Experimental simulation of materials degradation of plasma-facing components using lasers

Abstract

The damage and erosion of plasma-facing components (PFCs) due to extremely high heat loads and particle bombardment is a key issue for the nuclear fusion community. Currently high current ion and electron beams are used in laboratories for simulating the behaviour of PFC materials under ITER-like conditions. Our results indicate that high-power nanosecond lasers can be used for laboratory simulation of high heat flux PFC material degradation. We exposed tungsten (W) surfaces with repetitive laser pulses from a nanosecond laser with a power density ∼ a few GW cm −2. Emission spectroscopic analysis showed that plasma features at early times followed by intense particle emission at later times. Analysis of laser-exposed W surface demonstrated cracks and grain structures. Our results indicate that the typical particle emission features from laser-irradiated tungsten are consistent with high-power particle beam simulation results.

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

“…Transient thermal loads of high energy occurring in a tokamak under operative conditions have been simulated by the interaction with a single laser pulse delivered by the Nd:YAG laser TVLPS [30]. The source used in present experiments is a no-commercial laser composed by an Nd:YAG oscillator (QUANTEL SA, Orsay, France), based on Q-switched technique, followed by four amplification stages.…”

“…An aspect of fundamental importance is the interaction between W and plasma, which has been investigated either in fusion devices such as TEXTOR [20], ASDEX-U [21], and PF-1000 facility [22] or through laboratory simulations [23][24][25][26][27][28][29][30][31][32]. Particular attention has been paid to steady thermal loads, while some studies have focused on transient high heat loads, which may induce serious damage and degradation of W.…”

Cracking and damage behavior of tungsten under ELM’s like energy loads using millisecond laser pulses

“…In the previous study using nanosecond laser pulses, we have demonstrated that laser beam can be used for simulating the damage and erosion of PFMs under transient high power abnormal events occurring during the ELMs [11]. In this work, ELM-like conditions (time of exposure, energy and power loads) were replicated by exposing W to the repetitive millisecond pulsed laser pulses.…”

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

“…In addition, they have also been applied to the investigation of ablation and melting thresholds on different plasma-exposed W materials, in order to highlight the role of He bubbles on the behavior of W under extreme thermal loads [30,31]. Recently, thermal effects induced on W by ITER-relevant thermal loads have also been mimicked by nanosecond lasers [32]. However, the experimental investigation reported in [32] was performed in the ablation regime, and it did not explicitly consider the effect of different HFFs on W, making it difficult to compare with thermal effects induced by other irradiation techniques (e.g.…”

“…Recently, thermal effects induced on W by ITER-relevant thermal loads have also been mimicked by nanosecond lasers [32]. However, the experimental investigation reported in [32] was performed in the ablation regime, and it did not explicitly consider the effect of different HFFs on W, making it difficult to compare with thermal effects induced by other irradiation techniques (e.g. e-beams).…”