The European Task Force is motivated by the large extension of the plasma duty cycle, i.e. pulse length, expected in ITER compared with present devices. This requires essential knowledge to be acquired for the operation of ITER with respect to the expectations of the plasma-facing components lifetime (divertor and main chamber) and the tritium inventory build-up rates. In more detail, the Task Force’s topics of research are: erosion behaviour and impurity source location in tokamaks, transport and re-deposition of eroded material, fuel recycling, retention and removal, transient heat loads, erosion and re-deposition modelling, plasma edge physics processes related to material erosion and re-deposition (such as radial and parallel plasma flows) and their modelling, and development and test of diagnostics relevant to the previous topics.

Present experiments indicate that the use of carbon fibre composites as armour material for the divertor target area in ITER may result in unacceptable long-term tritium retention. The goal of the Task Force is to concentrate and co-ordinate European research in the PWI area on these topics and to offer scientific and technological concepts for a solution to the expected problems in this area for ITER operation. These concepts should be based on an improved understanding of the physical processes involved, which will provide the basis for better predictions of the relative importance of these processes in ITER discharges. An important task is to extrapolate the current knowledge, mainly from devices with a full carbon wall, to the ITER-like choice of wall materials in the foreseen starting configuration (beryllium in the main chamber, tungsten at the divertor baffles, and carbon in the lower divertor region). A parallel strategy which will be followed is to evaluate the concept of a fully metallic first wall in ITER and to provide the scientific basis for this alternative choice.

The Task Force will take advantage of the positive experience obtained at JET operated under EFDA, with the creation of Task Forces that have European-wide membership. The Task Force will also try to improve the efficiency of work by  synergies, which are expected from the expansion of the work from individual efforts towards the co-ordinated operation of all European devices. Naturally, an essential ingredient for its success is the commitment and close co-operation of all European Associations and all Association scientists are invited to contribute to it.

As a first step, the Task Force work programme has been formulated in a meeting with contact persons from the European Associations held in Augsburg (Germany) on the 14th and 15th November. This meeting has served to define the individual contributions of the different Associations to the various research topics of the Task Force. The Task Force will work in close co-operation with the JET Task Forces E and FT, which co-ordinate the European research at JET in this field.

More information on the EU-PWI Task Force: