Ion isotropy and ion resonant waves in the solar wind: Corrected Cassini observations

In an earlier paper [Kellogg et al., 2001], observations of electric field fluctuations in the range 0.5 to 25 Hz were reported. We have recently found that the data presented in that paper are seriously contaminated by broadband interference which appears to be generated in the spacecraft wake. Wake instabilities have been found by others, but the plasma conditions are quite different from those of any other observations of wake instabilities of which we are aware. In this paper, some characteristics of the wake interference are investigated, and an attempt is made to find conditions when it is not present. We believe that we have done this successfully and present a new spectrum and characteristics for electric field fluctuations in the solar wind. However, essentially no uncontaminated data were obtained nearer the Sun than 4.5 AU, and so the new results pertain only to the outer region. In the outer heliosphere the conditions are expected to be sufficiently different (large plasma beta) that the results may not pertain to the inner heliosphere.