De. Newman et al., THE DYNAMICS OF MARGINALITY AND SELF-ORGANIZED CRITICALITY AS A PARADIGM TURBULENT TRANSPORT, Physics of plasmas, 3(5), 1996, pp. 1858-1866
A general paradigm, based on the concept of self-organized criticality
(SOC), for turbulent transport in magnetically confined plasmas, has
been recently suggested as an explanation for some of the apparent dis
crepancies between most theoretical models of turbulent transport and
experimental observations of the transport in magnetically confined pl
asmas. This model describes the dynamics of the transport without rely
ing on the underlying local fluctuation mechanisms. Computations based
on a cellular automata realization of such a model have found that no
ise-driven SOC systems can maintain average profiles that are linearly
stable (submarginal) and yet are able to sustain active transport dyn
amics. It is also found that the dominant scales in the transport dyna
mics in the absence of sheared flaw are system scales rather than the
underlying local fluctuation scales. The addition of sheared flow into
the dynamics leads to a large reduction of the system-scale transport
events and a commensurate increase in the fluctuation-scale transport
events needed to maintain the constant flux. The dynamics of these mo
dels and the potential ramifications for transport studies are discuss
ed. (C) 1996 American Institute of Physics.