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Non-diffusive transport: Difference between revisions
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This could cause the waiting time distribution to become non-exponential; and thus the motion would be non-Markovian. Likewise, the phenomenon of ''streamers'', appearing in many models of plasma turbulence, could carry particles across long distances in the radial direction, and the distribution of particle steps could then also be deformed and develop ''long tails''. Consequently, the transport would then be non-local. Nobody knows exactly how important these phenomena are in the global transport picture. | This could cause the waiting time distribution to become non-exponential; and thus the motion would be non-Markovian. Likewise, the phenomenon of ''streamers'', appearing in many models of plasma turbulence, could carry particles across long distances in the radial direction, and the distribution of particle steps could then also be deformed and develop ''long tails''. Consequently, the transport would then be non-local. Nobody knows exactly how important these phenomena are in the global transport picture. | ||
Whatever the case, a well-established methodology exists to describe this deviation from standard diffusive transport (with characteristic scales): the Continuous Time Random Walk (CTRW) model. | Whatever the case, a well-established methodology exists to describe this deviation from standard diffusive transport (with characteristic scales): the [[Continuous Time Random Walk]] (CTRW) model. | ||
<ref>[http://books.google.es/books?id=Yaupom_qdKIC&lpg=PP1&ots=WmaABP3l92&dq=%22Balescu%22%20%22Aspects%20of%20anomalous%20transport%20in%20plasmas%22%20&lr=&pg=PP1 R. Balescu, Aspects of anomalous transport in plasmas, IOP Publishing (2005)]</ref> | <ref>[http://books.google.es/books?id=Yaupom_qdKIC&lpg=PP1&ots=WmaABP3l92&dq=%22Balescu%22%20%22Aspects%20of%20anomalous%20transport%20in%20plasmas%22%20&lr=&pg=PP1 R. Balescu, Aspects of anomalous transport in plasmas, IOP Publishing (2005)]</ref> | ||
The CTRW model provides a mathematical framework for handling non-diffusive transport (arising as as generalisation of the diffusive transport when eliminating the stated characteristic scales), but it does not explain why such non-diffusive transport should arise: answering the latter requires detailed computer simulations of turbulence and experimental observations. | The CTRW model provides a mathematical framework for handling non-diffusive transport (arising as as generalisation of the diffusive transport when eliminating the stated characteristic scales), but it does not explain why such non-diffusive transport should arise: answering the latter requires detailed computer simulations of turbulence and experimental observations. | ||