Radial dependence of the level of amplitude fluctuations of spacecraft radio signals probing circumsolar plasma
| Autor: | A. I. Efimov, Michael K. Bird, Neon A Armand, L. A. Lukanina, Dirk Plettemeier, I. V. Chashei, L. N. Samoznaev |
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| Rok vydání: | 2008 |
| Předmět: |
Physics
Photosphere Scintillation Spectral index Radiation Spacecraft business.industry Solar radius Astrophysics Plasma Condensed Matter Physics Electronic Optical and Magnetic Materials Amplitude Physics::Space Physics Exponent Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Electrical and Electronic Engineering business |
| Zdroj: | Journal of Communications Technology and Electronics. 53:1186-1194 |
| ISSN: | 1555-6557 1064-2269 |
| DOI: | 10.1134/s1064226908100057 |
| Popis: | The statistical characteristics of amplitude fluctuations of radio signals propagating through cir- cumsolar plasma at various distances from the Sun are investigated during various phases of solar activity. Pri- mary data obtained in large-scale series of radio-probing sessions are systemized. During these sessions, cir- cumsolar plasma was probed with signals from spacecraft launched by Russia and other countries. It is found that the dependences of the relative level of amplitude fluctuations (scintillation index) on the solar-offset dis- tance of a radio beam can be approximated with power functions with exponents depending on the heliocentric distance. When the distance between a probed region and the photosphere is large, this exponent is close to the value 1.5. As the Sun is approached, the exponent grows to a value of 1.8-2.05 reached at a heliocentric distance of about four solar radii. The scintillation index is calculated theoretically with allowance for the radial depen- dence of turbulence characteristics, such as the spectral index and outer scale. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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