The feasibility of the L-H transition for a purely electron-heated EU-DEMO tokamak

Abstract

We study numerically the feasibility of achieving the L-H transition in the current EU-DEMO tokamak baseline using uniquely direct electron heating. The ASTRA code coupled to the TGLF turbulent transport model is used to predict steady-state kinetic plasma profiles for diverse numerical scans. Among them, we have varied the separatrix electron density, the total amount of ECRH power, the microwave beam deposition profile and the plasma impurity content. The solutions are then compared to L-H transition scaling laws to assess whether the found plasma state would enter into H-mode. We find the plasma density and impurity content to be the key variables setting the boundaries in parameter space where the L-H transition is feasible. When impurities can be controlled under a certain threshold, given here for a fully shaped DEMO plasma, the L-H transition is achieved in all the studied conditions.

Keywords

• L-H transition
• DEMO
• ASTRA
• TGLF
• L-mode
• H-mode