Erosion of bulk TZM evaluated with an implanted depth marker in EAST*

Erosion of molybdenum (TZM) at the mid-plane on the low and high field side in the Experimental Advanced Superconducting Tokamak (EAST) was characterized by utilizing a novel implanted depth marker. Exposure on the Material And Plasma Exposure System (MAPES) on the outboard mid-plane at low fluence (\textless 10\textasciicircum 24 m\textasciicircum -2) shows limited erosion, \textless 40 nm, near the sensitivity limit of the technique, x\textunderscore sens\textasciitilde 20 nm. Lithium (Li) and deuterium (D) content in the near surface (\textless 200 nm) was characterized by Elastic Recoil Detection (ERD) and Nuclear Reaction Analysis (NRA). Accumulation of Li from plasma exposure without prior Li wall conditioning is apparent, even with the sample surface positioned 3 cm radially outward of the limiter, exhibiting Li migration on the run-day time-scale, at low fluence. The HFS samples incorporated in modified tiles with dovetail slot design were exposed for a full run campaign, and net erosion of 0.5-1 um is observed. Erosion of bulk TZM plasma-facing components has been quantified for the first time with the novel implanted depth marker technique, which can be utilized with in situ wall monitoring diagnostics, such as Laser-Induced Breakdown Spectroscopy (LIBS) or Accelerator-based In-situ Material Surveillance (AIMS).