Drift wave stability of PEP discharges in Tore Supra

The drift wave stability of pellet enhanced performance modes in Tore Supra has been investigated. It is found that these discharges are characterized by a combination of three different stabilizing mechanisms: density peaking, E ×B shear and magnetic shear. Drift wave stability appears to be very sensitive to magnetic shear, with the most favourable configuration corresponding to a slightly negative magnetic shear. The conclusions are compatible with the results from JET and TFTR.