Erosion and redeposition experiments in the PISCES facility

Technical Report · Thu May 01 04:00:00 EDT 1986

DOI:https://doi.org/10.2172/5271724· OSTI ID:5271724

Goebel, D M; Hirooka, Y; Conn, R W; Leung, W K; Campbell, G A; Bohdansky, J; Wilson, K L; Bauer, W; Causey, R A; Pontau, A E

The modification of surfaces during exposure to plasma bombardment is a critical issue in the development of limiter and wall materials for fusion confinement experiments. Controlled studies of the erosion and redeposition of materials during high flux and fluence plasma exposure are now possible in the PISCES facility. PISCES is a continuously operating plasma device which has achieved hydrogen plasma densities of over 10/sup 13/ cm/sup -3/ and electron temperatures of 5 to 24 eV over large areas. Ion fluxes of 10/sup 17/ to 10/sup 19/ cm/sup -2/ sec/sup -1/ and fluences of up to 10/sup 23/ cm/sup -2/ have been used to bombard biased samples inserted into the plasma. The plasma parameters can be selected to produce simple sputtering, or redeposition by the ionization and recycling of the sputtered target materials. Collaborative studies on the performance of Cu and Cu-Li alloys (with ANL), stainless steel (with SNLL), and graphite (with IPP at Garching, and SNLL) have been undertaken. Surface topography modification is always observed after a sufficient fluence is achieved. The net erosion rate is significantly lower during redeposition than one would expect from classical sputtering yields. The transport and deposition of different materials by the plasma to the samples during redeposition conditions results in greatly modified surface composition and morphology. Chemical sputtering of graphite during low energy, high flux (>10/sup 18/ cm/sup -2/ sec/sup -1/) plasma bombardment is observed. Chemically formed hydrocarbons are relatively easily redeposited compared to sputtered carbon. The performance of these materials, the surface morphology evolution, and the characteristics of the redeposited materials are discussed.

• Research Organization: California Univ., Los Angeles (USA). Center for Fusion Physics and Engineering; Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.); Sandia National Labs., Livermore, CA (USA); Argonne National Lab., IL (USA)
• DOE Contract Number: AS03-84ER52104
• OSTI ID: 5271724
• Report Number(s): UCLA/PPG-982; ON: DE86015000
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700209* -- Fusion Power Plant Technology-- Component Development & Materials Testing
ALLOYS
CARBON
COPPER
COPPER ALLOYS
DEPOSITION
ELEMENTAL MINERALS
ELEMENTS
EROSION
FIRST WALL
GRAPHITE
INTERACTIONS
LIMITERS
LITHIUM ALLOYS
METALS
MINERALS
NONMETALS
PLASMA
SPUTTERING
THERMONUCLEAR REACTOR WALLS
TRANSITION ELEMENTS