PPPL-4134

Self-organized T_e Redistribution during Driven Reconnection Processes in High Temperature Plasmas

Authors: H.K. Park, E. Mazzucato, N.C. Luhmann, Jr., C.W. Domier, Z. Xia, T. Munsat, A.J.H. Donné, I.G.J. Classen, M.J. van de Pol, and the TEXTOR team

Abstract:
Two-dimensional (2-D) images of electron temperature fluctuations with a high temporal and spatial resolution were employed to study the sawtooth oscillation in TEXTOR tokamak plasmas. The new findings are: 1) 2-D images revealed that the reconnection is localized and permitted the determination of the physical dimensions of the reconnection zone in the poloidal and toroidal planes. 2) The combination of a pressure driven mode and a kink instability leads to an "X-point" reconnection process. 3) Reconnection can take place anywhere along the q~1 rational magnetic surface (both high and low field sides). 4) Heat flow from the core to the outside of the inversion radius during the reconnection time is highly asymmetric and the behavior is collective. These new findings are compared with the characteristics of various theoretical models and experimental results for the study of the sawtooth oscillation in tokamak plasmas.