Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
One of the unsolved problems for a next step fusion device is the handling of the power flux into the divertor in particular the rapid heat deposition caused by Edge Localized Modes (ELMs). In recent JET experiments with the MKII Gas Box divertor, ELMy H-Mode discharges with impurity seeding of argon and nitrogen have been investigated. A possible method of mitigating the power flux to the divertor during ELMs is to seed the plasma with impurities. In nitrogen seeded discharges a measured radiated power fraction of up to 85% of the heated power is measured, accompanied by a transition to Type-III ELMs and a loss of confinement (H98(Y,2)=0.7). On the other hand, in argon seeded discharges Type-I ELMs are still observed after argon injection at a radiation level of up to 65%, but without a loss of confinement (H98(Y,2)=1.0). The power load on the target are studied with high time resolution IR thermography (65microseconds) to distinguish between the power fraction deposited during and in between ELMs. For a limited time no significant power load is observed after the injection of either impurity between ELMs and a reduced power load during ELMs. The efficiency of power detachment for Type-III and Type-I ELMs will be discussed.