Complexity, forced and/or self-organized criticality, and topological phase transitions in space plasmas

Tom Chang, Sunny W.Y. Tam, Cheng Chin Wu, Giuseppe Consolini

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


The first definitive observation that provided convincing evidence indicating certain turbulent space plasma processes are in states of 'complexity' was the discovery of the apparent power-law probability distribution of solar flare intensities. Recent statistical studies of complexity in space plasmas came from the AE index, UVI auroral imagery, and in-situ measurements related to the dynamics of the plasma sheet in the Earth's magnetotail and the auroral zone. In this review, we describe a theory of dynamical 'complexity' for space plasma systems far from equilibrium. We demonstrate that the sporadic and localized interactions of magnetic coherent structures are the origin of 'complexity' in space plasmas. Such interactions generate the anomalous diffusion, transport, acceleration, and evolution of the macroscopic states of the overall dynamical systems. Several illustrative examples are considered. These include: the dynamical multi- and cross-scale interactions of the macro-and kinetic coherent structures in a sheared magnetic field geometry, the preferential acceleration of the bursty bulk flows in the plasma sheet, and the onset of 'fluctuation induced nonlinear instabilities' that can lead to magnetic reconfigurations. The technique of dynamical renormalization group is introduced and applied to the study of two-dimensional intermittent MHD fluctuations and an analogous modified forest-fire model exhibiting forced and/or self-organized criticality [FSOC] and other types of topological phase transitions.

Original languageEnglish
Pages (from-to)425-445
Number of pages21
JournalSpace Science Reviews
Issue number1-2
Publication statusPublished - 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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