Retention behavior in tungsten and molybdenum exposed to high fluences of deuterium ions in TPE

Sharpe, John P.; Kolasinski, Robert; Shimada, M.; Calderoni, P.; Causey, R.A.

doi:10.1016/j.jnucmat.2009.01.195

Cited by 47 publications

(30 citation statements)

References 10 publications

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“…This maximum appears in both irradiated and unirradiated targets and has also been seen in other work [3,14,15], although the actual peak can range from 400-600 K. It must also be noted that other parameters such as plasma flux, and thus plasma fluence, are not held constant in the data shown in figure 5. Table 1 demonstrates the differences in plasma flux that correspond to the different local W surface temperatures.…”

Section: Spatial and Depth Distribution Of Dsupporting

confidence: 72%

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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Section: Spatial and Depth Distribution Of Dsupporting

confidence: 72%

Hydrogenic retention in irradiated tungsten exposed to high-flux plasma

et al. 2010

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“…Despite intense studies on the accumulation of H in metal vacancy, [25][26][27] the definitive interactions of H and vacancy are not fully understood yet, especially in fcc metals. Moreover, some thermodesorption spectrometry (TDS) experiments revealed that the release temperatures of H trapped in W defects ranged from 400 to 1000 K. [28][29][30][31][32] The release of H atoms accommodated in a vacancy is significantly influenced by temperature. Theoretical work is needed to examine the detailed detrapping of H in a vacancy at certain temperature, where experiments are hard to access.…”

Section: Introductionmentioning

confidence: 99%

Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

You¹,

Kong²,

Wu³

et al. 2013

AIP Advances

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First-principles calculations are performed to investigate the dissolving, trapping and detrapping of H in six bcc (V, Nb, Ta, Cr, Mo, W) and six fcc (Ni, Pd, Pt, Cu, Ag, Au) metals. We find that the zero-point vibrations do not change the site-preference order of H at interstitial sites in these metals except Pt. One vacancy could trap a maximum of 4 H atoms in Au and Pt, 6 H atoms in V, Nb, Ta, Cr, Ni, Pd, Cu and Ag, and 12 H atoms in Mo and W. The zero-point vibrations never change the maximum number of H atoms trapped in a single vacancy in these metals. By calculating the formation energy of vacancy-H (Vac-Hn) complex, the superabundant vacancy in V, Nb, Ta, Pd and Ni is demonstrated to be much more easily formed than in the other metals, which has been found in many metals including Pd, Ni and Nb experimentally. Besides, we find that it is most energetically favorable to form Vac-H1 complex in Pt, Cu, Ag and Au, Vac-H4 in Cr, Mo and W, and Vac-H6 in V, Nb, Ta, Pd and Ni. At last, we examine the detrapping behaviors of H atoms in a single vacancy and find that with the heating rate of 10 K/min a vacancy could accommodate 4, 5 and 6 H atoms in Cr, Mo and W at room temperature, respectively. The detrapping temperatures of all H atoms in a single vacancy in V, Nb, Ta, Ni, Pd, Cu and Ag are below room temperature

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“…Sample temperature is controlled by changing the materials (to vary thermal conductivity) and geometries (to vary effective thermal diffusion area) of the heat sinks between the sample and the water-cooled copper plate. The sample temperature is measured by a type-K thermocouple attached to the back of the sample, and the stable sample temperature range from 300 to 1100 K was achieved 1 . Langmuir probe is used to measure plasma parameters (electron temperature, electron density, ion flux density, plasma space potential, and float potential), and it can be mounted at two different axial positions (either at target side or source side) as illustrated in the Figure 1.…”

Section: Iia Tritium Plasma Experiments (Tpe)mentioning

confidence: 99%

“…TDS is equipped with two quadrupole mass spectrometers: a broad range one for AMU 1-50 and a high resolution one for AMU 1-6. The detail of the retention studies is in elsewhere 1 . Figure 1: The schematic of TPE gas flow system…”

Section: Iia Tritium Plasma Experiments (Tpe)mentioning

confidence: 99%