On Some Properties of Solar Radio Bursts of Spectral Type III

摘要

Solar type III bursts were observed with a swept frequency receiver in the 200 Mc/s range. A mean frequency drift velocity of - 60 Mc/sq s is found. The observed distribution of bursts of different drift velocities agrees with a calculated distribution curve based on other experimental data and simple assumptions. The time profile of the bursts is slightly asymmetrical, and it is possible to explain the profile from a simple model of the type III phenomenon. The analysis leads to a burst band-width of about 25 Mc/s. If the band-width depends on the size of the exciting disturbance, the source size is about 0.05 solar radu at the 200 Mc/s plasma level in the corona. Evidence of an increase in the source size on the way out through the corona is presented. The damping constant of the excited oscillations is larger than previously expected. If it is identified with the collision frequency between electrons and ions, a temperature of 2,000,000K is found for the active region corona. (Author)