RADIO PHYSICS AND RADIO ASTRONOMY

Purpose: The subject of research is the spatio-temporal charged particles in the Earth’s magnetosphere outside the South Atlantic magnetic Anomaly during the 11-year cycle of solar activity minimum. The work aims at searching for and clarifying the sustained and unstable new spatial zones of enhanced subrelativistic electron fluxes at the altitudes of the low Earth orbit satellites.

Design/methodology/approach: Finding and ascertainment of new radiation belts of the Earth were made by using the data analysis from the D1e channel of recording the electrons of energies of ΔE_e=180–510 keV  and protons of energies of ΔE_p=3.5–3.7 MeV of the satellite telescope of electrons and protons (STEP-F) aboard the “CORONAS-Photon” Earth low-orbit satellite. For the analysis, the data array with the 2 s time resolution normalized onto the active area of the position-sensitive silicon matrix detector and onto the solid angle of view of the detector head of the instrument was used.

Findings: A sustained structure of three electron radiation belts in the Earth’s magnetosphere was found at the low solar and geomagnetic activity in May 2009. The two belts are known since the beginning of the space age as the Van Allen radiation belts, another additional permanent layer is formed around the drift shell with the McIlwaine parameter of L = 1.65±0.05. On some days in May 2009, the new two inner radiation belts were observed simultaneously, one of those latter being recorded between the investigated sustained belt at L≈1.65 and the Van Allen inner belt at L≈2.52. Increased particle fluxes in this unstable belt have been formed with the drift shell L≈2.06±0.14.

Conclusions: The new found inner radiation belts are recorded in a wide range of geographic longitudes λ, both at the ascending and descending nodes of the satellite orbit, from λ₁≈150° to λ₂≈290°. Separately in the Northern or in the Southern hemispheres, outside the outer edge of the outer radiation belt, at L≥7–8, there are cases of enhanced particle fl ux density in wide range of L-shells. These shells correspond to the high-latitude region of quasi-trapped energetic charged particles. Increased particle fluxes have been recorded up to the bow shock wave border of the Earth’s magnetosphere (L≈10-12).

Key words: radiation belt, STEP-F instrument, electrons, magnetosphere, drift L-shell, particle flux density

Manuscript submitted 23.07.2021

Radio phys. radio astron. 2021, 26(3): 224-238

REFERENCES

1. PAULIKAS, G. A., 1975. Precipitation of Particles at Low and Middle Latitudes. Rev. Geophys. vol. 13, is. 5, pp. 709‒734. DOI: https://doi.org/10.1029/RG013i005p00709

2. SIBECK, D. G., MCENTIRE, R. W., LUI, A. T. Y., LOPEZ, R. E., and KRIMIGIS, S. M., 1987. Magnetic field drift shell splitting: cause of unusual dayside particle pitch angle distributions during storms and substorms. J. Geophys. Res. Space Phys. vol. 92, is. A12, pp. 13485‒13497. DOI: https://doi.org/10.1029/JA092iA12p13485

3. TAKAHASHI, K., ANDERSON, B. J., OHTANI, S., REEVES, G. D., TAKAHASHI, S., SARRIS, T. E. and MURSULA, K., 1997. Drift-shell splitting of energetic ions injected at pseudo-substorm onsets. J. Geophys. Res. Space Phys. vol. 102, is. A10, pp. 22117‒22130. DOI: https://doi.org/10.1029/97JA01870

4. BLAKE, J. B., KOLASINSKI, W. A., FILLIUS, R. W. and MULLEN, E. G., 1992. Injection of electrons and protons with energies of tens of MeV into L<3 on 24 March 1991. Geophys. Res. Lett. vol. 19, is. 8, pp. 821‒824. DOI: https://doi.org/10.1029/92GL00624

5. LOOPER, M. D., BLAKE, J. B., MEWALDT, R. A., CUMMINGS, J. R. and BAKER, D. N., 1994. Observations of the remnants of the ultrarelativistic electrons injected by the strong SSC of 24 March 1991. Geophys. Res. Lett. vol. 21, is. 19, pp. 2079‒2082. DOI: DOI: https://doi.org/10.1029/94GL01586

6. REEVES, G. D., MCADAMS, K. L., FRIEDEL, R. H. W. and O’BRIEN, T. P., 2003. Acceleration and loss of relativistic electrons during geomagnetic storms. Geophys. Res. Lett. vol. 30, is. 10, pp. 36-1‒36-4. DOI: https://doi.org/10.1029/2002GL016513

7. VAMPOLA, A. L. and KUCK, G. A., 1978. Induced Precipitation of Inner Zone Electrons, 1. Observations. J. Geophys. Res. Space Phys. vol. 83, is. A6, pp. 2543‒2551. DOI: https://doi.org/10.1029/JA083iA06p02543

8. NAGATA, K., KOHNO, T., MURAKAMI, H., NAKAMOTO, A., HASEBE, N., TAKENAKA, T., KIKUCHI, J. and DOKE, J., 1985. OHZORA High Energy Particle Observations. J. Geomag. Geoelectr. vol. 37, is. 3, pp. 329‒345. DOI: https://doi.org/10.5636/jgg.37.329

9. NAGATA, K., KOHNO, T., MURAKAMI, H., NAKAMOTO, A., HASEBE, N., KIKUCHI, J. and DOKE, T., 1988. Electron (0.19-3.2 MeV) and proton (0.58-35 MeV) precipitations observed by OHZORA satellite at low latitude zones L=1.6‒1.8. Planet. Space Sci. vol. 36, is. 6, pp. 591‒606. DOI: https://doi.org/10.1016/0032-0633(88)90028-1

10. GUSSENHOVEN, M. S., MULLEN, E. G. and BRAUTIGAM, D. H., 1996. Improved understanding of the Earth's radiation belts from the CRRES satellite. IEEE Trans. Nucl. Sci. vol. 43, is. 2, pp. 353‑368. DOI: https://doi.org/10.1109/23.490755

11. DUDNIK, A. V., PERSIKOV, V. K., ZALYUBOVSKY, I. I., TIMAKOVA, T. G., KURBATOV, E. V., KOTOV YU. D. and YUROV, V. N., 2011. High-sensitivity STEP-F spectrometer–telescope for high-energy particles of the CORONAS-PHOTON satellite experiment. Sol. Sys. Res. vol. 45, is. 3, pp. 212‒220. DOI: https://doi.org/10.1134/S0038094611020043

12. DUDNIK, O. V., 2017. Satellite telescope of electrons and protons STEP-F of the space scientific project CORONAS-PHOTON. Visn. Nac. Acad. Nauk of Ukr. no. 11, pp. 53–265. (in Ukrainian). DOI: https://doi.org/10.15407/visn2017.11.053

13. DUDNIK, O. V., SYLWESTER, J., KOWALIŃSKI, M. and BARYLAK, J., 2019. Utilization of design features of the particle telescope STEP-F and solar x-ray spectrophotometer SphinX for exploration of the Earth’s radiation belt properties. Proc. SPIE. vol. 11176 “Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments”. id. 111763L. DOI: https://doi.org/10.1117/12.2537296

14. DUDNIK, O. V., 2010. Investigation of the Earth’s radiation belts in May, 2009, at the low orbit satellite with the STEP-F instrument. Kosm. Nauka Tehnol. vol. 16, no. 5, pp. 12–28. (in Russian). DOI: https://doi.org/10.15407/knit2010.05.012

15. DUDNIK, O. V., PODGORSKI, P., SYLWESTER, J., GBUREK, S., KOWALINSKI, M., SIARKOWSKI, M., PLOCIENIAK, S. and BAKALA, J., 2012. X-Ray Spectrophotometer SphinX and Particle Spectrometer STEP-F of the Satellite Experiment CORONAS-PHOTON. Preliminary Results of the Joint Data Analysis. Sol. Sys. Res. vol. 46, is. 2, pp. 160‒169. DOI: https://doi.org/10.1134/S0038094612020025