  Non-thermal electrons accelerated in the solar corona can produce intense
coherent radio emission, known as solar type III radio bursts. This intense
radio emission is often observed from hundreds of MHz in the corona down to the
tens of kHz range in interplanetary space. It involves a chain of physical
processes from the generation of Langmuir waves to nonlinear processes of
wave-wave interaction. We develop a self-consistent model to calculate radio
emission from a non-thermal electron population over large frequency range,
including the effects of electron transport, Langmuir wave-electron
interaction, the evolution of Langmuir waves due to non-linear wave-wave
interactions, Langmuir wave conversion into electromagnetic emission, and
finally escape of the electromagnetic waves. For the first time we simulate
escaping radio emission over a broad frequency range from 500~MHz down to a few
MHz and infer key properties of the radio emission observed: the onset
(starting) frequency, {identification as fundamental or harmonic emission},
peak flux density, instantaneous frequency bandwidth, and timescales for rise
and decay. Comparing with the observations, these large scale simulations
enable us to identify the processes governing the key type III solar radio
burst characteristics.

Solar and Stellar Astrophysics