Solar wind electron parameters from quasi‐thermal noise spectroscopy and comparison with other measurements on Ulysses

Abstract

Plasma thermal noise spectroscopy was used for the first time on a large scale on the Ulysses radio receiver data to measure the solar wind electron density and temperature in the ecliptic plane. The validity and limitations of the results obtained with this method are discussed. Nearly simultaneous measurements of the electron density and temperature from the radio receiver, the sounder, and the electron analyzer on Ulysses are intercompared. The thermal noise measurements are found to compare quite well with the other measurements, apart from some discrepancies, which are discussed. The uncertainties on the core temperature, derived from a least squares model fitting of the radio data, are shown to be statistically consistent and significant.