Measurements Of Core Lithium Concentration In A Li-Conditioned Tokamak With Carbon Walls
Authors: M. Podesta, R. E. Bell, A. Diallo, B. P. LeBlanc, F. Scotti and NSTX Team
Abstract:
The National Spherical Torus Experiment (NSTX, [M. Ono et al. , Nucl. Fusion
40 , 557 (2000)]) is exploring the use of lithium as candidate plasma-facing material
to handle the large power flux to the wall of fusion devices. This paper reports on
the measurements of lithium concentration in the plasma core during the 2010 NSTX
experimental campaign, during which 1.3 kg of lithium was evaporated into the NSTX
vessel. It is shown that lithium does not accumulate in signi cant amounts inside the
plasma, resulting in an upper bound for the measured lithium concentration that is
well below 0.1% of the electron density for a broad range of experimental conditions.
Carbon, which constitutes the primary material of the NSTX inner wall, remains the
dominant plasma impurity even after large amounts of lithium, of the order of hundreds
of milligrams, are evaporated into the vacuum vessel.
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Submitted to: Nuclear Fusion (April 2011)
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Download PPPL-4703 (pdf 5.49 MB 21 pp)
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