The effect of different ICRH heating scenarios on the jet scrape-off layer

Abstract

Investigation of the scrape-off layer (SOL) at different toroidal and poloidal positions has been carried out in JET for limiter discharges with and without ion cyclotron resonance heating (ICRH). A wide range of plasma conditions ( I p ≈1−5 (rmMA), B T ≈1.8−3.5 T, 〈 n e 〉 ≈ (1−5) × 10 19 m −3 ), ICRH heating scenarios (H and He 3 minority, quadrupole, monopole, dipole antenna phasing) and different machine configurations were investigated. The total ICRH power coupled to the JET plasma was ≤ 7.2 MW, when three antennae were used, and ≤ 13 MW using eight antennae operation. Limiter discharges were produced with either eight discrete graphite limiters or two full toroidal belt limiters. Density profiles in the SOL were found to decay exponentially with an e-folding length, λ n e , which changes with total input power, wall conditioning and plasma species. The modification of the plasma edge depends on the antenna phasing. The scaling of edge temperature, edge density and impurity production with 〈 n e 〉 and P T for different scenarios is presented. Changes in SOL parameters are also compared with different torus wall and antenna conditioning.