Dust deposition on plasma-facing substrates extracted from the WEST Tokamak
Abstract
Dust particles deposited during the first phase of operation of the WEST tokamak were collected and analyzed from substrates positioned at four distinct poloidal locations along the inner wall. Among various particle types composed of materials present in the vacuum vessel, previously unreported tungsten molten splashes exhibiting highly distinctive "stethoscope-like" morphologies were discov- ered. These unusual tungsten particles were found in large numbers exclusively on substrates located closest to the lower divertor. They display a well-defined log-normal size distribution, with average lengths ranging from 0.75 to 1.5 μm, and a clear angular alignment pointing predominantly away from the divertor. This directional distribution provides compelling evidence that they were ejected from the lower divertor region. Additionally, more conventional tungsten spheroidal particles were identified across all four poloidal positions. These spheroids were most abundant near the divertor and exhibited progressively more elongated shapes and less distinct alignment patterns with increasing distance, suggesting a common origin but different transport histories. Their size distributions are also log- normal, with average diameters between 100 and 200 nm. The characteristics of both particle types (distribution, size scaling, and directionality) suggest a common origin in molten tungsten droplets expelled from the lower divertor, most likely as a result of arcing events.
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BibTeX
@article{nelson2026dust,
title = {{Dust deposition on plasma-facing substrates extracted from the WEST Tokamak}},
author = {N. Nelson and C. Martin and C. Arnas and A. Campos and E. Bernard and C. Xiao and Lénaïc Couëdel},
journal = {Nuclear Materials and Energy},
year = {2026},
month = oct,
doi = {10.1016/j.nme.2025.102056},
url = {https://hal.science/hal-05449070v2},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Dust deposition on plasma-facing substrates extracted from the WEST Tokamak
AU - N. Nelson
AU - C. Martin
AU - C. Arnas
AU - A. Campos
AU - E. Bernard
AU - C. Xiao
AU - Lénaïc Couëdel
PY - 2026
DA - 2026/10/20
JO - Nuclear Materials and Energy
DO - 10.1016/j.nme.2025.102056
UR - https://hal.science/hal-05449070v2
AB - Dust particles deposited during the first phase of operation of the WEST tokamak were collected and analyzed from substrates positioned at four distinct poloidal locations along the inner wall. Among various particle types composed of materials present in the vacuum vessel, previously unreported tungsten molten splashes exhibiting highly distinctive "stethoscope-like" morphologies were discov- ered. These unusual tungsten particles were found in large numbers exclusively on substrates located closest to the lower divertor. They display a well-defined log-normal size distribution, with average lengths ranging from 0.75 to 1.5 μm, and a clear angular alignment pointing predominantly away from the divertor. This directional distribution provides compelling evidence that they were ejected from the lower divertor region. Additionally, more conventional tungsten spheroidal particles were identified across all four poloidal positions. These spheroids were most abundant near the divertor and exhibited progressively more elongated shapes and less distinct alignment patterns with increasing distance, suggesting a common origin but different transport histories. Their size distributions are also log- normal, with average diameters between 100 and 200 nm. The characteristics of both particle types (distribution, size scaling, and directionality) suggest a common origin in molten tungsten droplets expelled from the lower divertor, most likely as a result of arcing events.
SN - 2352-1791
ER -