Physics Design Requirements for the National Spherical Torus Experiment Liquid Lithium Divertor
Authors: W. Kugel, M. Bell, L. Berzak, A. Brooks, R. Ellis, S. Gerhardt1, H. Harjes2, R. Kaita1, J. Kallman1, R. Maingi2, R. Majeski, D. Mansfield, J. Menard, R. E. Nygren,V. Soukhanovskii, D. Stotler, P. Wakeland, L. E. Zakharov
Abstract:
Recent NSTX high power divertor experiments have shown significant and recurring benefits of solid lithium coatings on PFC's to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. The next step in this work is installation of a liquid lithium divertor (LLD) to achieve density control for inductionless current drive capability (e.g., about a 15-25% ne decrease from present highest non-inductionless fraction discharges which often evolve toward the density limit, ne/nGW~1), to enable ne scan capability (x2) in the H-mode, to test the ability to operate at significantly lower density for future ST-CTF reactor designs (e.g., ne/nGW = 0.25), and eventually to investigate high heat-flux power handling (10 MW/m2) with longpulse discharges (>1.5s). The first step (LLD-1) physics design encompasses the desired plasma requirements, the experimental capabilities and conditions, power handling, radial location, pumping capability, operating temperature, lithium filling, MHD forces, and diagnostics for control and characterization.
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Presented at: Twenty-Fifth Symposium on Fusion Technology (SOFT 2008), 15 - 19 September 2008, Rostock, Germany
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Download PPPL-4352 (pdf 4.49MBB 16pp)
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