Characterisation of impurities in L and H modes created by divertor biasing and plasma triangularity in TdeV
A characterisation of the H mode in Tokamak de Varennes (TdeV), combining results obtained from spectroscopic measurements with observations of global plasma parameters is presented. Controlled L and H modes are obtained by applying an external biasing on the divertor plate and/or by varying the plasma triangularity using similar steady-state discharges with ECRH heating. The poloidal velocities are small with no significant variations with respect to the plate biasing, EC power and plasma triangularity. Toroidal rotation velocities show more consistent trends and have larger values in the H modes with respect to the L modes. No significant shear in the radial electric field is observed between the H and L modes. Differences in the electric field and in the ExB shear are observed for several discharges but they are not consistent overall. The energy confinement time decreases with the ELM severity and consequently with the neutral fluxes. The presence of a toroidal torque which affects the particle transport inside the plasma plays an important role in the TdeV H modes.
Bibliographic Reference: An oral report given at: The 28th EPS Conference of Controlled Fusion and Plasma Physics. Held in: Madeira (PT) June 2001
Record Number: 200013693 / Last updated on: 2001-09-18
Original language: en
Available languages: en