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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)
Anomalous momentum transport has been observed in Alcator C-Mod tokamak plasmas through analysis of the time evolution of core impurity toroidal rotation velocity profiles. Following the L-mode to EDA (enhanced D(alpha)) H-mode transition, the ensuing cocurrent toroidal rotation velocity, which is generated in the absence of any external momentum source, is(More)
Citation McDermott, R. M. et al. " Edge radial electric field structure and its connections to H-mode confinement in Alcator C-Mod plasmas. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available.(More)
High resolution measurements on the Alcator C-Mod tokamak [I.H. Hutchinson et al, of the transport barrier in the " Enhanced D α " (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 MPa/m. Evolution of the(More)
At modest 3 He levels (n 3He /n e ~ 8-12%), in relatively low density D(3 He) plasmas, e n ≤ 1.3×10 20 m-3 , heated with 50 MHz rf power at B t0 ~ 5.1 T, strong (up to 90 km/s) toroidal rotation (V φ) in the co-current direction has been observed by high-resolution x-ray spectroscopy on Alcator C-Mod. The change of central V φ scales with the applied rf(More)
The time evolution of toroidal rotation velocity profiles has been measured in Alcator C-Mod [I.mas using a tangentially viewing x-ray spectrometer array. The strong co-current toroidal rotation in enhanced D α (EDA) high confinement mode (H-mode) plasmas is observed to propagate in from the edge on a time scale similar to the energy confinement time. The(More)
to improve the productivity of fusion sciences research through the development and deployment of advanced software tools that reduce the technical barriers to collaboration and sharing on a national scale. Our vision is to make resources—data, computers along with analysis, simulation and visualization codes—widely and transparently available as network(More)
Parametric scalings of the intrinsic (spontaneous, with no external momentum input) toroidal rotation observed on a large number of tokamaks have been combined with an eye toward revealing the underlying mechanism(s) and extrapolation to future devices. The intrinsic rotation velocity has been found to increase with plasma stored energy or pressure in JET,(More)