L-H power threshold for neutral beam heated plasmas with Deuterium, Hydrogen, Helium and mixed ion species in TCV

A systematic study of the power threshold for L-H transition has been conducted in TCV. Only results from NB heated plasmas are reported. The dependencies of PLH on plasma current, plasma density and main ion species have been investigated. For Deuterium plasmas and at low q95, the L-H power threshold dependence on density is well described by the ITPA scaling law. Nevertheless at larger q95 values (reduced plasma current at constant toroidal magnetic field), the threshold deviates significantly from the scaling law and PLH increases with q95. As a consequence, a strong correlation of power threshold with transport is reported suggesting that L-H transition is more favorable for L-mode plasmas with already good confinement.