18 W/m2 corresponds to a power flux of 58 mW/cm2 at 2.45 GHz. This is well above the theoretically predicted threshold for an electron thermal runaway. Early predictions indicated limiting electron temperatures of nearly 2000K at altitudes below 100 km, 400 K at 110 km, and ambient (-230 K) at 120 km and above. The experimental results reported by L.M. Duncan (Ref. 4.2.13) show increases in temperatures that are less than predicted by theory. Temperature increases of 150-250 K above ambient were observed in the altitude range from 88 to 100 km (see Fig. 4.10) whereas theoretical considerations predicted increases on the order of 500 to 1000 K. The heating above 100 km fell off with height as predicted by theory, returning to ambient at approximately 120 km. Qualitative comparison of the measured heating and cooling time constants shows reasonable agreement with the theoretical expectations. Fig. 4.10. Results of July 12, 1978, Ionospheric Heating Experiment at Arecibo Observatory
RkJQdWJsaXNoZXIy MTU5NjU0Mg==