Investigation of Atomic Collisional.Radiative Processes in Neutral Particle Beams and Its Application to Plasma Diagnostics

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We investigated numerically the atomic collisional-radiative processes in neutral particle beam for plasma diagnostics in magnetic fusion plasmas 1. To make numerical studies on processes of excitation, ionization and radiation including laser-induced fluorescences in helium neutral particle beam injected into tokamak plasmas, we formulated a set of rate equations based on a collisional-radiative model. The proton-impact excitation, ionization and charge exchanges were taken into account as well as the electron-impact processes, and local selective excitations by pulse laser were also considered. The programing was made to numerically solve the simultaneous differential equations for the populations of helium excited states up to the principal quantum number n=5.A set of numerical solutions of the temporal and spatial changes of the populations was obtained in a tokamak plasma, and the result was shown to be useful for study of the atomic processes in the particle beam. 2. The Stark-Zeeman patterns of a laser-induced fluorescence line of the helium atom in the particle beam were calculated, the Stark effect being due to the vxB electric field in the tokamak magnetic field. The forbidden excitation due to the Stark effect from the triplet meta-stable state was the subject of calculation. For the lithium particle beam the polarization of the laser- induced fluorescence arising from the corresponding forbidden excitation was also studied. 3. The recombination processes of the helium atom were also investigated on the basis of a collisional-radiative model.