Drift wave stability of PEP discharges in Tore Supra

The drift, wave stability of pellet enhanced performance modes in Tore Supr a has been investigated. It is found that these discharges are characterize d by a combination of three different stabilizing mechanisms: density peaki ng, E x B shear and magnetic shear. Drift wave stability appears to be very sensitive to magnetic shear, with the most favourable configuration corres ponding to a slightly negative magnetic shear. The conclusions are compatib le with the results from JET and TFTR.