UC San Diego
Flux-driven simulations of turbulence collapse
- Author(s): Park, GY
- Kim, SS
- Jhang, H
- Diamond, PH
- Rhee, T
- Xu, XQ
- et al.
Published Web Locationhttps://doi.org/10.1063/1.4914841
© 2015 AIP Publishing LLC. Using three-dimensional nonlinear simulations of tokamak turbulence, we show that an edge transport barrier (ETB) forms naturally once input power exceeds a threshold value. Profiles, turbulence-driven flows, and neoclassical coefficients are evolved self-consistently. A slow power ramp-up simulation shows that ETB transition is triggered by the turbulence-driven flows via an intermediate phase which involves coherent oscillation of turbulence intensity and E × B flow shear. A novel observation of the evolution is that the turbulence collapses and the ETB transition begins when RT> 1 at t = tR(RT: normalized Reynolds power), while the conventional transition criterion (ω E × B > γ l i n where ω E × B denotes mean flow shear) is satisfied only after t = tC( >tR), when the mean flow shear grows due to positive feedback.
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