Microturbulence damping mechanisms in the DIII-D tokamak

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860727· OSTI ID:6484732

Rettig, C L; Peebles, W A; Burrell, K H; La Haye, R J; Doyle, E J; Groebner, R J; Luhmann, Jr, N C ^[1]

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1. Department of Electrical Engineering and Institute of Plasma and Fusion Research, University of California, Los Angeles, California 90024 (United States)

Although it has long been suggested that microturbulence is responsible for anomalous transport, relatively little is known about turbulence drive and suppression mechanisms which determine the observed fluctuation levels. In the DIII-D (DIII-D) tokamak [[ital Plasma] [ital Physics] [ital and] [ital Controlled] [ital Nuclear] [ital Fusion] [ital Research], 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159] during H-mode discharges, microturbulence has been observed to change in two stages. Collective far-infrared scattering has confirmed and quantified a rapid ([congruent]100 [mu]sec) suppression of edge microturbulence at the L[r arrow]H transition, as well as locally increased edge electric field shear, consistent with theoretical models which predict microturbulence suppression due to [bold E][times][bold B] sheared flow. Additionally, during the subsequent H-mode phase, a slower (10--100 msec) reduction of interior microturbulence is observed, coincident with increased electric field shear and reduced [del][ital n][sub [ital e]] in the same region. This reduction is much larger in boronized discharges which also generally have larger rotation velocity. Experiments have been performed whereby the interior radial electric field is reduced while maintaining similar pressure profiles through the use of magnetic braking'' of toroidal rotation. As expected, the [bold E][times][bold B] Doppler frequency shift of the scattered fluctuation spectrum decreased as the electric field was reduced. The microturbulence levels were observed to increase when the interior electric field and the associated shear were reduced. Therefore, radial electric field control of microturbulence appears to be a possible route to transport control

• DOE Contract Number: FG03-86ER53225; AC03-89ER51114
• OSTI ID: 6484732
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 5:7; ISSN 0899-8221; ISSN PFBPEI
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700310 -- Plasma Confinement-- (1992-)
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
CHARGED-PARTICLE TRANSPORT
CLOSED PLASMA DEVICES
CONFINEMENT
DOPPLER EFFECT
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
FAR INFRARED RADIATION
FLUCTUATIONS
INFRARED RADIATION
PLASMA CONFINEMENT
RADIATION TRANSPORT
RADIATIONS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE
VARIATIONS