Plasma Operation with Metallic Walls: Direct Comparisons with the All Carbon Environment
The transition to all metal plasma facing components is an essential step on the path to reactor scale fusion devices and has been a major focus of work in tokamaks and laboratory based experiments in recent years. The transformation of ASDEX-Upgrade to an all tungsten (DEMO-like) wall, and recent installation of the ITER-like Wall (ILW) in JET, allows direct comparison of operation in all carbon environments to all metal walls under otherwise nearly identical conditions. There is also a unique opportunity to compare and contrast operation with beryllium and tungsten in JET with ASDEX-Upgrade. The scope of the review ranges from experience with machine conditioning, residual impurities and breakdown to material migration, melt events, fuel retention, disruptions, impact on operational space, energy confinement and compatibility with impurity seeding.