Lithium Wall Conditioning And Surface Dust Detection On NSTX
Authors: C.H. Skinner, J.P. Allain, M.G. Bell, F.Q.L. Friesen, B. Heim, M.A. Jaworski, H. Kugel, R. Maingi, B. Rais, and C..N. Taylor
Abstract:
Lithium evaporation onto NSTX plasma facing components (PFC) has resulted in
improved energy confinement, and reductions in the number and amplitude of
edge-localized modes (ELMs) up to the point of complete ELM suppression. The
associated PFC surface chemistry has been investigated with a novel plasma
material interface probe connected to an in-vacuo surface analysis station.
Analysis has demonstrated that binding of D atoms to the polycrystalline graphite
material of the PFCs is fundamentally changed by lithium - in particular
deuterium atoms become weakly bonded near lithium atoms themselves bound to
either oxygen or the carbon from the underlying material.
Surface dust inside NSTX has been detected in real-time using a highly
sensitive electrostatic dust detector. In a separate experiment, electrostatic
removal of dust via three concentric spiral-shaped electrodes covered by a
dielectric and driven by a high voltage 3-phase waveform was evaluated for
potential application to fusion reactors.
__________________________________________________
Submitted to: Physics Scripta (May 2011)
__________________________________________________
Download PPPL-4625 (pdf 709KB 19pp)
__________________________________________________