Role of core toroidal rotation on the H-mode radial electric field shear, turbulence, and confinement as studied by magnetic braking in the DIII-D tokamak

Journal Article · Tue Feb 01 00:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870925· OSTI ID:5185364

La Haye, R J; Rettig, C L; Groebner, R J; Hyatt, A W; Scoville, J T ^[1]

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1. General Atomics, San Diego, California 92186-9784 (United States)

Magnetic braking'' of the plasma toroidal rotation in the high confinement H mode by applied resonant, low [ital m],[ital n]=1 static error fields is used in DIII-D [Nucl. Fusion [bold 31], 875 (1991)] as an independent control to evaluate the [bold E][sub [ital r]][times][bold B] stabilization of microturbulence in the plasma core. In the core ([rho][approx lt]0.9) of a tokamak, the radial electric field and its shear are dominated by toroidal rotation. The fundamental quantity for shear stabilization of microturbulence is shear in the velocity of the fluctuations [bold v][sub [perpendicular]][approx][bold E][sub [ital r]][times][bold B]/[bold B][center dot][bold B] which in the core is [ital v][sub [perpendicular]][approx][ital v][sub [phi]][ital B][sub [theta]]/ [ital B][sub [phi]]. With magnetic braking greatly decreasing the toroidal rotation and thus reducing the core radial electric field and shear, far infrared (FIR) measurements of density microturbulence show downshifting in frequency near [rho][approx]0.8 as a result of the reduced Doppler shift ([omega][approx][ital k][sub [theta]][ital E][sub [ital r]]/[ital B][sub [phi]]) and a factor of 2 increase in the turbulence level ([ital [tilde n]]/[ital n])[sup 2] in the period between edge localized modes (ELMs). There is also a large reduction in turbulence at an ELM which tends to compensate for the increase in turbulence with reduced radial electric field shear between ELMs. No significant change is found in H-mode plasma energy, confinement time, internal inductance [ital l][sub [ital i]], density profile, [ital T][sub [ital e]] profile, or [ital T][sub [ital i]] profile. Good H-mode confinement is maintained by the edge ([rho][approx gt]0.95) transport barrier where the reversed edge [ital E][sub [ital r]] and high edge [ital E][sub [ital r]] shear remain unchanged.

• DOE Contract Number: AC03-89ER51114; FC03-86ER52126
• OSTI ID: 5185364
• Journal Information: Physics of Plasmas; (United States), Vol. 1:2; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

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TOKAMAK DEVICES
PLASMA CONFINEMENT
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DOPPLER EFFECT
ELECTRIC FIELDS
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PLASMA CORE ASSEMBLY
ROTATING PLASMA
STABILIZATION
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CLOSED PLASMA DEVICES
CONFINEMENT
EXPERIMENTAL REACTORS
FLUID FUELED REACTORS
GAS FUELED REACTORS
HOMOGENEOUS REACTORS
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