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Snowflake Divertor Configuration in NSTX...

Publication Type
Conference Paper
Journal Name
Journal of Nuclear Materials
Publication Date
Page Numbers
365 to 368
Volume
415
Issue
1
Conference Name
19th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices (PSI)
Conference Location
San Diego, California, United States of America
Conference Date
-

Steady-state handling of divertor heat flux is a critical issue for present and future conventional and spherical tokamaks with compact high power density divertors. A novel "snowflake" divertor (SFD) configuration that takes advantage of magnetic properties of a second-order poloidal null has been predicted to have a larger plasma-wetted area and a larger divertor volume, in comparison with a standard first-order poloidal X-point divertor configuration. The SFD was obtained in 0.8 MA, 4-6 MW NBI-heated H-mode discharges in NSTX using two divertor magnetic coils. The SFD led to a partial detachment of the outer strike point even in low-collisionality scrape-off layer plasma obtained with lithium coatings in NSTX. Significant divertor peak heat flux reduction and impurity screening have been achieved simultaneously with good core confinement and MHD properties. (C) 2010 Elsevier B.V. All rights reserved.