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(EXP4/03) Impurity Control Studies Using SOL Flow in DIII-D

M. R. Wade, J. Hogan, R. C. Isler, R. Maingi

Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA

W. P. West, N. H. Brooks, A. W. Leonard, T. W. Petrie, M. J. Schaffer

General Atomics, P.O. Box 85608, San Diego, California 92186-9784, USA

D. N. Hill, S. L. Allen, M. E. Fenstermacher, C. J. Lasnier, R. D. Wood

Lawrence Livermore National Laboratory, Livermore, California, USA

J. A. Boedo, R. Lehmer, R. A. Moyer, D. G. Whyte

University of California, San Diego, La Jolla, California, USA

J. G. Watkins
Sandia National Laboratories, Albuquerque, New Mexico, USA

Abstract.  Experiments on DIII-D have demonstrated the efficacy of using induced scrape-off-layer (SOL) flow to preferentially enrich impurities in the divertor plasma. This SOL flow is produced through simultaneous deuterium gas injection at the midplane and divertor exhaust. Using this SOL flow, an improvement in enrichment (defined as the ratio of impurity fraction in the divertor to that in the plasma core) has been observed for all impurities in trace-level experiments (i.e., impurity level is non-perturbative), with the degree of improvement increasing with impurity atomic number. In the case of argon, exhaust gas enrichment using a modest SOL flow is as high as 17. Using this induced SOL flow technique and argon injection, radiative ELMing H-mode plasmas have been produced that combine high radiation losses ( P_rad/P_input > 70%), low core fuel dilution ( Z_eff < 1.9), and good core confinement ( $\tau_{\mathrm{E}}^{}$ > 1.0$\tau_{\mathrm{E,ITER93H}}^{}$).

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