Divertor heat flux mitigation in the National Spherical Torus Experiment

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3068170· OSTI ID:1018661

Soukhanovskii, V. A. ^[1]; Maingi, R. ^[2]; Gates, D. A. ^[3]; Menard, J. E. ^[3]; Bush, C. E. ^[2]

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1. Lawrence Livermore National Laboratory (LLNL)
2. Oak Ridge National Laboratory (ORNL)
3. Princeton Plasma Physics Laboratory (PPPL)

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono , Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6 MW m(-2) to 0.5-2 MW m(-2) in small-ELM 0.8-1.0 MA, 4-6 MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1018661
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 16; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CONFIGURATION
CONFINEMENT
DEUTERIUM
DIVERTORS
ELECTRON DENSITY
GAS INJECTION
HEAT FLUX
MAGNETIC FLUX
MITIGATION
PLATES
POWER DENSITY
PRESSURE MEASUREMENT
RECOMBINATION
SIMULATION
STABILITY
TRANSPORT