Recrystallization-mediated crack initiation in tungsten under simultaneous high-flux hydrogen plasma loads and high-cycle transient heating

Li, Y.; Morgan, T.W.; Vermeij, Tijmen; Vernimmen, J.W.M.; Loewenhoff, Th.; Hoefnagels, Jpm Johan; Dommelen, J.A.W. van; Wirtz, M.; Temmerman, G. De; Verbeken, Kim; Geers, M.G.D.

doi:10.1088/1741-4326/abe312

Cited by 18 publications

(18 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was verified that this variation has negligible influence on the obtained peak heat flux. The FEM analysis procedure has been elaborated in a previous study [24], the accuracy of which is below 15%.…”

Section: Numerical Thermal Analysismentioning

confidence: 99%

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Li¹,

Morgan²,

Berg-Stolp³

et al. 2021

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

The lifetime of plasma-facing components (PFCs) will have a strong influence on the efficiency and viability of future fusion power plants. However, the PFCs suffer from thermal stresses and physical sputtering induced by edge-localized modes (ELMs). ELMs in future fusion devices are expected to occur with a high plasma density compared to current day devices such that coupling of recycling neutrals and plasma ions will be strong. Because of the scale hierarchy of future fusion devices compared to the present ones, the influence of this coupling is difficult to predict. Here, we investigate the ELM-like hydrogen plasma induced heat loads on tungsten in the linear device Magnum-PSI, producing ∼1 ms plasma pulses with electron densities up to 3.5 × 10 21 m −3 . A combination of time-resolved Thomson scattering and coherent Thomson scattering was used to acquire plasma parameters in front of the target. Moreover, a fast infrared camera coupled to finite element thermal analyses allowed to determine the deposited heat loads on the target. We found a significant inconsistency between the plasma power calculated with a conventional collisionless sheath model and the absorbed power by the target. Moreover, plasma stagnation upstream and plasma cooling downstream were observed during the pulses. The observations are explained based on ionization and elastic collisions between the recycling neutrals and plasma ions. The results highlight the impact of plasma-neutral interaction on the power deposition behavior of ELM-like hydrogen plasma on tungsten.

show abstract

Section: Numerical Thermal Analysismentioning

confidence: 99%

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Li¹,

Morgan²,

Berg-Stolp³

et al. 2021

Plasma Phys. Control. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…The use of more advanced recrystallization model, such as nonisothermal JMAK models [15,4], is one of the perspectives of this work. Eventually, we determined a cracking threshold of 70±10 MW/m 2 s 0.5 for base temperature of W lower than 300 K. As claimed by Li et al [7] plasma-material interactions and related phenomena (e.g., fuel retention and W sputtering) can be strongly perturbed by surface cracks and annealing phenomena. In spite of the increasing number of works dealing with the effect of ELM-like transient heat events on W divertor [16], the understanding of W behavior requires further studies under fusion relevant conditions, in particular to study synergical impact of the simultaneous presence of heat loads and H/He plasmas.…”

Section: Discussionmentioning

confidence: 57%

“…Different methods were experimentally employed to simulate the effect of ELMs on PFCs: electron beams [5], plasma guns [6], or laser [7]. Nevertheless, the role of some key parameters (e.g., ELMs frequency and duration) on annealing phenomena still needs deeper investigation.…”

Section: Introductionmentioning

confidence: 99%

Grain growth and damages induced by transient heat loads on W

Minissale¹,

Durif²,

Kermouche³

et al. 2021

Phys. Scr.

View full text Add to dashboard Cite

During H-mode plasma in ITER, type-I Edge Localized Modes can occur naturally leading to transient heat load (<10 GW/m 2 ) on the tungsten divertor.Such high heat fluxes might therefore induce annealing effects, such as recovery and recrystallization, or even lead to surface melting and deterioration (e.g. cracks) of the plasma-facing components. To ensure sufficient lifetime of tungsten monoblocks is thus mandatory to understand how W will evolve when exposed to such transient heat loads.We present here results on the study of grain growth and damage threshold of tungsten induced by transient heat loads (from 1 to 15 ms, <3 GW/m 2 ). Using a high-power laser facility, we simulate ELMs and we submitted samples to various heating durations up to melting temperature. Laser heating is combined to several imaging techniques, like SEM and optical microscopy, to study grain growth and damages on W. We observed that the growth kinetics strongly depends on the repetition rate with a rapid grain growth for 100 Hz heat loads. We eventually built a finite element methods simulations, benchmarked against our experimental results, to evaluate temperature gradients and recrystallized fraction of the material when exposed to unmitigated ELMs.

show abstract

“…target surface temperature measurement was detailed in Ref. [30]. The detailed theory on the determination of D diffusive transport parameters has been given in Ref.…”

Section: Steady-state and Transient Heat Flux Exposurementioning

confidence: 99%

“…During exposure, a negative bias of −50 V was applied to the target. The sample temperature was about 823 K, measured by a fast-infrared camera (IR-cam, FLIR SC7500MB), which was calibrated by a spectropyrometer (FAR Associates R ) in the wavelength range of 900-1700 nm [30].…”

Section: Plasma Irradiationmentioning

confidence: 99%

Recent progress of thick tungsten coating prepared by chemical vapor deposition as the plasma-facing material

Chen¹,

Li²,

Cheng³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Chemical vapor deposition (CVD) is a promising technique for the preparation of Wbased plasma-facing materials (PFMs). An overview of the microstructure, chemical composition, thermal conductivity, thermal stability, thermal shock performance under disruption-like and edge localized mode (ELM)-like transient heat load, and neutron irradiation performance of CVD-W has been given in our previous work. However, for fusion applications, additional properties need to be assessed. To this end, deuterium (D) permeability, D plasma irradiation performance, and thermal fatigue resistance of CVD-W were investigated in this work. The results showed that the D permeability of CVD-W in the temperature range of 973-1173 K was larger than that of the commercial pure W, which was related to the columnar grain structure of CVD-W. Additionally, both CVD-W and commercial pure W were exposed to D plasma up to a fluence of 1 × 10 26 m -2 . Compared to commercial pure W, CVD-W exhibited a mitigated blistering behavior and lower D total retention, which could be attributed to its strong [001] crystallographic texture along the thickness direction and a lower number of defect density (e.g. grain boundaries). CVD-W and commercial pure W were also exposed to steady-state and transient heat load simultaneously, leading to a base surface temperature and surface temperature increase of about 953-1473 K and 250-300 K, respectively. A strong grain orientation dependence of the surface degradation induced by the combined heat load has been found. Consequently, CVD-W exhibited a much more uniform plastic deformation than pure W, and no surface cracks along grain boundaries were observed in CVD-W. Finally, the industrial-scale production of CVD-W-based PFMs and mockups was demonstrated. This work paves the way for the fusion applications of thick CVD-W coatings.

show abstract

Recrystallization-mediated crack initiation in tungsten under simultaneous high-flux hydrogen plasma loads and high-cycle transient heating

Abstract: Recrystallization-mediated crack initiation in tungsten under simultaneous high-flux hydrogen plasma loads and high-cycle transient heating. Nuclear Fusion, 61(4), [046018].

Cited by 18 publications

References 79 publications

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Power deposition behavior of high-density transient hydrogen plasma on tungsten in Magnum-PSI

Grain growth and damages induced by transient heat loads on W

Recent progress of thick tungsten coating prepared by chemical vapor deposition as the plasma-facing material

Contact Info

Product

Resources

About