Cosmic-Ray Modulation: an Ab Initio Approach
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| Natura: | Artículo científico |
| Lingua: | en |
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Sociedade Brasileira de Física
2014
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| _version_ | 1876444991726813184 |
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| author | N. E. Engelbrecht |
| author_facet | N. E. Engelbrecht |
| contents | Cosmic-Ray Modulation: an Ab Initio Approach N. E. Engelbrecht R. A. Burger Física, Astronomía y Matemáticas Drift Cosmic Diffusion Turbulence ray modulation A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model for cosmic-ray modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. This model is solved for periods of minimum solar activity, utilizing boundary values chosen so that model results are in fair to good agreement with spacecraft observations of turbulence quantities, not only in the solar ecliptic plane but also along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modelled slab and 2D turbulence energy spectra. The latter spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers commencing at the 2D outerscale. There currently exist no models or observations for this quantity, and it is the only free parameter in this study. The modelled turbulence spectra are used as inputs for parallel mean free path expressions based on those derived from quasi-linear theory and perpendicular mean free paths from extended nonlinear guiding center theory. Furthermore, the effects of turbulence on cosmic-ray drifts are modell ed in a self-consistent way, employing a recently developed model for drift along the wavy current sheet. The resulting diffusion coefficients and drift expressions are applied to the study of galactic cosmic-ray protons and antiprotons using a three-dimensional, steady-state cosmic-ray modulation code, and sample solutions in fair agreement with multiple spacecraft observations are presented. 2014 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46432476009 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.5 Vol.44 |
| format | Artículo científico |
| id | redalyc_46432476009 |
| institution | Redalyc |
| language | en |
| publishDate | 2014 |
| publisher | Sociedade Brasileira de Física |
| spellingShingle | Cosmic-Ray Modulation: an Ab Initio Approach N. E. Engelbrecht Física, Astronomía y Matemáticas Drift Cosmic Diffusion Turbulence ray modulation Cosmic-Ray Modulation: an Ab Initio Approach N. E. Engelbrecht R. A. Burger Física, Astronomía y Matemáticas Drift Cosmic Diffusion Turbulence ray modulation A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model for cosmic-ray modulation, incorporating for the first time the results yielded by a two-component turbulence transport model. This model is solved for periods of minimum solar activity, utilizing boundary values chosen so that model results are in fair to good agreement with spacecraft observations of turbulence quantities, not only in the solar ecliptic plane but also along the out-of-ecliptic trajectory of the Ulysses spacecraft. These results are employed as inputs for modelled slab and 2D turbulence energy spectra. The latter spectrum is chosen based on physical considerations, with a drop-off at the very lowest wavenumbers commencing at the 2D outerscale. There currently exist no models or observations for this quantity, and it is the only free parameter in this study. The modelled turbulence spectra are used as inputs for parallel mean free path expressions based on those derived from quasi-linear theory and perpendicular mean free paths from extended nonlinear guiding center theory. Furthermore, the effects of turbulence on cosmic-ray drifts are modell ed in a self-consistent way, employing a recently developed model for drift along the wavy current sheet. The resulting diffusion coefficients and drift expressions are applied to the study of galactic cosmic-ray protons and antiprotons using a three-dimensional, steady-state cosmic-ray modulation code, and sample solutions in fair agreement with multiple spacecraft observations are presented. 2014 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46432476009 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.5 Vol.44 |
| title | Cosmic-Ray Modulation: an Ab Initio Approach |
| topic | Física, Astronomía y Matemáticas Drift Cosmic Diffusion Turbulence ray modulation |
| url | https://www.redalyc.org/articulo.oa?id=46432476009 |