Design of Vacuum Spectroscopy System for SPARC

The preliminary design of a vacuum spectroscopy (VCSP) system for SPARC was performed based on the results of spectral simulations. The main objective of VCSP is to operate a real-time impurity monitor for SPARC core and divertor plasma in zones where electron temperatures range from 10's of eV to several keV. Line emission from EUV to VUV are to be measured, typically in the 1 – 200 nm wavelength range, using techniques established on existing tokamaks. The SPARC VCSP instrument consists of two sub-systems: a core and divertor survey spectrometers to cover both regions. Detailed physics design is conducted by a spectral simulation utilizing the Python open-source code, AURORA [1], with additionally developed code modules for synthetic diagnostics, and is supported by ANSYS calculations of electromechanical loads for survival of in-vessel mirrors. SOLPS-ITER simulation results of SPARC's Ne seeding scenario in the lower divertor improved the alignment design of VCSP components. Positioning optimization of mirror and beamline was conducted via calculations of etendue of the system and line brightness of Ne ions. Primary design review will be followed by design of out-vessel parts.