Microturbulence studies of pulsed poloidal current drive discharges in the reversed field pinch

Journal Article · Thu Jan 15 00:00:00 EST 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4905709· OSTI ID:22408000

Pueschel, M. J.; Anderson, J. K.; Terry, P. W. ^[1]

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1. University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

Experimental discharges with pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus reversed field pinch are investigated using a semi-analytic equilibrium model in the gyrokinetic turbulence code GENE. PPCD cases, with plasma currents of 500 kA and 200 kA, exhibit a density-gradient-driven trapped electron mode (TEM) and an ion temperature gradient mode, respectively. Relative to expectations of tokamak core plasmas, the critical gradients for the onset of these instabilities are found to be greater by roughly a factor of the aspect ratio. A significant upshift in the nonlinear TEM transport threshold, previously found for tokamaks, is confirmed in nonlinear reversed field pinch simulations and is roughly three times the threshold for linear instability. The simulated heat fluxes can be brought in agreement with measured diffusivities by introducing a small, resonant magnetic perturbation, thus modeling the residual fluctuations from tearing modes. These fluctuations significantly enhance transport.

• OSTI ID: 22408000
• Journal Information: Physics of Plasmas, Vol. 22, Issue 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASPECT RATIO
DISTURBANCES
ELECTRIC CURRENTS
FLUCTUATIONS
HEAT FLUX
ION TEMPERATURE
MAGNETIC RESONANCE
MST DEVICE
NONLINEAR PROBLEMS
PLASMA
REVERSE-FIELD PINCH
SIMULATION
TEARING INSTABILITY
TEMPERATURE GRADIENTS
TOKAMAK DEVICES
TRANSMISSION ELECTRON MICROSCOPY
TRAPPED ELECTRONS
TURBULENCE