Toroidal rotation and momentum transport in Alcator C-Mod plasmas with no momentum input

Rice, J. E.; Lee, W. D.; Marmar, E.; Basse, N.; Bonoli, P. T.; Greenwald, M.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Ince‐Cushman, A.; Irby, J.; Lin, Y.; Mossessian, D.; Snipes, J. A.; Wolfe, S.; Wukitch, S.; Zhurovich, K.

doi:10.1063/1.1646157

Cited by 66 publications

(72 citation statements)

References 46 publications

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“…Core rotation in Alcator C-Mod (ICRF and Ohmic) H-mode (and enhanced confinement L-mode plasmas) without external momentum input has been found to be mostly in the co-current direction [27,28,29,30,31,32,33,34]. Similar observations have been made in COMPASS-D [35] (Ohmic), JET [36] (ICRF) and DIII-D [37] (ECH and Ohmic) plasmas.…”

Section: Observed Rotation In H-mode and Enhanced L-mode Plasmassupporting

confidence: 68%

“…The usual sequence of events for ITBs induced with off-axis ICRF heating is first an L-to H-mode transition (in this case at 0.71 s), after which the electron density builds up at the edge, and then fills in to a relatively flat profile on a particle transport time scale. During this same interval, the toroidal rotation jumps to a co-current value at the edge, then propagates in to the center on a similar momentum confinement time scale [32,33]. The H-mode is fully developed at 0.85 s in this discharge.…”

Section: Rotation In Itb Plasmasmentioning

confidence: 99%

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Spontaneous core toroidal rotation in Alcator C-Mod L-mode, H-mode and ITB plasmas

Rice

Ince‐Cushman

Reinke

et al. 2008

Plasma Phys. Control. Fusion

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Spontaneous toroidal rotation, self-generated in the absence of external momentum input, exhibits a rich phenomenology. In L-mode plasmas, the rotation varies in a complicated fashion with electron density, magnetic configuration and plasma current, and is predominantly in the counter-current direction. The rotation depends sensitively on the balance between upper and lower null, and plays a crucial role in the H-mode power threshold. Rotation inversion between the counter-and co-current direction has been observed following small changes in the electron density and plasma current, with very distinct thresholds. In contrast, the intrinsic rotation in H-mode plasmas has a relatively simple parameter dependence, with the rotation velocity proportional to the plasma stored energy normalized to the plasma current, and is nearly always directed co-current. In plasmas with internal transport barriers, formed either with offaxis ICRF heating or LHCD, the rotation velocity inside of the ITB foot increments in the counter-current direction as the barrier evolves.

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Section: Observed Rotation In H-mode and Enhanced L-mode Plasmassupporting

confidence: 68%

Section: Rotation In Itb Plasmasmentioning

confidence: 99%

Spontaneous core toroidal rotation in Alcator C-Mod L-mode, H-mode and ITB plasmas

Rice

Ince‐Cushman

Reinke

et al. 2008

Plasma Phys. Control. Fusion

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“…Convective terms, which are second terms on the left-hand side of Eqs. (17) and (18), are typically small and can be ignored [22,23]. Toroidal electric field on the right-hand side of Eqs.…”

Section: Fluid Equations For Lhcd Induced Plasma Rotationmentioning

confidence: 99%

“…(25) and (26) are complete and can be used to study toroidal rotation. This method has been adopted previously to study toroidal rotations [23]. The differences here are that we use toroidal momentum equations of both bulk electrons and ions instead of just one for ions, and there is a driving force q e n er u r er B θ 0 in the equation of bulk electrons.…”

Section: Fluid Equations For Lhcd Induced Plasma Rotationmentioning

confidence: 99%

On the toroidal plasma rotations induced by lower hybrid waves

et al. 2013

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“…It should be noted that all C-Mod plasmas are free of external torque. Intrinsic core flows also have other components, which are complex and poorly understood; V tor tends to increment in a co-I p direction when plasma pressure increases 25 . Interestingly, V tor (0) was at about the same value at the L-H transition in all three configurations in the 5.4 T, 0.8 MA discharges studied, suggesting that a parameter related to the rotation is important for the transition and that the difference in edge flows may be responsible for the differences in threshold, though not necessarily for the L-H transition itself 24 .…”

mentioning

confidence: 99%

H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Mod

et al. 2007

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This paper reports on studies of the edge transport barrier and transition threshold of the High field at constant current, but the operational space at high B shifts towards higher temperature and lower density and collisionality. Experiments with reversed field and current show that scrape-off-layer flows in the high field side depend primarily on configuration. In configurations with the B×∇B drift away from the active X-point, these flows lead to more counter-current core rotation which apparently contributes to higher H-mode thresholds. In the unfavorable case, edge temperature thresholds are higher and slow evolution of profiles indicates a reduction in thermal transport prior to the transition in particle confinement. Pedestal temperatures in this case are also higher than in the favorable configuration. Both high field and reversed field results suggest that parameters at the L-H transition are influencing the evolution and parameters of the H-mode pedestal.

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Toroidal rotation and momentum transport in Alcator C-Mod plasmas with no momentum input

Abstract: The time evolution of toroidal rotation velocity profiles has been measured 2

Cited by 66 publications

References 46 publications

Spontaneous core toroidal rotation in Alcator C-Mod L-mode, H-mode and ITB plasmas

Spontaneous core toroidal rotation in Alcator C-Mod L-mode, H-mode and ITB plasmas

On the toroidal plasma rotations induced by lower hybrid waves

H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Mod

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