Plasma-material interactions in TFTR

Technical Report · Wed Oct 01 04:00:00 EDT 1986

DOI:https://doi.org/10.2172/7018318· OSTI ID:7018318

Dylla, H F; Bell, M G; Blanchard, W R; Boody, F P; Bretz, N; Budny, R; Bush, C E; Cecchi, J L; Cohen, S A; Combs, S K

This paper presents a summary of plasma-material interactions which influence the operation of TFTR with high current (less than or equal to 2 MA), ohmically heated and high power (approx. 10 MW), neutral-beam-heated plasmas. The conditioning procedures which are applied routinely to the first-wall hardware are reviewed. Fueling characteristics during gas, pellet, and neutral beam fueling are described. Recycling coefficients near unity are observed for most gas-fueled discharges. Gas-fueled discharges after helium discharge conditioning of the toroidal bumper limiter and discharges fueled by neutral beams and pellets show R < 1. In the vicinity of the gas-fueled density limit (at n/sub e/ = 5 to 6 x 10/sup +19/ m/sup -3/) values of less than or equal to 1.5. Increases in Z/eff of less than or equal to 1 have been observed with neutral beam heating of 10 MW. The primary low-Z impurity is carbon with concentrations decreasing from approx.10% to <1% with increasing n/sub e/. Oxygen densities tend to increase with n/sub e/, and at the ohmic plasma density limit oxygen and carbon concentrations are comparable. Chromium getter experiments and He/sup + +//D/sup +/ plasma comparisons indicate that the limiter is the primary source of carbon and that the vessel wall is a significant source of the oxygen impurity. Metallic impurities, consisting of the vacuum vessel metals (Ni, Fe, Cr), have significant (approx. 10/sup -4/ n/sub e/) concentrations only at low plasma densities (n/sub e/ < 10/sup +19/ m/sup -3/). The primary source of metallic impurities is most likely ion sputtering from metals deposited on the carbon limiter surface.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 7018318
• Report Number(s): PPPL-2386; ON: DE87003065
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700209* -- Fusion Power Plant Technology-- Component Development &amp; Materials Testing
CHARGED PARTICLES
CHROMIUM IONS
IMPURITIES
INTERACTIONS
IONS
IRON IONS
LIMITERS
MATERIALS
NICKEL IONS
OXYGEN IONS
PLASMA
REACTOR FUELING
RECYCLING
SPUTTERING
TFTR TOKAMAK
THERMONUCLEAR REACTOR MATERIALS
THERMONUCLEAR REACTOR WALLS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS