levels are reached as altitude increases, the corresponding re- ductions in recombination and attachment rates (reactions 10 and 17 in Table 2) and diffusion rates produce a slower decay downstream of the peak and therefore a longer plume. A study of the rates of electron production from reactions 10 and 14 shows that chemi-ionization does not make a significant contribution to the electron density level throughout much of the afterburning plume.** However, chemi-ionization dominates just downstream of the nozzle exit (within 1-2 ft). The total radar attenuation along a paths through the plume was computed from the simplified expression,