Kiel 2004 – scientific programme

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P: Plasmaphysik

P III: HV III

P III.1: Invited Talk

Tuesday, March 9, 2004, 10:30–11:00, H\"orsaal D

Plasma-facing Materials in Fusion Devices — •Harald Bolt — Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D 85748 Garching

To conceive and develop suitable materials for the plasma-facing components of fusion reactors is a major endeavour on the way towards economic fusion power production. During operation the plasma facing materials have to fulfil very complex and sometimes contradicting requirements which have to be reconciled by materials engineering. These requirements span from plasma compatibility, low erosion and the related long lifetime, controllable tritium inventory, thermomechanical stability and good heat transfer properties to stability under neutron irradiation and, possibly, to low neutron activation. At present, tungsten shows the highest promise as plasma-facing material. Experiments in the ASDEX Upgrade tokamak indicate that plasma operation is feasible with walls and divertor surfaces mostly covered with tungsten. Calculations of the erosion lifetime indicate that continued reactor operation for several years may be possible. Thick tungsten coatings have been deposited by plasma spraying on ferritic-martensitic steel and show good adhesion and stability. Alloying of tungsten with plasma compatible elements may intermit the runaway oxidation under accidental air ingress. Work on nanocrystalline tungsten is being launched to improve the mechanical properties under neutron irradiation which is especially important for designs, where tungsten has also to fulfil structural functions.