Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD

Technical Report · Tue Apr 01 00:00:00 EDT 2014

DOI:https://doi.org/10.2172/1148703· OSTI ID:1148703

Mikkelsen, David R. ^[1]; Tanaka, K. ^[2]; Nunami, M. ^[2]; Watanabe, T-H. ^[3]; Sugama, H. ^[2]; Yoshinuma, M. ^[2]; Suzuki, Y. ^[2]; Goto, M. ^[2]; Morita, S. ^[2]; Wieland, B. ^[2]; Yamada, I. ^[2]; Yashura, R. ^[2]; Akiyama, T. ^[2]; Pablant, Novimir A. ^[1]

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1. PPPL
2. NIFS
3. Nagoya University

Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC02-09CH11466
• OSTI ID: 1148703
• Report Number(s): PPPL-5019
• Resource Relation: Related Information: Use of parallel computer clusters at PPPL is also gratefully acknowledged.
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CARBON
ELECTRON TEMPERATURE
ION TEMPERATURE
PLASMA IMPURITIES
Carbon
Ion temperature gradient mode
plasma temperature
tokamaks
plasma impurities