Hydrogen and deuterium plasma interactions with brazed first wall elements
Four different high temperature brazes were used to join isotropic fine grain graphite and TZM, a high temperature alloy of molybdenum. The response of the brazes to a high flux deuterium plasma bombardment was examined using samples whose exposed surface intersected the braze line. Only in the case of Zr, which is known for its hydride forming properties, were near-surface layers chipped off in the braze region directly exposed to the plasma. The interaction of a hydrogen plasma and a braze surface was studied in more detail by bombarding specimens in the PISCES-B facility. The graphite was removed completely to enable an exaggerated plasma attack onto the bare braze. Even under these testing conditions the brazes CuTi and NiTi showed no particular sensitivity towards hydrogen. To prove the thermal stability of the brazed joints each quality was heat treated for 1 hr and 10 hrs respectively, 50 below the softening temperature of the braze in 1 bar of Ar or 96vol%Ar/4%H(2). No changes or damage were observed in the brazes AgCuTi and CuTi, whereas interstices were found in the widened NiTi-interlayer after 10 hrs in both Ar and Ar/H(2). Zr suffers different microstructural changes in particular after treatment in Ar/H(2) atmosphere.
Bibliographic Reference: Article: Fusion Technology 1990, Vol. 1 (1991) pp. 411-415
Record Number: 199111194 / Last updated on: 1994-12-02
Original language: en
Available languages: en