Bulletin of the American Physical Society
49th Annual Meeting of the Division of Plasma Physics
Volume 52, Number 11
Monday–Friday, November 12–16, 2007; Orlando, Florida
Session CO3: NSTX and General Spherical Tokamak
2:00 PM–4:48 PM,
Monday, November 12, 2007
Rosen Centre Hotel Room: Salon 9/10
Chair: Mickey Wade, General Atomics
Abstract ID: BAPS.2007.DPP.CO3.8
Abstract: CO3.00008 : Dependence of the L-H power threshold on magnetic balance and heating method in NSTX*
3:24 PM–3:36 PM
Preview Abstract Abstract
(Oak Ridge National Lab)
(Princeton Plasma Physics Lab)
(New York University)
H-mode access is a critical issue for next step devices, such as the International Thermonuclear Experimental Reactor (ITER), which is projected to have a modest heating power margin over the projected L-H power threshold (PLH). The importance of a second X-point in setting the value of PLH has been clarified in recent experiments on several tokamaks. Specifically a reduction of PLH was observed when the magnetic configuration was changed from single null (SN) to double null (DN) in the MAST, NSTX, and ASDEX-Upgrade devices . Motivated by these results, detailed PLH studies on NSTX have compared discharges with neutral beam and rf heating, as a function of drsep. Similar PLH values and edge parameters are observed with the two heating methods in the same magnetic configuration, with PLH $\sim$ 0.6 MW lowest in DN and increasing to $\sim$ 1.1 MW and 2-4 MW in lower-SN and upper-SN configurations respectively (ion grad-B-drift towards lower X-point). The evolution of the experimental profiles of parameters in L-mode before the L/H transition will be compared with simulations using the XGC code (C.S. Chang). \newline  MEYER, H. et al., Nucl. Fusion 46 (2006) 64.
*Sponsored by US DOE in part by contract \#DE-AC05-00OR22725.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.CO3.8
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