FUNDAMENTAL AND HARMONIC EMISSION IN TYPE-III SOLAR RADIO-BURSTS I - EMISSION AT A SINGLE LOCATION OR FREQUENCY

A model of type III solar radio bursts is developed that incorporates large-angle scattering and reabsorption of fundamental emission amid a mbient density fluctuations in the corona and solar wind. Comparison w ith observations shows that this model accounts semiquantitatively for anomalous harmonic ratios, the exponential decay constant of bursts, burst rise times, and the directivity of fundamental emission. It is c oncluded that the long emission tail on interplanetary type III bursts is mostly fundamental emission, while much of the anomalous time dela y of fundamental relative to harmonic emission from a given location m ust be ascribed to other causes.