Deposition of deuterium and metals on divertor tiles in the DIII-D tokamak

Conference · Mon Dec 31 23:00:00 EST 1990

OSTI ID:6044538

Walsh, D S ^[1]; Doyle, B L ^[2]; Jackson, G L ^[3]

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1. Idaho State Univ., Pocatello, ID (United States)
2. Sandia National Labs., Albuquerque, NM (United States)
3. General Atomics, San Diego, CA (United States)

Hydrogen recycling and impurity influx are important issues in obtaining high confinement discharges in the D3-D tokamak. To reduce metallic impurities in D3-D, 40% of the wall area, including the highest heat flux zones, have been covered with graphite tiles. However erosion, redeposition and hydrogen retention in the tiles, as well as metal transport from the remaining Inconel walls can lead to enhanced recycling and impurity influx. Hydrogen and metal retention in divertor floor tiles have been measured using external ion beam analysis techniques following four campaigns where tiles were exposed to several thousand tokamak discharges. The areal density of deuterium retained following exposure to tokamak plasmas was measured with external nuclear reaction analysis. External proton-induced x-ray emission analysis was used to measure the areal densities of metallic impurities deposited upon the divertor tiles either by sputtering of metallic components during discharges or as contamination during tile fabrication. Measurements for both deuterium and metallic impurities were taken on both the tile surfaces which face the operating plasma and the surfaces on the side of the tiles which form the small gaps separating each of the tiles in the divertor. The highest areal densities of both deuterium and metals were found on the plasma-facing surface near the inner strike point region of each set of divertor tiles. Significant deposits, extending as fast a 1 cm from the plasma-facing and containing up to forty percent of the total divertor deposition, were also observed on the gap-forming surfaces of the tiles.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6044538
• Report Number(s): SAND-91-1163C; CONF-911132--7; ON: DE92003648
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320 -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
700420* -- Fusion Technology-- Plasma-Facing Components-- (1992-)
BEAMS
CARBON
CLOSED PLASMA DEVICES
DEUTERIUM
DIAGNOSTIC TECHNIQUES
DIVERTORS
DOUBLET-3 DEVICE
ELEMENTAL MINERALS
ELEMENTS
FIRST WALL
GRAPHITE
HYDROGEN ISOTOPES
IMPURITIES
ION BEAMS
ISOTOPES
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
PLASMA IMPURITIES
STABLE ISOTOPES
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTOR WALLS
TOKAMAK DEVICES