Comparison of poloidal velocity measurements to neoclassical theory on the National Spherical Torus Experiment

Bell, R. E.; André, R.; Kaye, S. M.; Kolesnikov, R. A.; LeBlanc, B.P.; Rewoldt, G.; Wang, W. X.; Sabbagh, S. A.

doi:10.1063/1.3478571

Cited by 74 publications

(80 citation statements)

References 29 publications

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“…A literature review also indicates that stronger ion diamagnetic flow is observed more commonly, when the poloidal flow deviates from neoclassical. Some such examples of this are seen from JET [8,15] interior to a transport barrier, and NSTX [28,53].…”

Section: Resultsmentioning

confidence: 99%

“…These tests have been done in plasmas with relatively low ion temperatures, and hence in higher collisionality than fusion relevant conditions. A recent test of neoclassical poloidal rotation was done by Bell, et al on NSTX [28]. Here the measured impurity poloidal rotation was near neoclassical estimates, but smaller in magnitude.…”

Section: Introductionmentioning

confidence: 91%

“…For intermediate aspect ratios K 1 decreases in magnitude but remains positive in the banana regime. Impurity poloidal flow is generally smaller than the main-ion flow, but is more commonly measured [20,23,28,40,41]. Impurity poloidal flow can be expressed as…”

Section: Neoclassical Theorymentioning

confidence: 99%

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Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Grierson¹,

Burrell²,

Solomon³

et al. 2013

Nucl. Fusion

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Abstract. In tokamak plasmas with low levels of toroidal rotation, the radial electric field E r is a combination of pressure gradient and toroidal and poloidal rotation components, all having similar magnitudes. In order to assess the validity of neoclassical poloidal rotation theory for determining the poloidal rotation contribution to E r , D α emission from neutral beam heated tokamak discharges in DIII-D [J.L. Luxon, Nucl. Fusion 42, 614 (2002)] has been evaluated in a sequence of low torque (electron cyclotron resonance heating and balanced diagnostic neutral beam pulse) discharges to determine the local deuterium toroidal rotation velocity. By invoking the radial force balance relation the deuterium poloidal rotation can be inferred. It is found that the deuterium poloidal flow exceeds the neoclassical value in plasmas with collisionality ν * i < 0.1, being more ion diamagnetic, and with a stronger dependence on collisionality than neoclassical theory predicts. At low toroidal rotation, the poloidal rotation contribution to the radial electric field and its shear is significant. The effect of anomalous levels of poloidal rotation on the radial electric field and cross-field heat transport is investigated for ITER parameters.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

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Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Grierson¹,

Burrell²,

Solomon³

et al. 2013

Nucl. Fusion

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“…3.2 suggests that the local turbulence can affect the convective cell formation, perhaps since the estimated v ExB speed above is comparable to the poloidal turbulence speed in NSTX [23]. Timeaveraged edge poloidal flows can also be comparable to ~10 5 cm/sec in NBI-heated plasmas in NSTX [32]. Such turbulence and/or plasma flow effects have also been seen in the recent TORPEX biasing experiments [20,21] …”

Section: Preliminary Attempt At Quantitative Modelingmentioning

confidence: 60%

Local Effects of Biased Electrodes in the Divertor of NSTX

Roquemore¹,

Zweben²,

Campanell³

et al. 2012

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The goal of this paper is to characterize the effects of small non-axisymmetric divertor plate electrodes on the local scrape-off layer plasma. Four small rectangular electrodes were installed into the outer divertor plates of NSTX. When the electrodes were located near the outer divertor strike point and biased positively, there was an increase in the nearby probe currents and probe potentials and an increase in the LiI light emission at the large major radius end of these electrodes. When an electrode located farther outward from the outer divertor strike point was biased positively, there was sometimes a significant decrease in the LiI light emission at the small major radius end of this electrode, but there were no clear effects on the nearby probes. No non-local effects were observed with the biasing of these electrodes.2

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“…The most widely used method is the simultaneous measurement of the toroidal and poloidal rotation velocities and density profile of impurity ions or main ions with toroidal and poloidal charge exchange recombination spectroscopy (CES) systems. With these parameters, the radial electric field can be determined from the radial force balance relationship [2][3][4][5][6] …”

mentioning

confidence: 99%

E × B flow velocity deduced from the poloidal motion of fluctuation patterns in neutral beam injected L-mode plasmas on KSTAR

et al. 2016

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Articles you may be interested inA method for direct assessment of the equilibrium E Â B flow velocity (E Â B flow shear is responsible for the turbulence suppression and transport reduction in tokamak plasmas) is investigated based on two facts. The first one is that the apparent poloidal rotation speed of density fluctuation patterns is close to the turbulence rotation speed in the direction perpendicular to the local magnetic field line within the flux surface. And the second "well-known" fact is that the turbulence rotation velocity consists of the equilibrium E Â B flow velocity and intrinsic phase velocity of turbulence in the E Â B flow frame. In the core region of the low confinement (L-mode) discharges where a strong toroidal rotation is induced by neutral beam injection, the apparent poloidal velocities (and turbulence rotation velocities) are good approximations of the E Â B flow velocities since linear gyrokinetic simulations suggest that the intrinsic phase velocity of the dominant turbulence is significantly lower than the apparent poloidal velocity. In the neutral beam injected L-mode plasmas, temporal and spatial scales of the measured turbulence are studied by comparing with the local equilibrium parameters relevant to the ion-scale turbulence. Published by AIP Publishing. [http://dx

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Comparison of poloidal velocity measurements to neoclassical theory on the National Spherical Torus Experiment

Cited by 74 publications

References 29 publications

Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Local Effects of Biased Electrodes in the Divertor of NSTX

E × B flow velocity deduced from the poloidal motion of fluctuation patterns in neutral beam injected L-mode plasmas on KSTAR

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