Survivability of First-Wall Materials in Fusion Devices: An Experimental Study of Material Exposure to Pulsed Energetic Ions

Renk, Timothy Jerome; Provencio, Paula Polyak; Tanaka, T.J.; Blanchard, James P.; Martin, Carl J.; Knowles, Timothy R.

doi:10.13182/fst12-a13339

Cited by 18 publications

(41 citation statements)

References 28 publications

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“…In continuous mode, however, the defect concentration is so low that vacancy annihilation at the surface effectively competes with vacancy clustering, thus, reducing the trapping site concentration with respect to the pulsed case. The higher He retention in pulsed mode is relevant to the development of fusion materials and may be the origin of the low fluence threshold observed in pulsed irradiation experiments [13]. Further work to reproduce in detail these experiments is underway.…”

Section: Discussionmentioning

confidence: 93%

“…SEM images reveal that swelling and pore formation take place that eventually lead to W exfoliation with mass loss. A recent paper by Renk and co-workers [13] clearly shows that the situation is worse when W is subject to intense He pulses rather than to continuous irradiation. In this situation the fluence threshold for mass loss appears to be two orders of magnitude lower.…”

Section: Introductionmentioning

confidence: 99%

“…The origin of these adverse effects upon He irradiation is unclear, however, it is logical to consider excessive He retention as a possible cause [13]. A detailed study of He retention is not trivial due to the subtleties imposed by the exact temperature profile, ion energy, pulse duration and the presence of impurities, which lead to complicated evolution of defect clusters.…”

Section: Introductionmentioning

confidence: 99%

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Effect of ion flux on helium retention in helium-irradiated tungsten

Rivera¹,

Valles²,

Caturla³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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Helium retention in irradiated tungsten leads to swelling, pore formation, sample exfoliation and embrittlement with deleterious consequences in many applications. In particular, the use of tungsten in future nuclear fusion plants is proposed due to its good refractory properties. However, serious concerns about tungsten survivability stems from the fact that it must withstand severe irradiation conditions. In magnetic fusion as well as in inertial fusion (particularly with direct drive targets), tungsten components will be exposed to low and high energy ion irradiation (helium), respectively. A common feature is that the most detrimental situations will take place in pulsed mode, i.e., high flux irradiation. There is increasing evidence of a correlation between a high helium flux and an enhancement of detrimental effects on tungsten. Nevertheless, the nature of these effects is not well understood due to the subtleties imposed by the exact temperature profile evolution, ion energy, pulse duration, existence of impurities and simultaneous irradiation with other species. Object Kinetic Monte Carlo is the technique of choice to simulate the evolution of radiation-induced damage inside solids in large temporal and space scales. We have used the recently developed code MMonCa (Modular Monte Carlo simulator), presented at COSIRES 2012 for the first time, to study He retention (and in general defect evolution) in tungsten samples irradiated with high intensity helium pulses. The code simulates the interactions among a large variety of defects and during the irradiation stage and the subsequent annealing steps. The results show that the pulsed mode leads to significantly higher He retention at temperatures higher than 700 K. In this paper we discuss the process of He retention in terms of trap evolution. In addition, we discuss the implications of these findings for inertial fusion.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of ion flux on helium retention in helium-irradiated tungsten

Rivera¹,

Valles²,

Caturla³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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show abstract

“…In Table 1.1, the main characteristic parameters are compared [11] for a typical direct-drive target (yield per shot of 154 MJ) in the case of ICF and conditions assumed for ITER in the case of MCF. The heat flux parameter (H = E·Δt 1/2 ) Tungsten is proposed as a convenient PFM for both first-wall in ICF [13][14][15][16][17] and divertor regions in MCF [18][19][20][21][22][23]. W offers several advantages: high melting point (3695 K [24]), high thermal conductivity (1.75 W cm -2 s -1 at room temperature [24]), low sputtering coefficient [25] and low tritium retention [23].…”

Section: Acknowledgementsmentioning

confidence: 99%

“…Numerous studies [33,37] images reveal that swelling and pore formation take place, which eventually lead to W exfoliation with mass loss. Renk et al [16] clearly showed that the situation is even worse when W is subject to intense He pulses rather than to continuous irradiation. In this situation, the fluence threshold for mass loss is around two orders of magnitude lower (~10 15 cm -2 ).…”

Section: Introductionmentioning

confidence: 99%