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The ergodic magnetic limiter coils on TEXT have been reconfigured to produce the primary helical perturbation resonance at m = 7 n = 3 . The experiments continue to demonstrate that the weak resonant perturbations modify the edge conditions in keeping with model predictions. We observe a reduction in the intrinsic impurity levels accompanying the helical current pulse, presumably the result of a reduction in the electron temperature in the edge. Heat follows the perturbed field lines to the limiter, generating heat load patterns which reflect the geometry of a magnetic island-limiter intersection. A strong spatial modulation of the electron density in the scrape-off-layer also reflects the helical mode structure.

The JET scrape-off plasma during X-point discharges with L- and H-modes is described. There is a flow of current in the scrape-off layer which can influence equilibrium, transport, heating and impurity generation in the scrape-off layer. A local measurement of D ⊥ is obtained in the divertor region. The saturated flux of ions flowing parallel to the magnetic field, I SAT is ∼10 A/cm2 at the divertor separatrix in ohmic discharges. In L-mode with NBI it increases by a factor ⩽ 2, depending on injected power level ( P NBI MW ) and decreases with H-mode. The e-folding decay length, λ I SAT , is the same in ohmic and L-mode but decreases with H-mode. The electron temperatures at the divertor target are ~ 30 eV (OH) and ~ 50–60 eV (H-mode). Measurements of T e during L-mode are not reported because of the high level of fluctuations. An enhancement in the erosion of carbon due to ion-stimulated desorption at the divertor target is discussed. Flow reversal in the scrape-off layer is demonstrated.