Sensitivity of injected argon behavior to changes in magnetic balance in double-null plasmas in DIII-D

• Published in: Journal of nuclear materials 2009-06, Vol.390, p.242-245
• Main Authors: Petrie, T.W., Brooks, N.H., Fenstermacher, M.E., Groth, M., Hyatt, A.W., Lasnier, C.J., Leonard, A.W., Porter, G.D., Schaffer, M.J., Wade, M.R., Watkins, J.G., West, W.P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2009.01.071

Recent DIII-D experiments show that both magnetic balance and particle drifts are important to understanding how argon impurities accumulate in balanced and unbalanced double-null plasmas during ‘puff and pump’ radiating divertor operation. Unbalanced double-null shapes, which are biased in the direction opposite to the ion B × ∇ B drift direction, have produced the best result to-date in terms of coupling a radiating divertor approach with an H-mode plasma. The proximity to balanced double-null that can be used for puff-and-pump may depend on the width of the heat flux profile in the scrape-off layer. A comparison of plasma behavior in the open lower divertor to that of the more closed upper divertor determined that plasma density control was far more sensitive to the ion B × ∇ B drift direction than to the relative closure of the divertor.