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

Small time-independent magnetic perturbations (δ b r ), 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 ( P LH ≤3.3 MW) lower hybrid current drive (LHCD) discharges. MARFEs with 0.12 ≤ϱ m =π a 2 n e20 > I p −1 ≤0.22 (i.e., roughly a factor of 3 less than the smallest value of ϱ m previously reported) are obtained during the δ b r pulse when P LH >2.0 MW and the edge safety factor is slightly less than 3. These MARFEs generally appear to have the same characteristics as high ϱ m MARFEs and are positionally stable throughout the LHCD+δ b r 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.