Ion Microanalysis and Implantation Applied to Fusion Surface Research

Abstract

Ion microanalysis and implantation have been used to investigate and analyze plasma-surface interactions relevant to fusion plasma materials. Previous results for pure metals are reviewed and new results are presented for TiB₂ coatings for Tokamak surfaces. Enhanced trapping of implanted, low-energy hydrogen has been shown to occur at room temperature in W, Au, Pd, Mo, Nb, and TiB₂ for He or other ion predamage. Hydrogen depth profiles obtained using ¹H(¹⁹F,Αγ)¹⁶O resonant nuclear reaction show that the H decorates the He damage profiles at traps whose concentration is proportional to the He-induced damage. For room temperature implantation in TiB₂, H is trapped at the end of range, and isochronal annealing indicates that the H is lost by release from traps followed by rapid diffusion. For He predamaged samples, annealing at 400°C causes the H to be retrapped in the region of the He-induced damage at traps whose cross section is ≈ 1.8 × 10-¹⁸cm²/trap.