to nuclear damage and activation. may operate with all tungsten PFCs to provide the necessary operational(More)
The low-to-high confinement transition (L-H) has been systematically studied in Alcator C-Mod lower single null (favorable ion grad-B drift) plasmas, covering an extensive global plasma parameter space. Plasma density ( e n ), toroidal magnetic field strength (BBT), and plasma current (Ip) dependence of H-mode threshold power (Pth) and local plasma edge(More)