The IEA Implementing Agreement on ‘a co-operative programme for the investigation of toroidal physics in, and plasma technologies of, tokamaks with poloidal field divertors’ (‘Divertor Tokamak Implementing Agreement’) focuses on research on critical physics issues towards the realization of a tokamak burning plasma experiment. It enables coordination of research between the partners through programmatic discussions as well as joint research programs, including coordinated experiments between the various experimental facilities involved. The critical issues are for example identified by the International Tokamak Physics Activity (ITPA), which proposes joint experiments involving several research facilities on an international level. Some of these are best executed in medium size tokamak experiments such as ASDEX Upgrade (Germany), Alcator C-Mod, DIII-D and NSTX (USA) or KSTAR (Korea), which generally have a higher flexibility than the largest facilities.

Typical examples for such critical issues include:

• Development of Hybrid Scenarios for improved ITER operation
• Carbon vs. Tungsten as plasma facing components in next-step devices
• Physics of performance limiting Neoclassical Tearing Modes and means for their stabilization

At present, the joint implementation of experiments under this Implementing Agreement is done in ASDEX Upgrade, Alcator C-Mod, DIII-D and NSTX. From there, a verification of the physics concepts developed must be done in order to ensure applicability to burning plasma devices. This needs an extrapolation to larger machines (i.e. lower normalized gyroradius ?*), which is the scope of the Large Tokamak Implementing Agreements and to longer pulse, which considerably exceed all typical timescales including the current redistribution time. The latter point will be addressed under the Divertor Tokamak Implementing Agreement in the KSTAR device in Korea, which has comparable dimensions and geometry to the above mentioned devices, but at much longer pulse length due to the use of superconducting coils. In this field, we also anticipate interaction with other superconducting fusion devices in the EU such as Tore Supra in France or the Wendelstein 7-X stellarator presently under construction in Germany.

01. Investigation of Toroidal Physics & Plasma Technologies in ASDEX-Upgrade
Investigate toroidal physics & plasma technologies in tokamaks with poloidal field divertors