Electron Thermal Transport in NSTX and Tore Supra
We perform transport analysis of Tore Supra (TS) and NSTX discharges with centrally deposited fast wave electron heating, to derive the electron thermal fluxes from power balance. Measurements of the electron temperature and density profiles, combined with ray tracing computation of the power deposition, allow detailed interpretation of the thermal flux versus temperature gradient. We find evidence supporting the electron temperature gradient (ETG) turbulent transport in the two confinement devices. Evidence for this mechanism includes: (1) a consistent scaling in density and temperature both in the profiles and radial heat flux, (2) clear analytical and fundamental thermodynamic origin for the critical temperature gradient and its dependence on magnetic shear, (3) insensitivity of the turbulence to the mixture of trapped and passing electrons, (4) self-consistency turbulent generation of a magnetic flutter component from the parallel electron currents, and (5) goog agreement between the thermal flux formulas used in radial transport codes with auxiliary heating and the profiles measured both in radius and time. Finally, we describe how internal transport barriers created in certain TS and NSTX discharges may be examples of a universal feature of transport equations in the presence of a (partially broken) invariant curve that is generic to nonmonotonic rotational transforms in dynamical systems. Weakly reversed magnetic shear discharges in NSTX show improved confinement in L-mode discharges.
Bibliographic Reference: An oral paper given at: 20th IAEA Fusion Energy Conference Organised by: International Atomic Energy Agency Held at: Centrtro de Fusao Nuclear, Vilamoura (PT)
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: email@example.com
Record Number: 200517933 / Last updated on: 2005-02-24
Original language: en
Available languages: en