A computational study of nonresonant cross-field diffusion of energetic particles due to their interaction with interplanetary magnetic decreases |
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| Authors: | E. Costa E. Echer M.V. Alves B.T. Tsurutani F.J.R. Simões F.R. Cardoso G.S. Lakhina |
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| Affiliation: | 1. Instituto Nacional de Pesquisas Espaciais—INPE, P.O. Box 515, 12227-010 S. J. dos Campos, SP, Brazil;2. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States;3. Indian Institute of Geomagnetism, Navi Mumbai, India;4. Instituto Federal de Minas Gerais – IFMG – Campus Ouro Preto. Rua Pandiá Calógeras, 898, Ouro Preto - MG, 35400-000, Brazil;1. School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand;2. Indian Institute of Geomagnetism, Navi Mumbai, Mumbai, India;3. National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan;4. Department of Electronics and Telecommunication Engineering, Faculty of Engineering, National University of Laos, Vientiane 3166, Laos;1. Dept. of Physics, Manonmaniam Sundaranar University, Tirunelveli, Tamilnadu, India;2. Equatorial Geophysical Research Laboratory, Tirunelveli, Tamilnadu, India;1. Laboratorio de Meteorología espacial, Atmósfera terrestre, Geodesia, Geodinámica, diseño de Instrumental y Astrometría (MAGGIA), Facultad de Ciencias Astronómicas y Geofísicas (FCAG), Universidad Nacional de La Plata (UNLP), Paseo del Bosque s/n, B1900FWA, La Plata, Argentina;2. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina;3. Instituto de Astrofísica de La Plata (UNLP - CONICET), La Plata, Argentina;4. Observatorio Geofísico Trelew, Trelew, Chubut, Argentina |
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| Abstract: | We present a new method of calculating cross-field diffusion of charged particles due to their interactions with interplanetary magnetic decreases (MDs) in high heliospheric latitudes. We use a geometric model that evaluates perpendicular diffusion to the ambient magnetic field as a function of particle's gyroradius, MD radius, ratio between fields outside and inside the MD, and a random impact parameter. We use Ulysses magnetic field data of 1994 to identify the MDs and get the empirical size and magnetic field decrease distribution functions. We let protons with energies ranging from 100 keV to 2 MeV interact with MDs. The MD characteristics are taken from the observational distribution functions using the Monte Carlo method. Calculations show that the increase in diffusion tends to saturate when particles' gyroradius becomes as large as MD radii, and that particles' gyroradius increases faster than diffusion distance as the energy of the particles is increased. |
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