RESONANT SCATTERING OF LYMAN ALPHA-RADIATION AS A NEUTRAL DENSITY DIAGNOSTIC FOR FUSION PLASMAS

Resonance fluorescence of neutral hydrogen illuminated by Lyman alpha radiation (1216Å) provides a technique for spatially and temporally resolved density measurements of neutral hydrogen isotopes in magnetically confined fusion plasmas or other similar environments. An analysis of the magnitude of expected fluorescence signals and integrated background radiation is developed and applied to typical fusion plasmas. Assuming that intense Lyman alpha sources, based on nonlinear laser frequency mixing techniques, are available, the feasibility of the method is demonstrated for neutral densities as low as a few times 107 cm-3 in DITE, PLT and TFTR. Suggestions are made for spectroscopic measurements on current and future Tokamak devices, to obtain additional data of interest for this application. © 1978.