Evidence for Ionosphere Currents from Rocket Experiments Near the Geomagnetic Equator

Abstract

LETTERS TO THE EDITOR 957 indicated on the graphs. Measurements were made at 4600, 4900, 5200, and 5500 Mc/sec in a guide with cutoff at 4430 Mc/sec, over a range of gas pressures from 0.5 to 100 mm Hg, and at various dc pulse currents and voltages.The results obtained are readily explained in terms of decomposition of the "linear" TEn wave into two oppositely-rotating circularly-polarized waves, an "anomalous" and a "normal" wave. The "anomalous" wave exhibits, in the region of gyromagnetic resonance, very strong attenuation and a reversal of the sign of its phase shift with respect to propagation in vacuum. The "normal" wave is only slightly attenuated in this region and accounts for the circular polarization observed at gyromagnetic resonance.The roles of "anomalous" and "normal" waves are interchanged if the sense of the magnetic field is reversed. Consequently, each of the circularly-polarized waves is heavily attenuated by one or the other of two opposing magnetic fields, both at gyromagnetic resonance. This fact enabled the construction, with two independent solenoids, of a microwave analogue of crossed Nicol prisms.The circularly-polarized waves are not true propagating modes through the plasma in these experiments. Our interpretation remains, however, valid because a short section of plasma was employed. The theoretical details have been worked out for the case of the unbounded anisotropic plasma, including electron collision effects. Further theoretical work remains for the wave guide case.These results hold promise as a tool for the study of gas discharge phenomena. They are applicable also to switching, amplitude, phase or frequency modulation, and polarization control in an electronically controllable medium.

SOME PROBLEMS OF THE AEROMAGNETIC SURVEYS1)

“…This is too small a quantity to cause an appreciable error. Some experiments, however, which have been carried out (Maple andBowen 1951, Cahill andVan Allen 1956) show that it is necessary to assume dipole surface anomalies to account for the field of the earth. The experimental gradient was of the order of 2.5 gammas per IOO metres within the first 20 km.…”