Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft

Details Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft

Jun 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995sowi.conf...29a&link_type=abstract

Academy of Sciences (USSR), International Solar Wind 8 Conference, p. 29

Computer Science

Faraday Effect, Polarization (Waves), Solar Radiation, Solar Wind, Helios Satellites, Radio Occultation, Solar Magnetic Field, Magnetohydrodynamic Waves, Wave Propagation, Linear Polarization, Radio Waves

Scientific paper

Faraday rotation (FR) measurements using linearly polarized radio signals from the two Helios spacecraft were carried out during the period from 1975 to 1984. This paper presents the results of a spectral analysis of the Helios S-band FR fluctuations observed at heliocentric distances from 2.6 to 15 solar radii during the superior conjunctions 1975-1983. The mean intensity of the FR fluctuations does not exceed the noise level for solar offsets greater than ca. 15 solar radii. The rms FR fluctuation amplitude increases rapidly as the radio ray path approaches the Sun, varying according to a power law (exponent: 2.85 +/- 0.15) at solar distances 4-12 solar radii. At distances inside 4 solar radii the increase is even steeper (exponent: 5.6 +/- 0.2). The equivalent two-dimensional FR fluctuation spectrum is well modeled by a single power-law over the frequency range from 5 to 50 mHz. For heliocentric distances larger than 4 solar radii the spectral index varies between 1.1 and 1.6 with a mean value of 1.4 +/- 0.2, corresponding to a 3-D spectral index p = 2.4. FR fluctuations thus display a somewhat lower spectral index compared with phase and amplitude fluctuations. Surprisingly high values of the spectral index were found for measurements inside 4 solar radii (p = 2.9 +/- 0.2). This may arise from the increasingly dominant effect of the magnetic field on radio wave propagation at small solar offsets. Finally, a quasiperiodic component, believed to be associated with Alfven waves, was discovered in some (but not all!) fluctuation spectra observed simultaneously at two ground stations. Characteristic periods and bulk velocities of this component were 240 +/- 30 sec and 300 +/- 60 km/s, respectively.

Affiliated with

Also associated with

No associations

Rating

Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Faraday rotation fluctutation spectra observed during solar occultation of the HELIOS spacecraft will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-759746