Mobilization of dust and exfoliation of erosion product films in tokamaks
- National Research Centre Kurchatov Institute (Russian Federation)
The mobilization of dust (i.e., detachment and removal of dust grains from a substrate) and the exfoliation of a film of erosion products in tokamaks have been studied theoretically. The following mechanisms of dust mobilization have been taken into account: (i) sharp heating (thermal shock) as a result of, e.g., plasma disruption and edge instabilities; (ii) substrate vibrations; and (iii) gas and plasma flow (wind) action. The most effective mobilization takes place under the action of sharp heating. Power fluxes that are characteristic of edge instabilities can mobilize dust grains with dimensions within or even greater than 0.1-1 {mu}m. The velocities of detached grains reach {nu} {approx} 100 m/s for heavy grains and up to {nu} {approx} 300 m/s for the light ones. Conditions favoring the exfoliation of a film of erosion products are determined. It is shown that exfoliation under the action of edge instabilities can take place at a film thickness of h > 1 {mu}m. Under the action of thermal-shock-induced stresses, the exfoliated film flakes with a size ranging from fractions of a millimeter to several centimeters break into pieces.
- OSTI ID:
- 22047411
- Journal Information:
- Plasma Physics Reports, Vol. 38, Issue 4; Other Information: Copyright (c) 2012 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-780X
- Country of Publication:
- United States
- Language:
- English
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