The effects of main-ion dilution on turbulence in low q95 C-Mod ohmic plasmas, and comparisons with nonlinear GYRO

Ennever, P.; Porkolab, M.; Candy, J.; Staebler, G.; Reinke, M. L.; Rice, J. E.; Rost, J. C.; Ernst, D.; Hughes, J.; Baek, S. G.

doi:10.1063/1.4960315

The effects of main-ion dilution on turbulence in low q₉₅ C-Mod ohmic plasmas, and comparisons with nonlinear GYRO

Journal Article · Fri Aug 05 00:00:00 EDT 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4960315· OSTI ID:1894488

Ennever, P. ^[1]; Porkolab, M. ^[2]; Candy, J. ^[3]; Staebler, G. ^[3]; ^[4]; Rice, J. E. ^[2]; ^[2]; Ernst, D. ^[2]; ^[2]; Baek, S. G. ^[2]

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; OSTI
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
General Atomics, San Diego, CA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Recent experiments on C-mod seeding nitrogen into ohmic plasmas with q₉₅ = 3.4 found that the seeding greatly reduced long-wavelength (ITG-scale) turbulence. The long-wavelength turbulence that was reduced by the nitrogen seeding was localized to the region of r/a ≈ 0.85, where the turbulence is well above marginal stability (as evidenced by Q_i/Q_GB $$\gg$$ 1). The nonlinear gyrokinetic code GYRO was used to simulate the expected turbulence in these plasmas, and the simulated turbulent density fluctuations and turbulent energy fluxes quantitatively agreed with the experimental measurements both before and after the nitrogen seeding. Unexpectedly, the intrinsic rotation of the plasma was also found to be affected by the nitrogen seeding, in a manner apparently unrelated to a change in the electron-ion collisionality that was proposed by other experiments.

View Accepted Manuscript (DOE)

Research Organization:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Contributing Organization:: Alcator C-Mod Team

Grant/Contract Number:: FC02-99ER54512; FG02-94ER54235

OSTI ID:: 1894488

Alternate ID(s):: OSTI ID: 1283415

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 23; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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