Design of Wall Segments for Ferritic Wall Mode Studies on HBT-EP

Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective US component test facility and DEMO [1]. Understanding the interaction of plasmas with a ferromagnetic wall will be crucial physics for these experiments. Although there has been a linear FRWM experiment [2], the FRWM has not yet been observed in toroidal geometry. Using its high-resolution magnetic diagnostics, HBT-EP will explore the dynamics and stability of plasma interacting with ferromagnetic materials. We describe simple models [3] for plasma-wall interaction in the presence of ferromagnetic material, and compare material options for magnetic properties, cost, and ease of fabrication. Also, initial modeling, design, and installation of moderate permeability ($1<\mu<10$) wall segments on HBT-EP will be discussed.\\[4pt] [1] Kurtz, R.J., et. al. 2009 \emph{J Nucl Mater} \textbf{386-388}\\[0pt] [2] Bergerson, W., et. al. 2008 \emph{Phys Rev Lett} \textbf{101}\\[0pt] [3] Kurita, G., et. al. 2003 \emph{Nucl Fus} \textbf{43} 949-954