Creating space plasma from the ground

It was predicted (Carlson, 1987; 1993) that once HF radio waves achieved ionospheric energy densities comparable to that from the solar EUV, they could produce their own ionosphere. That work estimated a GW ERP of rf energy would produce an ionosphere half that from an overhead sun, assuming 15 efficiency conversion of rf energy to accelerated electron energy. [Until 2009 only one experimental estimate existed, 15 from Carlson, 1982.] The production mechanism proposed was impact ionization, by HF-accelerated electrons, to energies exceeding thermospheric ionization potentials. Solar EUV, aurora, and high-power HF radio-waves produce suprathermal electrons in the 15-100 eV energy range, yielding long-lived ionization in the ionosphere. Once suprathermal electrons are produced, the Aeronomy of production, transport, and recombination are in common. The key to understanding artificial ionization thus reduces to conversion efficiency of HF energy to ionization. By 2008 technology reached GW ERP. The prediction was tested, and confirmed [Pedersen et al, 2009, Blagoveschenskaya et al, 2009] at high latitudes.