The solar wind density spectrum near the Sun: Results from Voyager radio measurements

摘要: Spacecraft radio propagation data are analyzed to estimate the solar wind density fluctuation power spectrum across five decades of spatial wave number. The were from science observations made during superior conjunctions Voyager 1 and 2 spacecrafts in 1979 1980. These yield structure function, a statistic which is related to, but obtained more readily than, itself. Structure functions total 28 spanning heliocentric distance range 7-22 R{sub S}. Each function was composite two shorter segments estimated, respectively, phase scintillation spectral broadening analyses. tend be steep (approximately Kolmogorov) at large scales (10{sup 3}-10{sup 6} km) nearly always show some flattening smaller (10-100 km). inflection between flatter regions abrupt occurs 100-300 km. Most also turnover very smallest scales. results excellent agreement with shape model proposed by Coles Harmon (1989). A few transients seen characterized an overall increase powermore » steeping small similar appearance reported earlier Arecibo observations.« less