On April 24th the experimental campaign C15 started on JET, after one of the busiest shutdown periods, during which several new systems were installed and others modified. In particular, the divertor has been upgraded to run plasmas with ITER-like configurations at high current and magnetic field and with up to 40 MW heating power handling capability.

The divertor is the region to which the magnetic field deflects the exhaust particles that have escaped from the core of the hot plasma. In both JET and ITER this divertor region is positioned at the bottom of the vacuum vessel. The divertor structure has to be designed with great care as it is exposed to high power fluxes and has to provide an efficient pumping of particles.

In ITER, the plasma cross-section shape will be slightly more triangular than the shape originally conceived for the JET design. The flexibility of JET’s coil system allows the magnetic field to be set up to test the ITER plasma configuration. However, the divertor structure, used in previous experimental campaigns up 2004, was not ideally arranged to accommodate this magnetic field setup. Therefore the plasma auxiliary heating power and current in the ITER-like configuration had to be limited.

During the recent shutdown period, new plasma facing components (carbon tiles) were installed in the divertor so that JET can operate at high-power with ITER-like plasma configurations. The upgraded divertor “MKII-HD” will be exploited to document the new plasma shape by operating with plasma currents of up to 3.5 MA and with increased input power, up to about 30MW in a first stage.