1. presents a theoretical analysis of a slightly ionized argon system according to scheme A. The temperature is assumed not to exceed 2000°K. Relevant rate equations are solved simultaneously on a computer. In the analysis not only excitation due to energetic nuclear
2. reaction particles is considered, but also excitation due to recombination of thermal electrons and the associated radiative and collisional decay of such states. Results show that both thermal recombining electrons and direct excitation from high energy particles are important in the formation of population inversion. One inversion (5s-4p transition) is formed principally by the process of direct excitation by high energy particles and another inversion (4d-5p transition) is formed indirectly by the recombination of ehermal electrons. The gain of the latter transition is an order of magnitude larger than that of the former one. But this is found to depend on the density, as shown in Figure 8 (Reference 62). The figure suggests that at higher densities (which are desirable for nuclear pumping) direct excitation may become dominant. However, such a prediction is made with caution because the effect of increased dissociative recombination at large densities are not yet known to a sufficient degree of accuracy. MINIMUMFLUX DENSITIES
3. (X=840.0 nm) ' 2 .3 -164 5 6 7
4. l'"IG 8 Thresholdp0p1,tl 0f,on rotas as o function of the olom,c density for o neutron riu role of 2 54 xJO4cm-2 seC 1