The Radio-Wave Scattering Properties of the Solar Corona.

The results of observations of the occultation of Tau A by the solar corona each year from 1959 to 1962 are reported. The 1959-1961 observations were conducted with various portions of the Clark Lake Antenna during its construction, and the first observations with the completed antenna were made in 1962. The long wavelength employed, 11.4 m, is very sensitive to coronal scattering. The variation of scattering with separation from the Sun has been derived, and appears to decrease with the inverse square of the separation out to 60R0. This may also be an indication of the variation of electron density in the corona. Several idealized models of the radio-wave scattering in the corona are proposed, and the predictions of these models are compared in detail with the data concerning the variation of total flux, and onedimensional scans of the scattered brightness distributions. The models predict the gross features of the observations well, and this confirms the fact that multiple, small-angle scattering accounts for most of the observed effects. However, detailed comparisons suggest the presence of a wider-angle component as well. If the reasonable assumption is made that the scattering is caused by magnetically confined coronal filaments, the coronal magnetic fields are mostly random in direction, but have some preference for the radial direction.