Observation of the tungsten surface damage under ITER-relevant transient heat loads during and after electron beam pulse

Novel electron beam based test facility for observation of dynamics of tungsten erosion under intense ELM-like heat loads

“…Rejection of parasitic plume light in the latter case is provided with narrow band (0.2 nm and 1 nm) spectral filters centered at the laser wavelength. The technique of in situ imaging of tungsten target with the laser illumination is considering in reference [7]. The small angle light scattering system includes 3 channels for collecting light scattered within following angular ranges relative the direction of probing laser beam: 1=0.01-0.03 rad, 2=0.7-0.09 rad, 3=0.1-0.12 rad.…”

Observation of dust particles ejected from tungsten surface under impact of intense transient heat load

“…In the experiments carried out on the GOL-3 device, several techniques for in situ diagnostic of ablated material are employed [5,6]. Targets from rolled tungsten with mm 2 and thickness of 3 -4 mm were used in these experiments.…”

Comparison of tungsten modification after irradiation at different facilities for PSI studies

“…Under loads of about 0.5 MJ/m 2 , the tungsten surface did not melt, but after multiple plasma impacts crack patterns are formed (found after irradiation by using Nd:YAG laser [4], [5], quasi-stationary plasma accelerators QSPA Kh-50 [6], linear plasma machines PSI-2 [7], Nd:YAG laser, JUDITH-1 and GOL-3 [8], [9]). …”

“…At the QSPA Kh-50 plasma gun, a load 0.75 MJ/m 2 is above the melting threshold [6], but the surface did not melt after electron beam irradiation with the same load [9].…”

“…Crack network changes the heat conductivity; the resulting melting threshold decreased near cracks. Some cracks can have a large depth (up to several hundred microns) after irradiation at the GOL-3 [2], [9], QSPA Kh-50 [14], JUDITH-2 [3] and laser [15] (see Fig.1). Instead of individual cracks, a crack network was always formed and that can lead to destruction of the material as a whole.…”