ELECTROSTATIC FLUCTUATIONS AND RELATED TRANSPORT IN THE EDGE AND COREPLASMA OF THE KEDA TOKAMAK-5C

Using the swept double probe and triple probe technique, temperature, density and potential fluctuations have been measured in both the plas ma edge and core of the Keda Tokamak-5C (KT-5C) [World Survey of Activ ities in Controlled Fusion Research, Nuclear Fusion Special Supplement (International Atomic Energy Agency, Vienna, 1991), p. 190]. The fluc tuation-driven particle and energy fluxes were also estimated from the correlations of [(n) over tilde(e) (E) over tilde(theta)] and [(T) ov er tilde(e) (E) over tilde(theta)]. Evidence has been found that there exist substantial electron temperature fluctuations of (T) over tilde (e)/T-e similar or equal to 0.4 (n) over tilde(e)/n(e) in both regions . At the edge of KT-5C, many of the fluctuation features, such as the velocity shear stabilization of turbulence, the non-Boltzmann relation and the role of fluctuations in the edge confinement, are very simila r to those obtained from other tokamaks. In the plasma interior, the f luctuations do obey the simple Boltzmann relationship and the profiles of the normalized fluctuating levels (n) over tilde(e)/n(e) and <(phi )over tilde>/T-e vary roughly as (n) over tilde(e)/n(e) proportional t o n(e)(-3/2) and <(phi)over tilde>(p)/T-e proportional to n(e)(-1/2)T( e)(-1), respectively. In addition, a spiky, radially intermittent stru cture in the particle and energy fluxes with large levels at the low-q resonances and lower levels in between was found. The experimental re sults provide some new evidence, particularly in the plasma core, for a better understanding of the basic mechanism of turbulence. (C) 1996 American Institute of Physics.