Magnetic perturbation effects on boundary plasmas during high power lower hybrid current drive in Tore Supra

Small time-independent magnetic perturbations (δbr), produced with the Tore Supra ergodic divertor coils, have been used to control thermal loads on plasma facing components, current density profiles, the transport of non-Maxwellian particles, and the confinement properties of thermal plasmas during high power (PLH ≤ 3.3 MW) lower hybrid current drive (LHCD) discharges. MARFEs with 0.12 ≤ ρm=πa2Ip-1≤0.22 (i.e., roughly a factor of 3 less than the smallest value of ρm previously reported) are obtained during the δbr pulse when PLH>2.0 MW and the edge safety factor is slightly less than 3. These MARFEs generally appear to have the same characteristics as high ρm MARFEs and positionally stable throughout the LHCD+δbr pulse. Steady state conditions in which more than 90% of the total input power is radiated from a 0.15 m wide region near the high-field side wall were obtained. (orig.)