Title: Diagnose flaring source regions by using microwave type III burst pairs
Baolin Tan
Key Laboratory of Solar Activity, National Astronomical Observatories of the Chinese Academy
of Sciences, Beijing 100012, China
bltan@nao.cas.cn
Abstract: Microwave type III burst pair (type III pair) is believed to be a sensitive signature of the
primary energy release and electron accelerations in the source region of solar flares. A
type III pair is composed of normal and RS burst branches with fast oppositely
frequency drift rates. Based on a full MHD equation, we developed a set of diagnostic
formulas to diagnose the physical conditions of the source region of solar flares. These
conditions include plasma density and its scale length, velocity and energy of electron
beams, magnetic field and length of source regions. These formulas are applied to type
III pairs in a postflare phase, and found the magnetic field near source region is about
40-75 G, electron beam energies of both normal and RS branches are the same in each
type III pair event which implies that the upward and downward electron beams are
possibly accelerated by same mechanism in the same region, the length of source region
is 23--600 km. This method can also be applied to the much popular microwave type III
bursts to diagnose the physical conditions of source regions.