Interpretation of Thermal Conductivity and Toroidal Momentum Transport in DIII-D Taking Into Account IOL and Pinch Velocity

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Roveto, Jonathan
Stacey, Weston M.
Biegalski, Steven R.
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This work improves the methodology used to interpret the diffusive radial particle flux and the conductive radial heat flux from the experimentally inferred total radial particle and energy fluxes, respectively, to more accurately infer experimental heat conductivity and particle diffusion coefficients, respectively. The experimental radial particle, momentum, and energy fluxes are determined by phenomena other than diffusion, viscosity, and conduction, respectively. The contributions of these ``other phenomena'' must be subtracted from the ``experimental'' radial fluxes to obtain diffusive radial particle fluxes that can be used to interpret particle diffusivities and conductive radial energy fluxes, which can be used to interpret thermal conductivities. This methodology is employed to interpret particle diffusion and heat conductivity coefficients in several DIII-D shots in different confinement regimes (including QH- and SH-mode) and compare with theoretical models for particle and energy transport. This research also obtains a toroidal viscous drag and a pinch velocity using IOL-corrected radial particle fluxes, therein demonstrating the importance of non-diffusive particle transport. The effects of ion orbit loss (IOL) on the interpretation of the radial ion heat flux are significant in the edge plasma. Furthermore, correcting for convective heating and work done by the plasma on the pressure tensor is seen to in general substantially reduce the inferred radial ion conductive heat flux. Importantly, we also find that viscous heating, which is driven by asymmetries in the toroidal and poloidal rotation velocities, can be an important heat transfer mechanism that must be corrected for when inferring transport coefficients. We find that, upon correcting for these non-conductive heat transport mechanisms, some combination of neoclassical and ITG transport may be able to explain ion heat transport in the edge plasma. We also show that the particle pinch is an important driver of transport in the edge plasma. }
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