Performance of different tungsten grades under transient thermal loads

Abstract

Plasma facing components in future thermonuclear fusion devices will be subjected to intense transient thermal loads due to Edge Localized Modes (type I ELMs), plasma disruptions etc.. To exclude irreversible damage to the divertor targets, local energy deposition must remain below the damage threshold for the selected wall materials. For monolithic tungsten (pure tungsten and tungsten alloys) power densities above 0.3 GW/m² with 1 ms duration result in the formation of a dense crack network. Thin tungsten coatings for the so-called ITER-like wall in JET, which have been deposited on a 2-directional carbon-fiber composite (CFC) material, are even less resistant to thermal shock damage; here the threshold values are by a factor of 2 lower. First ELM-simulation experiments with high cycle numbers up to 10 4 cycles on actively cooled bulk tungsten targets do not reveal any cracks for absorbed power densities up to 0.2 GW/m² and ELM-durations in the submillisecond range (0.8 ms); at somewhat higher power densities (0.27 GW/m 2 , Δt = 0.5 ms) cracks have been detected for 10 6 cycles.

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

“…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.…”

Depth profiling of the modification induced by high-flux deuterium plasma in tungsten and tungsten–tantalum alloys

“…Several alloys were proposed with advantages in the sense of thermo-mechanical properties, one of such alloys being W-Ta [7]. This alloy was demonstrated to have better resistance to degradation under repetitive ELM-like heat loads [8].…”

Modelling Thermal Shock Based Cracking Behaviour of Armour Material for Fusion Reactor

“…The combination of tungsten and tantalum material has been considered the most appropriate material for the application of developing armor for nuclear fusion reactors, where it is subjected to face higher degree of temperature caused due to plasma in fusion devices [1][2][3][4][5][6]. Such material is known for its high melting point, high thermal conductivity, very low oxidation with hydrogen, and tremendously small rate of sputtering erosion to bear high thermal expansion.…”

“…These occasions show diverse pulses of thermal flux which extents and vitality discharge scales, individually [10]. There are a lot of trial reports on the negative effect of thermal shocks on the microstructural features of tungstenbased materials [3][4][5][6]11]. Normally, a powerful electron or plasma beam is utilized to recreate transient shocks within short pulses of time.…”

“…Normally, a powerful electron or plasma beam is utilized to recreate transient shocks within short pulses of time. One of the most prominent research works on this point is the electronbeam irradiation test consider directed by Linke et al [6]. By means of rehashed electron pillar blazing with ELM-like load conditions approximating ~1 MJ/m 2 within the pulse timing of ~1 ms, they watched an orderly pattern of progression of cracks and advancement in the lighted surface layer as a component of the information vitality, base temperature, number of heartbeats, and material review.…”