Experimental studies of zonal flow and turbulence

Abstract

There has been remarkable progress made in the research of structure formation by turbulence in nonequilibrium plasmas. One of the highlights has been the physics of zonal flow and drift wave turbulence in toroidal plasmas. Extensive theoretical as well as computational studies have revealed the various mechanisms in the system of turbulence and zonal flows, as highlighted in the recent review paper `Zonal flows in plasma—a review' by P H Diamond et al (2005 Plasma Phys. Control. Fusion} 47 R35).There has also been increasing research in experimental studies of zonal flows, geodesic acoustic modes, and the generation of global electric field by turbulence. In recognition of this a cluster Plasma Physics and Controlled Fusion occasionally publishes a small collection of articles on a specific topic. These special sections highlight a specific area of research that is of importance to the journal either as a new or growing research area. The subjects are selected by the Editorial Board and managed by a Guest Editor, Professor Itoh in this case. of 15 papers on `Experimental studies of zonal flow and turbulence' is presented in this issue of Plasma Physics and Controlled Fusion.Each paper in this special cluster describes the present research status and new scientific knowledge/results on the authors' machine involved, on the subject of experimental studies of zonal flows, electric field and nonlinear interactions with turbulence (including studies of Reynolds-Maxwell stresses, etc). Readers of, and contributors to, Plasma Physics and Controlled Fusion have been facing a new phase of plasma physics, with the expanding application of plasma physics to the explosive growth of our knowledge of the astronomical, space and laboratory plasmas, and the approach of ITER. The evolution of modern plasma physics into the new arena is backed up by extensive research as illustrated by this cluster of papers and review papers. We believe that this group of articles will stimulate further efforts to develop new knowledge into systematic understanding.