Measurement requirements for the advanced tokamak operation of a burning plasma experiment

The optimization of a tokamak towards steady state and high performance has been the focus of advanced tokamak (AT) research for the past decade. A central theme of AT research line is plasma control: control of the plasma shape; of the profiles of current, pressure, and rotation; of transport; and of MHD stability. To optimize the performance, measurements of crucial parameters such as the current density and the plasma pressure are required with appropriate spatial coverage and resolution. In addition, measurements of other parameters will be necessary to develop a fundamental understanding of the complex nonlinear interactions amongst the current density profile, the pressure profile and transport (e.g. turbulence) in high β AT plasmas. Present day experiments are providing physics insight into what a burning plasma experiment (BPX) will require as measurements. Recent research has focused on MHD stability aspects such as the neoclassical tearing mode and resistive wall mode stabilization and control of the current profile. However, in burning plasmas, new factors such as alpha particles, with their heating contribution and their relationship to transport barriers, will be increasingly important. The close relationship between measurements and active control, and the resultant impact on the requirements, will be discussed.