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icc_2011_maingi_v2.pdf2011-06-07 09:31:08Rajesh Maingi

The ORNL collaborative boundary physics program on LTX, and its synergy with the NSTX boundary physics program

Author: Rajesh Maingi
Requested Type: Poster Only
Submitted: 2011-06-09 12:15:55

Co-authors: T.M. Biewer, T.K. Gray, J.M. Canik, A.G. McLean, D.P. Boyle, E.M. Granstedt, R. Kaita, and R. Majeski

Contact Info:
Oak Ridge National Lab
c/o PPPL, Receiving 3, Route 1
Princeton, NJ   08543
USA

Abstract Text:
A large number of devices, e.g. CDX-U and NSTX, have shown the benefits of lithium as a plasma-facing component (PFC), including enhancement of energy confinement and suppression of edge localized modes [1, 2, 3]. Building on this success, the Lithium Tokamak Experiment (LTX) [4] was designed with a temperature-controlled metallic shell onto which lithium is evaporated, representing ~ 90% of the PFC surface area. The primary effect of lithium is to reduce the recycling at PFCs and edge neutral density; nearly all other effects follow from this. The ORNL collaborative boundary physics program on LTX aims to assess the effects of lithium on the edge power, momentum, and particle balance. A simple torque balance with momentum input from a diagnostic neutral beam (DNB) shows that the predicted toroidal rotation speed increases quickly with decreasing recycling coefficient or neutral density. To verify these basic predictions, a set of diagnostics is being implemented; the centerpiece is a dedicated Charge Exchange Recombination Spectroscopy (ChERS) system to quantify the poloidal and toroidal rotation speeds, ion temperatures, and radial electric fields. Filterscopes, calibrated Hα (and Lα) cameras, and medium resolution compact visible-range Czerny-Turner spectrometers will help quantify the change in edge recycling source with lithium, and dual-band thermography [5] will quantify the PFC response to plasma bombardment. Interpretive analysis of the effects of lithium will be accomplished through 2D fluid edge plasma and kinetic neutrals modeling with SOLPS package, which has already been used [6] to quantify the effects of lithium on the edge plasma in NSTX. Full implementation of the ChERS diagnostic awaits the availability of the DNB, presently scheduled for late 2011. An overview of the collaboration and initial results will be presented, including pertinent results from NSTX that demonstrate the key analysis techniques. An accompanying paper by T.K. Gray details the diagnostic development.

This work is supported by US DOE contracts DE-AC05-00OR22725 and DE-AC02-09CH11466.

[1] R. Majeski, et al., Phys. Rev. Lett. 97 (2006) 075002
[2] M.G. Bell, et al., Plasma Phys. Control. Fusion. 51 (2009) 124054
[3] R. Maingi, et al., Phys. Rev. Lett. 103 (2009) 075001
[4] R. Majeski, et al., Nucl. Fusion 49 (2009) 055014
[5] A.G. McLean, et al., Rev. Sci. Instrum. (2011) submitted.
[6] J.M. Canik, et al., Phys. Plasma 18 (2011) 056118

Characterization: A2

Comments:
Please place next to poster by T.K. Gray

University of Washington

Workshop on Innovation in Fusion Science (ICC2011) and
US-Japan Workshop on Compact Torus Plasma
August 16-19, 2011
Seattle, Washington

ICC 2011