Divertor heat load in ITER-like advanced tokamak scenarios on JET

Abstract

Heat loads on the JET MarkIIHD divertor are measured by IR thermography in high triangularity plasmas with edge conditions of advanced tokamak scenarios (AT). AT scenarios operate at low density ( n e , av < 5 × 10 19 m - 3 at JET) to maximise the non inductive current drive, leading to high target temperature ( 20 < T e < 40 eV ), hence high heat loads. Comparisons with a typical baseline inductive scenario ( n e , av ≃ 10 × 10 19 m - 3 ), show that for similar input power ( ≃ 20 MW ) the outer target heat load is higher by a factor 4 in AT scenario, and is above the limit for the ITER-like wall (ILW). Operating long pulses in AT scenarios in the ILW could then be an issue and heat load reduction using impurity seeding is investigated.