Stimulated scattering of large amplitude waves in the ionosphere: Experimental results

A powerful high-frequency radio wave propagating through the ionospheric plasma acts as a pump and excites parametric and other nonlinear processes. These processes can be observed by using diagnostic Thomson scatter radars to probe the pump-enhanced plasma turbulence or by analysing the scattered pump wave directly. Such analyses performed at high and low latitudes (Tromsoe, Norway and Arecibo, Puerto Rico) have shown that the physics in extremely complicated and that old theory cannot satisfactorily explain all results. These experiments can shed new light on nonlinear plasma physics in general but may also provide means for diagnosing the near-Earth plasma and for testing theories of astrophysical plasma processes. (orig.)