Deuterium pumping and erosion behavior of selected graphite materials under high flux plasma bombardment in PISCES
Deuterium plasma recycling and chemical erosion behavior of selected graphite materials have been investigated using the PISCES-A facility. These materials include: Pyro-graphite; 2D-graphite weave; 4D-graphite weave; and POCO-graphite. Deuterium plasma bombardment conditions are: fluxes around 7 /times/ 10/sup 17/ ions s/sup /minus/1/cm/sup /minus/2/; exposure time in the range from 10 to 100 s; bombarding energy of 300 eV; and graphite temperatures between 20 and 120/degree/C. To reduce deuterium plasma recycling, several approaches have been investigated. Erosion due to high-fluence helium plasma conditioning significantly increases the surface porosity of POCO-graphite and 4D-graphite weave whereas little change for 2D-graphite weave and Pyro-graphite. The increased pore openings and refreshed in-pore surface sites are found to reduce the deuterium plasma recycling and chemical erosion rates at transient stages. The steady state recycling rates for these graphite materials can be also correlated to the surface porosity. Surface topographical modification by machined-grooves noticeably reduces the steady state deuterium recycling rate and the impurity emission from the surface. These surface topography effects are attributed to co-deposition of remitted deuterium, chemically sputtered hydrocarbon and physically sputtered carbon under deuterium plasma bombardment. The co-deposited film is found to have a characteristic surface morphology with dendritic microstructures. 18 ref., 4 figs., 1 tab.
- Research Organization:
- California Univ., Los Angeles (USA). Inst. for Plasma and Fusion Research
- DOE Contract Number:
- AS03-84ER52104
- OSTI ID:
- 6988008
- Report Number(s):
- UCLA/PPG-1159; CONF-880512-8; ON: DE88012408
- Country of Publication:
- United States
- Language:
- English
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BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON
CLOSED PLASMA DEVICES
DATA
DEUTERIUM
DIVERTORS
ELEMENTAL MINERALS
ELEMENTS
EROSION
EXPERIMENTAL DATA
FIRST WALL
FLUIDS
FUEL PARTICLES
GASES
GRAPHITE
HELIUM
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
JET TOKAMAK
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PLASMA
PLASMA GUNS
PUMPING
RADIOISOTOPES
RARE GASES
RECYCLING
SPUTTERING
STABLE ISOTOPES
SURFACE PROPERTIES
TEXTOR TOKAMAK
TFTR TOKAMAK
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTOR WALLS
THERMONUCLEAR REACTORS
TOKAMAK DEVICES
TOKAMAK TYPE REACTORS
TRITIUM
YEARS LIVING RADIOISOTOPES