The role of the nonadiabatic electron drive in regulating the isotope mass scaling of gyrokinetic turbulence is assessed in the transition from ion-dominated core transport regimes to electron-dominated edge transport regimes. The scaling of the plasma energy confinement time with hydrogenic isotope mass is of critical importance, as most tokamaks operate with deuterium (D) as the main ion...
An accurate and predictive model for turbulent transport fluxes driven by microinstabilities is a vital component of first-principle-based tokamak plasma simulation. However, tokamak scenario prediction over energy confinement timescales is not routinely feasible by direct numerical simulation with nonlinear gyrokinetic codes. Reduced order modelling with quasilinear turbulent transport models...
Outline A novel scheme to predict the plasma turbulent transport is developed by combining the machine learning technique and the first-principle gyrokinetic simulations. The machine learning technique is applied to find the relevant input parameters of the nonlinear gyrokinetic simulations which should be performed and to optimize the reduced transport model. The developed scheme can...
Core transport in present tokamaks is mostly ascribed to micro-turbulence driven by the non-linear saturation of ion-scale ITG-TEM [1] instabilities ($k_\theta\rho_i\le1$, where $k_\theta$ is the poloidal wave number and $\rho_i$ the ion Larmor radius). It has been shown that electron-scale ETGs [2] ($k_\theta\rho_e\le1$) can also impact the heat transport, also exchanging energy with ITG-TEM...
Recent experiments in JET-ILW have been successfully exploring a high-performance H-mode scenario with no gas dosing at low $q_{95}$ ($I_p=3$ MA, $B_t$=2.8 T, $q_{95}=$ 3.2) and low triangularity, with peak neutron rates reaching values of 3.6$\times 10^{16}$ s$^{-1}$. This was enabled by operation at very low gas fueling, which is challenging in JET with the metal wall due the need to control...
