Initial Results of Local Island Divertor Experiments in the Large Helical Device

Journal Article · Thu Jul 15 04:00:00 EDT 2004 · Fusion Science and Technology

OSTI ID:20849731

Komori, Akio ^[1]; Morisaki, Tomohiro ^[1]; Masuzaki, Suguru ^[1]

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1. National Institute for Fusion Science (Japan)

A local island divertor (LID) experiment has begun in the Large Helical Device (LHD) to demonstrate improved plasma confinement, and fundamental LID functions were demonstrated in the sixth experimental campaign in 2002-2003. It was clearly shown that when an m/n = 1/1 island is generated by adding a resonant perturbation field to the LHD magnetic configuration, the particle flow is guided along the island separatrix to the backside of the island, where carbon plates are located on a divertor head. The particles recycled there are pumped out efficiently so that the line-averaged core plasma density is reduced by a factor of {approx}2 at the same gas puff rate, compared with non-LID discharges. Obvious improvement of the global plasma confinement was, however, not observed yet, because the discharge could not be optimized, due to a large amount of outgas from the divertor head to the core plasma. The size of the divertor head was found to be larger than the optimum one; hence, the core plasma impacted slightly on the core plasma-facing portion of the divertor head with which the core plasma was not expected to collide.

• OSTI ID: 20849731
• Journal Information: Fusion Science and Technology, Journal Name: Fusion Science and Technology Journal Issue: 1 Vol. 46; ISSN 1536-1055
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CARBON
DISTURBANCES
DIVERTORS
FIRST WALL
LHD DEVICE
MAGNETIC ISLANDS
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLATES