Interaction of adhered metallic dust with transient plasma heat loads

Abstract

The first study of the interaction of metallic dust (tungsten, aluminum) adhered on tungsten substrates with transient plasma heat loads is presented. Experiments were carried out in the Pilot-PSI linear device with transient heat fluxes up to 550 MW m−2 and in the DIII-D divertor tokamak. The central role of the dust-substrate contact area in heat conduction is highlighted and confirmed by heat transfer simulations. The experiments provide evidence of the occurrence of wetting-induced coagulation, a novel growth mechanism where cluster melting accompanied by droplet wetting leads to the formation of larger grains. The physical processes behind this mechanism are elucidated. The remobilization activity of the newly formed dust and the survivability of tungsten dust on hot surfaces are documented and discussed in the light of implications for ITER.

Survival and in-vessel redistribution of beryllium droplets after ITER disruptions

“…In both scenarios and regardless of size, low speeds of a few m s −1 and below dominate dust formation and only uniform and low-speed ULLN distributions lead [73].…”

Cross machine investigation of magnetic tokamak dust: Morphological and elemental analysis

“…Splash-shaped magnetic dust has been found in all devices except DIII-D. This is expected owing to the absence of vacuuming in the present DIII-D collection as well as the enhanced adhesion of splashes [18] or of immobile dust with high temperature pre-history [19]. Splashes are based on SS or Ni alloys, see Fig.…”

Observations of dust fragmentations in the Experimental Advanced Superconducting Tokamak

“…2016; Ratynskaia et al. 2016, 2018), the interaction between dust particles and plasma (Laux, Balden & Siemroth 2014; Autricque et al. 2018; Block & Melzer 2019), particle injections and transports (Delzanno & Tang 2014; Lunsford et al.…”

“…In recent years, studies of dust particles in fusion devices have been carried out in many aspects, including the generation and re-deposition of dust particles (Tolias et al 2016;Ratynskaia et al 2016Ratynskaia et al , 2018, the interaction between dust particles and plasma (Laux, Balden & Siemroth 2014;Autricque et al 2018;Block & Melzer 2019), particle injections and transports (Delzanno & Tang 2014;Lunsford et al 2018) and the characteristics of dust particles (Arnas et al 2017;Pardanaud et al 2020;Pan et al 2022). The applications of fast cameras provide an important method for particle and plasma diagnosis (Ratynskaia et al 2011;Shalpegin et al 2015).…”