Reduced-model scrape-off layer turbulence (nSOLT) simulations comparing three fueling scenarios: pellet injection (core), divertor recycling (edge), and neutral puffing (SOL)

Reduced-model scrape-off layer turbulence (nSOLT) simulations comparing three fueling scenarios: pellet injection (core), divertor recycling (edge), and neutral puffing (SOL)

Reduced-model scrape-off layer turbulence (nSOLT) simulations comparing three fueling scenarios: pellet injection (core), divertor recycling (edge), and neutral puffing (SOL) 150 150 Mathew
UKAEA-CCFE-PR(21)63

Reduced-model scrape-off layer turbulence (nSOLT) simulations comparing three fueling scenarios: pellet injection (core), divertor recycling (edge), and neutral puffing (SOL)

The 2D scrape-off-layer turbulence code (nSOLT) includes 1D Boltzmann neutral-plasma interactions, a model of divertor recycling (introduced here), and a fixed source of plasma concentrated at the core-side boundary. 1) Neutral injection in the far-SOL is accomplished by specifying the density of Franck-Condon distributed neutrals streaming in from the boundary. 2) Divertor recycling is modeled by injecting a fraction of the particle parallel flux in the SOL back into the edge region as a source of plasma. 3) A constant source fuels the edge plasma from the core-side boundary to model pellet injection. For machine parameters (B, Rm, L//) illustrative of the MAST-U device, and for a deuterium plasma, turbulent equilibria are obtained that share the same plasma fueling rate for each of the three fueling methods, with only one of the sources on in each case. In the presence of self-consistent turbulence, quasi-steady plasma and neutral (deuterium) profiles, fueling efficiencies, SOL transparencies, and heat flux widths are compared. Characteristics of the turbulent fluctuations, including skewness, cross-phases and power spectra, are described. The calculated fueling efficiencies, SOL transparencies and many of the turbulent properties are remarkably similar for all three fueling methods despite significant differences in the plasma profiles. The nonlinear states of the three cases are dominated by separatrix-spanning vortex cells that control particle and heat losses into the SOL.

Collection:
Journals
Journal:
Physics of Plasmas
Publisher:
AIP (American Institute of Physics)
Published date:
22/10/2021