Low Recycling and High Power Density Handling Physics in CDX-U with Lithium Plasma-facing Components
Authors: R. Kaita, R. Majeski, T. Gray, H. Kugel, D. Mansfield, J. Spaleta, J. Timberlake, L. Zakharov, R. Doerner, T. Lynch, R. Maingi, and V. Soukhanovskii
Abstract:
The Current Drive Experiment-Upgrade (CDX-U)[T. Munsat, P. C. Efthimion, B. Jones, R. Kaita, R. Majeski, D. Stutman, and G. Taylor, Phys. Plasmas. 9, 480 (2002)] spherical tokamak research program has focused on lithium as a large area plasma-facing component (PFC). The energy confinement times showed a six-fold or more improvement over discharges without lithium PFC's. This was an increase of up to a factor three over ITER98P(y,1) scaling[ITER Physics Basis Editors, Nucl. Fusion 39, 2137 (1999)], and reflects the largest enhancement in confinement ever seen in Ohmic plasmas. Recycling coefficients of 0.3 or below were achieved, and they are the lowest to date in magnetically-confined plasmas. The effectiveness of liquid lithium in redistributing heat loads at extremely high power densities was demonstrated with an electron beam, which was used to generate lithium coatings. When directed to a lithium reservoir, evaporation occurred only after the entire volume of lithium was raised to the evaporation temperature. The ability to dissipate a beam power density of about 60 MW/m2 could have significant consequences for PFC's in burning plasma devices.
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Physics of Plasmas 14, 056111 (May 2007) 8 pp
doi: 10.1063/1.2718509
© (2007) American Institute of Physics.
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