Physics requirements for the VUV survey spectrometer intended for the divertor radiation monitoring on JT-60SA

JT-60SA is a fusion experiment designed to support the operation of ITER and to investigate how best to optimize the operation of future fusion power plants. For the safe operation of the device, a survey spectrometer observing the plasma from an equatorial port is foreseen to monitor light impurities such as carbon and oxygen, metal impurities and extrinsic impurities injected ad hoc to mitigate the power exhaust problem. A second survey spectrometer, to be designed and constructed within the presented work, positioned on an upper port with a vertical line of sight, will complement the monitoring activity of the first system by measuring the relative contribution of the various impurities …