A full tungsten divertor for ITER: Physics issues and design status

http://oa.upm.es/35412/7/INVE_MEM_2013_192429.pdf

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

Tungsten as material for plasma-facing components in fusion devices

Proposed fusion and advanced (Generation IV) fission energy systems require high-performance materials capable of satisfactory operation up to neutron damage levels approaching 200 atomic displacements per atom with large amounts of transmutant hydrogen and helium isotopes. After a brief overview of fusion reactor concepts and radiation effects phenomena in structural and functional (nonstructural) materials, three fundamental options for designing radiation resistance are outlined: Utilize matrix phases with inherent radiation tolerance, select materials in which vacancies are immobile at the design operating temperatures, or engineer materials with high sink densities for point defect recombination. Environmental and safety considerations impose several additional restrictions on potential materials systems, but reduced-activation ferritic/martensitic steels (including thermomechanically treated and oxide dispersion–strengthened options) and silicon carbide ceramic composites emerge as robust structural...

Designing Radiation Resistance in Materials for Fusion Energy

Physics basis and design of the ITER plasma-facing components

https://pure.mpg.de/pubman/item/item_2141173_1/component/file_2141172/RothPSI08_Paper_v9.pdf

Recent analysis of key plasma wall interactions issues for ITER

Recrystallized polycrystalline tungsten was exposed to a deuterium plasma beam with high flux (1022 D m−2 s−1) and low energy (38 eV D−1) to fluences up to 1027 D m−2 The sample temperature was varied between 320 and 800 K The three-dimensional morphology of blister-like structures and the grain orientation were investigated by scanning electron microscopy combined with focused ion beam cross-sectioning and electron backscattering diffraction Cracks with distorted areas ( 480 K) were observed beneath the surface The surface blister-like structures and the defects underneath are correlated along crystallographic orientation of the W grains in accordance to the low-indexed slip system {110}111 The defects are mobile and accumulate under deuterium loading Samples exposed near room temperature do not form such large cavities by subsequent heating up to 1300 K Deuterium bombardment above 700 K does not lead to blister-like structures

/pdf/subsurface-morphology-changes-due-to-deuterium-bombardment-vwe8oyclzq.pdf

Subsurface morphology changes due to deuterium bombardment of tungsten

Four kinds of tungsten samples were exposed to 76 eV D-2(+) ions (38 eV D-1) at a flux of 10(22) D m(-2) s(-1). For plasma exposure at 315 K, blistering occurred more significantly on the unrecrystallized and single crystal W samples than the partially and fully recrystallized W samples. The un-recrystallized W sample showed the largest retention ratio at the same fluence. For samples exposed to higher fluences (up to 10(27) D m(-2)), the phenomena of bursting release of deuterium and blister bursting were clearly observed. Preliminary positron annihilation measurements indicated that the vacancy concentration in the near-surface region of tungsten increased after the deuterium plasma exposure. The results of electron back-scattering diffraction showed a strong dependence of blistering upon grain orientation, suggesting the possibility of alleviating blistering by selective texturing of tungsten for future fusion reactors.

https://iopscience.iop.org/article/10.1088/0031-8949/2007/T128/019/pdf

Microstructure dependence of deuterium retention and blistering in the near-surface region of tungsten exposed to high flux deuterium plasmas of 38 eV at 315 K

W. M. Shu

Papers

Recent analysis of key plasma wall interactions issues for ITER

Subsurface morphology changes due to deuterium bombardment of tungsten

Microstructure dependence of deuterium retention and blistering in the near-surface region of tungsten exposed to high flux deuterium plasmas of 38 eV at 315 K

Recent findings on blistering and deuterium retention in tungsten exposed to high-fluence deuterium plasma