Diagnostics

The primary mission of the BPX is to study the physics of D-T burning plasmas, that is, discharges in which most or all of the power arises from fusion alpha particles. To assess the physical processes involved in this unique set of conditions, it will be necessary to measure not only the standard plasma parameters, density, temperature, magnetohydrodynamic (MHD) phenomena, impurity concentrations and transport, magnetic properties, and fluctuation activity, but also a new set of phenomena associated with the behavior of the alpha particles themselves. In this paper, the authors want information about the alpha-particle birth rate, the prompt alpha loss rate, transport and slowing down of the confined alphas, and on the buildup or exhaust of the thermalized alpha ash. The effects of the alpha population on the background plasma, including Alfven modes and alpha-driven sawteeth, will need to be measured. In addition, the authors require diagnostics suitable for assessing the performance of the radio-frequency (RF) heating and for the unique divertor design where the thermal load is spread over the divertor plate surfaces by slow movement of the separatrix