Ion thermal transport in the H-mode edge transport barrier on DIII-D

S. R. Haskey, Arash Ashourvan, S. Banerjee, K. Barada, E. A. Belli, A. Bortolon, J. Candy, J. Chen, C. Chrystal, B. A. Grierson, R. J. Groebner, F. M. Laggner, M. Knolker, G. J. Kramer, M. R. Major, G. McKee, G. M. Staebler, Z. Yan, M. A. Van Zeeland

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The power balance ion heat flux in the pedestal region on DIII-D increases and becomes increasingly anomalous (above conventional neoclassical) in experiments with higher temperature and lower density pedestals where the ion collisionality (ν i*) is lowered toward values expected on ITER. Direct measurements of the main-ion temperature are shown to be essential on DIII-D when calculating the ion heat flux due to differences between the temperature of D+ and the more commonly measured C 6 + impurity ions approaching the separatrix. Neoclassical transport calculations from NEO and non-linear gyrokinetic calculations using CGYRO are consistent with these observations and show that while neoclassical transport plays an important role, the turbulent ion heat flux due to ion scale electrostatic turbulence is significant and can contribute similar or larger ion heat fluxes at lower collisionality. Beam emission spectroscopy and Doppler backscattering measurements in the steep gradient region of the H-mode pedestal reveal increased broadband, long-wavelength ion scale fluctuations for the low ν i∗ discharges at the radius where the non-linear CGYRO simulations were run. Taken together, increased fluctuations, power balance calculations, and gyrokinetic simulations show that the above neoclassical ion heat fluxes, including the increases at lower ν i*, are likely due to weakly suppressed ion scale electrostatic turbulence. These new results are based on world first inferred ion and electron heat fluxes in the pedestal region of deuterium plasmas using direct measurements of the deuterium temperature for power balance across ion collisionalities covering an order of magnitude from high ν i∗ values of 1.3 down to ITER relevant ν i∗ ∼ 0.1.

Original languageEnglish
Article number012506
JournalPhysics of Plasmas
Volume29
Issue number1
DOIs
StatePublished - Jan 1 2022
Externally publishedYes

Funding

The work was supported by the U.S. Department of Energy under DE-FC02–04ER54698, DE-AC02–09CH11466, DESC0019352, DE-FG02–08ER54999, DE-FG02–95ER54309, and DESC0019302. Part of the data analysis was performed using the OMFIT integrated modeling framework.29 The authors would like to thank Orso Meneghini and Sterling Smith for their support with OMFIT. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Fingerprint

Dive into the research topics of 'Ion thermal transport in the H-mode edge transport barrier on DIII-D'. Together they form a unique fingerprint.

Cite this