Improved diagnostics of magnetic fusion plasmas are needed for economically and environmentally viable fusion energy. Current measurements suffer from interference of large stray light and plasma luminosity. This project will develop a filtered coherent Thomson scattering system that is capable of suppressing large stray light and plasma luminosity. The approach relies on a dispersive resonance filter which exploits the narrow absorption profile of an optically thick atomic vapor. The system will have high light throughput and will be capable of spectrally dispersing the narrow ion and electron features characteristic of coherent Thomson scattering. In Phase I, a rubidium vapor dispersive filter will be constructed and used in concert with a narrow bandwidth Ti:Sapphire laser to provide attenuation and dispersion of the incident laser used in coherent Thomson scattering. Measurements of spectral profiles will be conducted, and filter performance will be evaluated for a range of scattering angles, extinction and dispersion. Finally, a prototype system will be constructed and tested.
Commercial Applications and Other Benefits as described by the awardee: This diagnostic should find wide application in magnetic fusion devices for monitoring plasma properties such as electron temperature and density. It should also benefit smaller plasma systems used in materials processing, remediation of hazardous and toxic wastes, and analytical instrumentation.
