Plasma Surface Interaction (PSI) studies at DIII-D

Wong, C.P.C.; Rudakov, D.L.; Brooks, J.N.; Brooks, N.H.; Buchenauer, D.; Chen, B.; Chrobak, C.; Doerner, R.; Elder, J.D.; Hassanein, A.; Hollmann, E. M.; Lasnier, C.J.; Leonard, A. W.; Litnovsky, A.; McLean, A.G.; Sizyuk, T.; Stangeby, P.C.; Tao, Rumao; Wall, Don; Wampler, W.R.; Watkins, J. G.; Wright, G.M.; Wright, Melissa A.; Luo, Guang–Nan; Zhong, Guangwu

doi:10.1109/sofe.2013.6635337

Cited by 2 publications

(1 citation statement)

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“…Erosion at that level is a factor of 10 6 higher than the most pessimistic estimates of fuzz erosion without arcing [45]. Experiments done with the Divertor Materials Evaluation System (DiMES) in DIII-D found that in a tokamak environment, arcing can occur on the W fuzz surface during vertical displacement event (VDE)-like exposures [49]. However, no particle emission was detected in these studies.…”

Section: In Situ Measurement Analysis Of Molybdenum Nano-fibre (Fuzz)...mentioning

confidence: 85%

Structural response of transient heat loading on a molybdenum surface exposed to low-energy helium ion irradiation

et al. 2016

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The advancement of fusion reactor engineering is currently inhibited by the lack of knowledge surrounding the stability of plasma facing components (PFCs) in a tokamak environment. During normal operation, events of high heat loading occur periodically where large amounts of energy are imparted onto the PFC surface. Concurrently, irradiation by low-energy helium ions present in the fusion plasma can result in the synthesis of a fibre form nanostructure on the PFC surface, called ‘fuzz’. In order to understand how this heterogeneous structure evolves and deforms in response to transient heat loading, a pulsed Nd:YAG millisecond laser is used to simulate these events on a fuzz form molybdenum (Mo) surface. Performance was analysed by three metrics: nanostructure evolution, particle emission, and improvement in optical properties. Experiments performed at the upper end of the expected range for type-I edge-localized modes (ELMs) found that the helium-induced nanostructure completely disappears after 200 pulses of the laser at 1.5 MJ m−2. In situ mass loss measurements found that the amount of particles leaving the surface increases as energy density increases and the rate of emission increases with pulse count. Finally, optical properties assisted in providing a qualitative indication of fuzz density on the Mo surface; after 400 pulses at 1.5 MJ m−2, the optical reflectivity of the damaged surface is ~90% of that of a mirror polished Mo sample. These findings provide different results than previous studies done with tungsten (W), and further help illustrate the complicated nature of how transient events of high heat loading in a tokamak environment might impact the performance and lifetime of PFCs in ITER and future DEMO devices (Ueda et al 2014 Fusion Eng. Des. 89 901–6).

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Section: In Situ Measurement Analysis Of Molybdenum Nano-fibre (Fuzz)...mentioning

confidence: 85%