On the origin of the DIII-D L-H power threshold isotope effect

The increased low to high confinement mode (L to H-mode) power threshold PLH in DIII-D hydrogen plasmas (compared to deuterium) is shown to result from lower impurity (carbon) content, consistent with reduced (mass-dependent) physical and chemical sputtering of graphite. Trapped Gyro-Landau Fluid (T...

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Published inNuclear fusion
Main Authors Callahan, Kyle, Schmitz, Lothar, Carter, Troy A., Belli, Emily A., Chrystal, Colin, Haskey, Shaun R., Grierson, Brian A., Thome, Kathreen E., Smith, Sterling P., McKee, George R., Staebler, Gary M., Holland, Christopher, Ashourvan, Arash, Yan, Zheng
Format Journal Article
LanguageEnglish
Published United States IOP Science 11.09.2023
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Summary:The increased low to high confinement mode (L to H-mode) power threshold PLH in DIII-D hydrogen plasmas (compared to deuterium) is shown to result from lower impurity (carbon) content, consistent with reduced (mass-dependent) physical and chemical sputtering of graphite. Trapped Gyro-Landau Fluid (TGLF) quasilinear calculations and local non-linear gyrokinetic CGYRO simulations confirm stabilization of Ion Temperature Gradient (ITG) driven turbulence by increased carbon ion dilution as the most important isotope effect. In the plasma edge, electron non-adiabaticity also contributes to the isotope dependence of thermal transport and PLH, however its effect is subdominant compared to changes from impurity isotopic behavior.
Bibliography:USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
FC02-04ER54698; SC0020287; SC0019352; FG02-95ER54309; SC0018287; AC02-09CH11466; FG02-08ER54999; AC05-00OR22725
ISSN:0029-5515
1741-4326