Hydromagnetic Signals in the Ionosphere.
A study of the ionospheric propagation of electromagnetic signals in the.01 to 10 cps frequency range. Equations governing the propagation of hydromagnetic signals in a spatially inhomogeneous, multi-species, anisotropic ionosphere are derived and applied to some special cases in order to calculate the dependence of the refractive indices on altitude and signal frequency. These numerical results are used to deduce a model ionosphere of two sharply bounded homogeneous layers, which, in turn, is used to estimate the transmission of downward-propagating hydromagnetic signals through the collision-dominated lower ionosphere. These signals propagating above the E-region are compared with second-phase geomagnetic disturbances observed during the high-altitude Argus nuclear explosions. Finally, an investigation is made of the possibility that the ionosphere is capable of supporting hydromagnetic surface waves along the "interface" between the two layers in the model. An appendix considers the effect of the negative ions in the ionosphere on the propagation of hydromagnetic waves