Unified Radio and Plasma Wave Investigation

The scientific objectives of the Ulysses Unified Radio and Plasma wave (URAP) experiment are twofold: l) the determination of the direction, angular size, and polarization of radio sources for remote sensing of the heliosphere and the Jovian magnetosphere and 2) the detailed study of local wave phenomena, which determine the transport coefficients of the ambient plasma. The tracking of solar radio bursts, for example, can provide three dimensional "snapshots" of the large scale magnetic field configuration along which the solar exciter particles propagate. URAP observations of Jovian radio emissions should greatly improve the determination of source locations and consequently our understanding of the generation mechanism(s) of planetary radio emissions. The study of observed wave-particle interactions will improve our understanding of the processes that occur in the solar wind and at Jupiter and of radio wave generation. A brief discussion of the scientific goals of the experiment is followed by a comprehensive description of the instrument. The URAP sensors consist of a 72.5 m electric field antenna in the spin plane, a 7.5-m electric field monopole along the spin axis and a pair of orthogonal search coil magnetic antennas. The various receivers, designed to encompass specific needs of the investigation, cover the frequency range from DC to l MHz. A relaxation sounder provides very accurate electron density measurements. Radio and plasma wave observations are shown to demonstrate the capabilities and limitations of the URAP instruments: radio observations include solar bursts, auroral kilometric radiation, and Jovian bursts; plasma waves include Langmuir waves, ion acoustic-like noise and whistlers.

(Abstract from: R.G. Stone et al., Astron. Astrophys. Suppl. Ser. 92, 291-316, 1992)

URAP (Unified Radio And Plasma Wave Experiment) plasma wave experiment Home Page at the Goddard Space Flight Center

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