Influence of blistering on deuterium retention in tungsten irradiated by high flux deuterium 10–100eV plasmas

Luo, G.-N.; Shu, W.M.; Nishi, M.

doi:10.1016/j.fusengdes.2005.09.023

Cited by 66 publications

(25 citation statements)

References 8 publications

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“…The different ranges of incident plasma flux density do not appear to have a strong effect on hydrogenic retention and both W and Mo targets display very similar retention properties. Since the measured retention levels in the ''as received'' tungsten targets is very low and in agreement with literature values [16][17][18], these results indicate that extrapolating low-flux laboratory results to high flux devices is acceptable for unmodified tungsten.…”

Section: à6supporting

confidence: 87%

Materials research under ITER-like divertor conditions at FOM Rijnhuizen

Wright¹,

Westerhout²,

Al³

et al. 2011

Journal of Nuclear Materials

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a b s t r a c tAt FOM Rijnhuizen, linear plasma generators are used to investigate plasma-material interactions under high-density (610 21 m À3), low-temperature (65 eV) plasma bombardment. Research into carbon-based materials has been focused on chemical erosion by hydrogen plasmas. Results from plasma exposure to high-flux (>10 23 H + /m 2 s) and low-temperature hydrogen plasma indicate silicon carbide has a lower relative rate of gross erosion than other carbon-based materials (e.g. graphite, diamond, carbon-fiber composites) by a factor of 7-10. Hydrogenic retention is the focus of research on tungsten and molybdenum. For target temperatures of 700-1600 K, the temperature dependence of hydrogenic retention is the dominant factor. Damage to the surface by heavy ion irradiation has shown to enhance retention by a factor of 2.5-4.1. Thermal stressing of W via. e-beam thermal cycling also enhances hydrogenic retention by a factor of 2.1 ± 0.2, likely due to the introduction of thermal defects, which act as trapping sites for implanted hydrogenic isotopes.

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Section: à6supporting

confidence: 87%

Materials research under ITER-like divertor conditions at FOM Rijnhuizen

Wright¹,

Westerhout²,

Al³

et al. 2011

Journal of Nuclear Materials

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show abstract

“…The low retention values at the 8 mm position are likely due to partial shadowing of the target from the plasma since this is the location of the edge of the molybdenum clamping ring that is used to clamp the target to the heat sink. This trend of strongly decreasing retention at these temperatures is not unexpected [12][13].…”

Section: Spatial and Depth Distribution Of Dmentioning

confidence: 53%

Hydrogenic retention in irradiated tungsten exposed to high-flux plasma

et al. 2010

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Two sets of identical tungsten (W) targets are irradiated at 300 K with 12.3 MeV W 4+ ions to peak damage levels ranging from 0.5-10 displacements per atom (dpa). This results in a damage profile that is peaked at ~0.8 µm and extends to a depth of ~1.5 µm. Both sets of targets are exposed to high-density (n e,center = 3 x 10 20 m -3 ), lowtemperature (T e,center = 1.6 eV) deuterium (D) plasma in Pilot-PSI. One set of irradiated targets is exposed at high surface temperatures (T W = 950 -680 K) and the other at low surface temperatures (T W = 480 K -340 K). The surface temperature is determined by the local plasma conditions. Nuclear reaction analysis (NRA) is used to determine the D depth profiles at specific radial locations, thus giving a surface temperature scan of the D retention in the damaged W. Global retention is determined by thermal desorption spectroscopy, which yields total D retained in the target and also gives information of the different types of lattice defects that are trapping the D in the W lattice. The main results are that there is no measurable difference between the different dpa levels, implying a saturation of the retention enhancement at a level ≤0.5 dpa. For both irradiated and unirradiated tungsten, a peak in the retention is seen at T W = 480 K, however the W 4+ irradiation clearly enhances the retention. This enhancement is also temperature dependent and increases with increasing surface temperature up to an enhancement by a factor of 15-23 at T W = 950 K. At the lowest surface temperatures, a fluence dependence appears since the implanted deuterium is diffusion limited to only a small fraction of the irradiated zone. TDS spectra show an enhancement of both low energy trap sites and high energy trap sites. For these conditions, diffusion-limited, low fill fraction trapping determines the hydrogenic retention of the W.

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“…The main impurity in the plasma was oxygen with a concentration less than 1 ppm [14]. The impact energy The main parameter that was changed in the experimental series was the sample temperature during plasma exposure, which was varied between 320 and 720 K. The exposure temperature was measured with a thermocouple pressed onto the rear side of the specimen [15]. The temperature was adjusted by varying the thermal contact of the specimen to the target holder in order to change the effective cooling of the plasma-heated specimen.…”

Section: Methodsmentioning

confidence: 99%