Abstract
Tungsten, the plasma facing material (PFM) for the divertor in ITER, must sustain severe, distinct loading conditions. This broad array of exposure conditions necessitates comprehensive experiments that cover most of the expected loading parameters to predict qualitative statements about the performance and as a consequence thereof the intended operation time. However, comprehensive experiments are inherently difficult to realize due to the fact that there is no device that is capable of simulating all loading conditions simultaneously. Nevertheless, the linear plasma device PSI-2 enables experiments combining thermal and particle exposure at the same time. In this work, sequential and simultaneous loads on pure tungsten at different base temperatures were investigated to study not only the performance of the material, but also the influence of the experimental parameters. The detailed analysis and comparison of the obtained results showed different kinds of damage depending on the loading sequence, power density, microstructure of the samples, and base temperature. Finally, samples with transversal grain orientation (T) showed the weakest damage resistance and the increase of the base temperature could not compensate the detrimental impact of deuterium.
Highlights
The plasma facing material (PFM) and in-vessel components (PFCs) will be exposed to massive steady state heat loads, transient thermal events, and particle fluxes, which demand a great deal of the PFMs and PFCs in terms of performance, durability, and reasons of economy [1,2,3,4]
Double forged pure tungsten samples with diverse microstructures were investigated at different base temperatures (400 °C and 730 °C) under transient thermal (Nd: YAG laser) and steady state particle loads
A direct correlation between the loading sequence and the pores/cavities was not descried, certainly there seemed to be a slight interrelation between power density and pulse number
Summary
Double forged pure tungsten samples with diverse microstructures were investigated at different base temperatures (400 °C and 730 °C) under transient thermal (Nd: YAG laser) and steady state particle (deuterium plasma) loads. Three different samples types (L, T, R) were tested under fusion relevant thermal shock conditions and particle exposure with varying loading sequences and at base temperatures of 400 °C and 730 °C. The number of detectable cracks on metallographic cross sections varied between 1 and 10, which produced a poor statistic but depicted that with rising power densities the crack depth increased.
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