Experimental results on the role of zonal flows and geodesic acoustic modes in formation of transport barriers in the H-1
heliac are reviewed.
PACS 52.25.Fi - 52.35.Ra
Key words zonal flow - transport barrier - H mode - pedestal
Presented at the Workshop “Electric Fields, Structures and Relaxation in Edge Plasmas”, Roma, Italy, June 26–27, 2006.