Polarization Spectra of Centimeter-wavelength Solar Bursts Using Whole-sun Observations

Book excerpt: The physics of microwave-burst emission is briefly examined to give the rationale for investigating polarization spectra. The instruments used to carry out the 9.4 GHz and 7 GHz circular-polarization measurements and the 5 GHz Stokes-parameter measurements are described. A survey of the August 1972 to December 1973 period produced a table of 45 bursts, from which some limited results were obtained. About 75 to 80 percent of all bursts are circularly polarized, with varying polarization over the 5 to 9.4 GHz range. For most bursts where the circular polarization pc increases toward the upper or lower end of the 5 to 9.4 GHz range, the total intensity I also increases in that direction. The few bursts having a pc sense reversal in the 5 to 9.4 GHz range also have a spectral maximum of I at roughly the same frequency. Some simplified explanations of the results are presented.