Snowflake Divertor Configuration in NSTX

Conference · Sat Jan 01 04:00:00 EST 2011

OSTI ID:1037042

Soukhanovskii, V A ^[1]; Ahn, Joonwook ^[2]; Bell, R E ^[3]; Gates, D A ^[3]; Gerhardt, S ^[3]; Kaita, R ^[3]; Kolemen, E ^[3]; Kugel, H W ^[3]; LeBlanc, B ^[3]; Maingi, Rajesh ^[2]; Maqueda, R J ^[4]; McLean, Adam G ^[2]; Menard, J E ^[3]; Mueller, D ^[3]; Paul, S F ^[3]; Raman, R ^[5]; Roquemore, L ^[3]; Ryutov, D D ^[1]; Scott, H A ^[1]

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1. Lawrence Livermore National Laboratory (LLNL)
2. ORNL
3. Princeton Plasma Physics Laboratory (PPPL)
4. Nova Photonics, Princeton, NJ
5. University of Washington, Seattle

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.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1037042
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COATINGS
CONFIGURATION
CONFINEMENT
DIVERTORS
HEAT FLUX
LITHIUM
MAGNET COILS
MAGNETIC PROPERTIES
PLASMA
POWER DENSITY