### Abstract

Anomalous diffusion of energetic charged particles (cosmic rays) is studied using a simple two-dimensional cross field diffusion model. Both super-diffusion and sub-diffusion can take place in the model. When typical Larmor radius of the particles is much less than the field correlation length, the particles essentially gradient-B drift along equi-contour lines of the magnetic field strength, and thus the diffusion in this parameter regime can essentially be understood by analyzing statistics of the magnetic field islands composed of these equi-contour lines. We numerically evaluate the statistics of the field islands such as the probability distribution function of island radius and fractal dimension of the island contour lines, as functions of the power-law index of the magnetic field turbulence. We find numerically and analytically the scaling laws of time-scale dependent diffusion coefficients using the parameters obtained by analysis of the field islands statistics.

Original language | English |
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Pages (from-to) | 204-211 |

Number of pages | 8 |

Journal | Progress of Theoretical Physics Supplement |

Volume | 162 |

DOIs | |

Publication status | Published - Aug 18 2006 |

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### All Science Journal Classification (ASJC) codes

- Physics and Astronomy (miscellaneous)

### Cite this

**Anomalous diffusion of cosmic rays in magnetic field turbulence - Linkage between diffusion statistics and turbulence statistics.** / Otsuka, Fumiko; Hada, Tohru.

Research output: Contribution to journal › Article

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TY - JOUR

T1 - Anomalous diffusion of cosmic rays in magnetic field turbulence - Linkage between diffusion statistics and turbulence statistics

AU - Otsuka, Fumiko

AU - Hada, Tohru

PY - 2006/8/18

Y1 - 2006/8/18

N2 - Anomalous diffusion of energetic charged particles (cosmic rays) is studied using a simple two-dimensional cross field diffusion model. Both super-diffusion and sub-diffusion can take place in the model. When typical Larmor radius of the particles is much less than the field correlation length, the particles essentially gradient-B drift along equi-contour lines of the magnetic field strength, and thus the diffusion in this parameter regime can essentially be understood by analyzing statistics of the magnetic field islands composed of these equi-contour lines. We numerically evaluate the statistics of the field islands such as the probability distribution function of island radius and fractal dimension of the island contour lines, as functions of the power-law index of the magnetic field turbulence. We find numerically and analytically the scaling laws of time-scale dependent diffusion coefficients using the parameters obtained by analysis of the field islands statistics.

AB - Anomalous diffusion of energetic charged particles (cosmic rays) is studied using a simple two-dimensional cross field diffusion model. Both super-diffusion and sub-diffusion can take place in the model. When typical Larmor radius of the particles is much less than the field correlation length, the particles essentially gradient-B drift along equi-contour lines of the magnetic field strength, and thus the diffusion in this parameter regime can essentially be understood by analyzing statistics of the magnetic field islands composed of these equi-contour lines. We numerically evaluate the statistics of the field islands such as the probability distribution function of island radius and fractal dimension of the island contour lines, as functions of the power-law index of the magnetic field turbulence. We find numerically and analytically the scaling laws of time-scale dependent diffusion coefficients using the parameters obtained by analysis of the field islands statistics.

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U2 - 10.1143/PTPS.162.204

DO - 10.1143/PTPS.162.204

M3 - Article

AN - SCOPUS:33747136647

VL - 162

SP - 204

EP - 211

JO - Progress of Theoretical Physics

JF - Progress of Theoretical Physics

SN - 0033-068X

ER -